食品冷凍冷藏新發(fā)展

1、食品冷凍冷藏新發(fā)展李云飛2005年10月20日年人均消費水平年人均消費水平年人均消費水平0 0101020203030404050506060kgkg美國美國丹麥丹麥英國英國瑞典瑞典法國法國日本日本中國中國臺灣臺灣上海上海冷凍產(chǎn)品狀況冷凍產(chǎn)品狀況冷凍產(chǎn)品狀況肉類肉類面食面食水產(chǎn)品水產(chǎn)品果蔬果蔬冷飲冷飲果蔬12% 水產(chǎn)品50% 面食18% 肉類20% 冷飲28%易腐食品低溫運輸狀況0 0101020203030404050506060707080809090100100冷藏運輸冷藏運輸公路公路鐵路鐵路發(fā)達國家發(fā)達國家中國中國冷藏運輸公路鐵路發(fā)達國家80707中國152555(%)易腐食品低溫貯藏

2、狀況53053026261701706.86.80 0100100200200300300400400500500600600低溫庫低溫庫高溫庫高溫庫全國全國上海上海萬噸易腐食品低溫貯藏狀況（上海）0 05 51010151520202525303035355050606070708080909020002000年代年代庫容量（萬噸）庫容量（萬噸）凍結(jié)速度對食品質(zhì)量的影響降溫速率與冰晶凍結(jié)與解凍過程特點特點凍結(jié)解凍熱導率 W (m K)-12.20.5比熱容 kJ (kg K)-12.14.2 食品與介質(zhì)的溫差可充分低不可充分高研究熱點問題研究熱點問題研究熱點問題速凍食品的質(zhì)量問題 超高壓速凍

3、技術 快速冷凍技術 部分玻璃化技術 介電解凍技術實現(xiàn)上述技術的裝備冷鏈建設與工藝管理問題螺旋速凍機螺旋速凍機螺旋速凍機單體流化速凍機單體流化速凍機低溫介質(zhì)速凍機低溫介質(zhì)速凍機低溫介質(zhì)速凍機隧道式速凍機氫與電負性很強，且具有獨立電子對、原子半徑又較小的原子可形成氫鍵（如氮、氟）水的物理性質(zhì)第VI族元素氫化物的融點和沸點H2O沸點融點H2SH2SeH2Te分子量溫度/ 1000-60-1002040120800The phase diagram of water. l represents the region in which ice XII has been observed by Lobba

4、n et al. (T = 260 K, p = 0.55 GPa) 2. Please note that this region is fully surrounded by the stability range of ice V. The inset sketches the pressure induced transition line of Ih (red line) as studied by O. Mishima 1. The green area indicates the region in which ice XII is successfully formed. Ho

5、rizontal arrows indicate that Ih transforms by compression below 150 K to ice XII or high-density amorphous state (HDA) and above 150 K to ice III/IX. The orange area displays the 150 K boundary studied by O. Mishima for HDA which is equally observed for ice XII.Triple pointsMPaCliquidgasIh0.0006120

6、.01liquidIhIII209.9-21.985IhIIIII213-35IIIIIV344-24liquidIIIV350.1-16.986IIVVI626-70liquidVVI632.40.16VIVIIVIII21005liquidVIVII221681.6冰晶形態(tài)I型冰晶形態(tài)III型冰晶形態(tài)IV型The H-bond framework of rhombohedral ice IV showing the auto-clathrate arrangement with H-bonds passing through the centre of 6 membered rings.冰

7、晶形態(tài)XII型The H-bond framework of tetragonal ice XIITransition of ice XII towards hexagonal ice upon heating. The upper left photograph a) shows ice XII as recovered from the pressure cell at low temperature. In contrast to high-density amorphous ice it has a milky appearance. The following photographs

8、 show the floking of ice XII as it transforms to the lower density forms cubic ice and hexagonal ice (b-d).冰晶XII型與冰晶I型凍結(jié)與解凍過程凍結(jié)過程解凍過程高壓凍結(jié)試驗裝置高壓凍結(jié)Pressure-Shift-FreezingPressure-Shift-FreezingPressure-shift-freezing (A) and pressure assisted thawing (B) of potatos at the phase diagram of waterPressur

