不同冻结条件下罗非鱼片的质构分析

对不同条件(-7,-21,-31℃)下冻结的罗非鱼片进行质地剖面分析(TPA)。研究罗非鱼片的硬度、内聚性、弹性、胶着性、咀嚼性的参数变化;分析罗非鱼片的干耗、汁液流失率的品质变化特征。结果表明,随着冻结温度的降低,弹性呈下降趋势;硬度、内聚性、胶着性、咀嚼性呈上升趋势;干耗、汁液流失率也呈现明显下降趋势,说明低温快速冻结条件比缓冻条件抑制罗非鱼体内酶活性更有效,减少蛋白质分解变性,从而保持鱼片的风味和品质。

冻结条件下土壤水热耦合迁移的数值模拟

以沈阳市季节性冻土为例,基于冻结条件下水热耦合迁移的数学模型,采用中心差分格式并用线性化迭代法求解,对现场土壤冻结过程进行了模拟。与实测结果对比表明,采用的参数及数学模型可成功模拟现场土壤冻结过程,并讨论了土壤冻结时水分与温度的迁移规律,可为后续研究奠定基础。

不同冻结条件对膨胀土三轴剪切强度的影响

为了研究季节性冻土区膨胀土力学性能随冻结条件变化的规律,对膨胀土在不同围压、温度和含水率条件下开展三轴固结排水剪切实验,分析了各组试样应力-应变曲线和强度指标的特点。

不同冻结条件对猪肉中心温度的影响

不同冻结方式、能量传递方式和包装处理会影响速冻过程中猪肉中心温度,结果表明:双面冻结速度比单面冻结快;平行于猪肉纤维的能量传递方式比较有利于冻结;无包装猪肉比保鲜膜包装猪肉更易于冻结。并对比了冻结时间模型计算结果与试验值,验证了模型的准确性。

调制初乳清粉的状态图研究

以差示扫描量热仪作为热分析手段,测量调制初乳清的冻结曲线、最大冻结浓缩条件和玻璃化转变线,并使用Chen、Gordon-Taylor模型对冻结曲线和玻璃化转变线进行非线性拟合,从而得到简化的调制初乳清粉的状态图,并对状态图进行贮藏条件分析.结果表明:Chen、Gordon-Taylor模型能较好地拟合调制初乳清的冻结曲线和玻璃化转变线,调制初乳清的最大冻结浓缩融化温度和玻璃化转变温度分别为237.24 K和226.24 K.状态图对选择合理的调制初乳清的脱水干燥工艺和调制初乳清粉的贮藏条件有重要的指导作用.

Variation characteristics of temperature and moisture content of seasonal frozen soil during freezing process in Changchun,China

In China, seasonal frozen soil is widely distributed. The freezing damage of subgrade soil in Jilin Province has been one of major engineering geological problems troubling the safety of road, in which some common damage phenomena, such as frost heave, subsidence deformation and frost boiling, are all caused by water translocation. Aiming at the phenomenon, the changes of moisture content of seasonal frozen soil in Changchun City are mainly studied by long-term field observation and indoor testing of physical properties under different conditions, and then the variation characteristics of moisture content in soil under different compactness and temperature conditions are realized. The results show that the increasing section of moisture content and negative temperature section all lie in O. 0 - 1.0 m of subgrade. Both lowest air and earth temperature occur in January to February, and the most negative temperature ranges from -7℃ to -10℃.