pasteurize

Pasteurization is a heat-treatment process used to kill pathogens and reduce microbial load in liquid foods and some products. Named after Louis Pasteur, who developed methods to prevent spoilage in wine and beer, the process aims to improve safety and extend shelf life without sterilizing the product. Because it does not achieve complete sterility, pasteurized products can still contain viable microorganisms and must be kept refrigerated and consumed within a timeframe.

There are several common methods. Batch pasteurization (low-temperature, long-time, LTLT) heats product around 63°C for about 30 minutes. High-temperature short-time (HTST) pasteurization heats to about 72°C for at least 15 seconds. Ultra-pasteurization (or ultra-high-temperature processing, UHT) heats to 135–150°C for a few seconds, producing a longer shelf life and allowing non-refrigerated storage in some cases. After processing, products are rapidly cooled and packaged under sanitary conditions.

Pasteurization is widely used on milk and dairy products, fruit and vegetable juices, eggs, and some liquid egg products, as well as certain beverages and sauces. The main goal is to destroy pathogens such as Salmonella, Listeria, and certain strains of E. coli and Coxiella burnetii, while reducing spoilage organisms. In some products, pasteurization may be combined with filtration or aseptic packaging to extend shelf life further. Spore-forming bacteria may survive pasteurization, so proper handling remains important.

Impact on quality varies by product. Heat can affect flavor, color, and some nutrients (notably heat-sensitive vitamins). Most dairy flavors are preserved with HTST, though UHT can impart a cooked taste and reduce certain nutrients. The decision to pasteurize and which method to use depends on desired shelf life, product type, and regulatory standards.