Explore applications for ultra-high pressure.

There is growing demand for convenience foods that retain the flavor, color and nutritional qualities of fresh foods, but which last longer. Traditional ways to preserve food, such as pasteurization and the use of chemical preservatives, tend to alter these features, which are so highly prized by consumers. The scientific challenge is to find ways to improve the safety of foods, but without losing the fresh characteristics.

Australian scientists (CSIRO, P.O. Box 225, Dickson ACT 2602, Australia) are exploring the use of ultra-high pressure (UHP) as an alternative to heat treatment or chemical preservatives. Their goal is to create foods that retain all their desirable fresh characteristics, but which have the shelf life of a processed food. The answer may lie in novel high-pressure technology, which has been the subject of much research in the United States and Europe.

Foods are placed in a water medium at pressures of 100 megaPascals (MPA) to 800 MPA. The intense pressure kills pathogenic microbes as well as bacteria that cause foods to spoil. The pressure causes damage to the outer cell membranes of the bacteria, which eventually kills them. Because food contains water, which is relatively incompressible, it causes minimal damage to the actual food itself. The result is a product which retains most of the features of fresh produce, but which keeps longer and is safe to eat.

Different food microbes and enzymes require different intensities of pressure to destroy them. Much of the research will focus on finding the precise treatments necessary to make various foods safe and wholesome with an enhanced shelf life. To begin with, the work will focus on using pressure as a way to treat acidic foods such as jams, fruit juices and sauces, as well as refrigerated products, such as meats and seafood. These are easily preserved using pressure techniques. Eventually, the research team also plans to explore the use of pressure to replace sterilization or the canning of foods, such as fruits and vegetables.

There are several challenges to overcome. Some enzymes which cause foods to spoil are very resistant to pressure, and the presence of oxygen residues in the food can also lead to spoilage. As a result, it may be necessary to combine pressure with other techniques, such as cool storage and hygienic packaging, to attain the best results.

Food Science Australia researchers will conduct the research using a UHP unit manufactured by Flow International. The UHP unit will allow Food Science Australia to work with companies to evaluate, first hand, the potential of this new technology to their businesses. Flow International has 41 UHP units in operation or on order. Currently, they are being used by food companies in the United States, Japan and Europe to process seafood, meat, fruit and juice products. Further information. Julian Cribb; phone: [phone];fax: [phone]; email: [e-mail].