TX 557 .04 Copy 1 Cfjc UniUersfitp of Cfjicaso CHANGES IN FOOD VALUE OF VEGETABLES DUE TO COOKING A DISSERTATION SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF ARTS AND LITERATURE IN CANDIDACY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF HOUSEHOLD ADMINISTRATION BY MINNA CAROLINE DENTON Private Edition, Distributed By THE UNIVERSITY OF CHICAGO LIBRARIES CHICAGO, ILLINOIS Reprinted from Journal of Home Economics, Vol. XI, No. 4 April, 1919 •«(■ ®fje ^anibergttp of Chicago CHANGES IN FOOD VALUE OF VEGETABLES DUE TO COOKING A DISSERTATION SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF ARTS AND LITERATURE m CANDIDACy FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF HOUSEHOLD ADMINISTRATION BV MINNA CAROLINE DENTON Private Edition, Distributed By THE UNIVERSITY OF CHICAGO LIBRARIES CHICAGO, rLLTNOIS Reprinted from Journal of Home Economics, Vol. XI, No. 4 April, 1919 MAY 2Q I9» Reprinted from Thb Journal of Home Economics, Vol. XI, No. 4, April, 1919 CHANGES IN FOOD VALUE OF VEGETABLES DUE TO COOKING* Effect of Varying Household Manipulations minna c. denton i. introduction Recent progress in nutrition is emphasizing heavily the inadequacies of a diet with a preponderance of cereal products and vegetable fats — our cheapest sources of protein and calories — at the same time that food scarcity puts some of their most effective supplements, such as eggs, milk, meat, and animal fats, very nearly out of the reach of all except the well-to-do classes. It seems that many of the fresh vegetables and fruits have some value, in several respects, as supplements to inadequate diets of certain types. But at most seasons of the year these, too, are considered to be out of reach of the limited purse, with a few exceptions, prominent among which are vegetables which may be canned in time of plenty, and the "winter vegetables." If these local products are to be more largely used in the diet, both as supplements to the cereals and meats and as substitutes for them, an extended knowledge of their value with regard to various dietary factors is desirable. This study is concerned with the factors which are usually the first ones to be determined — their fuel values and ash content^ — these being determined from the vegetables as served to us at the table, after household manipulation, possibly also after commercial manipulation, as in the case of canned foods. With the exception of potatoes, the winter vegetables are mostly strong-juiced or highly flavored, and their flavors do not commend themselves to all persons, particularly often not to those of highly dis- criminating or of irritable nervous organizations, unless the flavor can be somewhat modified. Partly for this reason and partly for purposes of convenience, the methods very generally employed in cooking and in canning them have involved the use of a greater or less excess of water, which has considerable extractive power at the temperatures employed. * This paper was presented as part fulfillment of the requirements for the degree of Ph.D. in Household Administration, University of Chicago, August, 1918. 1 2 THE JOURNAL OF HOME ECONOMICS [April Food conservationists are urging that these vegetable foods should be baked, or steamed, or boiled in their jackets, or that the vegetable stock should be utilized; yet practical objections, such as those in the following list, continue to be urged upon some occasions. 1. It is apparent that neither cabbage heads nor large root stalks can be boiled whole, — ^their size forbidding this possibility. 2. Chlorophyl-bearing tissue usually turns more or less brown when steamed, though boiling water (even distilled, but especially when" hard" or when salted or made alkaline with soda) satisfactorily "sets" the green color of cabbage, cauliflower, Brussels sprouts, peas, string beans, and the yellow color of blanched celery. If the cooking be not too long continued, this green color is satisfactorily retained in boiled vegetables. 3. The steamed product is dryer and less water-logged than the boiled, and of different texture; it has of course no flavor of added salt, and yet (steamed at 90° to 100°C.) it may retain its characteristic odor and taste more strongly than does the boiled vegetable. The consequence is that the uninitiated frequently pronounce steamed cabbage both rank and insipid, also "not done." 4. The washing of spinach or greens which have been transported for long distances "packed in mud" (cracked ice) is a tedious process and often more or less of a failure, even when a good deal of pains has been taken. Under these circumstances it is a great help to boil in excess of water and skim out the greens when done, because thus the remaining sand and grit fall to the bottom of the kettle, instead of sticking to the leaves, as is the case with the steamed product. 5. The strong taste of condensed spinach juice, such as is produced by cooking the leaves in a very small amount of water, proves objectionable to many persons, including children not old enough to express them- selves verbally upon the subject. 6. Baking is desirable, yet often impracticable for various reasons, among which are the expense of fuel, and the overheating of the kitchen from the oven. 7. Home and commercial canning methods alike usually call for a pre- liminary "blanching" process which is advisable for various reasons; yet this period of boiling in excess of water, which apparently is never utilized to advantage, seems inconsistent with our customary efforts to "save the juice." (This objection does not apply to the steam blanch or to blanching in skins.) 1919] CHANGES IN FOOD VALUE OF VEGETABLES 3 8. The vegetable canned in excess of water at high temperature, as arc some of the commercially prepared products, may well lose a large part of its nutrient values of various sorts to the "juice" drained off when the can is opened; yet this juice, especially when excessive in amount, is often not palatable, and is feared by some because of its pos- sible content in tin, lead, or iron salts derived from a metal container, 9. The cook often finds it a convenience to pare vegetables and cut them ready for serving, early in her preparation of the meal. She does not wish to add peeling of potatoes or carrots to the list of things which must be done in the busy period just before the meal is served when the biscuits are to be baked and the coffee to be put over, the gravy to be made, and the salad to be dressed. She therefore objects to cooking vegetables in their skins. 10. The use of a large rather than a small amount of water with vege- tables shortens the period of their cooking to such an extent that the average home cook often prefers to use an excess of water rather than barely water to cover. Thus it would appear that a single generalization does not suffice to dispose of all cases, but that the cooking of each vegetable is a question to be decided on its own merits, if the conservation of nutritive value is to be combined with maximum palatability and practical convenience. Other questions which occur to the dietitian who compares the cooked vegetable with the raw, are such as these: After careful consideration of the details of every-day practice to be observed all about us, how are we to estimate the dietetic value of vegetables cooked in diverse ways? Shall we in computing or planning dietaries, assign to the cooked vege- table 90 per cent or 75 per cent or 50 per cent of the caloric value of the edible portion of raw vegetables? What is the proportionate loss sus- tained by vegetables which have been "blanched" in excess of unsalted boiling water, as practiced in some canning processes; by vegetables covered with water and cooked in quart jars in batli of boiling water for two and three hours, as recommended for home canning? Does the vege- table with high content of soluble carbohydrate lose proportionately more than that with lower content? Does the root stalk cut into large pieces suffer considerable loss? Do uncut vegetables which present a large amount of exposed cuticle (leguminous seeds, leaf greens, fleshy buds and flowerets as loose-leaved cabbage and cauliflower) suffer con- siderable loss from the extractive effect of boihng water? Are the losses from steaming at 90° to 100°C. (efficient home steamer) negligible; are 4 THE JOURNAL OF HOME ECONOMICS [April those from direct exposure to steam at 100° to 120°C. (institutional cooker) also negligible? Does the addition of salt to the cooking water, in small amounts (1.5 per cent solution at beginning of process) increase or diminish the cooking loss? Does the loss diminish if section- ing be done longitudinally (parallel with the fibro-vascular bundles) rather than crosswise (across them, exposing their cut ends at both surfaces of each slice to the solvent action of water)? II. REVIEW OF LITERATURE ON LOSSES IN COOKING VEGETABLES Most of the work done on losses of cooked vegetables is concerned chiefly with mineral constituents. In many cases very few details as to method of cooking are given, which makes it difficult to compare results of different investigators. Wagner and Schaefer^ reported finding that potatoes steamed in their skins lost 1.17 per cent of their crude ash, 0.69 per cent of their potas- sium, 0.03 per cent of their phosphorus. Steamed after paring, these losses were 7.28 per cent, 6.93 per cent, and 4.57 per cent, respectively. Boiled in their skins, they lost 3.64 per cent of their crude ash, 3.32 per cent of their potassium, 1.12 per cent of their phosphorus; boiled after peeling, 28.86 per cent, 38.33 per cent, and 22.87 per cent, re- spectively. 1 kgm. of spinach lost 8.578 grams of dry matter (1.684 gram N, 3.375 grams of ash); 1 kgm. of carrot tops, chopped, lost 15.252 grams dry matter (3.312 grams N, 6.331 grams ash). Average losses in boihng were 9 to 18 per cent of the total soluble matter found in the unboiled vegetable food. Snyder, Frisby, and Bryan t^ found that potatoes when pared, soaked 3 to 5 hours, and put over to cook in cold distilled water, lost 46 to 58 per cent of their total nitrogen (about one-half of which is in the fomi of protein), 25 per cent of their protein, and 38 per cent of their mineral salts. When pared, put into either hot or cold distilled water, and cooked at once, the losses were half these amounts or less; when cooked in skins, the nitrogen loss was 1 per cent, the protein loss 0.5 per cent, the mineral loss 3.3 per cent. Frisby and Bryant, in another experiment, found that pared potatoes, put into cold distilled water and cooked, lost 9.2 per cent of their nitrogen, 2.7 per cent of their carbohydrate, 1 Sachs, Landw. Ztschr., vol. 33, p. 369, 1885. (Abstr. in Jahresh. f. Agrikidtur. Chem., N. F. 8, vol. 28, p. 443, 1885.) 