What is UHT milk?

The Star Malaysia - Star2 - - FRONT PAGE - Sto­ries by NG TSE MEI

It comes in a thick card­board box and can be kept with­out re­frig­er­a­tion for six to nine months if un­opened. Is it re­ally milk?

UHT milk has been avail­able in Malaysia since the 1970s. When it en­tered the mar­ket, it had to jos­tle with milk pow­ders, con­densed milk, evap­o­rated milk and pas­teurised milk for a slice of the big milk pie.

Now, 40 years on, UHT milk has not only man­aged to be­come a main­stay on su­per­mar­ket shelves, its con­sump­tion has in fact been in­creas­ing year on year, re­ports Dutch Lady Milk In­dus­tries Ber­had, Malaysia’s lead­ing milk brand and the first com­pany in the coun­try to mar­ket milk in UHT pack­ag­ing.

“We at­tribute this to the in­crease in aware­ness of the ben­e­fits of milk, cou­pled with trends that in­di­cate that a big­ger por­tion of con­sumers rely on the con­ve­nience that UHT pack­ag­ing of­fers,” says Aznil Sharizat Mahidin, head of the cor­po­rate com­mu­ni­ca­tions depart­ment in Dutch Lady.

“Also, as the so­cio-eco­nomic sta­tus of con­sumers im­proves, UHT milk is of­ten the pre­ferred choice over fam­ily pow­dered milk,” she adds.

Still, mar­ket re­search in­di­cates that the most pop­u­lar type of milk con­sumed in Malaysia is sweet­ened con­densed milk – that’s what goes into our teh tarik.

But what ex­actly is UHT milk? And how can it last so long with­out re­frig­er­a­tion?

UHT stands for Ul­tra Heat Treated or Ul­tra High Tem­per­a­ture pro­cess­ing – a method of ster­il­is­ing food by heat­ing it to tem­per­a­tures up­wards of 130°C for a few sec­onds, and then rapidly cool­ing it. The pro­ce­dure is used for ster­il­is­ing fruit juices, soymilk, soups, ketchup, salad dress­ings, and par­tic­u­larly, milk.

“Pas­teuri­sa­tion is the min­i­mum amount of pro­cess­ing for milk as re­quired by Aus­tralian law and is spec­i­fied as 72°C for 15 sec­onds,” ex­plains Michael Ock­erse of Pure­har­vest, one of Aus­tralia’s largest or­ganic milk pro­duc­ers. At Pure­har­vest, UHT milk is pro­cessed at 132°C for two to three sec­onds.

“The in­creased tem­per­a­ture at which (UHT) milk is treated re­sults in a greater re­duc­tion in bac­te­ria and heat-re­sis­tant en­zymes in com­par­i­son to milk that un­der­goes pas­teuri­sa­tion, giv­ing it an ex­tended shelf life,” ex­plains Amar Sri­vas­tava of Aus­tralia’s largest milk pro­ces­sor Murray Goul­burn, whose com­pany pro­duces Aus­tralia’s top UHT milk brand, Devon­dale, brought in by Pok Broth­ers Sdn Bhd.

Pas­teurised milk and UHT milk are both packed asep­ti­cally af­ter the heat treat­ment, the former in milk car­tons, and the lat­ter in Te­tra Paks.

“Te­tra Pak has seven lay­ers to main­tain the qual­ity of milk and re­duce bac­te­rial con­tam­i­na­tion,” ex­plains Sri­vas­tava.

The Swedish patented pack­ag­ing box is made from lay­ers of poly­eth­yl­ene plas­tic to keep it air­tight, foil-lam­i­nated to keep out light and thick card­board lay­ers to pro­vide struc­tural in­tegrity.

The re­in­forced pack­ag­ing and the high-heat treat­ment is the rea­son UHT milk can sit hap­pily at room tem­per­a­ture un­til opened (af­ter which it should be treated like any fresh milk: re­frig­er­ate and use within a few days), while pas­teurised milk must be re­frig­er­ated from fac­tory, all through the dis­tri­bu­tion sys­tem to the stores, and fi­nally to your home.

“UHT milk has a nine-month, best-be­fore date, but it is still safe for con­sump­tion up till 12 months,” says Ock­erse. “Pas­teurised milk has a shelf life of only 14 days.”

