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Vitamins in Canned Foods' 11-The Vitamin C Destructive Factor in Apples By E. F. Kohman, W. H. Eddy, and Victoria Carlsson KATIOKALCANNERS ASSOCIATION, WASHINGTON, D. C.,
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T E A C H BCOLLEGE, R~ COLUMBIA UNIVERSITY, NEW YORK,N. Y.
gradually lose their antiHAT vitamin C is When apple sauce is made, when apples are baked, or when apples scorbutic Potency, whereas very susceptible to are canned without a n y special treatment, the vitamin C is practioxidation has been cally all destroyed. stored canned apples undemonstrated by a number d e w no demonstrable deWhen apples are canned after covering them long enough with salt terioration within the time of investigators. It is also solution to enable the respiratory process to use up all oxygen in them, cornmonlY stated that vitathey may be canned without apparent loss of vitamin C, irrespective min C is lost t o such an exof the time of processing within the limits used in commercial pracEXPERIMENTAL tent duling the Process of tice. This method is common practice in the cornmcrcial canning of app[es. cooking and canning foods, The experiments divide particularly v e g e t a b l e s , When apples are held in cold storage from October to March there themselves into two series that they are no longer is a marked deterioration i n the vitamin C content. in that tlvo lots of apples significant sources of vitaStoring canned apples for 8 months after canning gave no evidence were used. I n the first min c. It iS not UmmmmOll that there was any deterioration in the oitamin C content. to designate the heat in series Albemarle Pippin apples were taken from cold cooking the d e s t r u c t i v e agent. The difficulty of excluding the oxidation factor, known storage in March for canning by the following methods: to be destructive, was recently2pointed out. Until we know (1) S-APPzEs-The apples were peeled and quartered bethe effect of even minute quantities of oxygen or other oxidiz- tween 4 and 5 o'clock in the evening, covered with a 2 per cent salt ing agents it is difficult to est'ablish the effect of heat. More solution, and held at basement temperature until 9 t o 10 o'clock recently3 it was demonstrated that by holding apples sub- the next morning. During this time the oxygen in the apples is consumed by the respiratory process and this is common commermerged in a weak salt solution for sufficient time their respira- cial practice. The salt solution was then drained off, the aptory processes may be employed to deplete their supply of in- ples weighed into No. 2 plain cans (about 11.5 ounces per No. 2 tercellular oxygen in a most efficient manner to avoid corro- can, t h e equivalent of 287 grams of freshly peeled apples), covsion after canning. At the same time attention was called to ered with boiling water, given a 2-minute water exhaust at boilclosed and processed. the possibility of bound respiratory oxygen and that this could ing temperature, SS-APPLES-The method was different from (1) only in also be eliminated by employing the normal respiratory process. t h a(2) t the apples, before filling into the cans, were steamed for This paper is the second of a series of joint researches to 6 minutes t o soften them. It was then possible, without crushestablish to what extent vitamin C is destroyed in present ing t h e pieces, t o p u t into t h e can the equivalent of 435 grams canning methods, the causes underlying this destruction, and of freshly peeled apples. This is commercial "solid packed" to evolve better methods for its preservation. In the first apples. (3) N-ApPms-After being peeled and quartered the apples paper Eddy and Kohman4 showed that about 4 grams of were filled a t once into the can (11 ounces per can) six cans a t a canned cabbage daily per guinea pig were adequate as against time, and subjected t o a vacuum of 650mm. (26.5inches) ormore 20 grams of home-cooked cabbage as found by Eddy and asso- under a bell jar. The vacuum was then released with nitrogen the process repeated two additional times. The bell jar was rec i a t e ~thus , ~ disproving, as far as cabbage is concerned, the idea and moved and the cans filled as quickly a s possible with boiling that vegetables, except when raw, cannot be a rich source of water, and then exhausted and processed as (1). These three vitamin C. Moreover, it was found that 30 minutes a t 127' C. lots of apples were relatively free from oxygen. Analysis showed had no measurably greater destructive action than 30 minutes from 0.3 t o 0.5 cc. per No. 2 can (11 ounces apples). These amounts are within t h e experimental error involved in the method a t 100" C. From that workit wasnot possible to say to what of analysis used and which is described by Kohman and Sanborn.8 this higher vitamin content in canned cabbage was due, (4) A-AppLEs-The apples were peeled, quartered, and whether to a richer concentration