2 BuU. 43, Office of Exp. Sta., U. S. Dept. Agr., 1897. ^^19] CHANGES IN FOOD VALUE OF VEGETABLES 5 and 17.2 per cent of their ash; when cooked in their skins, they lost 1.6 per cent of their ash. Varying the experiments by using "alkaHne water'' or "lime water," instead of distilled, produced no important variations in losses— except that it seemed that the lune water (and the cold alkaline water) took out a httle more protein than did the dis- tilled water controls. Carrots, scraped and cut into pieces, lost from 20 to 40 per cent of their nitrogen, and from 29 to 47 per cent of their ash, according to size of pieces. Half a solid cabbage, put into cold water and cooked, lost from 33 to 46 per cent of its nitrogen, 33 to 42 per cent of its fat and carbohydrate, 48 to 54 per cent of its ash; put into hot water and cooked, the losses were usually (but not always) a httle less. On the whole, the alkaline and lime waters had a slightly greater extractive action than did the distilled water. Kraus^ found that cabbage turnip when cooked had lost 20 per cent of its carbohydrate; cauliflower, 33^ per cent; spinach, 71 per cent; winter cabbage, 53 per cent. Zschokke" worked on losses in "blanching" (boilmg in hot water) of carrots (cut in pieces), peas, string beans cooked whole and also cut into pieces. In each case, one-half of the vegetable was steamed and the other half boiled for 25 to 30 minutes. The losses in total dry matter were about five times as much by boiling as by steaming; losses in salts, usually only from three to four times as great in boiling as in steammg.' He gives no data for raw foods, but, if wc were to judge from American analyses for these foods, we should conclude that his losses in protein and mineral salts were markedly lower than tliose reported by most workers, while his losses in "nitrogen-free extract" run only a httle lower than some losses in caloric value reported in the present paper. (He found a loss of 3.43 grams of nitrogen-free extract per 100 grams raw ma- terial in boiled carrots, 2.43 grams in boiled peas, 0.624 grams in beans boiled whole, 0.768 gram in beans boiled in pieces.) HaenseP reports a loss of about 0.08 gram of iron oxide from 100 grams of fresh vegetable, in boiling spinach; and 70 per cent of its iron, in boihng lettuce in water— if I have correctly interpreted his report. Williams^ gives a number of analyses of cooked foods, calculated to moist condition; but in her earlier articles, no corresponding analyses of ^^Ztschrf.f. Dim. u. physik. Ther., vol. 1, p. 69, 1898. Cited in Hutchison's Food and Dietetics. * Landu). Jahrb. d. Schwek., vol. 19, p. 615, 1905. ^ Biochem. Ztschr., vol. 16, p. 9. ^Jour. Amer. Chem. Sod:',' vol 26, p. 244, 1904. 6 THE JOURNAL OF HOME ECONOMICS [April raw materials were made, so that it is impossible to judge of the propor- tionate losses. A later article^ reports a loss of 10.59 per cent of its pro- tein and 5.36 per cent of its ash, by celeriac, pared, sHced thin, and cooked 30 minutes in boiling water. Chicory, borecole, and endive (procedure not stated) lost from 30 to 43 per cent of their protein and from 12 to 19 per cent of their ash. Dried legumes (butter beans, green flageolets, soy beans), soaked 12 hours and then cooked (whether in the same water, and how much, is not stated), lost into their cooking water 26 to 28 per cent of their protein, and 5.5 to 17.05 per cent of their ash. Chestnuts (evidently fresh) lost 54 per cent of their protein and 7 per cent of their ash. A still later paper^ evidently reports further work, especially with regard to protein losses. Cooked in boiling water by the usual method, spinach, with 10 per cent of total solids, loses one-fourth of these; celeriac loses half of its total soKds (7 per cent of its ash, 54 per cent of its protein) ; turnips, almost half; lettuce, one-fourth; aspara- gus, one-sixteenth; curly greens (borecole) 40 per cent (16 per cent of its ash, 54 per cent of its protein); chicory, 20 per cent (12 per cent of its ash, 43 per cent of its protein) ; butter beans, 10 per cent (19 per cent of its ash, 30 per cent of its protein); endive, 25 per cent (19 per cent of its ash, 30 per cent of its protein). Furthermore, Miss Williams gives the following analyses, together with those of many other foods, in a table in the Appendix of the third volume of Van Noorden's Metabolism and Practical Medicine, 1907. It is not stated, whether all of the analyses represent original work, or whether some of them are compiled from the works of others. No de- tails as to cooking procedure are given. Apparently the analyses for the raw vegetables are not intended as strict controls for those upon the cooked samples; rather, each represents a sample picked up more or less at random. Indeed, the editor's note states that in many cases these figures must be looked upon as merely illustrative, rather than as the basis for generalizations. It is therefore hardly possible to com- pare these results with those given in Tables I and II of this paper. These items have been rearranged alphabetically and also so as to places figures for raw and cooked samples side by side, instead of having them in different tables, as they were printed in the Van Noorden text. ^ Jour. Indust. Eng. Cheni., vol. 5, p. 653, 1913. ^ Chem. Neu's, vol. 113, p. 143, 1916. 1919] CHANGES IN FOOD VALUE OF VEGETABLES Analyst's of raw and cooked vegetables VEGETABLE Asparagus Artichoke, green Artichoke, Jerusalem Beans, haricot (dried) Beans, scarlet runner Beetroot Broccoli Brussels sprouts Cabbage, savoyf Carrots Cauliflower Kale (sea-kale) Leeks Lentils (dried) Onions Parsnips Peas, (dried) Peas, green Potatoes, boiled in skins Potatoes, boiled after pared . Spinach Turnips PROTEIN (NX 6.25) Raw Cooked per cent 1.8 4.8 2.0 23.0 2.3 1.6 3.8 1.5 1.5 0.5 1.8 1.4 1.2 24.2 1.5 1.6 21.0 7.0 2.1 2.1 2.1 1.3 Vegetable marrow 0.6 per cent 2.1 2.9 1.8 4.6 1.8 0.4 2.5 2.8 0.6 0.5 0.9 0.4 1.4 8.8 0.1 0.2 9.4 2.8 1.6 1.6 0.3 0.3 0.1 Raw Cooked per cent 0.7 1.6 1.1 3.2 0.8 1.1 0.9 1.3 1.2 1.0 0.7 0.6 0.7 2.6 0.5 1.4 2.6 1.0 0.7 0.7 2.1 0.8 0.5 j per cent 0.7 1.1 0.6 0.7 0.4 0.4 0.6 0.5 0.1 0.1 0.2 0.2 0.8 0.7 0.1 0.1 0.7 0.3 1.3 0.7 0.2 0.3 0.1 CALORIES PER 100 GRAMS Raw 22.7 72.4 71.8 344.4 42.4 47.2 33.2 17.9^ 34.5 6.7^ 31.2 21.1 23.3* 368.8 28.4 82.5* 329.9 102.7 109.5 109.5 24.4 36.1 14.8 Cooked 18.1 45.3 27.1 60.7 17.4 14.1 22.6 30.1 4.6 16.7 6.2 3.7 38.6 121.9 4.2 8.2 139.7 30.6 84.1 78.5 2.9 4.6 0.8 ^ * Evidently a misprint, for this number does not correspond to the analysis for pro- tein, fat, and carbohydrate printed in the table from which this is an abridgment. t It is not clear whether the raw and cooked cabbage were from the same or from dif- ferent varieties. Maurel and Carcassagne^ found that blanching for 30 minutes (or 15 minutes? the two reports conflict) in distilled water, removed 40 per cent of the total salts from cauliflower, 44 per cent from Brussels sprouts, 55 per cent from cabbage sprouts, 26 per cent from celery root (celeri pied), 37 per cent from celery leaves, 35 per cent from asparagus, 34 per cent from green beans, 19 per cent from white beans, 3Z per cent from lentils, 61 per cent from potatoes. Amounts of potassium lost were in all these cases, except two, relatively high, ranging from 25 to 73 per cent of total potassium. In general, 40 to 50 per cent of total salts (50 Compt. retid. Soc. Biol., vol. 67, p. 91, 211, 1909. 8 THE JOURNAL OF HOME ECONOMICS [April to 75 per cent of total potassium) was lost in this blanching process. In the case of legumes, 30 minutes' blanching removed a much larger amount of potassium (73 per cent in white beans, 38 per cent in lentils) than did the remainder of the three hours' cooking (16 and 22 per cent, respectively). These authors also quote Laborde^" as fhiding a loss of 75 per cent total salts (60 per cent of potassium) in the blalnching of cabbage; and LabiJle^^ as reporting losses of 29, 70, and 54 per cent of total potassium for 5 minutes' blanching of green beans, sorrel, and spinach, respectively; also, loss of 36 per cent of potassium in 10 minutes' blanching of potatoes. Poppe^^ cooked (or soaked) fresh green peas in two and one-half times their own weight of water or liquid, for 1 hour at 100°C., for two hours at 50°C., for 24 hours at 20°C. They used seven Kquids — distilled water, saturated NaCl solution (56 per cent), half-saturated, and quarter-sat- urated (10 per cent NaCl), saturated sugar solution (about 105 per cent), half -saturated, and quarter-saturated (18.4 per cent). They found that the peas boiled in distilled water lost 10 per cent of their ni- trogen (it seems the raw peas contained 19 per cent of protein), 13.6 per cent of their carbohydrate (6.92 per cent carbohydrate in raw peas), 3.9 per cent of their phosphorus (0.66 per cent in raw peas), none of their chlorine. The salt solutions removed less of the nitrogen than did dis- tilled water, and very little phosphorus or carbohydrate ; the stronger salt solutions removed less nitrogen, in general, than did the weaker, but there was little difference in their extractive effect on carbohydrate. All losses were, as a rule, greater at the higher temperatures, because these kill the protoplasm and convert it from a semi-permeable mem- brane to a permeable one, whereas at 20°C. the hving protoplasm, though it imbibes water, is able to regulate its loss of solutes and the entrance of solutes from its environment, to a considerable degree. The peas took up about 1 per cent of their own weight in salt from the boiling quarter-saturated salt solution, and about 1.5 per cent of their own weight of sugar from the boiling quarter-saturated sugar solution. It is not stated whether the solutions were kept at their original strength by renewal of water as they boiled, or whether they became more con- centrated as cooking proceeded. Unfortunately these most careful and scientifically made observations can apply only somewhat remotely to lo^oc. d. Hist. nat. Tou-l., March 28, 1900, p. 67. " Traile de V Alimentation, vol. 3, p. 522, 44, 35. ^Bul. Soc. chim. Belg., vol. 25, p. 136, 1911. 