Nutritional value of UHT milk can be retained through lactose free milk drink production method
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| 13th June 2008
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| UHT (ultra high temperature) dairy products have a long shelf life and can be stored at room temperature, which facilitates e.g. the export of fresh dairy products beyond nearby countries. Room temperature storage impairs the product's quality and nutritional value, however. Olli Tossavainen, Lic.Sc. (Tech.), studied in his doctoral dissertation the changes in lactose free, low lactose HYLA, and ordinary milks during manufacture and storage. He also developed a method to improve the shelf life of lactose free milk drink significantly.
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Due to the success of its lactose free milk drink, Valio is producing an increasing number of milks in which lactose is degraded into glucose and galactose. The lactose free milk drink manufacturing process first removes part of the lactose physically and then the rest is enzymatically degraded into the two components. In low lactose HYLA milk, more than 80% of the lactose is degraded into glucose and galactose.
Milk is treated at high temperatures (UHT or ESL (Extended Shelf Life process) to improve shelf life and meet export requirements. But glucose and galactose cause browning during heat treatment more easily than does lactose, so milks that contain them are more vulnerable to colour and taste defects and the nutritional value of the milk protein is impaired.
If UHT milk is stored at room temperature, browning and proteolysis (protein degradation) are strong and shelf life short. By removing the sugars from milk completely using a chromatographic separation process, Mr Tossavainen's project succeeded in producing lactose free UHT milk that keeps very well at room temperature as well as when refrigerated. The process also eliminated the proteolytic activity in milk.
The dissertation's results yielded a patent application for this method of manufacturing UHT milk that keeps very well.
Mr Tossavainen's doctoral dissertation, which underwent its public defence on June 13th, also compared low lactose HYLA milk and lactose free milk drink with ordinary milk in the context of different heat treatment processes; protein nutritional value in HYLA milk was slightly impaired and lactose free milk drink was found to be superior to HYLA milk in that respect. Any change in the taste, colour and nutritional value of UHT milk was considered non-significant if distributed via a cold chain.
Further information: Olli Tossavainen, D. Sc. (Tech.), Research Manager, Valio Ltd, Tel. +358 10 381 3235.
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Olli Tossavainen
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