食品速冻技术与冷链发展状况ppt课件

1、食品速冻技术与冷链开展情况年人均消费程度冷冻产品情况易腐食品低温运输情况易腐食品低温贮藏情况易腐食品低温贮藏情况上海冻结速度对食质量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)-12.20.5比热容 kJ (kg K)-12.14.2 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一样条件下，稀溶液中水的沸点高于纯水的沸点。在压力一样条件下，稀溶液中水的冰点低于纯水的冰点。研讨热点问题速冻食品的质量问题 超高压速冻技术 快速冷冻技术 部分玻璃化技术 介电解冻技术实现上述技术的配备冷链建立与工艺管理问题螺旋速冻机螺旋速冻机单体流

2、化速冻机单体流化速冻机低温介质速冻机低温介质速冻机低温介质速冻机隧道式速冻机氢与电负性很强，且具有独立电子对、原子半径又较小的原子可构成氢键如氮、氟部分玻璃化技术部分玻璃化技术冷冻稳定剂较高的Tg冷冻维护剂较强保水性常用添加剂对粘度影响玻璃态热力学特征果蔬田间热与呼吸热The respiration rate and the production of CO2 depends mainly on the storage temperature风冷风冷负压风冷水冷水冷水冷冰冷蒸发冷却Straw packinghouse真空冷却真空冷却装货挪动式真空冷却设备Forced-AirHydroIceVa

3、cuumTypical cooling time (hr)1-100.1-10.1-0.30.3-220-100Water loss (%)0.1-20-0.5No data2-40.1-2Water contactnoyesyes, unless baggednonoPotential for decay contaminationlowhighlownonelowCapital costlowlowhighmediumlowEnergy costlowmediummediumhighlowWater-resistant packaging needednoyesyesnonoPortabl

4、esometimesrarely donecommoncommonnoFeasibility of in-line coolingrarely doneyesrarely donecommonnoRoomComparison of Produce Effects and Costs for Common Cooling Methods风冷运输风冷运输低温运输国外运用例如Product arrives from the field on line trucks. Some is then cooled by icing and some is vacucooled.Vacuum cooling

5、involves placing cartons of produce in a chamber where the atmospheric pressure is lowered.国外运用例如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

6、 of produce with ice. At 25 pounds per carton, we use tons!国外运用例如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. 国外运用例如Over a period of hours, the produce is slowly cooled to the de