274 Meat refrigeration Table 13.1 Mean thermal conductivities in chilling Mean thermal ariation with type onductivity(wm-°C) ean m 0.49 (also kidney and liver) +0.02 ere Bone +0.02 compact bone spongy bone marrow Source: Morley. 1972a. 13.1 Chilling 13.1.1 Thermal conductivity Table 13. 1 shows the mean thermal conductivities during chilling of lean meats, fats and bones, together with the total variation amongst the differ ent samples considered. Thermal conductivity is given in watts per metre m It can be seen that the thermal conductivity of lean meat is roughly two and a half times that of fat. Rendering fat reduces its thermal conductivity owing to the ensuing loss of water, which has a relatively high thermal conductivity of 0.60Wm-oC-. The thermal conductivity of bone varies throughout its structure. Hard, outer compact bone has a similar thermal conductivity to that of lean meat, whereas inner spongy bone and marrow, having high fat contents, are similar in thermal conductivity to fat Beef liver has a similar thermal conductivity to lean meat, 0.49WmC, over the chilling temperature range from 30 to 0C(Barrera and Zaritzky, 1983) Little data are available on the thermal conductivity of meat in the cooking temperature range For predictive purposes Baghe-Khandan et al (1982) developed models based on the initial water(w) and fat (.)con tents at 30C to predict thermal conductivities at temperatures(T) up to 90C and heating rates of <0.5Cmin For whole beef: K=10-(732-4.326-3.56w+0.6367)[13.1 For minced beef.:K=10-3(400-4.496+0.147+1.747)[13.2 13.1.2 Specifie The specific heats of different types of meat are given in Table 13. 2. The pecific heats of fats are given in Table 13.3, and Table 13. 4 shows the vari- ability in specific heats between different bones.13.1 Chilling 13.1.1 Thermal conductivity Table 13.1 shows the mean thermal conductivities during chilling of lean meats, fats and bones, together with the total variation amongst the differ￾ent samples considered. Thermal conductivity is given in watts per metre per °C (Wm-1 °C-1 ). It can be seen that the thermal conductivity of lean meat is roughly two and a half times that of fat. Rendering fat reduces its thermal conductivity owing to the ensuing loss of water, which has a relatively high thermal conductivity of 0.60 W m-1 °C-1 . The thermal conductivity of bone varies throughout its structure. Hard, outer compact bone has a similar thermal conductivity to that of lean meat, whereas inner spongy bone and marrow, having high fat contents, are similar in thermal conductivity to fat. Beef liver has a similar thermal conductivity to lean meat, 0.49 W m-1 °C-1 , over the chilling temperature range from 30 to 0 °C (Barrera and Zaritzky, 1983). Little data are available on the thermal conductivity of meat in the cooking temperature range. For predictive purposes Baghe-Khandan et al. (1982) developed models based on the initial water (wo) and fat (fo) con￾tents at 30 °C to predict thermal conductivities at temperatures (T) up to 90 °C and heating rates of <0.5 °Cmin-1 . [13.1] [13.2] 13.1.2 Specific heat The specific heats of different types of meat are given in Table 13.2. The specific heats of fats are given in Table 13.3, and Table 13.4 shows the vari￾ability in specific heats between different bones. For minced beef: K f wT = -+ + ( ) o o - 10 400 4 49 0 147 1 74 3 .. . For whole beef: K fw T = -- + ( ) o o - 10 732 4 32 3 56 0 636 3 .. . 274 Meat refrigeration Table 13.1 Mean thermal conductivities in chilling Mean thermal Variation with type conductivity (W m-1 °C-1 ) Lean meat 0.49 +0.05 (also kidney and liver) Fats +0.02 Natural 0.21 Rendered 0.15 Bone +0.02 compact bone 0.56 spongy bone 0.26 marrow 0.22 Source: Morley, 1972a