B
A
FIGURE 1. COMPARATIVE GROWTH OF RATSON CANXED AND
C ON
RAWFOODS
A . Lower group received oanned foods, upper group raw foods: t h e parents of t h e t w o litters were litter mates; both litters were born t h e s a m e d a y a n d are 21 days old. B . R e resentative animals from t h e two litters in A , below when 21 a n d above when 45 days old; the animal receiving canned foods is at t h e right above a n t a t t h e left below. C. Representative animals from t h e t w o litters in A , 90 days old; upper females, lower males; t h e animal receiving canned foods is at the right above a n d a t the left below.
Vitamins in Canned Foods XIV. Calcium and Vitamin D in Foods E. F. KOHMAN, N. H. SANBORN, National Canners Association, Washington, D. C., W. H. EDDY, AND CELIAZALLGURIN,Teachers College, Columbia University, N e w York, N. Y. relatively short cooking period in a minimum amount of water. The canned foods were likewise purchased through regular commercial channels and did not therefore represent the same raw material as the raw and home-cooked foods. As in the previous experiment, a group of four or five foods was chosen for each 5-day period to procure a balanced diet. The same group was used concurrently in the three diets. In this way a number of types of meat, a few marine products, and most of the common vegetables and fruits were fed in the course of the experiment. The raw and homecooked foods were seasoned with salt to correspond to the salt in canned foods. The three diets-raw, home-cooked, and canned foodswere fed both without and with milk. Raw milk was given to the group of rats receiving the raw foods, freshly boiled milk to the @up receiving home-cooked foods, and evaporated milk to the group receiving canned foods. The experiment has progressed through the fifth generation for the animals receiving no milk. While the experiment in which milk was fed was started at a later date and only the second generation has been reached, the data are clearly significant. EXPERIMENTS WITH RAW, HOME-COOKED, AND CANNED Each group of animals receiving, respectively, raw, homeFOODS cooked, and canned foods without milk has produced approxiA preliminary report (2) has been made of an experiment mately 450 young. The weights at birth and a t weaning in which rats were reared through ten generations and guinea were somewhat higher for the group receiving home-cooked pigs through eight generations exclusively on canned foods. foods than the group receiving raw foods and materially The animals performed so excellently that it was considered higher for the group receiving canned foods. These weights worth while to find an explanation for the results. An ex- tend to be smaller as the number per litter is larger. The periment was therefore inaugurated in which three groups number per litter was appreciably smaller in the group on of rats, consisting of three pairs (male and female) per group, the raw foods. The number of deaths between birth and were f e d - o n e group on raw foods, another on portions of weaning time among the animals receiving raw foods was those same raw foods after so-called home cooking, and a considerably the greatest, and somewhat greater with the third on the same combination of similar foods that were animals fed home-cooked foods than for the group on canned. The raw foods were purchased in the New York canned foods, Growth after weaning was very comparable on city markets and portions of them cooked according to mod- the raw and home-cooked foods. Growth on the canned foods ern directions by home economics cooking schools-i. e., a was decidedly better. These data are summarized in Table I.
S
TATEMENTS, unaccompanied by concrete evidence, contending that a certain amount of raw food is a prerequisite to optimum well-being, are common. There is the implication that cooking, and particularly canning is detrimental to nutritive values. Market produce, frequently designated “fresh” in contradistinction to canned foods, is often given superior nutritive rating, without substantiating evidence. Vitamin knowledge has emphasized the nutritional importance of the seasonal products that either must be transported from tropical climes or canned in season to assure a constant supply. Data as to the nutritional efficacy of products so supplied are therefore in order. There is an impetus to the addition of some form of vitamin D to foods. Whether there is any benefit from this beyond the period in which rickets appears in children is questioned by many. It is even contended by some that harm may result. An intelligent approach to the subject demands information on what available foods naturally supply as an antirachitic. This paper is a presentation of data that throw light on the questions raised above.
