22 Meat refrigeration magnitude higher than most drip losses during refrigeration. Consequently, small differences in drip loss will have little affect on eating quality The potential for drip loss is inherent in fresh meat and is influenced by many factors. These may include breed, diet and physiological history, all of which affect the condition of the animal before it is slaughtered. After slaughter, factors such as the rate of chilling, storage temperatures, freezing and thawing can all influence the drip produced The mechanism of drip formation has been well described by Taylor (1972), Bendall (1974)and Penny(1974)and form the basis of this chapter To understand how drip occurs, it is useful to have a basic understanding of the biochemistry of meat. This includes the structure of muscle, the changes that take place after death and where water is held in the muscle The factors affecting drip production through the refrigerated cold chain can then be quantified 2.1 Biochemistry of meat 2.1.1 Structure of muscle The structure of muscle has been well described by Voyle(1974)and forms the basis of this section. Meat consists mainly of skeletal muscles which all have a similar structure. Figures 2.1-2. 4 show in diagrammatic form the levels of organisation of the components which together form a muscle. The gross levels of organisation can be resolved with the unaided eye, and it may be observed that each muscle is separated from its neighbour by a sheet of white connective tissue-the fascia. This gives support to the tional components of the muscle and connects it to the skeleton thr tendinous insertions. The connective tissue consists mainly of collagen and in some muscles includes elastic fibres. In cross-section(Fig. 2.1)a muscle appears to be subdivided into tissue bundles surrounded by thin layers of connective tissues. These bundles consist of a number of very long, multinucleated cells or fibres each sur- rounded by a thin layer of connective tissue. Each fibre is about as thick as a hair of a young child and may be several centimetres in length. Fibres are normally elliptical in cross-section and have blunt tapered ends(Fig 2.2) Fibre thickness varies between muscles within an animal as well as between species. It is also dependent on age, sex and nutritional status. As an example, the fibres of the eye muscle(M. longissimus dorsi) of an 18-month old steer are about 40um in diameter Each fibre is surrounded by a typical lipoprotein membrane, the sar- colemma, which in its native state is highly selective in its permeability to solutes. The space within the sarcolemma is mostly occupied by smaller lon- gitudinal elements, or myofibrils, each about 1 um in diameter. Figure 2.3 shows part of a single myofibril in longitudinal section. Figure 2. 4 repremagnitude higher than most drip losses during refrigeration. Consequently, small differences in drip loss will have little affect on eating quality. The potential for drip loss is inherent in fresh meat and is influenced by many factors. These may include breed, diet and physiological history, all of which affect the condition of the animal before it is slaughtered. After slaughter, factors such as the rate of chilling, storage temperatures, freezing and thawing can all influence the drip produced. The mechanism of drip formation has been well described by Taylor (1972), Bendall (1974) and Penny (1974) and form the basis of this chapter. To understand how drip occurs, it is useful to have a basic understanding of the biochemistry of meat. This includes the structure of muscle, the changes that take place after death and where water is held in the muscle. The factors affecting drip production through the refrigerated cold chain can then be quantified. 2.1 Biochemistry of meat 2.1.1 Structure of muscle The structure of muscle has been well described by Voyle (1974) and forms the basis of this section. Meat consists mainly of skeletal muscles which all have a similar structure. Figures 2.1–2.4 show in diagrammatic form the levels of organisation of the components which together form a muscle.The gross levels of organisation can be resolved with the unaided eye, and it may be observed that each muscle is separated from its neighbour by a sheet of white connective tissue – the fascia. This gives support to the func￾tional components of the muscle and connects it to the skeleton through tendinous insertions. The connective tissue consists mainly of collagen and in some muscles includes elastic fibres. In cross-section (Fig. 2.1) a muscle appears to be subdivided into tissue bundles surrounded by thin layers of connective tissues. These bundles consist of a number of very long, multinucleated cells or fibres each sur￾rounded by a thin layer of connective tissue. Each fibre is about as thick as a hair of a young child and may be several centimetres in length. Fibres are normally elliptical in cross-section and have blunt tapered ends (Fig. 2.2). Fibre thickness varies between muscles within an animal as well as between species. It is also dependent on age, sex and nutritional status. As an example, the fibres of the eye muscle (M. longissimus dorsi) of an 18-month￾old steer are about 40mm in diameter. Each fibre is surrounded by a typical lipoprotein membrane, the sar￾colemma, which in its native state is highly selective in its permeability to solutes.The space within the sarcolemma is mostly occupied by smaller lon￾gitudinal elements, or myofibrils, each about 1mm in diameter. Figure 2.3 shows part of a single myofibril in longitudinal section. Figure 2.4 repre- 22 Meat refrigeration