Refrigerated convenience foods, promoted for their freshness and improved quality, offer an ideal environment for the growth of microbiological contaminants, according to a federal advisory committee.
The group's concerns about fully cooked, ready-to-eat products were outlined last week at the Institute of Food Technologists annual meeting in Anaheim.
The National Advisory Committee on Microbiological Criteria for Food is composed of health officials, university researchers and private industry representatives. Its findings are sent as recommendations to federal regulatory agencies such as the U.S. Department of Agriculture, the U.S. Food and Drug Administration and the National Marine Fisheries Service.
Several committee members addressed the problems surrounding what is being called "a new generation of refrigerated foods" during the institute's five-day conference.
According to industry estimates, this rapidly growing field had sales of $100 million in 1989, a total that is projected to increase to $5 billion by 1995.
At issue are refrigerated entrees, pasta sauces, salads, desserts and sandwiches. Of particular concern are products that contain cooked, but uncured, meat or poultry. Precooked seafood, such as shrimp or crab, pose similar problems.
The products, which resemble restaurant takeout foods, are most often sold in grocery store meat, dairy and deli counters. Some also employ new packaging technology that extends shelf life, such as a European process known as sous vide in which raw ingredients are precooked, mixed together, then vacuum packed, pasteurized and chilled.
Martha E. Rhodes, assistant commissioner of Florida's Department of Agriculture and Consumer Services, who is also a microbiological advisory committee member, said that the shelf-life extension for these products has been dramatic.
"Although these foods are not sterile," she said, "processing and controlled atmosphere packaging have given a general extension of shelf life from 12 to 30 days for entrees, salads, desserts and sandwiches. Fresh pastas and sauces can be marketed for 90 days in some instances."
Meanwhile, consumers have little or no knowledge of the special nature of these ready-to-eat foods and the care required, Rhodes said.
For instance, all of these products must be kept properly chilled from the moment they leave the manufacturing plant until they are removed from home refrigerators for consumption.
Federal health statistics show that more than 40% of the food-borne illness outbreaks between 1961 and 1982 were believed caused by improper refrigeration, said Michael P. Doyle, food microbiology professor at the University of Wisconsin, Madison.
Doyle also cited studies that indicated a substantial number of supermarket refrigeration units, as well as household units, were kept at temperatures well above recommended levels.
Some of the pathogens that have been discovered in ready-to-eat foods include various Salmonella strains, Listeria monocytogenes, Clostridium botulinum and Staphylococcus aureaus. Some of these organisms are not destroyed or controlled by refrigeration alone.
Surprisingly, the proliferation of these ready-to-eat foods occurred in the virtual absence of federal regulations that exist for other categories. Only this February did the USDA begin the lengthy process of establishing new regulations for refrigerated foods.
One advisory committee member said that the federal government is merely trying to catch up with the health concerns likely to exist with ready-to-eat entrees. "They are trying to outrun problems created by the new generation of refrigerated foods," said William L. Brown, of ABC Research in Gainesville, Fla.
Brown also expressed concern that what little reheating the ready-to-eat foods get will be in the microwave. "The microwave just heats a food. It does not contribute to the destruction of pathogens that may be present," he said.
The microbiological advisory committee members each called for expanded labeling on ready-to-eat foods--such as inclusion of the phrase "Important. Must be kept refrigerated," in a prominent position.
Some suggested that ready-to-eat refrigerated foods be packaged differently from those products that are similar, but shelf stable, because they have undergone sterilization. Manufacturers of these items were also urged to maintain better quality standards in their processing plants so that contaminants do not enter the food in the first place.
But even these measures did not satisfy everyone on the panel.
Doyle, of the University of Wisconsin, said that consumers might ignore even bold new labeling. He proposed that time-temperature indicators be placed on the packages of all such perishable foods. The indicators would change color if the food had been stored improperly well before any bacterial threat emerged.
"If a product is abused (during handling), the consumer will be aware of it through the time-temperature indicators," Doyle said. "But manufacturers need to make sure the indicators turn color before toxins are produced."
Time-temperature indicators are likely to be included in any new regulations developed by USDA for ready-to-eat foods containing meat or poultry. But it will be some time before any such devices are actually required on these refrigerated foods.