FROZEN SWEET CREAM IN ICE CREAM 185 



Newlander and Ellenberger (3), in tlie same annual report, state that 

 frozen cream from fresli cream of initial high quality, testing 40 per 

 cent fat, after 9 months of storage at 0° F., made a 20 per cent cream 

 of good flavor e(jual to the cream made from butter oil stored under the 

 same conditions. 



Tracy (!•) found it possible to store fro/.en creaiu at low temper;itures 

 for three and one-half months without "greatly affecting the flavor of 

 the butterfat." He found that high-testing creams kept better than low- 

 testing creams. Pasteurized cream was found to keep better than raw 

 cream, and that with reduced acidity showed less deterioration than 

 cream with normal aciditv. Paraffined paper containers were found to 

 be satisfactory if air was excluded. Cream exposed to the air soon 

 acquired a bitter flavor. Rusty cans were reported as causing a metallic 

 flavor. Tenqieratures below 0° F. were found to be more satisfactory 

 than higher tenqjeratures. 



In the same investigation, Tracy also reports that concentrated ice 

 cream mixes were stored in the same nuinner as the frozen cream. In 

 comparing ice cream mixes made from frozen cream, frozen condensed 

 mix, and unsalted butter, all from the same lot of cream and stored for 

 four and one-half months, that from frozen cream ranked first in quality. 



In the previous investigations with frozen cream, factors aft'ecting the 

 keeping quality of the product were studied and their effects established. 

 However, no attention was given to the effect of this ingredient on the 

 physical properties of the ice cream mix. In this investigation, the first 

 consideration has been to compare fresh and frozen cream mixes as to 

 their relative viscosity, rate of freezing, microscopic appearance, etc. 

 Different methods of treating the cream previous to freezing have been 

 studied. Some data have also been collected on the keeping quality of 

 frozen cream. 



EXPERIMENTAL PROCEDURE 



The mixes were tested for fat and total solids by the Mojonnier method. 

 The composition varied within narrow limits and averaged 11 per cent 

 fat, 10 per cent serum solids, 1-5 per cent sugar, and O.-t per cent gelatin. 

 The milk products used were either fresh or frozen cream, skim milk, and 

 skim milk powder. The ingredients were pasteurized at 145° F. for 30 

 minutes. The mixes were homogenized at the pasteurization temperature 

 at a pressure of 2,500 pounds per square inch, immediately cooled to 45° 

 F., and then held for 24 hours at 40° F. before freezing. 



The initial cream used for frozen cream was of the same quality as that 

 used in the sweet cream mixes. No off flavors or odors were apparent. 

 The acidity range, expressed in terms of lactic acid upon titrating with a 

 tenth normal solution of sodium hydroxide, varied from 0.10 per cent to 

 0.13 per cent. When cream was homogenized or sugar or gelatin added 

 before freezing, a quantity of cream was divided into two equal parts. 

 Both were treated identically except for the factor being studied. All 

 batches of cream tested 40 per cent fat or nmre and all were pasteurized 

 I)revious to freezing. 



Viscosity readings were made with 100 c.c. sanqjles of the mix after 



