Effect of refrigeration on texture of meat 53 Table 3.1 Average taste panel scores for roasted joints from a 30-month steer carcass aged between 4 and 22 days at 2C Day Texture Flavour Overall Day Texture Flavour Overall tasted acceptability tasted rentability Silverside 4 4.0 1.4 2.4 Texture: an eight-point scale from extremely tough(4)to extremely tender(+4). Flavour and overall acceptabil- y: a five-point scale from not acceptable(1)to extremely good ( 5) Source: Dransfield. 1986. Table anel texture scores for roasted loin jo l5 daiedred with 18-month-old Day tasted Cow Heifer -3.7 +0.4 +3.2 oint scale from extremely tough(4)to extremely tender 3.2.4 Preslaughter factors Rates of conditioning differ widely between species. The tenderness of meat improves approximately as the logarithm of the storage time. Most of the improvement in tenderness therefore takes place in the initial storage period and tenderness eventually reaches a maximum. Table 3.3 shows the first order rate constants derived from the ntial decay of toughness of cooked muscles with time(Dransfield, 1986). Beef, veal and rabbit have a rate constant of 0.17 per day, which means that 80% of the tenderising that is theoretically possible occurred in 10 days at 1C. Although beef and eal condition at the same rate, veal is tenderer and therefore can reach ar acceptable tenderness in 5 days at 1C. Lamb conditions slightly faster than beef, and pig meat about twice as fast as beef. There is little information on the influence of breed on the rate of con ditioning. Purchas(1972)observed that Friesian Brahman cross bull beef improves more in tenderness than Friesian bull beef from 5 to 14 days post-mortem at4°C. There appears to be little difference in rate of conditioning between dif ferent muscles. Semlek and Riley(1974)reported that in 18 Hereford bulls, he longissimus muscle conditioned more during storage at 2C than did3.2.4 Preslaughter factors Rates of conditioning differ widely between species.The tenderness of meat improves approximately as the logarithm of the storage time. Most of the improvement in tenderness therefore takes place in the initial storage period and tenderness eventually reaches a maximum. Table 3.3 shows the first order rate constants derived from the exponential decay of toughness of cooked muscles with time (Dransfield, 1986). Beef, veal and rabbit have a rate constant of 0.17 per day, which means that 80% of the tenderising that is theoretically possible occurred in 10 days at 1 °C. Although beef and veal condition at the same rate, veal is tenderer and therefore can reach an acceptable tenderness in 5 days at 1°C. Lamb conditions slightly faster than beef, and pig meat about twice as fast as beef. There is little information on the influence of breed on the rate of con￾ditioning. Purchas (1972) observed that Friesian Brahman cross bull beef improves more in tenderness than Friesian bull beef from 5 to 14 days post-mortem at 4 °C. There appears to be little difference in rate of conditioning between dif￾ferent muscles. Semlek and Riley (1974) reported that in 18 Hereford bulls, the longissimus muscle conditioned more during storage at 2 °C than did Effect of refrigeration on texture of meat 53 Table 3.1 Average taste panel scores for roasted joints from a 30-month steer carcass aged between 4 and 22 days at 2 °C Joint Unaged Aged Day Texture Flavour Overall Day Texture Flavour Overall tasted acceptability tasted acceptability Sirloin 4 -2.2 2.5 2.5 22 0.8 3.6 3.2 Silverside 4 -3.0 2.4 1.8 15 1.0 4.2 4.0 Topside 4 -3.4 2.5 1.9 15 1.4 2.4 2.6 Texture: an eight-point scale from extremely tough (-4) to extremely tender (+4). Flavour and overall acceptabil￾ity: a five-point scale from not acceptable (1) to extremely good (5). Source: Dransfield, 1986. Table 3.2 Average taste panel texture scores for roasted loin joints of 6-year-old cow compared with 18-month-old heifer aged between 2 and 15 days at 2 °C Day tasted Cow Heifer 2 -3.7 -3.0 4 -3.2 -2.4 8 -1.8 -0.4 15 +0.4 +3.2 Eight-point scale from extremely tough (-4) to extremely tender (+4). Source: Dransfield, 1986