A comparison of the cooking performance of different appliances when following food manufacturers' instructions
The purpose of this research was to measure the temperature achieved in, and the microbiological count of, chicken burgers cooked following the preparation instructions given by the manufacturers. The work investigates the cooking of chicken burgers, manufactured by four different companies, cooked at different positions under a grill. Three appliances were used. Each showed uneven distribution of heat and a hot position and cool position was established for each grill. Differences in the temperature of the burgers cooked at different positions on the grills were also found. The burgers at the cool position attained a much lower cooking temperature and had a higher number of microorganisms surviving the cooking. The grill that produced the highest temperatures in the burgers had the lowest number of organisms surviving in the burgers. Only 24 out of the 72 burgers cooked to the manufacturers' instructions attained temperatures above 70°C. Some of the burgers appeared to be cooked when visibly assessed, but the core temperatures were low and had high microbial counts. The results obtained indicate that not all the cooking instructions were satisfactory and not all the appliances performed satisfactorily.
FOOD SAFETY IN THE HOME: CURRENT MICROBIOLOGICAL PERSPECTIVES
Despite the publication of two comprehensive reports (Richmond I and II) on the microbiological safety of food, together with new legislation, there has been little direct action concerning food safety in the home. Of particular relevance has been new research data which have shown that smaller numbers of bacteria are able to cause food poisoning, which stresses the importance of cross‐contamination. Doubts also have been raised about the safety of cooking raw meat in microwave ovens. Of perhaps greater impact have been the increased demands of food manufacturers and consumers on refrigeration. This has resulted, for example, from the increasing popularity of convenience foods and a reduction in the use of preservatives. Furthermore, many bacteria implicated in food poisoning are able to grow at relatively low temperatures. Recommendations include new standards by manufacturers of refrigerators and microwave ovens, together with a greater awareness and education of food safety issues.
The Effect of Freezing on Bacteria
It has been known for many years that cultures of bacteria can be cooled to very low temperatures without destroying all the cells present (see, for example, MacFadyen and Rowland 1900). More recently the preservation of bacteria and sera by rapid freezing and drying has come into general use. The fundamental changes accompanying these processes have not so far been investigated in much detail. This paper presents the results of experiments on the effects of cooling and freezing at various temperatures on a number of bacterial species, and an attempt to correlate the observed effects of freezing on viability with the effect of freezing on the cellular proteins of B. pyocyaneus [Pseudomonas aeruginosa] . Hypotheses previously put forward to explain the observed effects of low temperatures on living cells may be briefly summarized under three headings: