264 UNSWEETENED CONDENSED MILK DEFECTS 



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 tendency toward high acid in milk, render the milk most 

 sensitive to the sterilizing heat. The operator finds it difficult 

 to avoid the. formation 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 towards incomplete sterilization. . A very frequent 

 result of this " incomplete sterilization in the late summer 

 months, is the formation of a bitter curd. When the processor 

 returns to the proper sterilizing 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 un- 

 desirable and should be avoided, slats 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 distribu- 

 tion 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 than the steam. Uneven distribu- 

 tion of the heat may also be due to an improper condition of the 

 steam-distributing pipe located in the bottom of the sterilizer. 

 Some of the perforations in this pipe may have become too large 

 by wear, or may have become clogged with scale or the cap 

 at the end of the pipe may have come off. In all of these cases 

 the distribution of the heat in the sterilizer is found to be irregular, 

 interfering with the uniformity and dependability of the proces's 

 of sterilization. The processer should make sure, by daily in- 



