HIGH AGING TEMPERATURES FOR ICE CREAM 15 



of the finished ice cream were ditferent, although the composition of the mix was 

 the same as before. No explanation could be found at that time for the change 

 in the finished product. In another case, more recently, mixes were being cooled 

 over a surface cooler where tap water was the only cooling medium. The mix 

 left the cooler at approximately 70° F. and was stored in ten-gallon cans in a 

 cooler at 50^. Under those conditions the mix was really being initially aged at 

 a temperature above 50° for some time. These practical illustrations show that 

 in ice cream plants where the cooling of the mix after homogenization is not being 

 carefully checked, mixes may be aged for several hours at a temperature above 

 50° F. ' 



There are two methods by which the ice cream manufacturer may correct the 

 excessive retardation of melting and the curdled appearance on melting, when 

 they are due to a high initial aging temperature. (1) If he is using the optimum 

 amount of gelatin for low temperature aging, the mix should be cooled imme- 

 diately after homogenization to approximately 40° F. (2) If he wishes to initially 

 age the mix at approximately 68^ F. for two to four hours he should reduce the 

 gelatin (176 Bloom) content approximately 25 per cent from that ordinarily 

 used. Since the 68° F. temperature, alone or followed by a low temperature, re- 

 sults In an increase in gelatin efficienc}-, its use is quite flexible and therefore can 

 be adapted to the needs of the manufacturer. For instance the mix may be 

 frozen immediately after the high temperature aging period, or it may be cooled 

 to approximately 38° F. and frozen the following day. ' • 



SUMMARY AND CONCLUSIONS 



1. In an ice cream mix containing gelatin, the efficiency of the gelatin was 

 increased by aging for 4 hours at 68° F., whether this was followed by aging at a 

 lower temperature or not. 



2. This increased gelatin efficiency was evidenced by improvement in body 

 and texture, increase in melting resistance and slight retardation in rate of whip- 

 ping when compared to an identical mix aged at 38° F. 



3. When an ice cream mix containing 14 per cent fat, 10 per cent serum solids, 

 15 per cent sugar and 0.4 per cent gelatin (176 Bloom) was aged at 68°F. for four 

 hours, 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 the quality 

 of the finished product. 



4. A pasteurized ice cream mix was aged at 68° F. for 2. 4 and 6 hours without 

 any measurable efl^ect on bacterial growth, pH, or titratable aciditv, which 

 would be of any commercial significance. 



5. An ice cream mix containing gelatin showed a slight decrease in viscosity 

 when aged for 4 hours at 68° F. but a great increase in viscosity when this initial 

 aging period was followed by 20 hours at 38°. In both cases the comparison was 

 made with ice cream mixes aged for 24 hours at 38° F. 



6. The effects of high temperature aging could not be directly correlated with 

 basic viscosity values. 



7. Aging at 68° F. for 4 hours had no marked effect on the consistency and 

 whipping ability of the mix or on the melting resistance, body, and texture of the 

 finished product, when the ice cream mix contained no gelatin or other stabilizer. 



/ 