758
July, 1934
INDUSTRIAL AND EIVGINEERIXG
CHEMISTRY
759
TABLE I. REPRODUCTIVE RECORD OF RATS ON RAW,HOMEIt has been established that there is a marked difference COOKED, AND CANNED FOODS in the bone ash of the three groups of animals. Bone ash FOOD-determinations were made on a considerable number of each HomeRaw cooked Canned group a t 60 and 90 days of age. The alcohol- and etherTotal no. of litters 67 51 60 extracted dried tibia was used. A summation of the results Litters dead before weaning S 3 3 59 48 57 Litters weaned, age 21 days is found in Table 11. The data pertaining to animals re 482 405 476 No. of young at birth ceiving no milk represents the second to the fifth generation, 424 370 352 No. of young weaned 12.0 22.2 12.4 Young dead before weaning, % inclusive, whereas only second-generation animals receiving Av. no. per litter a t birth 7.10 7.94 8.00 4.68 4.96 5.28 Av. weight of young a t birth, grams milk are represented. 20.5 23.0 27.3 Av. weight of young when weaned, grama If cooking increases the availability of calcium, one would expect a t least as complete availability of calcium from homeWhen the experiment was inaugurated, litter mates were divided between the raw and canned-food diets, although cooked as from raw foods. The modern, short cooking pethe home-cooked-food experiment was started somewhat riod prescribed for vegetables and fruits should be recoglater as an afterthought. One pair of animals on raw foods nized as being a relatively mild heat treatment compared with and one on canned foods were obtained by mating females the process necessitated for sterilization in canned foods. from one litter with males of another litter of' the same age It should be borne in mind that for canning, such products and it so happened that both females gave birth on the same as peas, lima beans, green and wax beans, etc., are harvested day, the one on canned foods having 8 young weighing 45 in a distinctly less mature condition than for market produce. grams and the one on raw foods 9 young weighing 40 grams. Moreover, these vegetables as well as others such as spinach, Their average weights in grams a t varying intervals t h e r e turnip greens, cauliflower, carrots, etc., which are among the chief sources of calcium in the absence of milk, are held in after are as follows: the raw state after harvesting for materially longer periods 25 DAYS 45 D A Y B 60 D A Y B 90 D A Y S as market produce than is the case when used for canning. Litter on canned foods 27 60 78 138 Since this condition is conducive to toughening of the vegeLitter on raw foods 19 37 56 86 table fiber, the absorptive attraction for calcium may be afFigure 1 represents these two litters. f ected. These results might be explained by easier digestibility 11. AVERAGEBONEASH OF RATSON VARIOUS DIETS and more complete assimilability of canned foods, owing to TABLE the thorough cooking they receive, a suggestion made in Av. Av. WT. WT. Av. the previous report ( 2 ) . Under ordinary circumstances NO. OF OF OF BONB DIET ANIMALS -4QE ANIMAL TIBIA ASH such a condition might be expected to be studied by a meDaus Grams Gram % ,tabolism experiment. Due consideration has been given to Raw 73 0.0517 45.5 22 60 71 0.0508 39.1 such a procedure but the grinding and maceration necessary Home-cooked 35 60 49.9 24 60 89 0.0644 to secure a homogeneous food intake may hare a more far- Canned 19 00 125 0.1036 53.4 Raw 47.0 125 0.0943 reaching effect, owing to abnormal enzymic activity set up Home-cooked 15 90 15 90 149 0.1187 55.7 by maceration of raw foods, than the thorough cooking re- Canned Raw + milk 4 60 108 0.0803 58.3 ceived by canned foods. Finely grinding may also materi- Home-cooked + milk 4 60 101 0.1064 57.2 Canned + milk 4 60 160 0.1389 59.2 ally affect the digestibility of both a raw and a cooked food. An attempt was made to perform a metabolism experiment, I n connection with the relatively poor performance of the using but one food with the hope thus to secure homogeneous consumption. I n this experiment peas were fed in the raw animals on home-cooked foods, certain speculations based state and also in the canned form. A homogeneous food on related facts are suggested. I n two different experiments intake, however, was not secured because certain animals representing two lots of peas, there were extracted by cookseemed to prefer the cotyledons, leaving the hulls, whereas ing 200 grams for 10 minutes in 1500 cc. of distilled water, respectively, 10.7 and 10.9 per cent of the calcium. If an other animals did just the reverse. Other lines were therefore pursued in a n attempt to afford 8 per cent salt solution was used, there were extracted, rea n explanation for the above results. It was observed that spectively, 39.5 and 48.1 per cent of the calcium. The sodium the caeca of the animals receiving the raw foods nvere defi- chloride thus performs as in a zeolite water-softening system. The salt used for seasoning in the home-cooked foods unnitely enlarged in comparison with the animals receiving canned foods. Lack of accurate means of measurement is, doubtedly played a similar role, since there was little time however, a handicap, and there is a lack of basis for evalu- after cooking for' diffusion of the salt into the vegetable tissue