According to Hoist and Frolich 79 the juice of lemons and raspberries retain their antiscorbutic properties after heating to 100° C. for an hour, and Delf80 found less reduction in C in the case of orange juice subjected to temperatures up to 130° C. than with either cabbage or swede juice, this greater stability being maintained even when the juice was nearly neutralized before heating. Bassett-Smith81 reports that boiling lemon juice for five minutes does not appreciably diminish the antiscorbutic property, but that heating to 58° C. for three-quarters of an hour caused marked deterioration. Davey 82 states that orange and lemon juice lost but little in activity when preserved with the rind oil for two years at room temperature, but became inactive on keeping at 37°. Delf suggests that the unexpected stability of swede and orange juice at temperatures above 100° C, when the heating is conducted in the absence of air, may perhaps indicate that destruction of the antiscorbutic factor is an oxidation process.83 This observation naturally has an important bearing on the canning and preserving of fruits and vegetables.84

An observation made by Rossi85 is of interest in this connection. Rossi found that when young guinea pigs were fed a ration of oats and fresh hay which had been sterilized in an autoclave at a temperature of approximately 126° C. in open jars, they died of scurvy in a little more than 20 days. When animals of the same age were fed a ration containing the same amount of oats and fresh hay which had been sterilized in an autoclave at the same temperature but in hermetically sealed bottles, they remained in normal health after more than two months on this diet. He concludes that foodstuffs can be sterilized at high temperatures without loss of their nutritive properties provided the proper procedure be followed.

79 Hoist and Frdlich, Ztschr. Hyg. 71, 1, 1912.

80 Delf, Bioch. J. 14, 211.

81 Bassett-Smith, Lane. 1920, ii, 997.

82 Davey, Biochem. J. 25, 83, 1921.

83 See also Anderson, Dutcher, Eckles and Wilbur, Soi. 53, 446, 1921.

84 See also Bidault, Rev. Sci. 59, 13, 1921.

85 Rossi, Arch, final. 16, 125,1918; Physiol. Abe. 4, 335, 1919.

Harden and Robison 86 found that about half of the antiscorbutic vitamin was destroyed in dried orange juice kept at 29° C. for 14 months. Boiling orange juice under a reflux condenser for one-half hour did not affect the antiscorbutic vitamin according to Dutcher, Harshaw and Hall.87 On the other hand they found that this vitamin is partially destroyed by hydrogen peroxide, especially on warming.

Milk is comparatively poor in antiscorbutic power in the raw state, and the small amount present may be still further reduced by unfavorable treatment. Long before the vitamin hypothesis had been formulated, Neumann noted that frequent occurrence of infantile scurvy seemed to be associated with the use of milk which had been pasteurized at 90° to 95° C. and then heated again at or near 100° C. for 10 to 15 minutes before using.88

Frdlich89 found that raw; milk had more protective power than heated milk as an antiscorbutic for guinea pigs. Autoclaved milk, i.e. milk which has been heated to 115° to 120° C. in an autoclave for one to two hours, has frequently been used as a constituent of a scorbutic diet. Hart, Steenbock and Smith90 observed that an average consumption of 79 cc. per day of milk which had been heated to 120° C. for 10 minutes was insufficient to protect guinea pigs against scurvy, although this amount of raw milk had been found adequate. Commercial condensed milk (two brands investigated) was also lacking in C as compared with fresh raw milk. A commercial milk powder was found to be almost if not quite devoid of C, but the degree of heat to which this had been subjected was unknown. Hess and Unger91 found that 80 cc. of fresh milk daily or its equivalent in milk dried by the Just-Hatmaker process (exposure to a temperature of 116° C. for a few seconds) was sufficient to cure guinea pig scurvy, while Barnes and Hume92 found 100° to 150° cc. of raw milk necessary and got no protection with the Hatmaker product. They ascribe this discrepancy to the fact that Hess and Unger gave dried hay ad lib. in the basal ration, while Barnes and Hume used oats and bran only.

