Factors that influence the stabilization of the milk system and non-acid unstable milk: a review

Abstract

Stability is an important factor to increase the shelf life of dairy products, and this can be affected by several factors, thus ensuring this stability can provide a better quality of the final product. The occurrence of unstable non-acid milk (UNAM) causes losses to producers and dairy products, as it presents a risk of coagulation during thermal processing in the industry. Given the above, the aim of this study was to develop a review based on the composition of milk and address the main factors that affect its stability, which is essential to understand the behavior of dairy products and the development of new products. The stability of micelles is attributed to their net negative charge and steric repulsion by the flexible macropeptide region of κ-casein. Colloidal calcium phosphate is in dynamic equilibrium with the calcium phosphate present in serum. This balance depends on physicochemical conditions such as temperature, pH, the presence of different minerals, and ionic strength. Low pH, specific proteolytic enzymes, and ethanol can result in the destabilization of casein micelles. Thermal stability decreases as the acidity of the milk increases, or it can change according to environmental, genetic, and nutritional factors in dairy cows, such as the occurrence of Unstable Non-Acid Milk (UNAM). When the stability of the protein micellar structure is poor, due to factors such as acidity, the sample coagulates in the alcohol test.