and thus permitting reabsorption of extracted calcium. ating the significance of such differences as may be noted. That vegetable cellular tissue has an absorptive power Moreover, the salt, being concentrated in the cooking water, for calcium is an established fact. Morgan (3) demonstrated may have resulted in lack of consumption although the cookthat regenerated cellulose in the diet increased fecal calcium ing water was fed with the vegetable as was the liquor of the markedly and phosphorus slightly. Unpublished data canned foods. Also, the condition of the animals on the from this laboratory show that raw peas absorb appreciable home-cooked foods suggested other dietary effects, possibly amounts of calcium from water within a few seconds. It involving vitamin B. It is hoped that work under way will is a recognized fact in the canning industry that calcium from throw further light on this question. hard water used in canning peas is absorbed by the skins and VITAMIND IN ORDINARY FOODS thus causes toughening to the extent of lowering the quality Since vitamin D is involved in bone formation, the quesof the peas. There is evidence also that the calcium from the cotyledons of canned peas migrates during storage to the tion arises as to whether i t may be a factor in the above reskins and thus causes toughening to the extent of lowering sults. Vitamin tables, listing and rating foods with reference the quality. It is reasonable to assume that the thorough to their vitamin potency, generally mention only vitamins cooking which vegetables receive in canning might lower A, B, and C, and no reference is made to vitamin D. This the absorptive effect of the cellular tissue for calcium, thus might suggest the absence of vitamin D in these foods to one resulting in greater availability and manifesting itself in the not trained in the vitamin field. Most common foods, when bones. subjected to the prescribed vitamin D test, have been gen-
--
INDUSTRIAI,
760
A N D E N ( ; 1 N E E R I N G C H E &.II S T H Y
wdly r:tted as practically devoid of vitamin 11. Ijecaiise d t,lie riatiire of the test, Iiowever, foods so t tute ouly a s i u a l l portion of the entire diet. rnin 1it.erature mould lead otic til the coriclusiixl that ordinary foods have so lidtle vitamin I1 as to be of practically little
vahe. It is diiiicult, hu cr, to reconcile such a condition with refererice to a dietary necessity that has been recognized only within rccriit years. The possiliility that modern living couditirms m a y r e -
accrriniilat~ingto the effect that tlie rays of the w n dnd T l t i L nitn I) s t c 11ot an evact equnalent I t qeerned more logical to a55iiine that ordinary foodz irughht coiitwn more or less vitnniin 11
52
59 8
i i
25 0
phosphorus ratio ranging from 4.062 to 5.198. It was decided therefore to feed tliis mixture of five cantied foods witli a 4 to 1 and also with a 6 to 1 calcium to phosphorus ratio, both witli arid without cod liver oil. (:alcium lactate was added bccause it could be dissolved in the liquor of the caimed vegetables and thus easily incorporated into the ground rnixture or the five canned foods. T a l k I V gives tlic analysis of tlie diet made by mixing in iluplicate one can
xn
54 1
48 5'1 K
60 5
66 3 %3
25 $9 4
62 57 9
d u c e respectively a 4 to 1 and a G to 1 calciuin t o phosphorus ratio. Table V giver tlie comnpositiun of the Steenbock diet uzed m companw n mth t h e abovr tnixtiirr of canned
bl
iood..
ordinary food;. In order to arrive a t a workiub. coudition for such a deterniination, a mixture of five c a h x l foods--tianrely, meet jmtatoes, spinach, peas, carrots, arid roast bccf -WBS chosen. To the finely ground and homogeneous mixture, consisting of one cau each of the aho1-e-mentioned foods, was added celcium salts to produce the desired ealciimi to phosphorus ratio. Thc cornposition of two lots of the five oanned foods iised is rcprescnted in Table 111. Ilolnics and Tripp ( 1 ) have shown that in seven batches of the Steenbock diet, consisting of yellow corn meal 76 per ccnt, wlieat gluten 20, calcium carbonate 3, and sodium chloride 1, there resulted a phosphorus content ranging from 0.270 to 0.317 per cent or 511 average of 0.289 per cent on a dry liasis. Tabla 111 shows that the mixture of the five catiiied foods chosen resiilied in a very comparalile phosphorus content. TaBLx:
Vol. 20, No. 7
111. C ~ U P ~ S E TOFI ~MIXED N Net
TABLE
Iv.
~ I l M P O S l T l o NOF MIXED CANNED FOODS AX71ER CIIJM ADDITIONS
S*UP"&
Ch:P 4:1 Duntionteasiis Ca:P = 6:l DUpiiOuteeenr E
,.
IARLE
v.
(Per cent ou dry basis) Ca P 1.11 0.29 19.4 1.17 0.28 19.4 1.74 0.28 20.4 1.04 0.87
So&,"s 19.9
C O R N >I=*&
%
Solids
rmi CANCalcium
Plrasplrorus
Oiom
Gi*".B
-,
lfolrnes atid 'hipp, in tlie seveii batches of tlic Steenbuck diet for \vliicli they present analyses, found a calcium to
N
Cd'
4.02 4.28 4.30 4.21
3.8:l 4.2:I 6.9:l 6.33
CAI,-
CoMPosrTloN ox1 INaneDrsXrs "I STliENBOCK UlET
C l N N B U FOODS
Grams
--CoNreNTn
Qmm~
ifmixed canned foods (lot I .) with added calcium lactate irr two amounts, both nithout a i d xith cud liver oil (2 drops, G days per week per rat). It is apparent that the addition of cod liver oil to the diet had no effect on the bone ash as it does when added to the Steeubock diet..
M"int,uis
Cal
