BUEEAU OF ANIMAL INDUSTRY. 121 



siderable number of persons and allowing them a choice of three 

 concentrations of varj'ing ingredients. The results showed that a 

 large majority preferred an ice cream with high fat content and that 

 the choice was also usually in favor of the higher concentration of 

 milk solids not fat and sugar and gelatin. 



Studies of the influence of different ingredients on the yield 

 show that increases in the percentages of gelatin, milk solids not 

 fat, and sugar tend to lower the yield. Fat increases the yield in 

 homogenized mixes, and homogenizing produces a higher final yield 

 in mixes low in fat and in solids not fat, but under other conditions 

 the effect is not pronounced. Low brine temperatures tend tio 

 lower the yield. 



Investigations indicate that ice cream has no freezing point in 

 the usual sense. The freezing is rather the continuous precipitation 

 of solids from saturated solution with the lowering of the tempera- 

 ture. This work has developed a method for measuring the " sandi- 

 ness " of ice cream. 



Condensed milk. — Studies on the physical chemistry of milk are 

 giving information of ^alue in explaining and correcting difficulties 

 which occur both in sweetened and evaporated milk. It has previ- 

 ously been observed that forewarming to the usual temperatures 

 greatly increases the tendency to thicken on standing. More recent 

 studies indicate that by increasing the forewarming temperature two 

 or three degrees the tendency of the milk to thicken may be obviated. 

 The effect of the concentration of miliv solids not fat on the tempera- 

 ture of coagulation has been determined. The change in the coagu- 

 lation temperature per 1 per cent variation in solids not fat between 

 16 and 3G per cent is about 1.5° C. Homogenization of milk of low 

 concentration lowers the coagulation temperature, but homogeniza- 

 tion at pressures below 4,000 pounds has no effect on the coagulation 

 . of milk of normal composition. 



Swiss cheese. — Studies have been made of the effect of certain 

 variations of the manufacturing process on the texture of Swiss 

 cheese. The time of holding in the kettle seems to have little influ- 

 ence on the quality of the cheese, but small differences in the cooking 

 temperatures appeared to have a decided effect in suppressing ab- 

 normal gas formation. Cheese made from milk passed through a 

 separator had fewer e3'es of a much larger size than those in the check 

 cheeses. Very definite relations have been established between the 

 composition of the milk and what is known as glass cheese. A 

 method of determining casein has been adapted to factory conditions 

 so that it is possible to control this factor. The use of cultures has 

 been put on an introduction basis and very satisfactory results were 

 obtained with factories in Ohio and Wisconsin. 



Some attention has been given to the problem of disposing of 

 second-grade Swiss cheese. This is now done commercially by heat- 

 ing the cheese with the addition of some neutralizing agent and 

 running it into molds. This process is covered by patents and its 

 use is necessarily limited. A molded cheese of satisfactory flavor 

 may be made by heating carefully without neutralizing, but the tex- 

 ture is objectionable. 



Xo special investigations have been made on Camembert or Roque- 

 fort cheese, but considerable experience has been gained from their 

 manufacture on a commercial scale at Grove City, Pa. A method of 



