Heat Treatment of Milk | Sterilization of Milk and Other Products

Abstract

The aim of the sterilization process is to produce a long-life product by destruction of microorganisms capable of causing spoilage of the product during storage and also to destroy the microorganisms detrimental to public health. For the sterilization of milk and milk products, continuous sterilization, in-container sterilization in autoclaves, and ultra-high-temperature treatment (UHT) are used. Sterilization processes are characterized by the applied heating temperature and the holding time. To evaluate the effectiveness of a sterilization process regarding destruction of microorganisms and to quantify the chemical changes in the product, the temperature, treatment time, and the concentration of the product need to be considered. The heat treatment conditions, in terms of temperature and time, can be optimized, ensuring a sufficient destruction of pathogenic and spoilage microorganisms and at the same time limiting the heat load on the product to avoid undesirable chemical changes. Depending on the microorganisms responsible for restricting the shelflife and for important chemical or textural changes, and on other special demands or standards, process conditions can be determined using kinetic parameters such as the activation energy (EA), the rate constant (kT) of the reaction, and the order of the reaction (n).