Product testing device good under pressure

A new device at Massey University’s Food Pilot Plant allows food products to be pasteurised at low temperature by exposing them to high pressure. The high-pressure processing machine removes bacteria and pathogens from food products without compromising their nutritional value, flavour, colour or texture.

The device exposes products to pressure in the range of 100-700 megapascals (1000-7000 times atmospheric pressure) for a period of time, usually 2-15 minutes, explained Institute of Food, Nutrition and Human Health lecturer Dr Jon Palmer.

“Many bacteria and yeast are killed by this high pressure, eliminating potential pathogens and extending the shelf life of the product, all at relatively low temperatures.”

By avoiding heat processing, heat-sensitive nutrients such as vitamins are retained, as are inherent colours and flavours, giving processed products a natural appearance and fresh taste.

Dr Palmer with a high-pressure pasteurised Styrofoam cup.

“This process will work best for high-value food products that need to retain those characteristics of nutrition and taste,” said Palmer.

Massey’s new machine has a capacity of two litres, which makes it perfect for product testing, Dr Palmer says.

Packaged food can also be processed in this way, although any air in either the food or the packaging is removed. This is shown in the above picture in which Dr Palmer holds a Styrofoam cup that has been subjected to high-pressure pasteurisation alongside the original-sized cup.

The pilot plant, opened in 2008, serves as a facility for teaching students traditional and new processing techniques. Food manufacturers also use the pilot plant for cost-effective trials on new product formulations.