Secondary chilling of meat and meat products 329 Table 16.9 Examples of commercial two-stage cooling of pastry products in the Product vpe of Cooling Temperature Temp. Veloci )(C) Ambient kidne 0.67 mbient 3-5 0.3-1.4 Ambient Minced beef ie(140g) (45kg) Amb <04 slicing from delicatessen outlets. In a single-stage ambient cooling opera tion the centre temperature was still 25C (Table 16.8)after 8h; however in the two-stage process the centre of the pie had been reduced to 10C after 6.5h(Table 16.9) 16.2.2 Experimental studies Data from the most relevant experimental studies on pie cooling are shown in Table 16.10. The importance of achieving a minimum required air veloc ity around small products was clearly demonstrated by data obtained from cooling pork pies(Fig. 16.1). To guarantee that all the crust remained above -2C on the unwrapped 400g(70mm high, 95mm diameter) pies an air temperature of -1.5-t05C was used. At this temperature a small increase in air velocity from 0.5 to 1.0ms- reduced the cooling time by 85 min (almost 30%). Even at very high velocities(>6.0ms-)appreciable reduc- tions in cooling time were still being achieved. In a high throughput baking line(>1000 items per hour) the 7% increase in throughput, which would be achieved by raising the air velocity from 6 to 10ms and consequently reducing the cooling time by 10 min, could justify the higher capital and Inning costs of larger fans. With larger pies cooling times of up to 6h have been measured(Fig. 16.2). Only one reference(McDonald and Sun, 2000) to the vacuum cooling of pork pies has been located. This quotes a coolin time for 0.5kg pies from 80 to 10C of over &hslicing from delicatessen outlets. In a single-stage ambient cooling opera￾tion the centre temperature was still 25 °C (Table 16.8) after 8 h; however in the two-stage process the centre of the pie had been reduced to 10 °C after 6.5 h (Table 16.9). 16.2.2 Experimental studies Data from the most relevant experimental studies on pie cooling are shown in Table 16.10. The importance of achieving a minimum required air veloc￾ity around small products was clearly demonstrated by data obtained from cooling pork pies (Fig. 16.1).To guarantee that all the crust remained above -2 °C on the unwrapped 400 g (70 mm high, 95 mm diameter) pies an air temperature of -1.5–±0.5 °C was used. At this temperature a small increase in air velocity from 0.5 to 1.0 ms-1 reduced the cooling time by 85 min (almost 30%). Even at very high velocities (>6.0 ms-1 ) appreciable reduc￾tions in cooling time were still being achieved. In a high throughput baking line (>1000 items per hour) the 7% increase in throughput, which would be achieved by raising the air velocity from 6 to 10 ms-1 and consequently reducing the cooling time by 10 min, could justify the higher capital and running costs of larger fans. With larger pies cooling times of up to 6 h have been measured (Fig. 16.2). Only one reference (McDonald and Sun, 2000) to the vacuum cooling of pork pies has been located. This quotes a cooling time for 0.5 kg pies from 80 to 10 °C of over 8 h. Secondary chilling of meat and meat products 329 Table 16.9 Examples of commercial two-stage cooling of pastry products in the UK Product Type of Air Cooling Temperature chiller Temp. Velocity time Initial Final (°C) (ms-1 ) (h) (°C) (°C) Steak and Ambient 20 3–5 0.33 93 – kidney pie (185 g) Spiral -3 2 0.67 – 17–20 ≤ Ambient 20 3–5 0.33 93 – Spiral -3 0.3–1.4 0.67 – 22 ≤ Ambient 20 0.3 0.33 93 – Spiral -3 2 0.67 – 24–27 Minced beef Ambient 20 <0.2 0.16 96 80 pie (140 g) Chill room 12 1 1.08 80 20 Gala pie Ambient 20 <0.2 1.75 96 76 (4.5 kg) Chill room 0 <0.4 6.5 76 10 Source: James, 1990c