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

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

提出将扰流冷却技术应用于半固态合金制备中,在自制的倾斜冷却装置内安放扰流柱,制备半固态AlSi9Mg合金水淬试样,用定量分析技术分析试样组织,研究扰流柱形状、排列方式和排列间距对半固态AlSi9Mg合金组织的影响.结果表明:扰流柱为水滴形时,制备的半固态AlSi9Mg合金中初生α-Al相较多,组织均匀,边缘轮廓清晰,初生α-Al相为球形或近球形,水淬组织特征为初生固相率53.54%,晶粒尺寸5.59μm,形状因子0.61.扰流柱的排列方式和排列间距对半固态Al-Si9Mg合金组织有较大的影响,叉排优于顺排,理想的排列间距为行间距S=15 mm,列间距L=40 mm

第一节 食品冷冻技术 第二节 压缩制冷循环 第三节 制冷剂及载冷剂 第四节 制冷系统的主要设备

The quality of fresh meat exposed for retail sale is initially judged on its appearance. The presence of exudate or'drip', which accumulates in the container of prepackaged meat or in trays or dishes of unwrapped meat, substantially reduces its sales appeal (Malton and James, 1983). Drip can be referred to by a number of different names including purge loss',press loss'and 'thaw loss'depending on the method of measurement and when it is measured. In general, beef tends to lose proportionately more drip than pork or lamb. Since most of the exudate comes from the cut ends of muscle fibres

From the moment an animal is slaughtered the meat produced begins to lose weight by evaporation. Under typical commercial distribution condi tions, it has been estimated that lamb and beef lose from 5.5 to 7% by evap- oration between slaughter and retail sale(Malton, 1984). Weight losses from pork are probably of the same magnitude. In addition to the direct loss in saleable meat there are also secondary

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

Whilst a number of characteristics affect the overall quality and acceptability of both fresh and frozen meats, tenderness is the major characteristic of eating quality because it determines the ease with which meat can be chewed and swallowed. The tenderness of meat is affected by both chilling/freezing and storage. Under the proper conditions, tenderness is well maintained throughout the chilled/frozen storage life, but improper chilling/freezing can produce severe toughening and meat of poor eating quality

Thermophysical properties of meat In chilling, freezing, thawing and tempering processes heat has either to be introduced or to be extracted from the meat to change its temperature The rate at which heat can be removed or introduced into the surface of meat is essentially a function of the process being used, for example air blast, plate, immersion, and so on. However, the rate at which heat can flow from within the meat to its surface is a function of the thermophysical prop- erties of the meat. If we continue to

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