in the freshly harvested filled into t h e cans. The cans were then filled with t a p water cabbage, or to the exclusion of oxygen during cooking. In- which had been heated t o 70" C., after which t h e same exhaust dicative evidence was presented to show t.hat cabbage loses and process as in (1) was used. The water was heated only t o 70" C. t o retain the dissolved oxygen. These apples contained its antiscorbutic potency during storage in the raw state, approximately 4.5 cc. oxygen per No. 2 can (11 ounces apples). even though only the inner crisp leaves are fed. (5) 0-APPLES-The treatment was identical with (3) except The experiments presented herein were suggested by studies t h a t t h e vacuum was released with oxygen instead of nitrogen, on the nature of corrosion in canned fruits. This, it has been and t h a t water through which oxygen was bubbled a n hour and was then heated t o 70" C . was used instead of boiling water. pointed is an oxidation process. They add strong evi- which These apples contained approximately 40 cc. oxygen per No. 2 dence that vitamin C destruction is largely anoxidation process, can (11 ounces apples). that vitamin C is little affected by heat per se if this oxidation Each of the five lots of apples canned by the five methods factor is eliminated, and finally they demonstrate a method whereby apples may be canned with no evident loss of vita- given above were subdivided into three sublots, and procmin C. Moreover, they indicate that raw apples in st'orage essed respectively 5,10, and 30 minutes a t 100' C . (212' F.). These temperatures cover the range to which most fruits are 1 Presented before the Division of Agricultural and Food Chemistry a t subjected in commercial canning. A No. 2 can of fruit is the 67th Meeting of the American Chemical Society, Washington, D . C., never processed 30 minutes a t 100" C. (212' F.), but such a April 21 t o 26, 1924. process fairly represents the amount of heat received by the 2 Kohman, THISJOURSAL,15, 273 (1923). 3 Kohman, Ibid., 15, 527 (1923); Kohman and Sanborn, I b i d . , 15, 290 fruit in No. 10 cans. The basal diet used was that of Sherman, (1923). LaMer, and Campbell6 and was fed ad libitum.
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I b i d . , 16, 52 (1924). J . Home Econ., 15, 15 (1923).
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J. Am. Chem. Sac., 44, 165 (1922).
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For canning, Albemarle Pippin apples were taken from cold storage in March and feeding experiments begun within a few days. For the apple sauce and baked apple experiments similar apples were drawn from cold storage about every 10 days and held in an ice box for daily use.
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Controls. Liasal Diet A.
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10 gms. Raw a p p l e s every o t h e r d a y .
CHART1 The broken curves indicate the change from cold storage to early summer apples. Some improvement is evident. SYMBOLS USEDIN CHARTS ds = Died of scurvy Did not die of scurvy do cs = Chloroformed and scurvy found by autopsy cn = Chloroformed but autopsy showed no signs OP scurvy ns No symptoms of scurvy The numbers under these symbols indicate the number of days the pig was on the ration.
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the raw apples received these amounts only every other day -i. e., 5, 6, and 7.5 grams on a daily basis. After feeding the raw cold-storage apples for 20 days, the pigs were losing grovnd so rapidly that they were given instead fresh early summer apples purchased on the open market, because it was evident that these amounts of cold-storage apples would be inadequate. The results of the raw apple feedings are given in Chart 1,from which it appears there is a considerable difference between the stored and the fresh apples in that the pigs showed marked improvement when transferred to the fresh apples. I n all cases, however, the amounts fed were inadequate as an antiscorbutic. No charts are given for the canned apples that were processed for 5 minutes, because the amounts fed were not sufficient to procure protection against scurvy. Hence the results showing the survival period are given in Table I. The results with apple sauce and baked apples are also included. The apple sauce and baked apples were prepared in 'accordance with the method prescribed by the Cooking Department of Teachers College, Columbia University. For the sauce cold-storage apples were peeled, quartered, covered with cold water in a casserole, brought to boiling and continued boiling until a total of 15 minutes had elapsed, during about 7 of which the apples were actually boiling. For baking the apples were cored but not peeled, and baked for 45 to 60 minutes at 200° to 215" C. with a little water in the pan. The peels were not fed. 7 Proc. Soc. E x p l l . Biol. Med., 18, 140 (1921); A m . J . Diseuses Children, 23, 210 (1922).
