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below 5’ C. with an ~ q u e s u ssolution of 3.2 parts of sodium nitrite. After standing for another half hour a t this temperature, tests showed aniline still to be in slight excess. This solution was then poured slowly into one of 10 grams of the diaminosulfide in 500 cc. of water and 5 grams of concentrated hydrochloric acid a t 0” C. A well-cooled solution of sodium acetate was poured in gradually until
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the dye was all precipitated as a deep red, flocculent solid and the supernatant liquid was nearly colorless. It was purified by washing first with salt water and then with pure water. It was difficultly soluble in water or dilute acids, but dissolved easily in alcohol. Wool and silk were dyed orange-yellow by it. Its hydrochloride crystallized well from dilute alcohol.
Vitamins in Canned Foods’ V-Peaches By Edward NATIONAL C!ANSERS
F. K o h m a n , Walter H . Eddy, Victoria Carlsson, and Nellie Halliday
ASSOCIATION, WASHINGTON, D. C.,
AND
TEACHERS COLLEGE, COLUMBIA UNIVERSITY, NEWYORK, N. Y.
Vitamin C
N A previous report’ it was stated that apples canned with their normal oxygen content lose all detectable amounts of their vitamin C; that apples in which the gas was replaced by commercial nitrogen lose practically all their vitamin C upon canning; and that apples exhausted of their oxygen content by the respiratory process, as is now generally done commercially, lose no detectable amounts of vitamin C upon subsequent canning. In order to determine if a similar relationship holds in peaches, as well as to secure information as to their normal vitamin content, a study of peaches was made for which the following five lots were canned in California in July; 1924. A4fter the preliminary treatment described for each lot, the peaches were all canned by the following procedure: The peaches were filled into No. 2 cans, which were then filled with boiling water, exhausted 6 minutes a t 88’ C. in a steam exhaust box, and, after being closed, cooked for 15 minutes a t 100’ C., and then water-cooled. This was the regular procedure in the plant where the canning was done.
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Lot 166. The peaches were hand-peeled, halved, and pitted, subjected t o a vacuum of 735 t o 775 mm. (29 to 29.5 inches) twice, and the vacuum released each time with commercial nitrogen after passing it through an alkaline solution of pyrogallic acid. Lot 167. The peaches were halved, pitted, and lye-peeled by the regular commercial procedure. Lot 168. The peaches were halved, pitted, hand-peeled, and held 8 hours under a 2 per cent sodium chloride solution a t ordinary temperature. At the end of this time their oxygen content was reduced t o zero. Lot 169. The whole peaches were held under water overnight (13 hours). At the end of this time their oxygen content was zero. They were then given the regular commercial treatment described under Lot 167. Lot 170. The peaches were picked at the same time and from t h e same trees as the peaches in the previous lots, but were not fully ripe, but rather in the stage suitable for shipping. Two days after picking they were put in cold storage, where they were held for 4 days. They were then beld 3 days in t h e canning factory, when they were in the proper state of ripeness for canning. They were then canned by the regular procedure given for Lot 167.
During August, September, and October, 1924, peaches were purchased daily on the New York markets for feeding in the raw state and after “home cooking.” For this “home cooking” the peaches were peeled, halved, and then cooked 1 Presented in part under the title “Vitamins in Raw, Home-Cooked, and Canned Peaches” before a joint session of the Divisions of Biological and Agricultural and Food Chemistry at the 69th Meeting of the American Chemical Society, Baltimore, Md., April 6 to 10, 1925. Received December 15, 1825. 2 Kohman, Eddy, and Cartsson, THISJOURNAL, 16, 1261’ (1924).
in a loosely covered kettle with a reasonable amount of water. It required about 7 minutes for them to come to boiling and the boiling was continued for 8 minutes. During February to July, 1925, inclusive, the various lots of canned peaches were fed. For vitamin C studies the raw peaches were fed in 2.5, 5, 10, and 20-gram amounts; the “home cooked” in 5, 10, 20, and 40-gram amounts; while the’five lots of canned peaches were fed in 3, 5, 10, and 15-gram amounts daily. From three to nine guinea pigs were fed each amount. Control pigs were fed the basal diet only to demonstrate absence of vitamin C . Composite growth curves are given in the accompanying chart. The experimental period was 90 days. However, two of the pigs on 2.5 grams raw peaches died of scurvy in 61 and 79 days, respectively; the three pigs on 5 grams of home-cooked peaches died in 33,74, and 75 days, respectively; while two of the three pigs on 10 grams of home-cooked peaches died in 65 and 69 days, respectively. Therefore, the latter part of these three curves represents only two animals. All the pigs on all amounts of the canned peaches survived the 90-day period, although all but two of the fifteen pigs receiving only 3 grams showed definite symptoms of scurvy on autopsy, as well as two out of nine pigs receiving 5 grams of the peaches from Lot 167. Judging from these facts, as well as the appearance of the individual animals coupled with their growth curves, the following conclusions seem warranted: 1-The minimum antiscorbutic dose of raw and canned peaches is close to 5 grams per day per guinea pig, although a somewhat larger amount gives better growth. With the possible exception of Lot 167, in which no attempt was made t o remove t h e oxygen, 5 grams of canned peaches gave better results than 5 grams of the raw peaches. It should be noted t h a t this gives no clue as t o the extent of any appreciable destruction, since we have no data on the original vitamin content of the peaches used for canning. 2-There is a n indication that removal of oxygen from peaches previous to canning gives some protection t o vitamin C, but the extent is practically insignificant. These peaches contained about 1.2 per cent by volume of oxygen. 3-Ten grams of open kettle-cooked peaches have no more vitamin C than 2.5 grams of raw peaches, and considerably less than 3 grams of canned peaches. Probably the raw and canned peaches contain about five times as much vitamin C as the kettlecooked peaches. 4-Picking the peaches somewhat green and allowing them t o ripen off the tree for several days previous t o canning seems to make no difference in their vitamin C content.