Hay is probably not entirely without C. The addition of scalded milk which had been heated until it frothed up at the boil and then allowed to cool in air, amounting on the whole to exposure to a temperature of between 70° and 100° C. for about five and one-half minutes, to the diet of a scorbutic monkey brought about a rapid and complete cure. The amount fed was such that about 25 per cent of the antiscorbutic factor originally present might have been destroyed without being detected, but from the rapidity of the cure it was inferred that very little destruction had occurred and such scalding is suggested as a means of sterilization involving comparatively little deterioration of the antiscorbutic power 93

92 Barnes and Hume, Bioch. J. 13, 306, 1919.

86 Harden and Robison, Biochem. J. 15, 521, 1921.

87 Dutcher, Harshaw and Hall, J. Biol. Chem. 47, 483, 1921.

88 Neumann, Deutsche med. Wohnschr. 1902, 247.

89 Frdlich, Z. f. Hyg. u. Infeckt. 72, 155, 1912.

90 Hart, Steenbock and Smith, J. Biol. Chem. 38, 305, 1919.

91 Hess and Unger, J. Biol. Chem. 38, 293, 1919.

Much evidence has been accumulated with regard to the effect of drying at moderate temperatures on the C content of foodstuffs. Furat94 noted that germinated corn lost much of its antiscorbutic power on keeping. Hoist and Frdlich95 made a careful study of the effect of drying and storing on the antiscorbutic potency of potatoes, carrots, dandelion leaves and cabbage, dried in an incubator for some days at 37° C, or in vacuo at 30° C. After drying, the material was stored for six months or a year at summer temperatures, mostly in closed vessels, but in one case in open vessels in an incubator. When 30 g. per day of these vegetables in the fresh condition were fed to guinea pigs in addition to a dry grain and water diet, this amount was found sufficient to maintain the animals in health and prevent scurvy. In the case of the dried cabbage the material was soaked in water for half an hour before being fed to the animals. Any water which remained unabsorbed was fed to the animals separately. Six animals receiving cabbage dried and stored in the laboratory for one year, died with symptoms of acute scurvy in 21 to 28 days, the cabbage affording no protection whatever. Another eight animals receiving cabbage dried and stored for six months died with actue scurvy in 21 to 37 days.

These also received no significant protection from the disease. With the cabbage which was stored in open vessels in an incubator for six months after drying at 37° C, a certain amount of protection was afforded but three animals ultimately died of acute scurvy, in 51 to 71 days. Better results were obtained when the cabbage had been stored only six weeks. On this, two animals died of scurvy after 66 days, and two lived for 98 days, one with no apparent symptoms and the other showing evidence of scorbutic lesions on histological examination of the bony tissues. In one case guinea pigs received protection for over eighty days on a ration of dried cabbage equivalent to 30 g. of the fresh vegetable; the cabbage having been dried at 37° C. and kept at that temperature in a desiccator over sulphuric acid. No increase in weight took place during the experiment. Their experiments indicate that the time of storage has a marked effect upon the antiscorbutic value of dried cabbage, and that the value is greater when the material is kept in a very dry atmosphere and prevented from taking up moisture from the air, but even in this case the value is very small in comparison with fresh material.

The onset of scurvy in guinea pigs was prevented with as small an amount of fresh cabbage as 1 to 2.5 g. daily, and the most successful of the experiments with dried cabbage are far from comparable with this. Experiments with other dried vegetables showed similar deterioration on drying and storing, this being greatest with dandelion leaves and carrots, and least with potatoes. Givens and Cohen96 observed that cabbage, dried in a blast of air at 40° to 52° C, retained some of its antiscorbutic value in that it would considerably delay the onset of scorbutic symptoms, thereby prolonging life. Further, it could be employed as a curative agent if the signs of scurvy were recognized early enough and the animal would consume one gram daily. Cabbage which had been heated in an oven for two hours at 75° to 80° C, then dried at 65° to 70° C. for several days lost its antiscorbutic power. Cabbage cooked for 30 minutes, then subjected to drying for two days at 65° to 70° C, exhibited no antiscorbutic potency. Delf and Skelton97 found that the loss of antiscorbutic properties was more than 93 per cent when cabbage was dried at a low temperature and subsequently stored for two to three weeks at laboratory temperature.

Storage for five to six weeks at laboratory temperature induced a further loss of antiscorbutic properties and after storage for three months nearly all (96 to 97 per cent) of the protective value of the fresh material was lost. The residual amount was, however, distinctly greater if the cabbage was plunged into boiling water before drying. They conclude that the preservation of vegetables by drying is an unprofitable process having regard to labor and fuel involved, to the low nutritive and antiscorbutic value of the product, and to the subsequent deterioration on storage. In view of the present advocacy by others of dehydration as a useful means of preserving vegetables, this conclusion is of especial interest.

93See also Ch. XV.

94 Furst, Nord. Med. Arch. Abt. II, 1910, Supp. 340.

95Hoist and Frdlich, Ztsch. Hyg. 72, 1; 75, 334.

96Givens and Cohen, J. Biol. Chem. 36, 127, 1918. 97Delf and Skelton, Bioch. J. J2, 448, 1918.