1919] CHANGES IN FOOD VALUE OF VEGETABLES 9 the problem of cooking losses, since solutions as strong as these could not be used in preparing vegetables. Berry'* found that boiled spinach lost 50 per cent of its salts; boiled cabbage 40 per cent; boiled carrots (cut in pieces) 11.5 per cent of their salts (23 per cent of phosphorus) and 26 per cent of soluble carbohydrate. Berg'^ suggests that in some cases the losses in alkali as a result of boiling vegetables are so great that the vegetable may actually lose its basic ash, and come to possess an acid ash. Bodinus'^ announces that the loss of solids in boiled potatoes is at least 2 per cent if pared. If sodium chloride be added to the water, the loss is 1.25 per cent of the starch and 10 per cent of the potato salts; if no salt is added, the potato loses 33 per cent of its salts. Morgan^^ reports a smaller loss of salts in peas canned by the com- mercial process than in those canned by the three-day sterilization home process. (Specifications and detailed results not given.) She found a loss of 18 per cent of the ash (25 per cent of phosphorus) due to blanching. Blunt and Otis^^ boiled 5 to 10 grams of spinach, string beans, navy beans, and peas, respectively, in 25 to 75 cc. distilled water in a covered beaker for 20 to 40 minutes (navy beans two hours) ; potatoes were also boiled (seven were scraped, cooked together, and mixed). These vege- tables, both raw and cooked, and the cooking water were then analyzed for iron. The losses found were: spinach, between 43 and 50 per cent of its total iron; string beans, between 39 and 43 per cent; navy beans, between 32 and 39 per cent; peas, 36 per cent; potatoes, between 15 and 22 per cent. Visawanath^^ found that neutral salts (of calcium, magnesium, and sodium) retard, and alkaline salts (e.g., Na2C03) accelerate the cooking of legumes (dhall) because they retard or accelerate respectively, the solution of protein and starch, but more especially of protein. Courtney, Fales, and Bartlett^^ cooked seven varieties of vegetables by "thorough boiling" for 30 to 150 minutes, and analyzed cooked vege- tables and cooking water for calcium, magnesium, phosphorus, chlorine, " Jour. Home Econ., vol. 4, p. 405, 1912. " Nahrimg. u. Genus smiltd, Aschhcslindleile, Dresden, 1913. 1^ Chem. Zentr., Bd. 2, p. 37, 1915. 1^ Jour. Home Econ., vol. 7, p. 72, 1915. " Jour. Home Econ., vol. 9, p. 213, 1917. 18 Mem. Dept. Agri., India, Chem. Ser. 4, No. 5, p. 149, 1916. Abstr. from Chem.Abstr., 1917. '9.4/«cr. Jour. Dis. Children, vol. 14, p. 34, 1917. to THE JOURNAL OF HOME ECONOMICS [April potassium, sodium, sulphur, iron, and nitrogen. The percentage losses on most salts were greater than losses in calcium and nitrogen. New Zealand spinach was an especially heavy loser (72 per cent of total ash), yet it lost very Httle of its calcium, and the same thing was true of ordi- nary spinach. (Both these vegetables are especially good sources of calcium, if one were to judge from chemical analyses alone, — a ques- tionable proceeding.) Carrots, onions, and asparagus lost but a trace of iron; spinach, 28 per cent of its iron; New Zealand spinach 51 per cent. Reducing the time of cooking made little difference in the losses (spinach cooked 10 minutes instead of 90, string beans cooked 60 minutes instead of 150 minutes lost almost as much as before). Steaming, however, reduced the losses materially (spinach only half as much loss as when boiled, asparagus one-third as much, carrots one-fourth as much). New Zealand spinach and onions still lose 20 to 30 per cent of their more soluble constituents, when steamed (for 30 minutes). WeibulP" concludes that while potatoes do not lose appreciably if boiled in their skins, they lose 0.5 per pent of their solids if pared before boiling. If sweetened by chilling, they lose 0.5 per cent when boiled in skins, 1.5 per cent when pared before boiling. Cooked in hard water, they retain their solanin; cooked in distilled water, they lose one- third of it. Wardall,^^ working to develop a method of making vegetables free of digestible carbohydrate for the use of the diabetic, placed the finely cut vegetables in cold water, brought this to the boil, boiled for several minutes, then poured the water off and repeated the process. She found that, while beets give a test for reducing sugar after two such extrac- tions and are then exhausted of such carbohydrate, cabbage still gives the test after 8 extractions, carrots after 6, eggplant after 7, parsnips after 6, pineapple after 9. Extracted in water at 60° C, 1 hour was re- quired to extract all reducing carbohydrate from beets; 1| hours for carrot; 2 hours for eggplant; 1 hour for parsnips; 3| hours for pine- apple. Cabbage seemed to give up little of its reducing substance to a 60°C. extraction. ^°Ktmgl. Landtbruks-akad. Handling ar Tidskrijt, vol. 56, p. 348, 1917. Abstr. in Chem. Abstr., 1917. '^ Jour. Amer. Med. Assti., December 1, 1917. 1919] CHANGES IN FOOD VALUE OF VEGETABLES 11 t Masters^^ tried the effect of boiling dried beans in a large excess of water (five times their own weight) treated in various ways. She found that soaking the beans overnight reduced the time of cooking only from 2 hours and 5 minutes to 2 hours. (The experience of the author of this paper is very nearly in accord with hers, though there is a good deal of variability among the different kinds and different grades of maturity. If the beans be put directly into boiHng instead of into cold water to cook, the time is still further reduced in some instances.) The soaked beans lost a larger proportion of their solids than did the unsoaked (12.2 per cent instead of 10.5 per cent in tap water; 12.6 per cent instead of 11.1 per cent, in distilled water). Salting the water reduced the losses considerably: in 0.25 per cent NaCl, they lost 9.2 per cent of their solids; in 0.5 per cent NaCl, 8.7 per cent; in 1 per cent NaCl, 8.3 per cent. Even the salts of tap water had a slight effect in this respect (11.1 per cent loss when boiled without soaking, instead of 10.6 per cent loss in tap water), when soaking and cooking were not too much prolonged. Adding soda increased the losses ; boiled (without soaking) in 0.1 per cent solution of sodium bicarbonate in tap water, they lost 11.3 per cent of their solids; in 0.25 per cent solution, 14.3 per cent; in 0.5 per cent solution, 22.3 per cent; in 1 per cent solution, 27.3 per cent. Disintegration was very rapid at the higher concentrations, and the flavor was such that the beans were uneatable; the most ..satisfactory results were those when 0.1 per cent sodium bicarbonate was used. Cooking by steaming was also tried; 100 grams beans were covered with 250 grams boiling water, the basin was placed quickly in a steamer, and closed with a tightly fitting Kd. When thus steamed witliout pre- vious soaking, they lost 8.9 per cent of their soHds; soaked overnight and thus cooked, they lost 10.4 per cent; cooked (without soaking) in 0.25 per cent NaCl, they lost 8.4 per cent; cooked (without soaking) in 0.1 per cent sodium bicarbonate and 0.25 per cent salt, they lost 7.8 per cent; cooked in 0.1 per cent soda and 0.25 per cent salt after previous soaking they lost 8.1 per cent of their original weight. Denton and Kohman^^ fed young white rats raw carrots, boiled carrots with the concentrated cooking water, boiled carrots without t This thesis was prepared in March 1918. The foUomng notes were added in March, 1919, in order to bring the bibliography up to date. 22 Biochem. Jour., Oct., 1918. 2' Jour. Biol. Chcm., vol. 36, p. 259, November, 1918. 12 THE JOURNAL OF HOME ECONOMICS [April the cooking water, and canned carrots (processed two hours in boiling water bath). During the short period (five weeks) when carrots formed the sole diet (except for certain salts which were added), it was clear that those animals fed on raw carrots had the advantage over the others. Difficulties which the animals had in accommodating themselves to the unsuitable diet appeared to be greater, in proportion to the length of time the carrots had been cooked. However all animals ralUed and began to improve in time, except those on the canned carrots, who were started later than the rest and had not sufficient time to show what they could do before a change in diet was made. When protein, fat, and starch were added to the diet in such proportions that the carrots furnished only one-half to two-thirds of the solids and of the calories of the diet, cooldng of the carrots seemed to have no deleterious effects. True, however, it was observed that those animals which received carrots with the concentrated juice cooked down to some degree of caramelization did, after a time, fall considerably behind the rest in food consumption and also somewhat in rate of growth. The reason for this difference, which was perfectly apparent to all those who handled the animals and their food, cannot be stated, so far as I know, at the present moment. Those animals fed boiled carrots without the juice, on the other hand, developed unusually large appetites, though their growth curves were not quite as good as those of animals similarly fed on raw carrots. Presum- ably this shows the effect of the loss of a considerable portion of the caloric value of the vegetable into the cooking water. Daniels and McClurg^* fed young white rats on a diet in which cab- bage (raw, or boiled in water or in soda and water, or autoclaved) was the only source of water-soluble vitamine. The cooking water was in- clued in the diet in all cases. If my method of figuring this dietary is correct, the cabbage of these diets furnished 15 per cent of the calories; 250 grams of cabbage were used to 100 grams of dry ration (casein plus starch plus salts plus fat). The soda was added in the proportion of 1| teaspoons per cup of raw beans {33 cc. of 5 per cent solution of so- dium bicarbonate to 50 grams of soy beans); and 1| teaspoonful to 1 pound of cabbage (63 cc. of 5 per cent solution, to 250 grams cabbage) ; this proportion of soda is about what is very commonly used in cooking these vegetables. Their experiments continued only through one month ^* Jour. Biol. Ckem., vol. 37, January, 1919. 