713. The relation between the chemical composition of milk and the stability of the caseinate complex: II. Coagulation by ethanol

Abstract

1. The variation in the stability of milk protein to ethanol and the relationship between milk composition and ethanol stability were examined.2. Samples of herd bulk milk were very similar in stability to ethanol; the range of aqueous ethanol solutions required to coagulate the caseinate complex in an equal volume of milk was only 80–84% (v/v) ethanol. Samples from individual cows showed a wide variation in stability; coagulation was caused by ethanol solutions ranging in strength from 66 to 90% (v/v) ethanol.3. Colostrum was very unstable to ethanol but stability rapidly increased during the post-colostrum period to higher levels in mid-lactation. Late lactation and subclinical mastitis milk showed no definite bias towards stability or instability.4. The strength of ethanol required to coagulate the caseinate complex in an equal volume of milk was inversely related to the concentration of ionized calcium in the milk. The correlation coefficient was –0·76 (significant at 0·001 level) indicating that approximately 60% of the variation in stability was accounted for by the variation in the concentration of ionized calcium.5. The relationships between the concentrations of other milk constituents and stability to ethanol could be attributed to the interrelations of the concentrations of these constituents and the concentration of ionized calcium.

Improvement of low fat mozzarella cheese properties using denatured whey protein

“…The curd tension was determined using the method of Chandrasekhara et al. (1957).The rennet coagulation time (RCT) was determined according to Davies and White (1958) whereas the curd synaeresis was measured as given by Mehanna and Mehanna (1989). Actual cheese yield was determined by dividing the weight of cheese by the weight of milk used to make cheese, multiplied by 100, then adjusted to 55% moisture and 1.5% salt cheese yield as per Metzger et al.…”

Effect of the kappa-casein gene polymorphism, breed and seasonality on physicochemical characteristics, composition and stability of bovine milk

“…Milk stability was determined by the ethanol test according to Davies & White (1958), with alcoholic solutions at 70,76,80 and 84ºGL (v/v). Given results were classified as stable (without coagulation) or unstable (with coagulation), according to the alcohol solution used.…”

Acid-base balance of dairy cows and its relationship with alcoholic stability and mineral composition of milk

“…The potassium changed the load between the casein micelles and thus caused a decrease in their repulsive forces. This cation, as well as modifying the ionic forces, also has the effect of lowering the pH of milk, which increases the micellar instability (Davies & White 1958).…”