48 MASS. EXPERIMENT STATION BULLETIN 347 



In a general way, these results show no marked differences in the urine excreted 

 by rats which received the Dutch and American process cocoas. However, dif- 

 ferences were noted when the urine excreted by rats which received cocoa was 

 compared with the urine of rats in the control group. Further trials are necessary 

 before definite conclusions can be drawn. 



Fecal pH studies. Fecal pH studies on samples collected from animals receiving 

 no cocoa, 4 percent Dutch process, and 4 percent American process, showed no 

 marked differences when the quinhydrone electrode was used. 



Digestion of chocolate-flavored milk in vitro. The purpose of this study is to 

 check, if possible, the results on the animal feeding experiments. Only prelim- 

 inary experiments were made with whole milk pow-der plus cane sugar, alone 

 and when supplemented with 4 percent of Dutch process cocoa (on a fluid milk 

 basis). Digestion was carried out with artificial gastric juice, in a rotating machine 

 set in an incubator at 37°C.,in order that digestion might go on under conditions 

 somewhat approaching those of the stomach. Samples were removed after five 

 hours and analyzed for soluble nitrogen by the direct micro-Kjeldahl method. 

 Preliminary results show that milk alone gives a greater total rise in soluble 

 nitrogen than does the chocolate milk. However, it was observed in the pre- 

 liminary work that the micro method was not sensitive enough and it will be 

 replaced by the regular Kjeldahl method in further studies. 



This year's work on the nutritive value of chocolate-flavored milk seems to 

 indicate that when cod liver oil and yeast were fed, as good gains were noted in 

 the rats receiving chocolate milk as with the control group receiving whole milk. 

 The same amounts of yeast and cod liver oil were fed to both groups. 



Some Factors Affecting the Properties of Whipped Cream. (W. S. Mueller.) 

 Additional factors studied during the past year were the effect of agitating the 

 cream after pasteurization and the effect of oat flour on whipping cream. The 

 same whipping procedure was used in these investigations as was used in the 

 previous studies. 



Cream containing 30 percent butterfat was cooled over a surface cooler to 

 40° F. after pasteurization and then portions were subjected to one-half, one, and 

 two minutes of agitation with the cream whipper. The cream was then aged for 

 24 hours at 40" F. before whipping. Results seem to indicate that preliminary 

 agitation had no significant effect on maximum stiffness and serum drainage, and 

 slightly decreased the overrun. The sum total of the preliminary and final whip- 

 ping time was practically equal to the whipping time for the control, which was 

 not agitated before aging. Effect of agitation after pasteurization at temperatures 

 other than 40° F. are being studied. 



The addition of 0.5 percent by weight of oat flour to whipping cream (30' 

 percent butterfat) increased the viscosity, decreased whipping time, slightly 

 increased maximum stiffness of the whipped cream, and slightly reduced the 

 serum drainage, but had no significant effect on overrun. 



The addition of a skim milk extract of oat flour to whipping cream (30 percent 

 butterfat) had no significant effect on the viscosity of the cream or on the whipping 

 qualities of the cream. 



The Effect of Aging Treatments on Gelatin and Other Ice Cream Stabilizers. 



(W. S. Mueller.) A photo-electric tyndallmeter was developed in the dairy lab- 

 oratory for studying the effect of aging treatments on the tyndall phenomenon 

 of gelatin-water solutions. A detailed description of this instrument appeared in 

 Food Research 2:51-54, 1937. 



It was shown that the effect of gelatin in ice cream mixes can be increased by 

 using a higher initial aging temperature. By cooling only to 68° F. after homogeni- 



