WASHING POWDERS FOR DAIRY USE 



By A. W. Phillips, Assistant Research Professor of Dairying, M. J. Mack, 



Assistant Professor of Dairying, and J. H. Frandsen, Professor of Animal 



and Dairy Husbandry' 



Introduction 



Tlie most iiii]vortaiit factor I'onnected with any food supply is cleanliness. 

 This is particularly the case in the handling of dairy products because, owing 

 to their greasiness and solid particle content, these products adhere very tena- 

 ciously to all utensils with which they come in contact, and, being very good 

 food upon which many micro-organisms can live, offer excellent breeding 

 grounds for bacteria. Therefore, it is extremely important that all milk 

 utensils should receive a thorough cleaning after each use. 



This paper reports a study of the cleansing of dairy utensils and how it 

 may he accomplished satisfactorily. There are two phases of the problem due 

 to the complexity of the milk products themselves: first, the cleaning of the 

 utensils from adhering particles of the dairy product; and second, the steril- 

 ization of the cleaned surface. The cleaning operation is by far the more 

 important step, for without thorough cleaning sterilization would be extremely 

 difficult if not impossible. Also, sterilization is accomplished to a certain de- 

 gree during the cleaning process. 



Chemical Changes in Cleaning 



Milk and the products manufactured from milk are of a very complex 

 physico-chemical nature. In the handling of dairy products we are dealing 

 with a very delicately balanced system of emulsions, colloids, and solutions 

 which, even when unaltered by any treatment, possess great adhesive 

 properties for surfaces with which they come in contact. When the products 

 are altered by intrinsic agencies such as souring or by outside agencies such 

 as heat, then the original systems of enuilsions and colloids are changed and 

 the solid and liquid materials thus thrown out are found to adhere even more 

 tenaciously, and the difficulties of the cleaning operation are therefore greatly 

 increased. The problem in cleaning is, then, to re-einulsify these deposits or 

 bring them back into the colloidal state. 



The fat or oily ingredients in dairy products can be separated from the 

 surfaces to which they adhere by the action of some emulsifying agent pro- 

 vided they are not bound there by some other ingredient. This enuilsifying 

 action is not, as is popularly l)clieved, due to neutralization of fatty acids 

 and saponification. If the fatty substance is not rancid there is scarcely any 

 free acid present and, moreover, saponification does not take place under con- 

 ditions existing in the washing process. 



An alkali is capable of assisting in the formation of a surface layer by 

 reacting with the free fatty acid in the grease to be removed. The "surface 

 activity" of the detergent is increased by adding alkali (1). The alkali lowers 

 the interfacial tension between oil and water but does not saponify the oil to 

 any extent. In order to maintain a constant alkali strength buffer salts are 

 needed in the detergent. 



1 Acknowledgement is made to Professor H. F. .ludkiiis. former head of the Dairy 



Department, who originally proposed this problem. 

 (1) Shorter: Proc. Roy. Soc. London A92:'_';!l (1916). 



