I buy lactose-free milk. The sell-by day is generally as much as eight weeks from the date of purchase, which is in the area of twice that of consistent milk. This appears puzzling; lactose-totally free milk, which still has actually the same mass of sugar, has twice as many kind of sugar molecules as continuous milk, because all the lactose molecules have actually been break-up in to galactose and also glucose. With twice as many type of sugar molecules per unit volume, one would think lactose-cost-free milk would last half as long as constant milk, not twice as lengthy.

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edited Aug 9, 2015 at 18:14

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Apparently the procedure offered by manufacturers (ultra-pasteurization) to create lactose-cost-free milk is responsible for the longer shelf life.

One source reports:

Lactose-free milk is pasteurized at a greater temperature than continuous milk. The process, known as ultra-pasteurization, is designed to remove the bacteria content completely, providing lactose-free milk a refrigerated shelf-life of 60-90 days, compared with constant pasteurized milk, which retains some bacteria. It has actually a shelf life of 1-3 weeks.

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A producer (in the United States) of organic dairy assets (Organic Valley) defines ultra-pasteurization and the extfinished shelf-life below as:

Ultra Pasteurization (UP), or Ultra High Temperature (UHT) pasteurization, is the process of heating milk to approximately 280 °F for just 2 seconds and also then chilling it back down quickly. The result is milk that"s 99.9% complimentary from bacteria. This pasteurization procedure creates an extended shelf-life for milk products of up to three times the size as HTST pasteurization; while giving the very same wholesome, high quality dairy product. This permits us to distribute UP milk assets regionally and to other areas of the country that could not have accessibility to our dairy products. This is described as "ultra pasteurized" on the milk package. Organic Valley provides its quarts and some of its half gallons of milk through Ultra Pasteurization (UP).