I n the writers’ experiment with apples they found evidence of some vitamin C destructive factor other than elementary oxygen, which can be eliminated by making use of the respiratory process and which therefore seems to be loosely
>larch, 1926
1-1-D C'STRI.4 L -4ND E-VGINEERlYG C H E X I S T R Y
bound respiratory oxygen. They have additional evidence of this in apples in a different line of study. Their data indicate only a slight effect of such a factor, :f any, in the peaches used for canning, since there is no evidence of much vitamin C destruction, unless they assume :t very much higher initial vitamin content than the raw peaches fed contained. As reported in a previous paper,3 peas experience relatively little loss in vitamin C in home cooking, and even less in canning, when compared with spinach and cabbage. Canned tomatoes hare been reported by several investigators in this country t o he equivalent to raw tomatoes in vitamin C content, whereas Delf4 in England reports a loss of threefourths or more of the vitamin C in canning. It is known that oxygen is destructive oi vitamin C, but the foregoing facts can scarcely be explained on the 4
Eddy, Kohman and Carlbson Blociicnl J 18, 6T4 (1924)
THISJ o L R ' ~ ~ L ,18, 85 (1926)
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basis of a variation in gaseous osggen content. The plausibility of respiratory oxygen, varying in different products and under different conditions in the same product, therefore suggests itself. Whether such a factor, or some other, is operating remains to be demonstrated. Vitamin A
I n an attempt to determine the vitamin A content of canned peaches, the amounts fed in the beginning were unfortunately too high to ascertain the minimum protective dose in all lots, and by the time this was realized the supply was too low to permit a repetition. The main concern was between Lots 167 and 17G-that is, the effect of degree of ripeness-since there is no evidence to indicate any effect on vitamin A in the canning process. The data for Lots 167 and 170, of which 2, 1, and 0.5-gram amounts were fed daily, is fairly indicative. The average growth was normal on these amounts except in the case of 0.5 gram of Lot 170, on which the average gain over an 8-week period was 25 grams, after a 65-day period on vitamin &free diet. This is about the equivalent of 20 mg. of butter fat. On a dry basis, the peaches picked when only partially ripe, therefore contain about one third the vitamin A present in butter fat. The riper peaches of Lot 167 are more highly endowed, but to what extent the data do not reveal. Vitamin B
The data obtained on vitamin B are also inconclusive. It can only be stated that rats receiving 1, 2, 4, or 6 grams of raw peaches showed evidence of vitamin B deficiency and with the larger amounts so much of the basal diet was replaced that other nutritional deficiencies resulted. Summary
Composite Growth Curves of Groups of Guinea Pigs Receiving. Varying A m o u n t s of Raw, H o m e Cooked, a n d Canned Peaches The amounts fed daily are given above each curve except for the five lots of canned peaches, where they are given only for the first as the same amounts were fed for each lot. The number of animals represented by each curve is given just below the beginning of each: and as a denominator of this is given the number of the group that had scurvy. Thus 3 / S - 2 means that the curve represents 3 animals, two of which had scurvy. As some of the pigs receiving 2.5 grams of raw peaches and 5 and 10 grams of home-cooked peaches died before the end of the 90-day period, the latter part of the curves representing these amounts only represent a part of the original grouQ
l-The minimum protective dose against scurvy of raw peaches purchased on the New York markets during August. September, and October was found to be about 5 grams daily per guinea pig, but increased growth resulted from somewhat larger amounts. 2-The equivalent of 5 grams of raw peaches canned in California in July and fed during the succeeding February to July, inclusive, gave results comparable to 5 grams of the Kew York market raw peaches. 3-Elimination of oxygen from the peaches previous to the regular canning procedure, the exhaust of which is intended to eliminate the greater part of the oxygen, gave only slight evidence that there resulted more vitamin C in the canned product. 4-After cooking the New York market peaches in a covered kettle for 15 minutes (actual boiling time 8 minutes) two of three pigs on 10-gram daily feedings died of scurvy in 65 and 69 days, respectively, while the third survived the 90-day period, but had severe symptoms of scurvy. On 20 grams, growth was practically normal. 5-Since the 15 pigs receiving 3 grams of the variousry canned peaches all survived the 90-day period, though showing definite symptoms of scurvy on autopsy, it is estimated that the canned peaches had between four and five times as much vitamin C as the kettle-cooked peaches. &To make a gain of 25 grams in 8 weeks, after the usual vitamin A-free period, rats required 0.5 gram or less of canned peaches daily, making them, on a dry basis, about one-third as potent in vitamin A as butter fat. 7-The vitamin B content of the peaches was so low that the large feeding required to supply it upset the general nutrition.
