4.2.1 空调系统构成 4.2.2 空调系统冷、热源自动控制

Contents Part 1 Refrigeration and meat quality 1 Microbiology of refrigerated meat 1.1 Factors affecting the refrigerated shelf-life of meat 1.1.1 Initial microbial levels 1.1.2 Temperature

342 Index bowl chopping 178, 179 and chilling 73-4 brittleness of frozen meat 180 and conditioning 74-5 bulk storage rooms 224 and freezing 76 and frozen storage 76-8 80-1 live animal factors 73 calpain-tenderness model 5

Meat is chilled immediately after slaughter. Most of the subsequent opera- tions in the cold chain are designed to maintain the temperature of the meat Cooking is a very common operation in the production of many meat products and operators appreciate the importance of rapidly cooling the cooked product. However, any handling such as cutting, mixing or tumbling will add heat to the meat and increase its temperature. A secondary cooling

It is often stated by those in the meat and refrigeration industries that 'anyone can measure a temperature. Many millions of measurements are made of both meat and environmental temperatures in the meat industry. However, in many cases the measurements made are an unreliable guide to the effectiveness of the refrigeration process. Even when the correct tem- peratures have been obtained the data are often poorly analysed and rarely acted upon

Since the mid-1980s there has been a considerable increase in legislation defining maximum temperatures during the production, distribution and retailing of chilled food. However, as soon as the food is purchased by the consumer, it is outside of any of these legislative requirements. Increasingly food poisoning incidents have been found to be due to mishandling of food in the home with insufficient refrigeration or cooling being the most fre

Theoretically, there are clear differences between the environmental con- ditions required for cooling, which is a heat removal/'temperature reduction process, and those required for storage where the aim is to maintain a set product temperature. However, in many air-based systems, cooling and storage take place in the same chamber and even where two separate facil- ities are used, in many cases not all the required heat is removed in the

Thawing has received much less attention in the literature than either chill- ing or freezing. In commercial practice there are relatively few controlled thawing systems. Frozen meat, as supplied to the industry, ranges in size and shape from complete hindquarters of beef to small breasts of lamb, although the major- ity of the material is 'boned-out' and packed in boxes ca. 15 cm thick weigh- ing between 20 and 40kg. Thawing is usually regarded as complete when the centre of the block or joint has

The increased application of temperature legislation in many countries. coupled with economic requirements to maximise throughput, minimise weight loss and operate refrigeration systems in the most efficient manner, has created a very large demand for process design data on all aspects of

The appearance of meat at its point of sale is the most important quality attribute governing its purchase. The ratio of fat to lean and the amount of marbled fat are important appearance factors and another is the colour of the meat. The changes in colour of the muscle and blood pigments (myoglobin and haemoglobin, respectively) determine the attractiveness