High-pressure-process low-acid foods.
This effort involves demonstrating feasibility, optimizing the process and generating data relevant to product safety, addressing regulatory issues, optimizing equipment and achieving consumer-market acceptance. Consortium partners include the Hormel Food Engineering Division (Austin, MN), Procter and Gamble Co. (Cincinnati, OH), ConAgra Grocery Products Co. (Fullerton, CA), Kraft Foods (Glenville, IL) and U.S. Army Soldier Systems Center (Natick, MA).
Specific objectives of this three-year project, which began in June 2000, include: characterizing the effect of pressure, temperature and other hurdles on selected food spoilage spores during HPP and modeling their time-temperature-pressure inactivation behavior; documenting the compression heating effects of selected foods; studying the effect of pressure on selected packaging materials; assisting in the development of criteria for the validation of high-pressure-processed low-acid shelf-stable foods; and providing various pilot plant services. The partners have first access to the equipment to produce products for evaluation.
HPP provides the potential for processing low-acid foods at a combination of elevated pressures and temperatures, which promotes minimal thermal degradation. Researchers are studying the compression heating of different materials during HPP. Materials under study include soy bean oil, olive oil, a glycol-water mixture, beef fat, chicken fat, mashed potatoes, orange juice, tomato salsa, fresh salmon flesh and water up to 600 MPa.
Water gave the lowest temperature rise (2.8 C to 3 C per 100 MPa) at all pressure levels. Olive oil (8.7 C to 6.3 C per 100 MPa) and soybean oil (9.1 C to 6.2 C per 100 MPa) gave the highest temperature rise. Within the range of conditions studied, water is likely to have the lowest compression heating. Change in product or pressurization media temperature as a result of compression heating and subsequent heat transfer should be considered during HPP microbial inactivation studies in media of different compositions, especially those involving bacterial spores.
Researchers fabricated a special HPP furnace. The half-liter-size furnace can be used for testing microbial samples over a range of pressures (up to 100,000 psi) and temperatures up to 120 C. Experiments are in progress to compare the effectiveness of isostatic pressure and dynamic pulsing pressures using C. sporogenes as a model system. Pressure-temperature resistance characteristics of selected bacterial surrogate spores are being tested under selected process conditions.
The research should have a positive impact on both military and civilian food production needs. HPP technology offers the potential to improve the quality of foods, and the military benefit will be maximized if the technology can become feasible for shelf-stable items that do not require refrigeration. The extreme shelf life requirements for combat rations of three years at 80 F and six months at 100 F present challenges that normal commercial processing and packaging systems cannot meet.
Further information. V. M. "Bala" Balusubramaniam; phone: 708-563-8175; fax: 708-563-1873; email: email@example.com; URL: www.ncfst.iit.edu.
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|Publication:||Microbial Update International|
|Date:||Dec 1, 2001|
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