ANNUAL REPORT, 1944-45 45 



completely protected the added 1-ascorbic acid from oxidation. If bottled grape 

 juice is fortified with ascorbic acid so that it is equal to citrus juice as a source of 

 vitamin C, the ascorbic acid is well retained during storage. Added ascorbic 

 acid is quite stable in apple juice and cranberry juice during processing. 



Ascorbic acid has been shown to function as an antioxidant in processed fruits 

 and fruit juices because increased concentrations of it shifted oxidation reactions 

 away from flavor and color substances and more toward the ascorbic acid in 

 accordance with the Law of Mass Action. Redox potential measurements 

 indicate that ascorbic acids also function as antioxidants because they set up 

 low, highly poised potentials in foods. The poising capacity of a processed food 

 has been found to be of greater relative importance than its actual redox potential 

 in determining resistance to oxidative deterioration. 



Storage at 40°F. in the dark significantly retards the development of rancidity 

 in corn and cottonseed oils. A good quality oil can be stored for one year at room 

 temperature without serious deterioration if protected from the light. Amber 

 glass containers are very effective in protecting edible oils against the effects of 

 diffused daylight. Metal containers protect these oils against the effect of light 

 but a slight off-flavor, due apparently to the container, develops during storage. 

 To date no entirely satisfactory antioxidants have been found which are effective 

 in retarding the development of rancidity in edible liquid oils. Many of those 

 which retard rancidity impart an objectionable off-flavor to the oil. The initial 

 quality of an oil is of major importance in governing its keeping quality. 



From an investigation of bacterial load on fresh vegetables it would appear 

 that potential home-canning spoilage bacteria such as spore-forming anaerobes 

 and thermophiles are present in relatively small numbers except in occasibnal 

 samples, and that their numbers are subject to wide variation. Washing and 

 blanching prior to canning are an effective means of reducing the bacterial content 

 of vegetables. The number of putrefactive anaerobes encountered was very low 

 and may account for the fact that in some sections of the country the boiling 

 water bath method of processing has been used successfully by many people. 



In experimental packs of orange juice the addition of small amounts of d-iso 

 ascorbic acid enhanced the retention of the fresh fruit flavor during processing 

 and storage. 



During the past two years complaints have been received from home canners 

 that the jar rings they used imparted an off-flavor to home-canned foods. This 

 problem has been investigated in cooperation with the War Food Administration 

 and the jar ring industry. Two promising test methods have been developed by 

 which it is possible to determine the tendency of jar rings, made from different 

 types of rubber and other constituents, to impart off-flavors to foods. These 

 methods have been of value in ascertaining the source of off-flavors in jar rings, 

 and may also be of value in maintaining quality control in their manufacture. 



Fifteen different varieties of peaches, provided by the Pomology Department, 

 were canned according to home-canning techniques. The canned products were 

 evaluated as to qualitA- after storage for six months. Ideal, Valiant, and Amber- 

 gem varieties were graded as very good; Red Rose, Champion, New Jersey 116, 

 Golden East, Golden Glow, Golden Globe, Hale Haven, Summer Crest, and 

 Vedette as good; and New Jersey 66, Delicious, and Radiance, as fair. 



Tests were also conducted to determine the effect of different processing 

 methods on the quality of home-canned peaches. The boiling water bath method 

 and processing at to 1 pound steam pressure in a pressure canner gave the best 

 product. Processing at 5 or 10 pounds steam pressure for a short time in a 

 pressure canner resulted in a product inferior to that obtained by the former 

 methods. 



