The Effect of Time and Temperature Variations on the Microbial Load and Deterioration Criteria of Leftover Cheeseburger Sandwiches

Abstract

A s a result of the hectic lifestyle and most people, especially youth spend a long time outside their homes, so this gives the chance for the fast food industry to grow up all over the world. Globally, there are approximately 2.5 billion persons eat fast food daily (FAO, 2007). Ready to eat foods (RTE), such as hot dogs, fermented sausage, burger, shawarma, and meatballs, are products that are sold at the quick-service restaurants and can be consumed immediately without further preparation (Tsang, 2002). Among these different types of fast foods, Sandwich is the most popular way of consumption because of its easy and quick preparation, delicious taste beside it contains different types of foods as producers add salads from fresh vegetables to sandwiches as cabbage, carrot, cucumber, onion, ketchup, and mayonnaise. However, the quality of these sandwiches greatly depends on several factors such as the initial load of microbial contamination of meat and raw vegetables, method of preparation, time, and temperature research Article Abstract | Sixty cheeseburger sandwiches were bought from sixty different fast food outlets and street vendors in Cairo as well as the governorate of Giza. Sandwiches were divided into three groups; room temperature (25°C), refrigerator (5°C), and high temperature (37°C). The three groups were examined after 30, 60, and 120 minutes for bacteriological quality (aerobic plate count, psychrotrophic, total coliform, fecal coliform, E.coli, total staphylococci, and salmonella) count and deterioration criteria (pH, TVBN, and TBA). The findings showed significant growth in aerobic plate count, psychrotrophic, total coliform and staphylococci count while salmonella failed to be detected under different storage temperatures. Moreover, Citrobacter diversus, Citrobacter freundii, Serratia fonticola, Enterobacter intermedius, Enterobacter aerogenes, Enterobacter cloacae, Klebsiella oxytoca, and E.coli can be isolated from sandwiches kept under high temperature (37 ºC) for 120 minutes. The deterioration criteria tests discovered that the increase of storage temperature as well as period of storage resulted in a significant raise in pH, TVBN, and TBA values. Moreover, deterioration criteria of examined leftover sandwiches kept under high temperatures (37 ºC) for the longest period (120 minutes) exceeded the permissible limit according to E.S.S. (2005). According to this, holding sandwiches at high temperature for an extended period increased microbial load and deterioration criteria resulting in food-borne diseases and health risks and consequently rendering them unfit for human consumption.