Effects of heating and calcium and phosphate mineral supplementation on the physical properties of rennet-induced coagulation of camel and cow milk gels
Abstract
The physical properties of rennet-induced coagulation of preheated camel and cow milk gels (50 and 70 °C for 10 min) enriched with calcium chloride (CaCl 2 ) and hydrogen phosphate dihydrate (Na 2 HPO 4 2H 2 O) were evaluated using the dynamic low amplitude oscillatory shear analysis. The storage modulus ( G ʹ) and loss modulus ( G ʺ) of camel milk gels showed significant ( P < 0·05) lower values than those of cow milk gels. The preheating of camel milk at 50 °C affected negatively the gelation properties, while the preheating at 70 °C prevented the formation of rennet-induced milk gels. No effect was observed on the gelation properties of cow milk gels. The CaCl 2 added at 10 and 20 mM to preheated camel and cow milk reduced significantly ( P < 0·05) the gelation time and increased the gel firmness. In contrast, Na 2 HPO 4 2H 2 O added at 10 and 20 mM induced the formation of weak gels for preheated camel and cow milk at 50 °C, and even no gelation for preheated camel milk at 70 °C.