Freezing of meat 147 Table 7. 8 Predicted freezing time from 4 to-7C in thermal centre of unwrapped and stockinette wrapped carcasses -30°,4ms -30°C,0.5ms 20°C.0.5ms Unwrapped 30kg 11.0 14 190 40kg 12.0 178 26.5 Source: Creed James, 1984 Table 7.9 ezing time equations for liver in plat Block thickness Equation 76 Y=-0.3547+ R+002138I Y=-0.1917+1 R+005203I 15.2 Y=-0.8020+ R+0.08880I Source: Creed James, 1983. luthors found that liver was amenable to plate freezing and the freezing time to-7C (Y was related to the initial temperature(n)and R the reci rocal of -15C, the refrigerant temperature(Table 7.9) The authors extended their studies to examine the effect of different packaging materials on freezing time(Creed and James, 1985) 7.5.5 Small products ezine g of unwrapped small meat products definitely affects the weight loss, with loss increasing as freezing rate decreases. There is also some evidence that it affects losses during cooking and sensory properties. Freezing times of individual meat patties can range from tens of seconds to over an hour in different systems(Hanenian et al., 1989). Everington (2001)has shown that when freezing thin(11mm) burgers high air veloci ties will substantially reduce freezing times(Fig. 7. 4). Freezing in nitrogen and CO2 can substantially reduce the amount of weight loss from un wrapped patties when compared with air systems(Table 7.10).However, cooking losses were higher and overall patty quality lower in those frozen in nitrogen. This was mainly due to cracking in the immersion system. When patties are stacked and placed in boxes before freezing, the freez ing times increase by at least an order of magnitude Studies carried out packaged patties looked at freezing rates between 2 and -18C ranging from 24 to 96h( Berry and Leddy, 1989). Before freezing, tenderness scoresauthors found that liver was amenable to plate freezing and the freezing time to -7 °C (Y) was related to the initial temperature (I) and R the reci￾procal of -1.5 °C, the refrigerant temperature (Table 7.9). The authors extended their studies to examine the effect of different packaging materials on freezing time (Creed and James, 1985). 7.5.5 Small products The rate of freezing of unwrapped small meat products definitely affects the weight loss, with loss increasing as freezing rate decreases. There is also some evidence that it affects losses during cooking and sensory properties. Freezing times of individual meat patties can range from tens of seconds to over an hour in different systems (Hanenian et al., 1989). Everington (2001) has shown that when freezing thin (11mm) burgers high air veloci￾ties will substantially reduce freezing times (Fig. 7.4). Freezing in nitrogen and CO2 can substantially reduce the amount of weight loss from un￾wrapped patties when compared with air systems (Table 7.10). However, cooking losses were higher and overall patty quality lower in those frozen in nitrogen. This was mainly due to cracking in the immersion system. When patties are stacked and placed in boxes before freezing, the freez￾ing times increase by at least an order of magnitude. Studies carried out on packaged patties looked at freezing rates between 2 and -18 °C ranging from 24 to 96 h (Berry and Leddy, 1989). Before freezing, tenderness scores Freezing of meat 147 Table 7.8 Predicted freezing time from 4 to -7 °C in thermal centre of unwrapped and stockinette wrapped carcasses -30 °C, 4 m s-1 -30 °C, 0.5 m s-1 -20 °C, 0.5 m s-1 Unwrapped 30 kg 5.5 11.0 16.4 40 kg 8.5 15.6 23.4 Wrapped 30 kg 8.0 12.5 19.0 40 kg 12.0 17.8 26.5 Source: Creed & James, 1984. Table 7.9 Freezing time equations for liver in plate freezer Block thickness Equation (cm) 7.6 Y = -0.3547 + 54.4632 R + 0.02138 I 10.2 Y = -0.1917 + 79.9314 R + 0.05203 I 15.2 Y = -0.8020 + 212.119 R + 0.08880 I Source: Creed & James, 1983