Food dehydration method keeps quality but cuts cost
produces granulated food of the quality of vacuum freezing-dying at
a fraction of the cost, writes Anthony Fletcher.
"The growing use of powdered foods is due to the fact that many people wish to put less time into preparing meals," said professor Ingvald Strømmen, one of the developers of the new technology at the Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology (SINTEF).
"We have gone into this field with the aim of giving people the best possible ingredients in bags of granulated food."
Indeed the major strength of the process is that it provides the quality of vacuum freezing-dying but is much less expensive. The Norwegian scientists achieved this through the combination of two technologies.
Firstly, a fluidised bed is used to dry the particles suspended in a vertical current of gas. This dehydrates them on all sides at once, shortening the drying time and increasing the capacity of the system.
The process of dehydration in a chamber kept at sub-zero temperatures makes the food highly porous and gives it good capacity to absorb water again in the cooking pot.
The second innovation is the use of air treatment in a heat pump. The drying air circulates in a closed loop connected to a heat pump and acquires the correct properties for drying when it meets the hot side of the heat pump.
It is then dehydrated again as it passes through the heat pump's cold side, reducing energy consumption.
Ready meals remains one of the most dynamic sectors of the food and beverage industry. The European market for example now accounts for an annual consumption in excess of 480,000 tonnes.
The market has grown by 20 per cent in the UK alone over the past five years, and the trend shows no sign of having peaked. Most food and beverage manufacturers and retailers believe that changing lifestyles will continue to fuel the marketplace, and that by 2007 European ready meal tonnage will top the 500,000 tonne-mark.
With consumption likely to increase and manufacturing costs likely to remain high with record raw material and oil prices, the Norwegian freezing innovation could offer food processors a new cost-efficient means of production.
Norwegian company Dtech AS - a spin-off of SINTEF and NTNU - is now in the process of building a large factory on the basis of the results obtained by the study.
The new plant will supply the international food industry with dried maize and dried peas, ingredients that will end up in dried soups and powdered casserole dishes all over the world. Dtech claims that in terms of taste, aroma and colour of the end-products, the new technology approaches the quality of vacuum freeze-drying.