外源添加物对毛豆仁熔融相变区热特性的影响

Effect of exogenous additives on thermo-physical properties of soybean kernels during melting phase transition

为研究毛豆仁冻结(或解冻)相变过程中能量和品质的变化,确定适宜的冷冻(或解冻)工艺,采用差示扫描量热仪(DSC)测定毛豆仁在-30～25℃范围的冰点、熔融温度、表观比热等热特性参数,并考察氯化钠和海藻糖添加量对毛豆仁熔融相变区热特性的影响。结果表明:原料毛豆仁的冰点为-1.01℃,熔融相变温区为-4.96～0.23℃,相变潜热为191.40 J/g。随着氯化钠浓度的增加,毛豆仁冰点不断降低,熔融相变温区变宽,相变潜热变小,表观比热峰值降低;而随着海藻糖浓度的增加,毛豆仁熔融相变区热特性参数变化不大。表明添加一定浓度的氯化钠有利于毛豆仁低温加工。

In order to investigate energy and quality changes during melting phase transformation of soybean kernels and provide a suitable freezing-thawing process, the freezing point, thawing phase transition range and apparent specific heat of soybean kernels at temperatures from -30℃ to 25 ℃ were determined by differential scanning calorimetry （DSC）, and the effects of NaCl and trehalose on those thermo-physical properties were also observed. The results showed that the freezing point, thawing phase transition range and apparent specific heat of soybean kemelss were -1.01 ℃, -4. 96-0.23 ℃, and 191.40 J/g, respectively. As NaC1 concentration increased, freezing point decreased, phase-transition tempera- ture shifted to the wider temperature range, and both latent heat and apparent specific heat decreased; however, there was little chang in parameters of thermal properties for soybean kernels with the increase of trehalose concentration. Certain con- centrations of NaCl additives were in favor of soybean kernels cryogenic processing.