“There are no preser­va­tives in UHT milk. The long shelf life is guar­an­teed through high tem­per­a­ture pro­cess­ing and asep­tic fill­ing con­tain­ers,” Sharizat re­it­er­ates.

In many parts of the world, UHT milk is still re­garded as sus­pect, if not for the pre­sumed pres­ence of preser­va­tives, then for the ef­fects of the high-heat pro­cess­ing.

“UHT pro­cess­ing does not change the molec­u­lar struc­ture of milk,” ex­plains Sharizat. “How­ever, it does change the con­fig­u­ra­tion of the pro­teins. This process is called de­nat­u­ra­tion, and is also the rea­son eggs be­come hard when boiled and meat be­comes firm when cooked.”

UHT milk pro­duced in the early years of the tech­nol­ogy’s de­vel­op­ment was char­ac­terised by a strong burnt taste, an ef­fect of Mail­lard brown­ing caused by the high-heat treat­ment. But UHT milk pro­duc­tion has ex­pe­ri­enced quan­tum leaps of im­prove­ment since then.

Stud­ies have dis­cov­ered that by al­ter­ing the pro­cess­ing pa­ram­e­ters of UHT milk, such as us­ing in­di­rect steam in­jec­tion rather than di­rect heat ap­pli­ca­tion, and in­creas­ing the speed at which the milk is cooled af­ter heat­ing, the re­sult­ing milk tastes sweeter, and the burnt taste is sig­nif­i­cantly re­duced to the point where it is not dis­cernible to most con­sumers.

The ad­di­tion of epi­cat­e­chin, an an­tiox­i­dant-rich flavonoid com­pound abun­dant in tea and choco­late, has also been found to re­duce the “cooked” aroma of UHT milk. But for those wary of ad­di­tives, a quick check of the la­bel should re­veal if there are ad­di­tives in your milk, and the nu­tri­tional con­tent is shown on the pack, too.

“UHT milk has the same nu­tri­tional good­ness as pas­teurised milk, and a sim­i­lar taste pro­file,” says Sri­vas­tava. “Like fresh milk, UHT milk is a rich source of over 10 es­sen­tial nu­tri­ents, in­clud­ing cal­cium, phos­pho­rus, potas­sium, ri­boflavin, potas­sium, vi­ta­mins A and B12, mag­ne­sium, car­bo­hy­drate, pro­tein and zinc.”

“UHT pro­cess­ing does not change the nu­tri­tional con­tent of milk,” con­curs Sharizat, “but it can af­fect digestive prop­er­ties, which is mainly of im­por­tance to new­borns,” and by ex­ten­sion, ex­pect­ing moth­ers.

“The only nu­tri­ents af­fected by heat treat­ment are some of the vi­ta­mins, es­pe­cially vi­ta­min C. This is, how­ever, not present in sig­nif­i­cant amounts in milk,” says Sharizat. Hence, we don’t usu­ally rely on milk for our in­take of vi­ta­min C. “Losses for other vi­ta­mins are min­i­mal,” she adds.

“Based on the Malaysian Adult Nu­tri­tion Sur­vey pub­lished in 2008, we know that pro­tein and vi­ta­min A in­take in Malaysia is at the rec­om­mended level, but cal­cium in­take is on av­er­age only at about 50% of the rec­om­mended value. This is a clear in­di­ca­tion that Malaysian adults are not con­sum­ing suf­fi­cient amounts of dairy prod­ucts,” ob­serves Sharizat.

Did you know? DUE to its long shelf life and high nu­tri­tional con­tent, UHT milk is one of the pro­vi­sions on stock­pile in food banks ready to be dis­patched for dis­as­ter re­lief.

Glass milk bot­tles were used in the West as re­cep­ta­cles for the dis­tri­bu­tion of milk un­til the 1950s, when they were largely re­placed with milk car­tons.

The ro­tary milk­ing ma­chine, one of two types of modern mech­a­nisms for har­vest­ing milk, the other be­ing the her­ring bone milk­ing ma­chine.

Safe to glug: UHT milk is packed asep­ti­cally into the sev­en­lay­ered Swedish­patented Te­tra Pak to main­tain its long shelf life.

Michael ock­erse of Pure­har­vest says uHT re­sults in a greater re­duc­tion in bac­te­ria and heat-re­sis­tant en­zymes.

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