ANNUAL REPORT, 1941 73 



Change in Oxidation-Reduction Potential in Packaged Fruit Juice. (VV. B. 

 Esselen, Jr.) A preliminary study has been made on changes in oxidation-reduc- 

 tion potential in canned and bottled fruit juice. In glass-packed orange juice, 

 there was no correlation between the oxidation-reduction potential and flavor 

 changes which took place immediately after packing. The oxidation-reduction 

 potential of apple juice was much lower in plain tin cans than in enamel-lined 

 cans or bottles. Any beneficial efi^ect that the low oxidation-reduction potential 

 of the apple juice in plain tin cans might have in preventing deleterious oxidative 

 changes was ofi^set by an undesirable metallic flavor of the juice. 



Glass Container Research. (C. R. Fellers, W. B. Esselen, Jr., W. H. Fitz- 

 patrick, E. L. Moore and J. J. Powers.) Because of the scarcity of tin plate, 

 there has been a marked renewal of interest in glass containers for food packing. 

 Extensive studies have been made on the problems of packing fruits and fruit 

 juices in glass packages. Earlier work on the efficacy of ascorbic acids in pre- 

 venting discoloration of glass-packed fruits has been confirmed. The use of 1 or 2 

 one-grain tablets of d-isoascorbic acid or d-glucoascorbic acid in pint or quart 

 jars of canned fruit or vegetables effectively prevented discoloration and off- 

 flavor due to oxidation. 



After sealing, commercially packed foods in glass containers lose but little 

 vitamin A and C {Food Research 6: 135-141, 1941). Further studies have shown 

 that the total decrease in ascorbic acid is approximately proportional to the 

 enclosed oxygen. Thus, among the important factors influencing ascorbic acid 

 retention are: (1) volume of headspace, (2) degree of vacuum, (3) amount of 

 dissolved and tissue oxygen. Similarly, these same factors may also afi^ect color, 

 flavor, and other characteristics. Modern commercial packaging methods seek 

 to eliminate oxygen from canned foods. This study shows the efl^ect of varying 

 oxygen content on ascoibic acid retention. In fruits and vegetables with high 

 ascorbic acid content (citrus fruits, strawberries, broccoli, etc.), only a small 

 percentage of the ascorbic acid is lost in canning. However, in those initially 

 low in ascorbic acid (pears, peaches, apple juice, plums, carrots, beets, etc.), a sub- 

 stantial percentage, or all, of the ascorbic acid may be lost through reaction 

 with oxygen. Color and flavor of the latter fruits are also adversely affected. 

 High storage temperatures and exposure to light accelerate the ascorbic acid- 

 oxygen reaction in glass-packed foods, but the final total loss of ascorbic acid is 

 unaffected by these factors. 



The No. 10 size (105-ounce) glass jar was used experimentally for frozen-packs 

 of strawberries, raspberries, and peaches, packed with and without vacuumiza- 

 tion. Results show that vacuum sealing is generally preferable and that this 

 large glass package is very satisfactory for frozen fruits. As in the case of canned 

 fruits, the use of ascorbic acid in small amounts resulted in decreased surface 

 discoloration due to oxidative changes. 



Marine Products Research. (C. R. Fellers and J. Lubitz.) Cooperative with 

 Poultry Department. New England poultrymen are constantly searching for new 

 low-cost feeds. Recent developments in canning Atlantic coast crabs have made 

 available considerable quantities of crab meal. This product contains about 34 

 percent protein, 40 percent ash (mainly calcium), and 2-4 percent fat. The 

 riboflavin content is 3-4 gammas per gram. Pantothenic acid, thiamin, and 

 vitamin K are also present. The meal is an especially good source of calcium, 

 magnesium, iodine, manganese, iron, and copper. 



In feeding experiments with rats 85 percent of the nitrogen was available, the 

 balance being present largely as unavailable chitin. Upon hydrolysis chitin 

 yields glucosamine, which proved to be entirely unavailable to rats and chicks 



