ความคิดเห็นที่ 7
HIGH PRESSURE PROCESSING OF FOODS
Consumers demand high quality, minimally processed foods with fresh characteristics and no additives. A novel food preservation method receiving wide attention is High Pressusre Processing. (HPP also known as high hydrostatic pressure processing or ultra-high pressure processing) wherein the food is treated at elevated pressures of 30,000-130,000 pounds per square inch for a specified temperature and time.
Contrary to prevailing belief, recent studies conducted at the National Center and elsewhere lead to the conclusion that HPP should be considered a thermal process assisted by pressure. Compared to retorting of canned food or pasteurization of juice and milk, HPP significantly reduces the process temperature and time. This results in a food with improved attributes.
Until now, HPP has been used mainly for refrigerated and high-acid foods. The first HPP applications were in heat-sensitive, value-added products. Foods "pasteurized" by HPP undergo pressures of up to 80,000 psi at or near ambient temperatures (under 45°C). Under these conditions, HPP was found to be effective in inactivating most vegetative pathogens commonly found in the foods. Commercially available HPP-processed products in Europe and Asia include juices, jams, jellies, meat and yogurts. Consumers in this country can buy HPP-processed guacamole and oysters. There is significant commercial interest in development of other products.
Food processed by HPP reportedly has better retention of flavor, texture, color, and nutrients. The processing cost is slightly higher (two to three cents per pound) than for conventional processes.
Though preservation of low-acid foods is more difficult, it may be possible to use HPP successfully by combining moderate heat (80-110°C) with very high pressures (up to 130,000 psi). A new research project at the National Center will examine this possibility. The National Center, in partnership with Flow International, U.S. Army Soldier System Command, Kraft Foods, Procter & Gamble, and ConAgra, will assess the potential of HPP for producing high-quality, shelf-stable foods.
Flow's Dr. Edmund Ting will serve as principal project director. Dr. Bala Balasubramaniam, NCFST/IIT, will direct research at the National Center, which houses state-of-the-art HPP equipment. Dr. Patrick Dunne, U.S. Army NATICK, Dr. Charles Sizer, NCFST director, and representatives from food processors will form a management board providing guidance to the team on research needs. Dr. John Larkin of NCFST/FDA will advise the team from a regulatory perspective.
The team will address the regulatory, quality, and hardware aspects of commercial production. The team also faces the challenge of establishing criteria for safe high pressure processing of low-acid foods. Team members further hope that their research will lead to the commercial development of many shelf-stable, low-acid, heat-sensitive foods-such as soups, potatoes, and cheese products-for the military and consumer markets.
In the coming years, HPP is likely to be used commercially before the underlying science and its full potential are well understood. Like any novel technology, HPP is not likely to replace traditional processing methods. It may complement such methods or find niche applications. Nevertheless, the unique physical and sensory properties of HPP-processed food offer exciting opportunities for industry.
-V. M. (Bala) Balasubramaniam, Ph.D., NCFST/IIT Associate Professor
High Pressure Processing of Foods
Food Safety Watch
Autumn 2000
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