食品速冻技术与冷链发展状况食品速冻技术与冷链发展状况.pptVIP

水冷 水冷 水冷 冰冷 蒸发冷却 Straw packinghouse 真空冷却 真空冷却 装货 移动式真空冷却设备 Forced-Air Hydro Ice Vacuum Typical cooling time (hr) 1-10 0.1-1 0.1-0.3 0.3-2 20-100 Water loss (%) 0.1-2 0-0.5 No data 2-4 0.1-2 Water contact no yes yes, unless bagged no no Potential for decay contamination low high low none low Capital cost low low high medium low Energy cost low medium medium high low Water-resistant packaging needed no yes yes no no Portable sometimes rarely done common common no Feasibility of in-line cooling rarely done yes rarely done common no Room Comparison of Produce Effects and Costs for Common Cooling Methods 风冷运输 风冷运输 低温运输 国外应用示例 Product arrives from the field on line trucks.? Some is then cooled by icing and some is vacucooled. Vacuum cooling involves placing cartons of produce in a chamber where the atmospheric pressure is lowered. 国外应用示例 This causes the boiling point of water to drop and it is boiled off. Cold water is simultaneously added to the cartons so the product emerges cold and undamaged. Regular icing involves packing each carton of produce with ice.? At 25 pounds per carton, we use tons! 国外应用示例 Bonipak Produce Company can manufacture 300 tons of ice each day and we can store 400 tons. When large quantities of product come into the cooler over a short period, we cool the produce in our Air Tunnels.? We have 8 tunnels, which hold 14 pallets of produce each. ?? The cartons are covered with a tarp and cold air is then forced through the holes in the cartons. 国外应用示例 Over a period of hours, the produce is slowly cooled to the desired temperature.? Thermometers constantly monitor the process so the product is not over cooled. 食品速冻技术与冷链发展状况 年人均消费水平 冷冻产品状况 易腐食品低温运输状况 易腐食品低温贮藏状况 易腐食品低温贮藏状况（上海） 冻结速度对食品质量的影响 冻结与解冻过程特点 特点 冻结 解冻 热导率 W · (m · K)-1 2.2 0.5 比热容 kJ · (kg · K)-1 2.1 4.2 食品与介质的温差 可充分低 不可 充分高 溶质对冻结与蒸发温度的影响 稀溶液中水的蒸气压比纯水蒸气压低 在压力相同条件下，稀溶液中水的沸点高于纯水的沸点。 在压力相同条件下，稀溶液中水的冰点低于纯水的冰点。 研究热点问题 速冻食品的质量问题 超高压速