Time-Temperature Observations of Food and Equipment in Airline Catering Operations

Abstract

Foods served on aircraft have been implicated as vehicles of food-borne illness. Preparation practices that could contribute to growth or survival of foodborne pathogens were surveyed in several airline catering operations. Although most of the practices would provide bacteriologically safe foods, some would permit pathogenic food borne bacteria to survive cooking and reheating processes and permit the bacteria to multiply during cold-or hot-storage. Many of the prepared foods were exposed to temperatures within the 45 to 140 F range for several hours. Some of the equipment used could not maintain food temperatures above 140 F or below 45 F because of capacity, insufficient refrigerating medium, or poor condition. Outbreaks of foodborne illness sporadically affect passengers and crew of aircraft. Several outbreaks appear in public health and disease surveillance literature (2, 5-14, 16-18). Others, no doubt, have occurred. But if the disease has an incubation period longer than the plane ride, passengers scatter, and their subsequent illnesses are seldom associated with the meal they had on the airplane. Staphyloenterotoxicosis, salmonellosis, Vibrio para-haemolyticus gastroenteritis, non-cholera vibrio gastro-enteritis, and shigellosis have been acquired by eating airline-catered foods. Inadequate refrigeration or inadequate hot-holding of foods, or both, were usually reported as contributing factors that permitted the contaminating pathogenic bacteria to multiply to such an extent that the outbreaks ensued. Temperatures of various foods and of the units in which they were held during cold storage, preparation, cooking, chilling, hot-and cold-holding, delivery to aircraft, and reheating were evaluated during routine 1 L'.1e n(trude names is)r~r identification purposes on~v and does not cunstituli' endorsement by the U.S. Department of Health, Education, und \Veltilre. 1 Food and IJmfi Admini5tration. Refiion V. Chicago. Illinois. and simulated operations in airline catering kitchens. Data are interpreted by reference to temperatures that are known to kill vegetative bacteria, that allow or enhance growth of common pathogenic foodborne bacteria, and that are within a temperature range not permitted under codes that regulate food service operations (15). METHODS Six flight kitchens servicing five airlines at three airports were investigated. The operations were selected because they typified operations elsewhere and used similar types of equipment. The following operations were evaluated: (a) frozen, precooked meals were reheated in ovens and held in hot-holding transporters in the kitchen, transported in the same modules to the aircraft, and stored hot on the aircraft until served; (b) frozen, precooked meals were held frozen in the kitchen, delivered to the aircraft and held there in transporters, and reheated in convection ovens on the aircraft; (c) chilled, raw foods were cooked in the kitchen, after which they were assembled into individual-service casseroles and oven inserts and chilled; the following day they were transported to the aircraft and reheated in convection ovens; (d) chilled, raw foods were cooked in the kitchen, assembled in meal trays, held in hot-storage transporters in kitchens, and later delivered to the aircraft and held in these modules until they were served; (e) precooked, chilled foods or kitchen-prepared foods were chilled, if necessary, put in cold-storage transporters, delivered to the aircraft, and held in these modules until served. Equipment in the various operations differed somewhat. Hot-storage transporters differed in size; they were electrically heated, usually with a high setting of 175 F and a low setting of 145 F. Several devices were used for storage and delivery of chilled foods. Metal tray carriers were used to hold trays of sandwiches, salads, rolls, and desserts. Low temperatures were maintained by placing dry ice in the doors of the tray carriers. Chilled meals to be reheated on the aircraft were held in oven racks which were put in cardboard boxes. Dry ice was added to the boxes to maintain low temperature during delivery and aircraft storage. Large cold-storage transporters also were used. Interiors were cooled either by putting dry ice into a center holding-well or onto the top shelves of the units, depending on construction. A transporter that had a dry-ice-activated freon-refrigeration system was used on some wide-body aircraft. Transporters for frozen foods had a large, dry-ice holding-well between two compartments. Small convection ovens, with a fan in the rear, were used to reheat foods on narrow-body aircraft. Each oven could hold approximately 30 meals for reheating. A large convection oven with an internal baffle along the side walls to facilitate