Condensed Milk and Milk Powder 173 ' 



limited portion of each batch. This fact suggests that the distribu- 

 tion of heat in the sterilizer is not uniform, some cans getting less 

 heat than others. 



This defect occurs generally in summer, a fact which may be 

 due to one or both of the following conditions : 



While it is well known that there is a variety of species of bac- 

 teria, yeast and torula that are capable of producing a bitter curd, 

 either direct, or through the secretion of casein-curdling enzymes, 

 and while these different species of micro-organisms come from a 

 variety of sources, the most common sources are, the soil, pasture, 

 water and the udder itself. It is a noteworthy fact that .this defect 

 is most commonly found in milk and milk products when the cows 

 are on pasture. It is, therefore, probable that, in most cases, this 

 troublesome germ is" carried into the milk on the farm. 



Again, in summer, at a time when this defect generally occurs, 

 the effect on the cows of the summer heat and flies, and the ten- 

 dency toward high acid in milk, render the milk most sensitive to 

 the sterilizing heat. The operator finds it difficult to avoid the for- 

 mation of a disastrous curd in the sterilizer. In order to guard 

 against this trouble he is tempted to either lower the temperature, 

 or shorten the duration of the sterilizing process. This tends to- 

 wards incomplete sterilization. A very frequent result of this in- 

 complete sterilization in the early summer mdhths, is the formation 

 of a bitter curd. When the processor returns to the proper sterili- 

 zing process, the occurrence of bitter curd in the cans disappears 

 and the product is normal. 



A further safeguard against the recurrence of this trouble lies 

 in providing for uniform distribution of heat in the sterilizer. If 

 the cans have to be stacked in deep tiers, which is undesirable and 

 should be avoided, slats of wood or iron should be placed over the 

 top of every second row of cans. This will make possible the free 

 access of steam to at least one end of each can. If the circulation 

 of steam in the sterilizer is poor, the uniform distribution of heat 

 can be facilitated by filling the sterilizer about one-third full of water 

 so that, with every revolution of the frame-work, the cans have to 

 pass through this water once. The water reaches every nook in the 

 interior of the sterilizer, distributing the heat much more uniformly 