TABLEI-AVERAGESURVIVAL PERIODS (DAYS)OF THRZEGUINEAPIGSPER RATIONWHICHDIED OF SCURVY WHEN FED ON VARYING AMOUNTS OF RAWAPPLES,APPLESAUCE, BAKEDAPPLZS,AND APPLESCANNED U N D ~ RVARYINGCONDITIONS BUT ALL PROCESSED 5 MINUTES Amount fed Apple Baked I CANNED APPLES Grams sauce apples 0-Apples A-Apples N-Apples S-Apples SS-Apples 5 22 22.6 21.3 2 8 . 3 21.3 29 27.3 2 9 . 0 42 37.3 10 25.6 26 21.3 2 0 . 5 21.8 24 26.6 3 1 . 5 51.3 43.3 30.6 26 20 24.6 28 26 41 24.6 28 56.6 46
Throughout this paper, the figures giving the amounts fed represent the equivalent of raw apples. By taking the weight of apples before and after treatment it was possible t o determine the amount of canned or otherwise cooked apple necessary to represent a I I I 1 stated amount of raw apple. By thoroughly macerating the apples, then incorporating the juice to a homogeneous mixture and using aliquot portions of this, all the experiments are put on a directly comparable basis. The very poor showing of the pigs suggested that perhaps the animals used were not normal. The italicized figures represent a duplication of the test with another lot of pigs and these confirm the results of the first lot. It is evident from the table that the SApples and SS-Apples were markedly better than any of the other l o t s . T h i s will b e brought out more definitely in succeeding charts, where results with the 10 and 30minute processes are given, as well as the results with another lot of apples. I I I I The pigs receiving CHART 2 the apples processed 5 m i n u t e s were f e d The vitamin C in armles _ _ was not destroved shortly after canning by canning if the oxygen in them was first consumed by the respiratory process. Rein March' The lots Of placing the gas in them with commercial nitroapples processed 10 and gen did not afford protection. The canned 30 minutes were held apples used in Charts 2 and 3 were held 8 through the Summer months before feeding. From a comparison the results in using the $-Apples and SSand fed during t h e of Apples with the results in using. these two COUrSe Of the following lots 8 months earlier as shown in-Table I, no winter, and are given loss of vitamin C is evident as a resultIof in Charts 2 and 3. It such storage. will be seen from these charts that there is no appreciable difference between the 10-minute process and the 30-minute process, but, emphasizing the data in Table I, there is a striking difference between the S-Apples and SS-Apples as contrasted with the other lots, in that the animals
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on these apples gave evidence of having received decidedly more antiscorbutic vitamin. Since these canned apples were fed approximately 8 months later than the canned apples mentioned in Table I, it is inferred that no vitamin C was lost in the canned apples over this period of holding. These results gave strong indicative evidence that here was a method which rendered vitamin C stable, irrespective of the time of heating within the limits used. But the vitamin content of this lot of apples was so low that a repetition of the experiment with a different lot of apples was felt desirable. Hence Stayman Winesap apples were canned in October a t the time they were being put into cold storage. Only three lots of apples were canned-namely, S-Apples, N-Apples, and A-Apples. Description of the methods used is given above. At the same time apples from the same lot were withdrawn from cold storage about every 10 days and held in an I 1 1 ice box for feeding raw to guinea pigs; some were also held in cold storage until March and then fed in the raw state again. The results are given in Chart 4. From this chart it amears that the vita-
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-apples.
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Apples canned from the same lot. One point should be borne in mind in examining the results of this chart. The con-
CHART4 Note the efficacy of removing the oxygen from the apples by the respiratory process before canning. Chart 4 shows a marked loss of vitamin C in raw apples held in cold storage over winter. The pigs fed cold storage apples in March had t o receive them ad lib. (40-41 grams daily) to make as good growth as those receiving 20 grams of canned apples (S-Apples). In this chart there is some protective action demonstrated by replacing the gas in apples with nitrogen.