1919] CHANGES IN POOD VALUE OF VEGETABLES 13 in the case of cabbage feeding; but it is believed that the effects of a decided deficiency of water-soluble vitamine should be apparent within that time. Yet animals on all of these cooked diets throve equally well with those fed raw cabbage, and all animals kept pace with or exceeded the normal rates of growth. Evidently, then, cooking of cabbage even at high temperatures or even in alkahne medium did not sufficiently impair the water-soluble vitamine so that growth was perceptibly interfered with, under the conditions above described. It must, however, be noted with respect to the last two investigations reported, that it is possible the results might have been slightly dif- ferent if the amount of vegetable fed had been reduced to the minimum, or that which would furnish barely sufficient vitamine to meet the needs of growth. In case cooking does have a slightly prejudicial effect on vitamines, it would be more Hkely to appear when the margin of safety is a narrov/ one than when it is a very wide one. It may be added, that tlic am.ounts of vegetables fed (especially in the carrot diets) in the diets described above are larger, proportionately, than is usually con- sidered possible in human dietaries. Even in the case of the cabbage diets, it will be observed that the vegetable furnishes 15 per cent of the calories; this would call for 2.45 pounds edible portion, or 2.91 pounds of cabbage as purchased, in the 2500-calories-a-day dietary; or 2.94 pounds edible portion, or 3.48 pounds as purchased, in the 3000 calorie diet of man. As Miss Daniels remarks, this excessively wide margin of safety in respect to vitamines may perhaps account for the fact that her results are different from those of McCollum and co-workers (Jour. Biol. Chem., Vol. 33, p. 55) who found that the water soluble vitamine extracted from the wheat embryo was apparently destroyed by 60 minutes boiling in alkaline medium. Stanley-^ gives tables showing losses due to blanching varying from 19 per cent in wax beans to 53 per cent in cabbage. Another table shows 52 per cent of mineral matter lost in boiled spinach, 9 per cent in steamed; 41 per per cent in boiled cabbage, 11.5 per cent in steamed. Details of manipulation are not given. III. PURPOSE OF THIS INVESTIGATION This work was undertaken with a view to determining how great are the variations in food value resulting from different methods of house- 2s Cooking of Vegetables. Cir. 1, Agr. Ext. Service, Univ. of Mo., 1915, 14 THE JOURNAL OF HOME ECONOMICS [April hold manipulation, in any given process of cooking. The process most frequently studied was that of boiling vegetables. The details consid- ered cover such points as those mentioned on page 3 of the introduction. rV. METHODS The methods which were used by the writer in cooking these vegetable samples are described in the tables given below. After cooking, the vegetable was ground or mashed or thinly sliced into lead caps or on to glass plates, and dried at 30° to 80°C. in an oven, or warm air blast, or over a water bath. The amounts of vegetable cooked were ordinarily between 50 and 100 grams, or often much more. This amount was necessary in order that the process should have some resemblance to the ordinary household process; also, in order to secure an approach to homogeneity of samples. After drying, the samples were finely ground for burning in the bomb calorimeter. Often they were formed into pel- lets by hammering against a metal rod in a m.etal tube. This was done in order to prevent scattering when the first rush of oxygen enters the bomb; usually, however, this precaution was unnecessary. The control (uncooked vegetable) was always taken from the same lot as were those that were cooked. As individual specimens, even from a given lot, may often vary considerably among each other in water con- tent and consequently in percentage composition, the control was, whenever possible, a part of the same individual vegetable specimen. In cutting the samples used as controls (uncooked), pains was taken to secure strips running lengthwise through every region of bud or root- stock, so that proportionate amounts of cortex, pith, fibro-vascular bundles, parenchyma, or growing region, would be about the same in control as in other samples. Where it was necessary to take transverse sections, these were selected alternately from the various regions, so that each sample might contain representatives or every region. Combustion was conducted in a platinum or nickelled capsule, by means of a Riche adiabatic bomb calorimeter (vacuum insulation; igni- tion by means of linen thread instead of iron wire was frequently used). A differential thermometer was read so as to show differences in tem- perature of 0.001°C. Bomb calorific values are thus obtained directly, for the dried material. It is not practicable to give calorific values in terms of weight of cooked vegetables, since this weight varies enormously according to the 1919] CHANGES IN FOOD VALUE OF VEGETABLES 15 details of manipulation, and varies, indeed, from moment to moment as the steaming vegetable cools and loses water. I have therefore cal- culated all values for cooked vegetables upon the basis of raw weight. For example, suppose that 100 grams of raw parsnips weigh 95 grams after cooking (at the moment of manipulation), which dry down to 20 grams; and that this dried parsnip shows a caloric value of 4000 (gram- calories) per gram. Then the raw vegetables with a corresponding value should be assigned 20 per cent of 4000 calories, or 800 gram- calories per gram; which is 363 kilo-calories per pound. If the control or uncooked parsnip shows a value of 1000 gram-calories per gram of fresh vegetable (or 454 kilo-calories per pound), then it is evident that this parsnip has lost 20 per cent of its caloric value in the cooking process. DupKcate samples taken from the same vegetable specimen (or from the same lot if of very small size, as peas) should check within 2 or 3 per cent at farthest. A closer check (0.5 per cent) is usual, but not always possible with raw vegetables, because of the lack of homogeneity of the material. When a high salt content (spinach, some beans) inter- feres with complete combustion in the calorimeter (by the fusing of salts so as to encase carbon particles and protect them from combustion), the difficulty may sometimes be remedied by spreading the dried pow- dered sample over a piece of filter paper, whose dry weight and caloric value per gram are known, rolHng the whole like a cigarette and be- stowing it in the capsule for combustion. Substracting the calories due to the filter paper, one has then left the calories due to the dried vege- table. Usually, however, if the linen thread (instead of the iron wire) be used for igniting, there is no difficulty. Furthermore, the calorie value of the total cooked sample plus the calorie value of the concentrated cooking water must be approximately equal to the calorie value of an uncooked sample of the same size, as calculated from the control. This check was conducted in a number of instances (though by no means in case of all samples reported) by evaporating the cooking water to a few cc. of sirup, taking it up on a weighed piece of filter paper of known calorific value, drying and burn- ing the whole mass together, or in fractions, as might be necessary. In those cases where the amount of extract is too great to be concentrated into a volume convenient for such a test, it may be dissolved in a rela- tively large volume of water (e.g., 100 to 250 cc), mixed until thoroughly homogeneous, and divided into aliquot portions in any convenient 16 THE JOURNAL OF HOME ECONOMICS [April manner. One of these portions is then concentrated, collected, dried, and burned as above. Any suspended particles must be allowed to settle, and then be filtered out of the whole sample before division into aliquots, finally to be dried and burned separately. Doubtless the question will suggest itself, why should so large a per- centage of these determinations have been made with carrots and pars- nips? The reasons were that their cheapness (price per pound) and the ease with which they are stored have put them into general use; that they are usually pared and cut before cooking, largely as a matter of con- venience to the cook; that their high sugar content makes them sensi- tive indicators upon which the effect of vaiying manipulations may be detected. Total salts were determined by the water-leaching method (Official Methods, Association Official Agricultural Chemists, Bureau of Chem- istry, Bulletin 107) ; ignition in muffie furnace. VI. DISCUSSIONS AND CONCLUSIONS^^ 1. The vegetables experimented on, when boiled until tender in ex- cess of water which is thrown away, lose from 15 to 60 per cent of their fuel value. (It is a very simple matter to demonstrate these losses ocularly, by cooking pared parsnips, pared carrots, some varieties of peapods, cabbage, onions, etc., finely cut or even coarsely cut, in plenty of water, and then concentrating this water, after pouring off, to small bulk, when it takes the form of a molasses.) The losses are, of course, less, proportionately, when there is less soluble matter to lose. Turnips, cabbage, cauliflower, young carrots, aspara- gus, onions, spinach, peas, string beans, lose less than do parsnips and mature sweet carrots and Brussels sprouts (compare C III, 2, also C IV, 3, with C I and C II). Apparently carrots have their carbohydrate more largely in soluble form, than do parsnips, for their losses are pro- portionately heavier, under the same treatment, especially in those cases where their calorie values at all approach those of parsnips. (See P II, 6 and C I, 6.) 2. The losses in salts in every case except one (Spinach I, 2 steamed) parallel the calorie losses, and usually rather closely. They are, as a rule, slightly greater than the calorie losses. (The same thing was true of nitrogen losses, in those cases where such determination was made.) 2** References are to table 1, unless otherwise stated. 1919] CHANGES IN FOOD VALUE OF VEGETABLES 17 TABLE I Losses in cooking vegetables, caloric values fe o s o n H o o b X is < www H w n 06 MHO O "S H o < ri H O -1 w O 1-1 g SERIAL NUMBER MANIPULATION «3 p< < H 5a W i-l > > B 2 b i-l ^ O < < u en g m O >-' CJ « >^ c^ w H H < n u ;<4 is ai W '^ OS Id 0. o o o O o « 5 w o ►J w w >J o «>u s° <>B. <>». S" Peas, I. Young green, purchased May 9, 1917 ; pods well filled, peas quite juicy Peas I, 1 Peas 1,2 Uncooked.* 82 grams vegetable blanched 4 min- utes in 400 cc. salted distilled wa- ter (1.4 per cent); cold-dipped un- der running tap. Then placed in 80 cc. boiling salted distilled water (1.5 per cent); boiled twenty min- utes; peas had taken up all the wa- ter. Washed in 90 cc. distilled wa- ter, brought to boil in four and one half minutes, then drained off. Weight, after cooked, 90 grams. 