ANNUAL REPORT, 1935 35 



some instances much less than that. In berries from plots dusted twice with 

 copper sulfate-lime dust on wet vines the loss up to December 1 was only 

 about 10 percent less than that in berries from check plots. The same dust 

 applied to dry vines had no effect on storage rots. In berries from plots dusted 

 once or twice with a combined insecticidal — fungicidal dust containing sulfur, 

 the loss due to storage rots to December 1 was not only not reduced but was 

 noticeably greater than in berries from plots not dusted. 



DEPARTMENT OF DAIRY INDUSTRY 

 J. H. Frandsen in Charge 



Explanation for High Initial Aging Temperature Phenomenon of 

 Gelatin Solutions. (W. S. Mueller.) In two previous studies it has been 

 shown that the initial aging temperature has a great influence on the basic 

 viscosity and gel strength of a gelatin-water solution and also of ice cream 

 mixes containing gelatin. When such solutions were divided after pasteuriza- 

 tion and one part promptly cooled and aged at 40°F., while the other part was 

 cooled to 68°F., held at that temperature for four hours and then cooled and 

 aged at 40°F., the latter had a considerably firmer gel structure. Various initial 

 aging temperatures, from 50° to 149°F. were tried. It was found that 

 temperatures above 99.8°F. did not increase the gel strength. The maximum 

 increase in gel strength was produced at 68°F. and when an ice cream mix was 

 held for four hours at this temperature the efficiency of the gelatin was increased 

 to such an extent that the gelatin content could be reduced approximately one 

 fourth without any loss in quality of the finished product. 



In order to find a possible explanation for this interesting phenomenon, 

 optical rotation and Tyndall studies were undertaken. Aging for 4 hours at 

 68 °F. plus 20 hours at 40° was compared with aging for 24 hours at 40°. The 

 optical rotation was the same for both treatments. Observations with a photo- 

 electric tyndallmeter showed a slight increase in light-scattering ability of the 

 solution when the high initial aging temperature was used. These results in- 

 dicate that the phenomenon associated with high aging temperature is due to 

 changes in size or number of micellae and not to a rearrangement within the 

 gelatin molecule. Other physical properties of the gelatin solution must be 

 studied before definite conclusions can be drawn. 



Nutritive Value of Milks — Plain versus Chocolate Flavored. (W. S. 



Mueller and W. S. Ritchie, Department of Chemistry.) The consumption of 

 chocolate milk has increased during the last few years to such an extent that it 

 has now become an important dairy product. However, the nutritive value 

 of cocoa is still a debatable question and the question of whether cocoa should 

 be included in children's dietaries is far from being settled. Most of the reported 

 experimental work on this problem is controversial. 



The extensive use of cocoa has been criticized because it contains theobro- 

 mine, and to a lesser extent caffeine. Another objection raised to chocolate 

 milk is its sugar content, which is considerably higher than that of whole milk. 

 It has been generally conceded by other investigators that the tannic acid con- 

 t?nt is too small to be of any significance; ye" the cacao red con- 

 tent is high, being from 2 to 5 percent, and it resembles tannin in many of its 

 properties. It has been reported that tannin will decrease the solubility of 

 milk solids and that the addition of cocoa to other articles of food seems to 



