In specifying refrigeration equipment the function of the equipment must be absolutely clear. Refrigeration equipment is always used to control tem- perature. Either the meat passing through the process is to be maintained it its initial temperature, for example as in a refrigerated store or a packing operation, or the temperature of the meat is to be reduced, for example in a blast freezer. These two functions

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

In general, display cabinets have to accommodate three types of meat and meat products: (1)chilled wrapped, (2) chilled unwrapped and (3)frozen wrapped products. The required display life and consequent environmental conditions for wrapped chilled products differ from those for unwrapped products. The desired chilled display life for wrapped meat and meat prod- ucts ranges from a few days to many weeks and is primarily limited by microbiological considerations. Retailers of unwrapped meat and deli

Developments in frozen transport in the 19th century established the inter- national food market. In 1877, a cargo of frozen meat was sent from Buenos Aires to France. The following year 5000 frozen mutton carcasses were transported from Paraguay to France. In 1880, the SS Strathleven arrived in London with a cargo of 40 tons of frozen Australian beef, and by 1910

leat for industrial processing is usually frozen in the form of carcasses, quarters or boned out primals in 25 kg cartons. Most bulk meat, consumer portions and meat products are frozen in air blast freezers. Some small ind viduals items, for example beefburgers, may be frozen in cryogenic tunnels and a small amount of offal and other meat is frozen in plate freezers. It is not unusual for meat to be frozen twice before it reaches the consumer During industrial processing frozen raw material is often thawed or tem-

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

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

Microbiology of refrigerated meat There are many pertinent texts on the microbiology of meats. The purpose of this chapter is to examine briefly the types of micro-organisms and con- ditions that are of interest in relation to the refrigeration of meat and meat products. In a perfect world, meat would be completely free of pathogenic(food poisoning

改善金属材料的性能,主要可以通过如下几种途径:合金化即加入合金元素,调整材料的化学成分。可显著媞高钢的强度、硬度和韧性,并使其具有耐蚀、耐热等特殊性热处理即金属材料通过不同的加热、保温和冷却的方式。使基内部的組结构发生变化,以达到改善加工工艺性前和强化力学性能的目的。 5.1 金属材料的改性处理理论基础 5.2 钢的热处理 5.3 钢的表面强化处理

利用制冷剂液体在气化时(沸腾时) 技产生的吸热效应,达到制冷目的