Department of Science

Food Processing FSE 99-21 ______Extended Shelf-Life Refrigerated John E. Rushing, Ph.D. ______Refrigeration has, over the years, been a oxygen packaging. Traditional spoilage mainstay of . The process organisms compete with pathogens. They lends itself to maintaining "freshness" for also can provide spoilage clues to the raw to partially processed foods, as well as consumer. The growth of these organisms for maintaining the quality of processed might be eliminated in this altered foods after packages have been opened. environment. Packaged refrigerated foods have been characterized by high quality and If these foods were mishandled, they could wholesomeness. Traditional refrigerated pose a serious public health threat to the foods, with minor exceptions, exhibit a very consumer, especially to those groups good safety record. considered vulnerable such as infants, the infirm, the aged and immunocompromised Recently, certain pathogens such as individuals. Since these populations are at Clostridium botulinum Type E, Yersinina risk, it is imperative that retailers, distributors, enterocolitica, Listeria monocyogenes, and and the food service industry, as well as other organisms have been associated with consumers, are in a position to make informed outbreaks. In an often and responsible decisions related to quoted presented at a USDA maintaining the safety of these foods. It is workshop, Palumbo (1987) questioned the necessary to train retail food handlers in adequacy of in preserving the procedures that minimize microbial hazards safety of refrigerated foods. He expressed and maintain the quality of traditional and concern that the above organisms could newer extended shelf life refrigerated foods. grow at temperatures below 5oC. Furthermore, considerable numbers of these Control of temperature is the most critical pathogenic organisms could develop when stability factor of these foods. The the foods are temperature abused. Association of Food & Drug Officials (AFDOS, undated) and other professional Coinciding with the concern associated organizations (NFPA, 1989) have with psychotropic pathogens, new recommended that there be secondary safety refrigerated foods have gained in consumer barriers for foods that are packaged in a acceptance and popularity. reduced oxygen atmosphere and offered at retail. Extended shelf life refrigerated foods are now appearing in the marketplace. Many of these foods are packaged in reduced Recommendations include: large number of retail stores and the high degree of employee turnover, it is important A) aw, < 0.91, that supervisors be trained so they can train B) pH (acidity) pH < 4.6, their own employees. Through the training of C) high levels of nonpathogenic supervisory personnel, more food handlers can competing organisms present to be educated in recommended food handling inhibit the growth of pathogenic practices thus minimizing opportunities for organisms foodborne illness outbreaks associated with D) meat or poultry products processed food stores. under USDA supervision which have a nitrite level of at least 120 ppm References [initially] and a minimum brine Palumbo, S.A., 1987. Can Refrigeration Keep concentration of 3.5%, Our Foods Safe? and Food Sanitation E) frozen foods be maintained frozen 7:2 p. 56-60. during and after packaging. (AFDOS, undated) AFDOS (undated) Retail guidelines, Refrigerated Foods in reduced oxygen In addition, it has been recommended that packages. Association of Food and Drug raw or processed fish and fisheries products Officials, York, PA. not be sold at retail packaged in reduced oxygen atmospheres unless held frozen NFPA, 1989. Guidelines for the development, before, during and after packaging. The production & handling of refrigerated foods. Food and Drug Administration is in the National Food Processor's Association, process of developing refrigerated foods Washington, DC. regulations at the present time. Due to the

Extended shelf life refrigerated foods fit generally into the following categories:

Cook-Chill- The cooked food is packaged hot, sealed into moisture/oxygen barrier packages and blast or tumble chilled. These foods are usually stored at temperatures between 28o and 32oF. Centralized institutional commissaries have been particularly interested in utilizing this technology.

Vacuum Packaging- Air is mechanically removed from the package prior to sealing. Many retail stores have developed processing procedures for these products on the premises. Most state regulatory agencies have moved to block this activity without guidance from FDA.

Sous Vide- Prepared raw ingredients are vacuum packaged and sealed in a , partially cooked, and rapidly chilled to below 32oF. The heating process is not sufficient to make the food shelf stable so it must be held under refrigerated temperatures. Current markets tend to be foodservice and major retail markets.

Modified Atmosphere Packaging (MAP) - The package is gas flushed and then sealed. Active or passive means may be employed to alter the internal atmosphere of the package.