~Checked\/Approved\/Final<\/p>\n
Preserving nutrients in milk via UHT technology<\/p>\n
Made Astawan
\nJakarta
\nastawan@indo.net.id<\/p>\n
Milk is the best food for land mammals because it
\ncontains an almost perfect composition of nutrients, such as
\nwater, protein, carbohydrates, minerals, fat, along with
\nsufficient amounts of vitamins A, C and D.
\nToday, unlike decades ago, it is seldom that milk is
\nconsumed fresh, straight from a cow. Generally, in liquid form,
\nit is processed either via UHT or pasteurization treatment or is
\nmade into a powder form.
\nPasteurization basically means heating milk to between 63
\nand 720 C for about 15 seconds to kill the pathogen bacteria.
\nPasteurized milk has to be refrigerated at around 50 to 70 C and
\nthis milk is good for only about 14 days.
\nPowdered milk, meanwhile, is derived from fresh milk
\ncombined with or without other ingredients, such as fat or
\nprotein, which is dried using the spray or roller dryer method.
\nThis type of long-life milk can be kept for a maximum of two
\nyears if stored correctly. There are three categories of powdered
\nmilk: Full cream milk powder, composite skim milk powder and skim
\nmilk powder.
\nFinally, there is Ultra High Temperature (UHT) milk. UHT
\nheats milk at between 1350 and 1450 C for about two to five
\nseconds to kill all of the microorganisms while at the same time
\nnot disrupting the nutritional ingredients of the milk, including
\nthe color, aroma and taste.
\nFactors that contribute to the quality of UHT milk
\ninclude the cow feed, the composition of the raw milk, and the
\nmilking and packaging process that must be hygienic.
\nAt the factory, processing is conducted using highly
\nsophisticated sterile tools to minimize milk's contact with
\nbacteria. Multi-layer packaging is used in the milk cartons to
\nprevent any bacteria and damaging ultra violet rays from entering
\nthe package.
\nThese safeguards ensure the freshness and quality of UHT
\nmilk as required by international hygienic standards. Besides
\nbeing free from bacteria, the UHT process makes it possible for
\nthe milk to be stored for a long time without preservatives and
\nwith no refrigeration, for up to 10 months after production,
\nwhich is much longer than pasteurized milk. Once the pack is
\nopened however, the milk must be stored in a refrigerator for
\nfurther use.<\/p>\n
Some tips on checking UHT Milk<\/p>\n
UHT Milk in cartons can go bad if there is a leak in the
\npackage. An easy way to check this is to see if the pack is
\nbloated or 'puffed'. This is the result of microbes entering the
\ndamaged pack, fermenting the milk, causing CO2 to be released,
\nthus causing the pack to bloat.<\/p>\n
Avoid consuming UHT milk which appears thick of lumpy -
\nbacteria which has infected the milk causes coagulation leading
\nto a break-up of proteins and a decrease of organic acid.<\/p>\n
Damage to the product can of course be easily detected by its
\nsmell and taste. One precaution to be borne in mind is storing
\nUHT milk in very high temperature - above 50 degree centigrade -
\nas this causes the milk to go sour quickly.<\/p>\n
--- the writer is a senior lecturer on Food and Nutrition at the
\nBogor Farming Institute (IPB)<\/p>",
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