25.50 24.97 gram- calories 4102 4139 gram- calories 1044 1033 kilo- calories 473 469 per cent 0.8 Peas, II. Young green, purchased June 5, 1917; pods filled with varying sized peas, some large ones Peas II, 1 Peas II, 2 Peas II, 3 Peas II, 4 Uncooked.* 102 grams raw vegetable blanched six minutes in 500 cc. boiling dis- tilled water; cold-dipped under running faucet. Weight, after cooled, 106 grams. 115 grams raw vegetable blanched six minutes in 500 cc. boiling salted distilled water (1.4 per cent); cold- dipped. Weight, after drained and cooled. 111 grams. 103 grams raw vegetable blanched six minutes in 500 cc. boiling tap water; cold-dipped. Drained, and cooled, weight = 106 grams. 26.16 4249 1112 504 21.99 4270 939 426 24.4 4212 1028 466 22.6 4288 969 440 15 13 * Omit word "cooked" throughout, in reading column headings, for this sample. TABLE 1— Continued SERIAL NUMBER MANIPULATION »2 S « R pa '^ I. < D £^ H W p« J ^ Q o S 8ps & mS »-5 w * < 3 S > B g w ?* S M H ? WW* O O « iJ W W < > a. ft ^ o o h) O String Beans, I. Young green, purchased May 9; strung, cut into half -inch lengths grams gram- calories gram- calories kilo- calories per cent S. B. I, 1 Uncooked.* 10.16 3960 402 183 S. B. I, 2 80 grams raw vegetable blanched five minutes in 500 grams salted distilled water (0.2-4 per cent salt), cold-dipped. Drained, cooled, 99 grams. 9.317 3750 349 159 13 S.B.I, 3 71 grams raw vegetable blanched five minutes in 500 grams boil- ing distilled water, cold-dipped. Drained, cooled, 92 grams. 8.43 4046 341 155 15 String Beans, II. Young green, purchased June 5; "strung" and cut into half-inch lengths S. B.II, 1 S. B. II, 3 S. B.II, 4 S. B. II, 2 Uncooked.* 80 grams raw vegetable boiled in 500 cc. distilled water (0.4 per cent salt) for twenty minutes. Drained, cooled, weight = 89 grams. (Not quite "done" enough to eat.) 87 grams raw vegetable steamed twenty minutes on wire gauze, 3 inches from level of boiling water; covered, but not perfectly tight. Drained, cooled, weight = 85 grams. (Not quite "done" enough to eat.) 199 grams raw vegetable autoclaved in wire basket twenty-five minutes at pressures between 10 and 15 pounds; entire period of steaming in autoclave, forty-four minutes. Cooled, weight = 174 grams. Flavor unpleasant, like hay, other- wise tasteless; mealy texture. 11.7 10.16 11.52 11.04 3768 3890 3872 3862 441 395 446 436 200 179 202 198 10 1+, (gain)t *Omit word "cooked" throughout, in reading column headings, for this sample. t This apparent gain may probably be due to some error in determining the factor noted in the third column. The sample used for drying was an unusually small one. Or, it may be due to lack of homogeneity in raw materials. 18 TABLE 1 — Continued Sa n "1 ^ S w R •< S w a Q O H Q n H ^ WWW MHO H H n ;^ H o HI Pa ,_] p. < 5> S p s ft ■-> 5 o < 5 §23 o 3 =: o < < o g SERIAL NUMBER MANIPULATION H W O < hJ 5 < 3 9 5 s Q > « 3 > B g <-> o w w a « 3 o a w < 5 S H O a W B< 2 o o o o « O O oi o o a w o ►J w w h) 14 M g>a <>A. <>0. 3" String Beans, II. (Continued) S. B. II, 5 159 grams raw vegetable in pint jar with 260 grams water and 1.7 grams salt, cover screwed down; cooked in autoclaved run as de- scribed in S. B. II, 2, above. Jar was opened fifteen minutes after removal from autoclave; tempera- ture of contents, 90°. Drained and cooled, beans weighed 191 grams. Flavor of beans and of juice, fairly good; juice rather cloudy. grams 9.535 gram- calories 3785 gram- calories 361 kilo- calories 164 Per cent 18 String Beans, III. Purchased March 18, 1918. Green, tender. "Strung," cut into finch pieces S. B.III, 1 S. B.III, 2 Uncooked.* 133 grams raw vegetable boiled thirty minutes in 700 cc. tap wa- ter; cooking water at end of proc- ess, 350 cc. Weight of beans after cooked, 150 grams. 9.8 6.646 3926 4120 387 274 176 123 30 Spinach, I. Purchased March, 1918. Somewhat stale. Not v/ashed Spin. I, 1 Uncooked.* 8.636 3491 302 137 Spin. I, 2 1 1 1 grams of raw vegetable steamed seventeen minutes on false bottom over 150 cc. water. Drained and cooled, 107 grams. 8.180 3257 266 121 12 Spinach II. Purchased April, 1918. Fresh . W^ashed with ordinary care Spin. II, 1 Uncooked.* 8.235 Spin. IT, 2 205 grams boiled twenty- five min- utes in 3000 cc. tap water (2200 cc. at close). \\'eight after cooled and drained, 168 grams. 5.200 Spin. II, 3 200 granis steamed twenty-five min- utes on wire gauze. Weight after drained, 169 grams. 7.450 *Omit word "cooked" tliroughout, in reading column headings, for this sample. 19 20 THE JOURNAL OF HOME ECONOMICS [April TABLE I— Continued SLRIAL NUMBER MANIPDLATION < 2 s a Q Q Q b < u o S H M n MHO °u U > ^ OS H (-, W n M M « 1-1 £S P^ ^ w p-^5 o < •< i-l M -< > ii ►J (d « < iJ « as® < ij g > « z oi H 0< O o o o o O O OJ O (^ 3 wo >J H H 5° <>a, g>P. a O o G 2; S3 o o •i ° < u Cauliflower, I. Half-pound head. Leafy bracts and petioles tender green, vertically Head divided grams gram- calories gram- calories kilo- calories per cent Caul. I, 1 Uncooked.* 14.24 3828 545 247 Caul. 1,2 55 grams raw vegetable boiled in 500 cc. tap water (150 cc. at end of period) for fifteen minutes. Cold, drained, weight = 52 grams. 10.26 4059 416 189 23 Caul. I, 3 50 grams raw vegetable steamed twenty-five minutes. Cold, drained, weight = 49 grams. 14.36 3773 542 246 Caul. I, 4 Outer leaf stalk only, uncooked.* 15.02 3702 556 252 Caul. I, 5 Outer leaf stalk only, 25 grams raw stalk boiled in same water with Caul. I, 2, above, for twenty-five minutes. Cold, drained, weight = 25 grams. 11.60 3671 426 194 23 Caul. I, 6 Outer leaf stalk only, 15 grams steamed twenty-five minutes. Cold, drained, weight = 12 grams. 12.60 Brussels Sprouts, I. A good fresh green. A little dry B.S.I, 1 B.S.I, 2 B. S. I, 3 B.S.I. 4 Uncooked.* 94 grams raw vegetable boiled whole, five minutes in boiling tap water (500 cc). Cooled, weight = 108 grams 94 grams raw vegetable boiled whole twenty-five minutes in 500 cc. tap water. Cooled, weight = 112 grams. 97 grams raw vegetable, each head cut lengthwise into three or four slices, boiled twenty-five minutes in 500 cc. tap water. Cooled, weight = 120 grams. 17.055 4154 709 322 14.31 4246 608 276 10.96 4539 414 ISS 14.41 4266 615 270 14 42 13 *Omit word "cooked" throughout, in reading column headings, for this sample. TABLE I — Continued & g ^ Q Q Q Q H < S-iRlAL NUMBER MANIPULATION a a « Q < g w W w « O in H < > i^ H t^ §gi '.^ iJ > O < 5 c> « -< ►J W OS 5 -J y > n a « H O ° 3 3 o < "^ r. <-» *= r m 5 2S§ « w f^ H O a E s: o o « g>o a- 2><. g>g S" Cabbage, I. Purchased January, 1918. Firm, white head about If pounds. Outer leaves missing. No green. Cut vertically grams gram- calories gram- calories kilo- calories per cent Cab. I, 1 Uncooked.* 7.914 3803 301 137 Cab. I, 2 188 grams rav/ vegetable (one- fourth of cabbage head), steamed thirty minutes. Weight, after cooked and cooled, 175 grams. 8.388 3763 316 143 4.4 (gain)t Cab. I, 3 203 gram.s raw vegetable (one- fourth of head), cooked thirty minutes in 1000 cc. boiling tap water (700 cc. at end of cooking period). Weight after cooked and cooled, 215 grams. 5.835 4-001 234 106 21 Cab. L 4 180 grams raw vegetable (one- fourth of head), cooked thirty minutes in 1000 cc. boiling salted tap water (1.5 per cent salt); 750 cc. at end of cooking period. Cooked and drained, 167 grams. "Cooked to pieces" more than Cab. I, 3 (which was a more com- pact piece). 7.591 3335 253 115 14 Cabbage, II. Purchased November, 1917. Small, compact, crisp heads; outer leaves pale green. Cut vertically Cab. II, 1 Cab. II, 2 Uncooked,* ground and dried. 900 grams raw vegetable (one small solid head cut into eighths) blanched in 4500 cc. boiling tap v/ater ten m.inutes, then cooled un- der running tap. Packed tightly into quart jar, with hot water and 10 grams salt. (57.5 grams re- maining as juice at end of process.) Tar processed two hours in bath of boiling water. Weight of drained cabbage, 797 grams. 10.00 10.107 3809 3664 381 371 173 168 * Omit word "cooked throughout, in reading column headings, for this sam{)le. t This discrepancy is, so far, unexplained. 21 22 THE JOURNAL OF HOME ECONOMICS [April TABLE I— Continued SERIAL NUMBER MANIPULATION Q Q H O Q H 3 HUM U H n SO H O WHO o < « w O >-l S o 1-1 S w OS i-i U D & b PS < U> » g? ^a& ^^S W W M o < < o <: < < > ►J s o > B 5 > 5 5 S H ^ 2 o o o o « O « S w o ^s >J w w J W w O o o Cabbage, II. (Continued) Cab. II, 3 Duplicate of Cab. II, 2, except not packed so closely. 276 grams of drained cabbage and 120 cc. liquid in pint jar. (375 grams of raw cabbage had been packed into it.) grams 5.7 gram- calories 3654 gram- calories 209 kilo- calories 94 per cen I 46 Onions, I. Ordinary yellow. Purchased February, 1918. Outer scaly leaves rejected 0.1,1 0.1,2 0.1,3 0.1.4 O.I, 5 Uncooked,* vertical halves of two onions. Control for O. I, 2. 83 grams raw vegetable, vertical halves of same onions used for O. I, 1. Soaked twelve and one- half hours in 650 cc. water, after slicing horizontally (went all to pieces). Drained, weight = 104 grams. Bud swelled, unequal tis- sue strains apparent. Uncooked,* lower half of an onion, same lot. Control for O. I, 4 (???) 44 grams raw vegetable, upper half same onion as in O. I, 3. Soaked in 350 cc. salted tap water (two per cent salt) for twelve and one-half hours, having been cut into three horizontal slices. Held together fairly well; wilted, except for smallest inner bud. Drained, weight = 48 grams. 68 grams raw vegetable, (1 onion), cut crosswise into halves. Boiled forty minutes in 1100 cc. tap water (700 cc. at end of period). Cooked and drained, weight = 58 grams. Cooking water concen- trated, yielded 8438 kilo-calories. 8.075 7.394 11.89 9.527 4.421 3817 3783 3940 3585 •1007 313 280 469 342 181 142 127 213 15.S cS2 11 27t * Omit word "cooked" throughout, in reading column headings, for this sample. t See p. 31 for discussion of comparison between O. I, 2 and O.I, 4. 1919] CHANGES IN FOOD VALUE OF VEGETABLES 23 TABLE I— Continued MANIPULATION SERIAL NUMBER *2 3 Q H HUM O Q H 82a n 0) 82i3 iaS S" OPS OPS H W M eg o < 5 r"^ i-i a ago O < 5 < 3 Q M < P 3 w 0- 2 oo o o o a Bi O O M S H O H w w d w « O o o o >i o < o Onions, I. (Continued) grams gram- calories gram- calories kilo- calories per cent 0.1,6 50 grams raw vegetable (1 onion), boiled whole forty minutes in 1000 cc. tap water (700 cc. at end of cooking period). Weight, after cooled and drained, 41 grams. Cooking water concentrated, yielded 6878 calories. 