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Some Factors Affecting the Fat Clumping Produced in Milk and Cream Mixtures When Homogenized^*

F. J. Doan

Department of Dairy Husbandry, Pennsylvania Experiment Station, State College, Pennsylvania

ABSTRACT

The following statements seem warranted as a result of facts brought out in this study of the fat-clumping produced in milk and cream mixtures when subjected to homogenization.

1. Homogenized mixtures, regardless of fat-clumping or the absence thereof are stable emulsions, but when diluted with fluid skimmilk or whole milk, cream pronouncedly if fat-clumps are present.
   
2. The clumping of the small fat globules in homogenized mixtures of normal milk and cream is greatly stimulated by increases in the fat content and also by increases in the pressure used in homogenization.
   
3. Changes in the acidity of the plasma have little influence on the fat-clumping tendencies exhibited by such mixtures when homogenized.
   
4. Heated plasma has an inhibiting effect on the production of fat-clumps by the homogenizer.
   
5. The ratio of the amount of plasma solids to the amount of fat in the mixtures processed is a limiting factor in the fat-clumping phenomenon. There is a critical ratio above which no clumping is obtained but below which clumping is evident or even pronounced.
   
6. Due to many factors which are difficult or impossible to control, it is not possible to establish a definite value for the critical ratio, since mechanical efficiency of the homogenizer, individuality in the physical properties of different samples of milk, the fat concentration of the mixture and other undefined factors influence the value.
   
7. The critical ratio appears to be between 0.60 and 0.85 for mixtures compounded from raw products (with the exception of plain condensed skimmilk), warmed to 38°C. (100°F.), homogenized with a Union Steam Pump Company Viscolizer at 3500 pounds pressure, and of fat concentrations from 8 to 18 per cent.
   
8. Similarly treated mixtures containing lower concentrations of fat appear to have somewhat lower critical ratios, the values for 4 per cent fat mixtures lying between 0.40 and 0.50.
   
9. Fat clumping seems to be best explained on the basis of an interfacial tension effect although it is realized that the complete explanation is probably based on more than one effect.
   

^* Publication authorized by the Director of the Pennsylvania Agricultural Experiment Station as Technical Paper No. 461.

Assistance in preparing and processing many of the mixtures used was rendered by H. V. Green.

This article has been cited by other articles:

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