LT: Farmers and dairy processors frequently struggle with fluctuations in supply and demand. UHT milk does not require refrigeration until it is opened – up to which time it enjoys a shelf life of six to nine months when kept at ambient temperatures of between 20 to 30 C. The milk is then filled aseptically – in air-proof, light-proof and sterile containers. To guarantee product stability, high-pressure homogenization is often used, followed by heat treatment to ensure product stability. Ultra-pasteurized or UHT milk is heated to at least 138 C for two to four seconds, inactivating all bacteria it is then sterile. Alternatively, these methods can also be combined. Removal can either be done mechanically with bacteria-removing clarifiers or microfiltration, or by using ultra-pasteurization at a temperature of around 127 C for four seconds to inactivate the bacteria. This is achieved by removing or inactivating the bacteria in the milk before bottling. Pasteurized milk has a shelf life of roughly 12 to 20 days from the time of packaging.Īnother option is ESL or extended shelf-life milk, which must be refrigerated after packaging and has a shelf life between 21 and 45 days. The milk is then cooled and from thereon must be refrigerated given that any remaining bacteria can grow and multiply otherwise.
This process is sometimes referred to as high temperature/short time (HTST) pasteurization and as a result, about 99.9 percent of the pathogens are inactivated. Pasteurized milk is heated from 72 to 75 degrees Celsius for a duration of 15 to 30 seconds. Because it is not heat treated, raw milk retains its pathogens and therefore has a relatively short shelf life – normally seven to 10 days. In many countries it not allowed to sell raw milk in stores as consumer safety cannot be guaranteed.
#Shelf stable milk full#
Some people prefer the taste and full nutritional value that raw fresh milk provides, buying direct from farmers. Raw fresh milk undergoes very little processing between the dairy farmer and the consumer.
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