6.868 3842 264 120 34 Turnips, I. White, purchased January 15, 1917; 290 grams each. Pared, quartered length- wise, in T. I, 1 and 2 T.I, 3 T.1,1 T.I, 2 Uncooked.* 61 grams raw vegetable cooked thirty minutes in 500 cc. boiling tap water. Weight, after drained and cooled, 57 grams. 65 grams raw vegetable cooked thirty minutes in 500 cc. boiling salted tap water (1.5 per cent salt). W^eight, after drained and cooled, 59 grams. (Water boiled almost dry.) 5.29 3850 204 92 3.761 4098 154 70 6.041 3283 198 90 24 Asparagus, I. Purchased March, 1918. Base of stems tough, trimmed off. Aspar. I, 1 Aspar. I, 2 Uncooked.* 76 grams blanched five minutes in 1000 cc. boiling tap water. Weight, after cooled and drained, 76 grams. 7.953 7.185 4068 4139 324 297 147 135 Asparagus, II. Purchased May, 1918. Trimmed, washed Aspar. II, 1 Aspar. II, 2 Uncooked.* 69 grams cut into 1| inch lengths, blanched five minutes in 500 cc. boiling tap water. Weight, after drained, 71 grams. 7.590 7.597 ♦Omit word "cooked throughout, in reading column headings, for this sample. TABLE I— Continued > o s Q Q H Q a H < 2 <: M M n M H P MHO a « Q < S w CJ P ? Cu 1-1 P 2 3 i3 o SERIAL NUMBER MANIPULATION 2S§ p o < > O < < bj u as S J a < 3 Q > S z H H < a S W M W < M 2 w 0- Sz 2 o o o ^ O o Bj O O oj o o S w o iJ s. ■J w w i-I o g>u <; o <: > p< Parsnips, 11. Purdiased January, 1917. Medium size, pared, cut lengthwise into eighths. Wilted p. II, 8 P. II, 7 P. II, 6 Uncooked.* Blanched five niinutes in 1000 cc. tap water; cold dipped; 86 grams of vegetables cooked twenty-two minutes in 1000 cc. hot unsalted tap water; weight, after cooking, 83 grams. Blanched in 1000 cc. salted distilled water (ttt per cent salt) five minutes; cold dipped; 85 grams of vegetables cooked twenty-two minutes in 1000 cc. hot salted distilled water f-nj- per cent salt) ; Weight after cooking, 83 grams. 26 17 20 gram- calories 3916 4125 3941 gram- calories 1018 701 788 kilo- calories 462 318 357 per cent 31 23 Parsnips, III. Purchased January, 1918. Medium size, badly wilted before used, pared P. Ill, 1 P. Ill, 2 P. Ill, 3 P. Ill, 4 P. Ill, 5 Uncooked.* 61 grams of raw vegetable (one half parsnip, cut lengthwise), cooked thirty minutes in 900 cc. boiling tap water. Weight, after cooked and drained, 68 grams. Control, P. Ill, 1. Uncooked* (second parsnip from same lot as P III, 1). 58 grams of raw vegetable cut cross- wise from same parsnip as P. Ill, 3, alternately from top and tip; blanched three and one-half min- utes in 500 cc. boiling tap water; weight after cooked and drained, 67 grams. 50 grams raw vegetable, duplicate of P. Ill, 4, but cooked seven minutes in boiling tap, 500 cc. Weight, after cooked, 58 gram.s. 31.38 4450 1396 633 26.57 3967 1054 478 38.11 3912 1491 676 26.93 4013 1081 491 25.26 4027 1018 462 25 27 32 *Omit word "cooked" throughout, in reading column headings, for this sample. 24 1919] CHANGES IN FOOD VALUE OF VEGETABLES 25 TABLE I— Continued SERIAL mjMBER MANIPULATION H w 2 2 o o B w o §2 S ri s > M ^ H H "^ B« W O o o aJ J M W < > B. o q H ops o < < ,., ^ « > P5 Z a w 0, O C5 M ►J W W fa z as Parsnips, IV. Purchased February, 1918. Medium size, mature, unwilled, pared P. IV, 1 P. IV, 2 P. IV, 3 P. IV, 4 P. IV, 5 Uncooked.* 74.5 grams raw vegetable (one-half of same individual as P. IV, 1, cut lengthwise), cooked thirty-three minutes in 550 cc. boiling tap wa- ter (380 cc. at end of cooking period). Weight, after cooked and drained, 72 grams. 33 grams raw vegetable (one-quarter of same individual as P. IV, 1, cut lengthwise). Cooked thirty- three minutes in 550 cc. boiling tap wa- ter (230 cc. at end of cooking period). Weight, after cooked, 32 grams Uncooked,* second parsnip from same lot as P. IV, 1. Sliced cross- wise, slices taken alternately from top and tip. 58.5 grams raw vegetable, duplicate of P. IV, 4, cooked thirty-three minutes in 550 cc. boiling tap wa- ter (310 cc. at end of cooking period). Weight, after cooked, 55 grams. 22.78 18.77 17.94 21.42 13.45 gram- calories 3858 3989 4118 3987 4022 gram- calories 879 749 739 854 541 kilo- calories 399 340 335 387 246 per cent 15 16 36 Carrots, I. Purchased January, 1917. Mature, medium size, pared, and sliced crosswise. (Dry, slightly wilted.) C.I, 8 Uncooked.* 21.4 3632 777 352 C.I, 4 70 grams of vegetable put into 500 cc. cold distilled water; ten min- utes coming to boil; boiled twenty- five minutes. Weight cooked, 55 grams. 8.1 3809 308 140 60 *Omit word "cooked" throughout, in reading column headings, for this sample. 26 THE JOURNAL OF HOME ECONOMICS [April TABLE I— Continued SERIAL NUMBER MANIPULATION te a S Q Q H' Q Q H M H m (d H d «w WHO WHO o < r! §3g O & S w 5 ►J g U P P a « Q < S w U ►J U CR ^^^ ^a& Hi o < < o < << & o P m S ►J w o < 1-1 a > pq 5 H - h > n a M w a o o w ■< S S H p « w "• o o o O O M O O Bi 3 w o g > o dBS iJ W W H w S d° g>B, O o H5 Carrots, I. (Continued) C.I, 5 C. I, 1 C.I, 6 87 grams of vegetable put into 500 cc. cold distilled water; five min- utes coming to boil; boiled fifteen minutes. Weight cooked, 77 gram.s. Water boiled away quite extensively. Not quite "tender." 92 grams of vegetable put into 500 cc. hot salted distilled water (1.5 per cent NaCl), cold dipped. Boiled thirty-two minutes. Weight cooked, 88 grams. Boiled gently, water level not miuch low- ered at end of period. 83 grams of vegetable blanched seven minutes in 500 grams, salted distilled water (1.5 per cent NaCl), cold dipped; boiled twenty-two minutes in 500 cc. hot salted dis- tilled water (1.5 per cent NaCl). Weight (cooked), 67 grams. Wa- ter boiled away quite extensively. grams 12.0 13.0 12.0 gram- calories 3682 2835 3117 gram- calories 442 368 374 kilo- caiories 201 167 170 per cent 43 53 Carrots, II. Purchased April, 1917. Mature, pared, and sliced crosswise, unless otherwise designated. (Wilted somewhat.) C. II, 3 84 grams vegetable cooked thirty minutes in 500 cc. boiling distilled water. Weight, after cooked, 93 grams. Volume of water at end of process not observed. 9.29 3720 346 157 56 C. II, 4 18 grams vegetable (one fourth carrot sliced lengthwise) cooked thirty minutes in 500 cc. boiling distilled water. Weight, after cooked 30 grams. 15.44 3724 575 261 26 Omit word "cooked" throughout, in reading column headings, for this sample. 1919] CHANGES IN FOOD VALUE OF VEGETABLES 27 TABLE I— Continued < z a < H H Q w a a 2 K a a !i >-) U^> uu^ 2 H H 0, < fe d ^ fc. Hi S H o < < o <: < M SERIAL NUMBER MANIPULATION < > > Q < h) « > n 5 S w" q o Bi > M 5 oi W A. o o « 2 S w S P, %o >j w w •-) H S ►J o S>o 3>B. <>P, 5" Carrots, II. (Continued) grams gram- calories gram- calories kilo- calories per cent C. II, 6 71 grams cooked vegetable which came from steam pressure insti- tutional cooker. Pared and sliced crosswise before cooking as usual. Weight, before cooking, unknown . f 7.58 3638 276 125 65 Carrots, III. Purchased May, 1917. Small, young, pared, and sliced crosswise C. Ill, 1 C. Ill, 2 C. Ill, 3 Uncooked.* 54 grams vegetables boiled in 500 cc hot distilled water for twenty- three minutes. Weight, after cooked, 57 grams. 62 grams vegetable steamed thirty minutes over 1000 cc. water. Weight, after cooked, 57 grams. 11.6 7.002 11.78 3597 3776 3646 418 265 416 190 120 189 37 0.95 Carrots, IV. Purchased January, 1918. Medium size, pared, and sliced as described C. V, 1 C. IV, I Uncooked.* (Control for C. IV and C. V.) 39 grams vegetable cut into length- wise slices, 10 grams each; blanched in 500 cc. boiling tap wa- ter, five minutes. Weight, after blanched, cold dipped and drained, 36 grams. 10.8 6.885 3618 3788 391 268 177 118 33 * Omit word "cooked" throughout, in reading column headings, for this sample. t Steam cooked vegetables usually lose weight in cooking, but it may be that these pieces were so situated that they took up some water (condensed steam) which washed over them. In calculating this sample, the raw weight has been assumed to be identical with the weight after cooking. If the weight of raw vegetable was greater than the weight cooked, then the cooking loss is still greater than here calculated; if less, then the loss would be somewhat less. 28 THE JOURNAL OF HOME ECONOMICS [April TABLE 1— Continued SERIAL NUMBER MANIPULATION < s s Q a H o a H «i: W H « (4 H ta « H U « H O "[^ ?^2S 823 a « o < w w fe h) & o ;S Swg Www o < < w w Ij w < > p (/ fc- ►J H O < Hi a w 2 5 3«" > » 5 « w »< o o o o o « o o « S w o g > c^ •-) M H < > fti Carrots, IV. (Conlinutd) C. IV, 3 C. IV, 5 C. IV, 6 34 grams vegetable cut lengthwise into strips of 10 grams each; cooked twenty-five minutes in boiling tap water, 500 cc. Weight, after cooked, 28 grams. Water cooked down to 180 cc. at end of cooking period 72 grams vegetable cut lengthwise into 7 strips laid on wire gauze screening, autoclaved fifteen min- utes at 15 pounds; total length of time in autoclave, thirty-seven minutes. Weight, after cooked, 55 grams. 82 grams vegetable cut crosswise into 1 5 slices, autoclaved over wire gauze in same cooker and at same time as above. Weight, after cooking 61 grams. Surface ex- posed, considerably less than in C. IV, 5. grams 5.027 8.714 8.834 gram- calories 4035 3603 3598 gram- calories 203 314 318 kilo- calories 92 142 144 per cent 48 20 19 Carrots, V. Purchased January, 1918. Medium sized, pared, and sliced crosswise C. V, 1 C. V, 2 C.V, 3 Uncooked.* 46 grams vegetable put into 500 cc. salted boiling tap water (1.5 per cent), cooked thirty-sLx minutes. Weight, after cooked, 32 grams. 51 grams vegetable put into 500 cc. unsalted boiling tap water, cooked thirty-six minutes. Weight, after cooked, 43 grams. 10.8 3618 391 177 12.4 2036 252 115 5.945 3725 222 101 35 43 'Omit word "cooked" throughout, in reading column headings, for this sample. 1919] CHANGES IN FOOD VALUE OF VEGETABLES 29 TABLE 1— Concluded SERIAL NUMBER MANIPLTLATION > o S Q Q H a o H ? z < H w a H M n 12 H o « w o < ti o < ri W O Hi w O Hi w S gR (J a is o . < W H t. i-I 5: h J 5= ■^ < H H H i-l !4 < > 1-1 Id o f2w " O < < < 3 9 > B 5 Www 5 2 w ■< g S h O 0- H a, O O 0! O O OS «^B d £• H W W >J w w 3® g>». l_ o fa SS o o d o Carrots, VI. Purchased November, 1917. Fairly large, juicy; pared, and sliced crosswise C.VI, C. VI, C. VI, 3 Uncooked.* 700 grams vegetable blanched six minutes in about 5000 cc. boiling tap water; cold-dipped, packed tightly into quart glass jar; spaces filled with boiling water, cover and rubber gasket adjusted; jar set into boiling water bath covering it. Time of process, two hours. Water bath boiled away some- what, jar lost water, 2 to 3 inches space (and partial vacuum) above level of juice in jar when cold. Contents when opened, 699 grams of cooked and drained carrots, 283 cc. juice. Duplicate of C. VI, 2, from different jar, 700 grams raw carrots; cooked and drained, 672 grams, 300 grams (290 cc.) of juice. 