Pas­teur­iza­tion

Consumer Voice - - Packaged Full-Cream Milk -

Pas­teur­iza­tion is the process of heat­ing a food, usu­ally liq­uid, to a spe­cific tem­per­a­ture for a def­i­nite length of time, and then cool­ing it im­me­di­ately. This process slows mi­cro­bial growth in food. Un­like ster­il­iza­tion, pas­teur­iza­tion is not in­tended to kill all micro­organ­isms in the food. In­stead, pas­teur­iza­tion aims to re­duce the num­ber of vi­able pathogens so they are un­likely to cause dis­ease (as­sum­ing the pas­teur­ized prod­uct is stored as in­di­cated and con­sumed be­fore its ex­pi­ra­tion date). Pas­teur­iza­tion is typ­i­cally as­so­ci­ated with milk. It is the main rea­son for milk’s ex­tended shelf life. High tem­per­a­ture–short time (HTST) pas­teur­ized milk typ­i­cally has a re­frig­er­ated shelf life of two to three weeks. There are two main types of pas­teur­iza­tion used to­day: HTST and ex­tended shelf life (ESL) treat­ment. In the HTST process, milk is forced be­tween metal plates or through pipes heated on the out­side by hot wa­ter, and is heated to 71.7 de­grees C (161 de­grees F) for 15–20 sec­onds. ESL milk has a mi­cro­bial fil­tra­tion step and lower tem­per­a­tures than ul­tra­high tem­per­a­ture (UHT).

Ster­il­iza­tion

Micro­organ­ism is the term ap­plied to all mi­cro­scop­i­cally small living or­gan­isms. We tend to as­so­ciate micro­organ­isms with dis­ease. Micro­organ­isms that cause dis­ease are called pathogens. How­ever, few micro­organ­isms are pathogens and micro­organ­isms play a cru­cial part in the life of our planet. For ex­am­ple, they pro­vide food for fish; they oc­cur in soil where they pro­vide nu­tri­ents for plants; and they play an im­por­tant role in ru­mi­nant di­ges­tion. In dairy­ing, some micro­organ­isms are harm­ful (for ex­am­ple, spoilage or­gan­isms, pathogens) while oth­ers are ben­e­fi­cial (cheese and yo­ghurt starters, yeasts and moulds used in con­trolled fer­men­ta­tions in milk pro­cess­ing). The micro­organ­isms prin­ci­pally en­coun­tered in the dairy in­dus­try are bac­te­ria, yeasts, moulds and viruses.

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