Factors affecting the clotting properties of sheep milk

Abstract

A Formagraph was used to test the effects of some of the exogenous factors that can affect the processing properties of milk (pH, soluble calcium, rennet concentration, coagulation temperature), and two of the endogenous factors (protein and fat concentration), on the comparative clotting properties of sheep and cows' milk, namely renneting time (r), rate of ®rming (k20) and curd consistency (A30). A lower pH decreased r and k20 and increased A30 in both sheep and cows' milk. The addition of calcium chloride did not affect the clotting properties of sheep milk, but in cows' milk it decreased r and k20 and increased A30. Increasing the concentration of rennet decreased r and k20 and increased A30 for both sheep and cows' milk. Increasing the coagulation temperature from 30 to 38°C decreased r for both sheep and cows' milk, but it decreased k20 and increased A30 only in cows' milk. Increasing the protein concentration decreased r in both sheep and cows' milk; it did not affect k20 of sheep milk, but it decreased that of cows' milk and increased A30 in both milks. Increasing the fat concentration had little effect on r and k20 in either sheep cows' milk, but it decreased A30 in both milks. In general, sheep milk had faster renneting times and rates of ®rming and greater curd consistency than cows' milk, and its clotting properties tended to be less affected by changes in the clotting conditions.

Changes of physico-chemical characteristics, somatic cell count and curd quality during lactation and their relationships in Lacaune ewes

“…On the other hand, Jelínek et al (1990) reported that from 90th day of lactation the CT gradually shortened till the end of lactation. In our opinion, elongation of CT in our study was mainly influenced by the gradual increase of the contents of TP, casein Bencini (2002) reported that pH of sheep milk is a factor of paramount importance of the rennet coagulation time, but in our study no significant correlation between these parameters was found.…”

Legume grain-based supplements in dairy sheep diet: effects on milk yield, composition and fatty acid profile

“…There were no significant differences among the groups with regard to SCC, TBC, or milk clotting ability (r, k 20 , and a 30 ) (Table 3). However, it is worth noting that in all diets, milk urea levels were within normal limits for dairy ewes (Cannas et al 1998), and the milk clotting parameters were close to those recorded for sheep milk (Bencini 2002).…”

Seasonal changes of the chemical composition of cheese obtained from the milk of indigenous Polish breeds of sheep

“…The content of milk components (mainly fat and protein) and also other factors such as casein micelle diameter and mineral equilibrium, which also change during lactation, can affect curd firmness (Remeuf et al, 1991;Pellegrini et al, 1997). Bencini (2002) found that increasing the protein content (4.9%-6.84%, pH 6.71) of ewe milk decreased its rennet clotting time (RCT) and increased its curd consistency, but the same author reported that the relationship between the concentration of milk protein and curd firmness is curvilinear and curd does not increase when the milk protein exceeds ≈ 6.3%. The same observation was made for a high fat content of milk -curd consistency increases when the fat concentration in milk is less than 6.85%.…”