High-pressure processing: beyond microbial inactivation.

High-pressure processing (HPP) has a wide range of applications. Though it is less effective in the presence of fat, which acts as a protective layer, it can retain the freshness of jams and fruit and vegetable juices; extend the shelf life of white and red grape musts; inactivate enzymes, such as polyphenol oxidase (PPO) in guava puree; and inactivate bacterial spores when used with heat.

Moreover, HPP allows swollen starch granules to keep their granule-like structure. It improves enzyme digestibility and gelatinized structure without retrogradation; rapidly freezes and thaws products; tenderizes meat; inactivates Salmonella and Listeria in liquid whole eggs while improving functional characteristics; improves the coagulation properties of milk; and increases moisture retention of fresh cheese.

There is no doubt that HPP represents another promising dimension for food processing, not only because it inactivates microorganisms but also because it provides opportunities for the development of new value-added food products. The need for an alternative to thermal processing as the primary means of eliminating pathogenic and spoilage microorganisms is substantial. HPP holds promise since food materials treated by this method retain their natural flavor, color and texture without loss of their vitamin or nutrient content.

Little work has been done to predict changes in functional characteristics of proteins and complex carbohydrates. This means that there are some exciting avenues of research in the HPP treatment of foods that remain to be explored.

Despite the challenges associated with understanding the interactive components of the process, HPP shows promise in its ultimate usefulness for food processing. Further research will help to mitigate any high capital costs associated with this technology and enable processors to take advantage of HPP to bring safe, value-added products to consumers.

Further information. Gaurav Tewari, Guelph Food Technology Center, 88 McGilvray St., Guelph, Ontario N1G 2W1, Canada; phone: [phone]; fax: [phone]; email: [e-mail].