ANNUAL REPORT, 1937 49 



zation, and aging at that temperature for several hours, followed by aging at the 

 usual temperature, a more viscous mix results, and the ice cream frozen from this 

 mix showed a higher melting resistance. The gelatin content can be reduced b\' 

 one-fourth by this method of aging. Gelatin-water solutions aged under com- 

 parable conditions after solution at 45° F. exhibited a similar difference in gel 

 strength and basic viscosity. This study was continued by subjecting water 

 solutions of sodium alginate, karaya gum, and oat flour to high initial aging tem- 

 perature treatment as described for gelatin. These substances, which are used to 

 some extent as stabilizers for ice cream, ices, and sherbets, did not exhibit the 

 differences in gel strength and basic viscosity that were noted with gelatin. Further 

 studies are being made with other stabilizers. 



These results indicate that it would be of no advantage to an ice cream man- 

 ufacturer to use a high initial aging temperature when using stabilizers such as 

 sodium alginate, karaya gum, and oat flour, without gelatin. 



Improving the Flavor and Keeping Properties of Milk and Some of Its Products. 



(VV. S. Mueller and M. J. Mack.) It is generally conceded that the butterfat 

 (including fat-like substances) is the major constituent affecting the flavor and 

 keeping properties of milk and its products. A slight oxidative change in the 

 butterfat content of the dairy product will produce flavor defects which are vari- 

 ously described as storage, cappy, cardboard, metallic, oxidized, and old ingredient. 

 Among the many factors that have been mentioned as accelerators in the produc- 

 tion of oxidized flavors in milk fat are light, heat, moisture, acidity, enz\mes, 

 and metals. 



The addition of edible antioxidants to dairy products appears to be a feasible 

 method for preventing or retarding oxidized flavors. The object of this study is to 

 obtain more information on the effect of the following antioxidants on the flavor 

 and keeping quality of dairy products: Carotene, ascorbic acid (Vitamin C), 

 lecithin, cereal flours, and possibly ice cream stabilizers of vegetable origin. Most 

 of the work to date has dealt with the effect of oat flour on the keeping property 

 of ice cream, butter, frozen cream, whipped cream, and whole milk powder. 



The use of only 0.25 percent of oat flour in ice cream mix delayed the develop- 

 ment of off-flavors during the storage of the resultant ice cream, although 0.5 

 percent proved more effective. Oat flour also proved to have stabilizing properties. 

 The stabilizing action of this antioxidant increased mix viscosity, improved the 

 body and texture, and increased the melting resistance of the ice cream. When 

 oat flour is added to the mix, a reduction should be made in the amount of gelatin 

 or other stabilizer used if an overstabilized condition is to be avoided. The results 

 indicate that a reduction of at least 25 percent of the gelatin content is desirable 

 when 0.5 percent oat flour is incorporated in the mix. The use of oat flour as an 

 antioxidant in ice cream is described in the October 1937 issue of the Ice Cream 

 Trade Journal. 



Oat flour, at the rate of one percent of the fat weight of the cream added to 

 cream before pasteurization retarded the oxidative deterioration of butter. Also, 

 the addition of an aqueous extract of this antioxidant to cream prior to pasteuri- 

 zation improved the keeping quality of the butter. 



Butter was wrapped in parchment paper treated with oat flour, and stored 

 at temperatures of 38° F. and 0° F. These samples have not been in storage long 

 enough for marked differences to appear. 



Cream containing two percent by weight of oat flour, which was added before 

 pasteudzation, was frozen and stored at 0° F. A control sample was also placed in 

 storage at the same time. After three months in storage the cream was examined 

 and no marked differences in flavor were noted, except that the cream containing 



