RENNETABILITY OF CHEESE‐MAKING MILK PROCESSED BY NONTHERMAL TECHNOLOGIES

Abstract

ABSTRACTHeat treatments (HT) modify the renneting properties of raw milk, hence nonthermal technologies seem to be a good option to ensure the microbial quality of milk without modifying its renneting properties. The effect of pulsed electric fields (PEF) and high hydrostatic pressure (HHP) on the rennet coagulation properties of milk was compared with the effect caused by HT. Milk was processed by HHP (400 and 500 MPa from 0 to 20 min) and PEF (36 and 42 kV/cm for up to 64 pulses). HHP reduced the rennet coagulation time (RCT) of milk to ∼60% of the RCT of raw milk. Contrarily, PEF and HT increased RCT in ∼10%. Gels made from HHP milk presented G′ values of 170 Pa after 20 min, raw milk reached only 50 Pa after 60 min, and PEF and HT showed lower G′ values. HHP increases rennet coagulation efficiency, whereas PEF milk behaves similarly than raw milk.PRACTICAL APPLICATIONSNonthermal technologies have been suggested as a means to ensure the microbiological safety of milk without modifying its nutritional and technical attributes, and as a way to enhance its various functional properties. High hydrostatic pressure and pulsed electric field treatments applied in this study modified the renneting properties of milk, providing as a useful tool for the redesigning of cheese‐making processes. Rheological data presented in this paper clearly characterize the formation of curds out of milk treated with nonthermal treatments over milk proteins might result in the development of novel cheeses with different textures, flavors and nutritional content.