共查询到18条相似文献,搜索用时 109 毫秒
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以毛豆为试材,研究了-35℃鼓风冻结(风速8 m/s)、-35℃静止冻结和-18℃静止冻结三种冻结方式对毛豆冻结温度变化曲线及冷冻毛豆在-18℃冻藏过程中解冻后汁液流失率、硬度、细胞膜透性、丙二醛、叶绿素、维生素C等品质指标的变化,为选择适宜的毛豆速冻方式提供参考。结果表明:-35℃鼓风冻结冷冻速度最快,毛豆通过最大冰晶生成带的时间最短,仅为40 s,而-35℃和-18℃静止冻结所用时间分别为6 min和1 h左右。三种不同冻结方法对冷冻毛豆贮藏过程中解冻后的质构和汁液流失率,及冻藏过程中的细胞膜透性、丙二醛、叶绿素和维生素C含量等指标有显著影响。毛豆冻结过程中冻结温度越低、风速越高,毛豆冻藏过程中的质构、细胞膜完整性和营养成分等劣变速度越慢。-35℃鼓风冻结的毛豆在冻藏过程中品质显著好于-18℃静止冻结,是较好的毛豆冻结方法。 相似文献
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食品在低温箱和连续式冻结隧道中的冻结过程的比较分析 总被引:1,自引:0,他引:1
本文通过食品在低温箱中的冻结过程和在连续冻结隧道装置中的冻结过程的实验研究结果的进行对比分析,得出食品在低温中冻结时,冻品表面温度在冻结中心温度处于—1℃~—5℃的区域时会出现温度回升的现象,而连续式冻结隧道中不存在这个现象,并从理论上对其原因进行了分析。另外,冻结曲线的结果还表明,在相同冻品和品质要求的前提下,采用连续冻结隧道比较节能。 相似文献
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不同冻结速度对猪肉,青鱼肌肉咀嚼性和持水能力的影响 总被引:2,自引:0,他引:2
本文以新鲜猪肉、青鱼为原料,研究不同冻结速度对青鱼肌肉、猪肉咀嚼性和持水能力的影响。结果表明:(1)冻结速度对猪肉和青鱼肌肉咀嚼性的影响不显著。(2)冻结速度对不同食品的持水能力具有不同水平的显著影响,新鲜食品的持水能力总是大于冻结后食品的持水能力,冻结速度越快,持水能力减小的程度越小。 相似文献
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通过实验的方式,分别研究了初始温度为30℃的Na Cl蓄冷板在-25、-35和-40℃的环境中的冻结过程以及初温度为-25℃的Na Cl蓄冷板在-10、-5和0℃环境中的释冷过程。实验结果表明:在冻结过程中,当环境温度低于Na Cl共晶液的共晶温度-21.2℃时,环境温度对共晶液开始结晶的时间有较大影响,而对共晶液从开始结晶至完全冻结过程所需时间影响较小;释冷过程中,环境温度高于Na Cl共晶液共晶温度-21.2℃时,外界环境对蓄冷板释冷所需时间以及共晶冰开始融化到完全融化的过程影响较大。 相似文献
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冻结速度堆黄土物性参数具有总要影响。使土样在封闭系统开展天然状态不同冻结速度的冻融循环试验。试验表明:土在冻结过程中,环境水分向冻结锋面迁移,致使土体的含水量增大:随着冻结速度的增大,即冻结时间的缩短,环境水分迁移的量减小。对于冻结速度较慢的情况,水分冻胀作用对黄土的体积影响不明显:对于冻结速度较快的情况,冻结速度越大,体积变化越小,液塑限越大。试验表明昼夜温差的变化对黄土土性的影响大于数月温度缓慢变化的影响。 相似文献
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质地特性是评估冷冻制食品制量优劣的重要指标,本文就两种不同的冻结方式对马铃署片细胞结构和质地特性的影响,研究了马铃薯质地下降与冻结过程中其细胞结构受损情况之的的相关性。 相似文献
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Hiroyuki Kumano Tetsuo HirataShutaro Takeda Tomoya Kudoh 《International Journal of Refrigeration》2011,34(8):1999-2006
The effect of poly-vinyl alcohols (PVAs) on the supercooling of water was investigated experimentally for varying sample volumes and degrees of polymerization and saponification. A statistical analysis was carried out on the experimental results and a quantitative evaluation of the inhibition effect of PVA on release of the supercooled state was attempted by introducing a coefficient representing the inhibition effect of PVA. Experimental results and the values calculated from the statistical analysis agreed well and it was found the statistical analysis could be applied to the freezing of supercooled water containing PVA. Moreover, the effects of the PVA on the release of the supercooled state were evaluated quantitatively, using the statistical analysis. The effect of the degree of polymerization is insignificant but it was found that the inhibition effect of PVA increased with increasing degrees of saponification. 相似文献
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直接蒸发冰盘管蓄冷系统结冰过程的计算模拟及实验研究 总被引:3,自引:0,他引:3
建立了直接蒸发冰盘系统结冰过程的数学模型,并对其进行了模拟求解和实验研究,实验结果和模拟结果相一致,从而验证了模型的合理性,为系统蓄冰性能的研究和工程设计提供了依据。 相似文献
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Subsurface behavior of spilled fuel in freezing and frozen porous media including fractured bedrock is not well understood. To simulate a bedrock fracture, a freezing cell consisting of two parallel glass plates filled with glass beads was constructed to study the impact of cyclic freeze-thaw on LNAPL movement. The test procedure involved introduction of LNAPL atop the cell that contained water mixed with fluorescein dye. Freezing progressed from the top down, with observation and measurement of the LNAPL migration using a high-resolution digital camera and time-lapse photography. Both diesel and soluble oil were used for the experiments. Tests with soluble oil involved thorough mixing at 12.5% volume ratio with the fluorescein-water mixture in the freezing cell. The results showed upward mobility of the LNAPL under cyclic freezing and downward progressive expulsion of the soluble oil ahead of the advancing freezing front. The results corroborated literature findings on organic solute expulsion ahead of freezing front, and provided insight into the behavior of trapped LNAPL below the water table when subjected to freeze-thaw conditions. Additionally, micro fissures were observed in the formed ice inside the freezing cell under prolonged freezing. Such micro fissures may provide potential migration pathways for fresh spilled fuel in permafrost environments. 相似文献
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The freezing point of aluminum is one of the ITS-90 defining fixed points widely used for thermometer calibration. However,
long-term investigations have revealed slow temperature depressions of the aluminum freezing temperature and alterations of
the metal structure that are probably due to metallic contamination caused by the partial dissolution of crucible material.
The objective of this work was to study the interaction of liquid aluminum with graphite and boron nitride in order to select
a nonreactive material. Two crucibles made of high purity graphite and boron nitride were filled with Al of 6N5 purity; then,
40 melting-freezing cycles were carried out. The total time of contact between aluminum in the liquid phase and the crucible
was 240 h. After that, the composition of Al, graphite, and boron nitride was studied and the results were compared with the
analysis of the initial samples. The Al ingot in contact with boron nitride was found to be contaminated by boron. 相似文献