A Study of the Factors that Influence the Coagulation of Milk in the Alcohol Test

Abstract

Summary 1. A slight increase in the magnesium or calcium content will cause a positive alcohol test; an increase of potassium, sodium, chloride, citrate, and phosphate, will not cause a positive alcohol test. 2. The effect of the calcium and magnesium on the alcohol test is counteracted by the citrates and phosphates in the milk. A positive test with fresh milk depends mainly upon the relative amounts of these four salts present in it. 3. A high calcium content in a ration fed to cows can cause coagulation of milk in the alcohol test. 4. The effect of milk salts is of such importance that it can easily account for any lack of correlation between the alcohol test, acidity, and bacterial counts. The effect of acidity and the milk salts are additive. 5. Prepared rennet will cause a positive reaction in the alcohol test. The degree to which a sample of milk becomes positive will depend on the amount of rennet and the time it is allowed to act. 6. The coagulating enzymes produced by rennet forming organisms, numbering 856,000 per cubic centimeter are sufficient to cause a positive alcohol test. However, rennet forming organisms must be regarded as a minor factor in the alcohol test for their prevalence in milk rarely approaches this figure.