A study of the natural acidity of milk in southwest Virginia

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Virginia Agricultural and Mechanical College and Polytechnic Institute

Recently interest has been aroused over the topic of acidity of milk in southwest Virginia. Certain manufacturers of skin milk powder have manufactured products, which upon being reconstituted have exceeded the government limits in titratable acidity to be classified as "Extra Grade." This is the highest grade and cannot exceed 0.15 per cent in titratable acidity.

Normal milk when freshly drawn, will naturally be slightly acid in reaction. This acidity of milk has been shown by various workers to be due to the presence of natural constituents such as the phosphates, proteins, carbon dioxide, and citrates. Any increase in acidity upon standing is due to the action of fermenting bacteria, changing lactose to lactic acid.

It has been proven that normal milk with a high natural acidity is not objectionable in the manufacture of dairy products. However a highly-developed acidity is undesirable and may cause serious economic losses if used to any great extent.

It is the opinion of certain dairymen and dairy manufacturers in this locality that due possibly to some natural existing condition in this area (such as soil type), the fresh milk may have a higher natural acidity than milk produced in other sections of the country. Should this be the case, it would seem logical that the standards should be modified so as not to reject that milk exceeding 0.15 percent titratable acidity, if the acidity is entirely natural.

The nature of this problem is to attempt to find out if the milk produced in this area has a higher natural acidity than is expected; and if so, what the factors are contributing to it.