11.56 9.911 8.024 gram- calories 3643 3546 3802 gram- calories 421 351 305 kilo- cslories 191 159 138 per cent 18 28 *Omit word "cooked" throughout, in reading column headings, for this sample. It is, however, the more soluble, rather than the difficultly soluble or insoluble carbohydrates and salts, which are the measure of available food; therefore the food losses exceed rather than run below the per- centage here stated. 3. The "blanching" process as ordinarily used in home canning, causes losses of 8 to 15 per cent (Peas II, 2, 3, 4; Aspar. I, 2; Spin. I, 2; Brussels sprouts I, 3; String beans, 1, 2, 3) and 27 to 33 per cent if vegetables are peeled and sHced (sliced parsnips, P III, 4 and 5) . These peas were blanched for 6 minutes, the string beans and carrots for 5 minutes. The peas might have received a somewhat shorter blanch (2 to 4 minutes), which would reduce their loss somewhat, but not propor- TABLE II Losses in mineral salts due to cooking Asparagus II, 1, raw Asparagus II, 2, blanched five minutes. Beans, String, S. B. Ill, 1, raw Beans, String, S. B. Ill, 2, boiled thirty minutes Brussels Sprouts, I, 1, raw Brussels Sprouts, I, 2, blanched five minutes.. Brussels Sprouts, I, 3, boiled twenty-five minutes Cabbage, I, 1, raw Cabbage, I, boiled thirty minutes tap . Carrots, II, 5, raw Carrots, II, 1, boiled thirty minutes. Cauliflower, I, 1, raw Cauliflower, I, 2, boiled fifteen minutes Cauliflower I, 3, steamed twenty- five minutes. Onions, I, 1, raw Onions, I, 2, soaked twelve hours. Onions, I, 3, raw Onions, I, 6, boiled forty minutes whole . Parsnips, III, 3, raw Parsnips, III, 4, boiled three and one-half min- utes Parsnips, III, 5, boiled seven minutes Peas, II, 1, green, raw Peas, II, 2, boiled in distilled water, six min- utes Peas, II, 4, boiled in tap water, six minutes. . . . Spinach, I, 1, raw, unwashed* Spinach, I, 2, steamed seventeen minutes. Spinach, II, 1, raw, washed* Spinach, II, 2, steamed twenty-five minutes... Spinach II, 3, boiled twenty-five minutes WEIGHT 1 00 GKAMS VEGETABLE AFTER COOKED AND DRIED 7.590 7.597 9.863 6.646 17.055 14.31 10.96 7.786 5.835 14.21 8.74 14.24 10.26 14.36 8.075 7.394 11.89 6.868 38.11 26.93 25.26 26.16 21.99 22.6 8.636 8.180 8.235 7.450 5.200 ASH IN DRIED VEGETABLE MATERIAL Per cent 8 ^.^ 7.86 5 . 897 5.479 6.50 6.244 5.10 7.27 7.18 10.51 6.80 9.04 6.91 8.13 3.17 3.07 4.70 4.28 4.84 3.84 3.42 3.31 3.27 3.25 23.66 24.2 24.34 16.55 12.42 ASH CALCU- LATED TO FRESH WEIGHT per cent 0.63 0.60 0.58 0.36 1.11 0.89 0.56 0.57 0.42 1.46 0.59 1.29 0.71 1.17 0.26 0.23 0.56 0.29 1.85 1.03 0.86 0.87 0.72 0.74 2.04 1.98 2.01 1.26 0.67 per cent 38 20 50 26 60 45 9 12 42 54 17 15 2.94 37 67 *The determinations on spinach were made on washed and unv/ashed lots, after reading Rubner's statement (Berl. Klin. Wchnschrft. Apr. 10, 1916) that, owing to the cook's custom of washing spinach on one side of the leaf only, a large part of the "ash" is sand which clings to the leaves. This may have been true of the spinach which he analyzed, which showed half of the dry matter to be ash. 30 1919] CHANGES IN FOOD VALUE OF VEGETABLES 31 tionately to the reduction in time of blanching, since the losses are rela- tively heavier in the earliest moments of the extraction period. (Com- pare Parsnips III, 4 and 5.) String beans, fresh prime stock, are often blanched even longer (3^ to 6 minutes or more) under trade conditions. 4. The losses in blanching might be somewhat decreased by the use of a salted water. In case of peas the loss decreases from 15 per cent in distilled water (Peas II, 2 or 4) to 8 per cent in a 1.5 per cent salt solution (Peas II, 3); for string beans, from 15 per cent for dis- tilled water (S. B. I, 3) to 13 per cent for 0.25 per cent salt solution (S. B. I, 2) or 10 per cent loss on 20 minutes' boiling in 0.4 per cent salt solution (S. B. II, 3). Stronger solutions could well be used when short cooking is given. Here a slight increase in strength of salt solution has made more difference in amount extracted than has a fourfold in- crease in time. In case of longer boiling "until tender," the decreases in fairly comparable samples are: Parsnips, from 31 per cent in tap water (P II, 7) to 23 per cent (P II, 6) in 0.7 per cent salt solution; white turnips, from 24 per cent (T I, 1) to 2 per cent (T I, 2) in 1.5 per cent salt. See also Cabbage, 1, 3;, and 4. Boiled in a small amount of salted water, or in water which eventually boils down to a small amount, the losses are still smaller. See C VI, 2 — only 18 per cent loss, though they went through a 6 minutes' blanch before this long cooking period of several hours very near the boiling temperature. See also Peas I, 2, in which the salted water was entirely taken up; they apparently show less than 1 per cent loss, though they went through a 4 minutes' salt blanch before cooking. The difference in extractive power between distilled and tap water (Lake Michigan at Chicago), is evident but not great enough to be of practical significance (Peas II, 2 and 4). In comparing Onions I, 2 and 4, it should not be too hastily concluded that the effect of salt has been to increase the extraction. Unfortunately O I, 4 contains only the upper half of the bulb, and this may easily have been before soaking considerably lower in sugar than was the lower half (0 I, 3) from which the amount of extraction is estimated. 5. Cooking losses are, of course, still further decreased by cutting the vegetable into large instead of into small pieces, particularly so if the cut runs parallel with fibro-vascular bundles rather than across them. Compare P II, and P III, 2, with P III, 4 and 5; 3| to 7 minutes extract as much from the cross-cut parsnip as do 30 minutes (or 27 minutes) from the lengthwise-cut parsnip. 32 THE JOURNAL OF HOME ECONOMICS [April 6. Steaming, if properiy performed, results in losses so small as to be ordinarily quite devoid of significance (Caul. I, 3; Spin. I, 2, table II, — ^but see also table I; Cab. I, 2; S. B. II, 4; C III, 3); this may be the case, even when the temperature is so high and the process so greatly prolonged as to result in serious detriment to flavor, as is possible in high pressure cooking (S. B. II, 2). However, this considerable period of steaming at higher temperatures than the boihng point is likely to extract a considerable amount of soluble material, when this is abun- dantly present (C IV, 5 and 6). Again, if the arrangement is such that steam condenses and water washes down over the heated vegetable tissue, the losses may be as great as in any other possible method of treatment (C II, 6); this is true in steamers of the household type as well as in those of institutional type, as those who may have seen the yellow water under steaming squash or pumpkin can testify. 7. It is obvious that extraction of soluble constituents will depend largely upon length of the period of cooking (e.g., P III, 4 and 5, C I, 4 and 5), and upon relative proportions of water and vegetable (e.g., compare P II, and P III, with P IV), especially as the cooking process nears its end and the water boils away more or less rapidly according to the rate at which heat is applied; e.g., compare C I, 1 with C I, 6 (differing amounts of water at close). These two factors are widely variable and exceedingly uncertain, in ordinary household practice, as is also the relative surface exposed, when the vegetable is cut or pared. Add to this the varying degree of extraction possible with different vegetables, owing to the different proportions of readily soluble carbo- hydrate and salts which they contain, and it will be seen that there is no possible universal factor which can be applied, in dietary calculations, to show losses of fuel or other values of foods, incurred in cooking; or none which can lay claim to the sHghtest approximation to accuracy upon all occasions. Such statements as, "Boiling extracts three-fourths of the iron in spinach," or "one-fourth of the salts of potato" or "two-thirds of the sugar of carrots" may fit one instance precisely and yet be far from the truth in another. Naturally these generalizations do not apply to the "conservation" methods of cooking (steaming, baking, boiling in jackets, utilization of vegetable stocks as soups or sauces) where the loss is reduced to practi- cally nothing at all. One of the best of these economical methods is that in which the edible portion of the vegetable is cut fine and cooked 1919] CHANGES IN FOOD VALUE OF VEGETABLES 33 in a small amount of water or milk which is almost entirely absorbed, and which consequently is served with the vegetable. This cooking may be done directly over the flame, or on a hot plate of asbestos or heavy metal, or on the back of the range, or in a double boiler. The hard, sweet core of young cabbage heads, heated 15 to 30 minutes in this fashion, is a very different product from that which has been long boiled in water. The same thing is true of the outer stalks at the base of a head of cauliflower, which, though often discarded as refuse, ap- parently may have a higher food value than the fleshy part, and one as easily extracted as that of the fleshy floweret which is usually eaten. (See Caul. I, 1 and 4.) It is also evident that preliminary soaking in cold water, or starting the cooking process in cold instead of in boiHng water, will greatly in- crease cooking losses by prolonging the period of cooking, and by adding the extractive power of the water at lower temperatures to that at boiling temperature. (C I, 4 and 5; O I, 2 and 4.) 