Understanding Thermization: A Heat Treatment for Milk Storage and Quality

Thermization of milk is a heat treatment distinct from pasteurization, specifically designed to control spoilage without significant alteration of the milk's properties. Unlike pasteurization, thermization lacks a legal definition or standardized criteria. The process involves heating milk to 62–65 °C for 10–20 seconds, followed by immediate refrigeration.

This treatment is ideally applied soon after milk collection and remains effective only if the thermized milk is kept at a low temperature, around 4 °C. Thermization significantly reduces spoilage bacteria with minimal impact on the milk's components, preserving its natural flavor. This makes it an excellent prepasteurization method to maintain milk quality during extended storage in insulated silos.

Thermization is also employed as a postpasteurization treatment for various dairy products. Its primary purpose is to protect against microorganisms, particularly Gram-negative psychotropic bacteria, which can proliferate during raw milk storage. The treatment allows milk to be stored below 8 °C (46 °F) for up to three days or at 0–1 °C (32–34 °F) for as long as seven days. Subsequently, the milk can undergo more rigorous heat treatments for extended preservation.

A critical aspect of thermization is the cooling phase before any reheating, which is necessary to delay or prevent the outgrowth of bacterial spores. This cooling step ensures that the milk remains safe and high-quality until it can be further processed or consumed.

In summary, thermization is a strategic heat treatment that extends the shelf life of milk by reducing spoilage bacteria while preserving its flavor and nutritional qualities. Although not legally defined like pasteurization, it serves as an effective measure for maintaining milk quality during storage and transportation.
Understanding Thermization: A Heat Treatment for Milk Storage and Quality