Supermarket shelves today need to cater to the gourmet cook as well as the time harried parent. Increasingly all types of consumers are demanding minimally-processed foods that are high in quality, nutritionally superior, and easy to prepare. Food processors have met this demand by developing refrigerated foods with extended shelf life.
Ready-to-eat luncheon meats and complete heat-and-eat meals are some examples. By their very nature, however, these foods present challenges to ensure microbiological quality and safety. Extended shelf life refrigerated foods are foods that have received minimal processing or precooking and have an enhanced but limited shelf life; refrigeration is a key preservation measure. These foods include conventional products, such as luncheon meats and cured meats, as well as a new generation of partially processed refrigerated foods (NFPA, 1988) such as meat, seafood, egg, and vegetable salads, fresh pasta and pasta sauces, other sauces, soups, entrees, complete meals, and uncured meat and poultry items. Sous-vide foods, cooked inside a hermetically sealed plastic package under vacuum, are also included in this definition. If extended shelf life refrigerated foods are heat processed, the heat treatment is much less than that required for commercial sterility. Canned foods are, therefore, excluded from this food category. Sous-vide foods and others that receive a lower heat treatment than that used for canning and that require refrigeration are described by some authors as “refrigerated processed foods of extended durability.”
The types of microorganisms that may be found in various refrigerated foods are diverse. To further complicate matters, each type of microorganism has its own preferred growth temperature range known as minimum, optimum and maximum temperature. These microorganisms are classed into categories: thermophiles (grow at high temperatures, range 45°C to 70°C [113°F to 158°F]); meshophiles (grow at ambient temperature, range 10°C to 45°C [50°F to 113°F]) and psychrophiles (grow at cold temperature, range -5°C to 20°C [23°F to 68°F]). Under ideal conditions some bacteria may grow and divide every 20 minutes. Consequently, one bacterial cell may increase to 16 million cells in 8 hours.Download PDF