9、e-Shift-FreezingPressure-Shift-FreezingFreezing of potato tissue water to ice IIIPressure-Shift-FreezingPressure-Shift-Freezing新鮮目魚細胞Pressure-Shift-FreezingPressure-Shift-FreezingPressure-Shift-FreezingPressure-Shift-Freezing部分玻璃化技術部分玻璃化技術玻璃態(tài)DSC曲線彈塑性與溫度關系玻璃態(tài)轉(zhuǎn)變理論自由體積理論 RTEBexp鏈段能量與周圍的自由體積大小冷凍穩(wěn)定劑較高的Tg

10、冷凍保護劑較強保水性常用添加劑對粘度影響果蔬田間熱與呼吸熱The respiration rate and the production of CO2 depends mainly on the storage temperature計算示例56.6103. 09 . 02280kg水3101 .155252056.61kJ3104 .1725252 . 49 . 02280kJ08.8204. 09 . 02280kg水3108 .206252008.82kJ水的存在狀態(tài)自由水：在組織和細胞中容易結(jié)冰、也能溶解溶質(zhì)的這部分水。 毛細管水細胞間隙內(nèi)水； 滯化水組織內(nèi)顯微或亞顯微 結(jié)構(gòu)與膜 所阻

11、留的水；流動水植物導管、細胞內(nèi)液泡中的水。水的存在狀態(tài)束縛水：在組織內(nèi)通過氫鍵與其它物質(zhì)結(jié)合的這部分水。其特點是冰點低（約40）；不能作為溶劑。溶質(zhì)對凍結(jié)與蒸發(fā)溫度的影響稀溶液中水的蒸氣壓比純水蒸氣壓低sxppp水溶液水在壓力相同條件下，稀溶液中水的沸點高于純水的沸點。sxKTT水溶液在壓力相同條件下，稀溶液中水的冰點低于純水的冰點。sxKTT溶液水植物細胞結(jié)構(gòu)葉面組織結(jié)構(gòu)葉面表層氣體運動葉面表層氣體運動壓力與蒸發(fā)溫度壓力與蒸發(fā)溫度壓力（Pa）溫度（）壓力（Pa）溫度（）10130010087352339206110170615402-5123010260-10壓力與蒸氣體積1克水體積常溫常壓

12、下1毫升873Pa，5下150000毫升RTMmPV 278K KkmolJ8314 18 0.001kg Pa873TRMmP壓力與蒸氣體積如果每小時蒸發(fā)82kg水，則水蒸氣體積達到0.1582100012300m3。需要真空泵抽出速率為205m3/min。捕水器抽出水蒸氣保護油封泵真空泵羅茨泵與油封泵性能10510310110-20255075100壓強 Pa抽氣速率 影響真空預冷效果的因素v 可用于汽化的水份含量；v 表面組織的性質(zhì)；v 體表面積大小。果蔬材料果蔬堆放狀態(tài)v 果蔬堆放密度；v 包裝材料的氣密性。設備性能v 降壓速率。風冷風冷負壓風冷水冷水冷水冷冰冷蒸發(fā)冷卻Straw pa

13、ckinghouse真空冷卻真空冷卻裝貨移動式真空冷卻設備真空冷卻冷卻曲線Forced-AirHydroIceVacuumTypical 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 costlowmediummediumh

14、ighlowWater-resistant packaging needednoyesyesnonoPortablesometimesrarely donecommoncommonnoFeasibility of in-line coolingrarely doneyesrarely donecommonnoRoomComparison of Produce Effects and Costs for Common Cooling Methods風冷運輸風冷運輸?shù)蜏剡\輸國外應用示例Product arrives from the field on line trucks. Some is th

15、en cooled by icing and some is vacucooled.Vacuum cooling involves placing cartons of produce in a chamber where the atmospheric pressure is lowered.國外應用示例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

16、 and undamaged.Regular icing involves packing each carton of produce with ice. At 25 pounds per carton, we use tons!國外應用示例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 a