8. When steamed, all vegetables lose weight, mostly because of evaporation of water. (C III, 3; C IV, 5 and 6; S. B. II, 4; Caul. I, 3 and 6; Cab. I, 2; Spin. I, 2 and II, 3.) When boiled in an open dish in excess of water, a starchy, or dry, or wilted vegetable, or one with air spaces which can become waterlogged, or one unusually high in crystal- loids (salts and sugars, which increase osmotic powers of the tissues), will take up water enough to gain in weight, even though it may have lost considerable amounts of solid matter (Pars. Ill, Car. II, green peas, string beans, Brussels sprouts). But a juicy or watery vegetable, or one protected by impermeable cuticle, loses water as well as solids, even when boiled in water, due no doubt to disturbances of colloidal systems within the tissues by the application of heat. The ease with which juice flows from heated meat or fruit (or from heated proto- plasmic structures seen under the microscope) is a matter of com- mon observation, as is the dryness of boiled meat in comparison with properly roasted meat. Again, a sound potato, boiled in its unpierced jacket, almost always loses a little in weight; and often a slight ac- cumulation of water may be perceived underneath the skin, before it has succeeded in escaping. Vegetables cooked in salted water (see Peas, Turnips, Cauliflower, Cabbage) tend to lose weight more strongly than do those cooked in distilled or tap water; the strong solution out- side the tissues draws water out of them by osmosis, as does salt on meat, or sugar on berries. Soaking vegetables in cold distilled or tap water, 34 THE JOURNAL OF HOME ECONOMICS [April however, swells them but does not cause heavy loss of soHds (Onions I, 2), since the protoplasm is not killed and is able to retain its solutes to considerable degree for a time, at least before bacterial action shall have made itself felt. It is evident, then, that a comparison of weights before and after cooking can give no information as to the extent of loss of solids. Yet we sometimes hear the commercial canners using this line of argument, in denying that losses take place in blanching. But the circumstance that young peas may show no increase in weight during blanching, does not prove nor indicate that no loss of salts, sugar, or protein of the pea, takes place. 9. It may be readily observed in case of a well-packed jar that the processing method used in home canning of vegetables or fruit sub- merged in a boiling water bath results in the presence of a mini- mum amount of juice in the jar. In Cab. II, 2 and 3, the combined weight of vegetables and brine or juice is less than the original weight of raw vegetable. In S. B. II, 5, there is an excess of water, due partly to the fact that there were not enough beans on hand to fill the jar, but also to the different method of canning, that of cooking with pressure steam while the jar is completely sealed, thus preventing any escape of liquid.) This small amount of juice is a very different condition from that which sometimes has obtained in commercially canned goods. While due chiefly to differences in closeness of pack, it is also due to the fact that during the two or three hours of processing in boiUng water bath the contents of the partially sealed jar are continually giving off steam to the water bath (even when the bath completely submerges jar and cover), or to the atmosphere above it, in case submersion is incomplete. The constantly escaping stream of air and steam bubbles, over or under the rubber gasket, can readily be observed during the entire period of processing. When the jar is lifted out of the bath, presumably the operator at once makes the seal tight; and, even though the seal should perhaps not chance to continue absolutely tight during the process of cooling, there is more or less vacuum remaining until the jar is opened, in a successful product which "keeps" well. The smaller amount of water or juice in the jar, then, may have only a moderate or even a rela- tively low extractive value, in spite of the long boihng period. Further- more, the flavor of this juice is good, and it can be served with the vege- table, which is often not the case with jars or cans containing a large amount of watery juice in metal containers. 1919] CHANGES IN FOOD VALUE OF VEGETABLES 35 We may conclude, then, that the methods for home canning, as prac- ticed in following the directions issued by extension workers in agri- culture and home economics, U. S. Dept. of Agriculture, compare very favorably with other methods of canning as to effect upon nutritive value of product, provided pains he taken to reduce losses from the blanching process. This precaution is particularly important in case of young tender peas, carrots, corn, vegetables of the cabbage and onion families, and any vegetables pared and cut or broken into shreds or short lengths before blanching. It is clearly of the greatest importance (as has been so often dem- onstrated) that the juice of vegetables escaping into cooking water should be conserved, and methods of making this juice palatable de- serve the cook's attention. If onions must be boiled in excess of water to reduce their flavor, at least this water may be concentrated by boil- ing until it can furnish a suitable flavor for milk or cream soups, or broths or sauces, for vegetable or meat hash or stew, or loaf or croquettes. A great deal of trouble has been taken to discover the best method of cooking each cut and kind of meat so as to secure optimum results. It is time that vegetable cookery received a larger share of attention from the average woman. The problems which arise in the cooking of each kind of vegetable should be given attention on their own merits. General directions for the cooking of the different classes as underground tubers and root stocks, green vegetables, etc., are exceedingly useful, yet further details appropriate to each occasion should not be forgotten. Here is one small illustration concerning a point too often overlooked: When some parts of a vegetable are very much tougher and more re- sistant than others the two should not as a rule be cooked together until the toughest part is "done," for this is likely to destroy the more delicate flavor of the tender parts. We do not expect to cook the ten- derloin strip and the tail piece of a porterhouse steak successfully by the same process; or if this is done, the tougher pieces are finely chopped before cooking, and this reduces the extra time needed. Often the same method of procedure can be used with vegetables. It is a clear waste, in time of high prices, to throw away the leaf petioles of kohlrabi or cauliflower, the centra) core of young cabbage or parsnips; very Ukely these have as high a soluble carbohydrate value as does the remainder of the vegetable. If grinding or chopping be substituted for a portion of the cooking process, or if these more resistant parts can be given a separate long slow cooking in fireless cooker or double boiler, then the palata- 36 THE JOURNAL OF HOME ECONOMICS [April bility of the combination may be greatly enhanced, and its nutrients conserved. One word remains to be said, from the standpoint of modem theories of nutrition. Indications are not lacking that we may at last come to believe that spring "rheumatism" and pallor and skin disturbance; those cases of pyorrhea which are akin to what has sometimes been called scurvy, low resistance to many winter infections, and that common evil, constipation, can conceivably be favorably affected by such an increase in the diet of these vegetable salts, acids (and possibly " vitamines") , as occurs when we change from a winter diet of canned and heavily extracted vegetables to a spring diet of fresh or lightly cooked ones." At least it seems worthwhile to take measures to prevent our foods from being de- pleted of these vegetable extracts which should no more be thrown away than should the drippings of fat and juice which cook out of meat. Yet many a woman, who would be shocked at the idea of throwing away a meat broth, does not hesitate to discard a much more highly nutritious vegetable broth. Since the above words were written a study has appeared (Jour. Amer. Med. Assn., March 30, 1918) which exactly illustrates the point in view. Dr. Hess, a notable authority on scurvy, rickets, and other phases of pediatrics, considers it likely that the rickets, so commonly occurring among negroes in New York City, may have some relation to the lack of fresh vegetables and fruits in the diet. He finds that these emigrants from the West Indies never have the disease while living where the diet contains large amounts of fresh vegetables and fruits. SUMMARY 1. Boiled vegetables may lose as low as 15 per cent or as high as 60 per cent of their fuel value, according to the method of manipulation. (Those vegetables which are cooked within their own heavy, intact jackets, such as unpeeled Irish potatoes and beets, will of course lose much less even than this minimum.) The extent of the loss depends upon the amount of soluble carbohydrate and protein present in the vegetable tissues, as well as upon the manipulation. 2. Losses in salts and nitrogen often, if not always, sHghtly exceed the fuel or caloric losses. 2' It is of great interest and pleasure to the first holder of the Ellen H. Richards Fellow- ship, at the University of Chicago, who writes these lines, to learn that this doctrine was vig- orously propagated by that wise and far-seeing woman. 1919] CHANGES IN FOOD VALUE OF VEGETABLES 37 3. Blanching for 5 or 6 minutes causes losses of 8 to 15 per cent (salts, fuel value). Peeled and sliced vegetables lose twice as much. 4. Salting the water (1.5 per cent solution, or about 1 tablespoon to the quart) decreases the losses in fuel value due to boiling. 5. Cutting the vegetable crosswise instead of lengthwise, or into small instead of large pieces, increases the losses. 6. Steaming usually cuts the caloric losses down almost to zero; also the salt losses, except in case of leafy tissues which expose a very large amount of surface to the action of the condensing vapor (cabbage, spinach) . However, if conditions within the steamer are such that water washes down over the vegetable mass, steaming may cause very large losses. Particularly is this the case with pressure steamers. 7. The two factors most potent in causing variations in cooking losses are varying lengths of time of cooking, and varying amounts of water used in proportion to mass of vegetables to be cooked. 8. Steamed vegetables always lose in weight. Boiled vegetables may gain in weight because their intercellular spaces take up water at the same time that they are losing heavily in mineral salts and soluble carbohydrates and proteins. 9. Home canning often results in a maximum amount of vegetables and a minimum amount of watery juice in the jar, partly because of close packing and partly because Hquid is driven off during the period of processing v>'ith seal only partially made. This relatively small amount of juice in the jar is a great advantage from the standpoint of true nutritive economy, — whatever may be its effect upon ease of steriHzation of the vegetable mass. LIBRftRY OF CONGRESS 014 420 188 7 •