| 摘要: |
| 本文通过控制冷却速率观测了洋葱内表皮细胞结构的动态变化，根据透光强度定量分析了胞内冰晶对细胞结构的影响，对内压与体积的变化关系进行讨论，并研究了冷却速率对过冷度、结晶时间及细胞形变的影响。结果表明：冷却速率越慢，细胞内产生的冰晶数量越少，体积越大，对细胞造成的机械损伤越大。冷却速率从2 ℃/min升至90 ℃/min时，细胞的平均灰度值下降了37.2%；体积随内压的增大而减小，内压变化越大，细胞结构的变化越显著，在2 ℃/min时，冷却-复温后，内压增大了0.388×10-2 Pa，体积减小了2.264×10-13 m3。冷却速率对细胞的过冷度、结晶时间及变形量影响显著，在90 ℃/min时，冷却-复温后相对体积变化为1.24%。 |
| 关键词: 冻结食品 胞内冰 内压 过冷度 冻结点 |
| DOI： |
| 投稿时间：2018-01-30
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| 基金项目:国家自然科学基金（51676139）和天津市自然科学基金青年项目（16JCQNJC14000）资助。。 |
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| Effects of Cooling Rate on the Structure of Onion Epidermal Cells |
| Wang Yabo,Zhu Kai,Dai Baomin,Wang Jinshan,Liu Shengchun,Xie Yanqi |
| (Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce) |
| Abstract: |
| The dynamic variation characteristics of an onion epidermal cell structure under different cooling rates and the impact of intracellular ice crystal on the cell structure were investigated experimentally. The internal relations between pressure and volume were also discussed. The relationship between the supercooling degree, crystallization time, and cell deformation was analyzed. Additionally, the structural feature of the cells after rewarming was shown. The results indicate that the number of intracellular ice crystals formed is decreased and their size is increased with the decrease in the cooling rate, which result in more mechanical damage of cell. The average gray scale decreases by 27.5% from 2 ℃/min to 15 ℃/min and 37.5% from 2 ℃/min to 90 ℃/min. The volume of the cell decreases with increases in the internal pressure, and the cell collapses at a critical internal pressure. When the cooling rate is 2 ℃/min, the internal pressure is increased by 0.388×10-2 Pa and the volume is decreased by 2.264×10-13 m3 following the freezing–thawing process. The differences in the cooling rates have influence on the supercooling degree, crystallization time, and cell deformation. When the cooling rate is 90 ℃/min, relative volume change in the cell is 1.24% following the freezing–thawing process. |
| Key words: frozen food intracellular ice crystal cellular pressure supercooling degree freezing point |
