棕榈酸单甘酯-巴西棕榈蜡大豆油凝胶热性质及结晶动力学研究

    Study on the thermal properties and crystallization behaviors of soybean oleogel formed with monopalmitate and carnauba wax

    • 摘要: 油凝胶是一种热可逆的塑性脂肪,其中饱和脂肪酸和反式脂肪酸含量较低,具有替代传统塑性脂肪的优势。采用棕榈酸单甘酯(MP)与巴西棕榈蜡(CW)混合物作为凝胶剂制备大豆油凝胶,凝胶剂添加量(以油凝胶质量计)为10%,研究二者的比例对油凝胶热性质和结晶动力学的影响。采用差示扫描量热法(DSC)、脉冲核磁共振法(p-NMR)分别分析油凝胶的热性质和结晶动力学特性。DSC数据表明,熔化和结晶过程中的峰值温度和焓变受MP与CW比例的影响,第1次熔化时的峰值温度高于第2次熔化时相应峰的峰值温度;熔化时的峰值温度均高于结晶时相对应的峰值温度;熔化和结晶时,随着CW含量的增加,低温区峰值温度均先降低而后增加,高温区峰值温度则一直增加,熔化焓变和结晶焓变均先降低后增加。采用Gompertz模型对等温结晶数据进行拟合,结果表明:MP与CW比例对结晶平衡时的固体脂肪含量(SFCmax)、结晶速率(μ)和结晶诱导时间(λ)有很大影响,在相同温度下,随着CW含量的增加,SFCmaxμ先减小而后增加,λ则先增加而后减小。

       

      Abstract: Oleogels were thermally reversible plastic fats with low content of saturated and trans fatty acids and had the application prospect of replacing traditional plastic fats. The soybean oleogels were prepared using the mixture of monopalmitate (MP) and carnauba wax (CW) as gelator with the amount of 10% (based on the mass of the oleogel). The effects of the ratios of MP to CW on the thermal properties and crystallization kinetics of the oleogels were investigated. The thermal properties and crystallization kinetics of the oleogels were determined by differential scanning calorimetry (DSC) and pulsed nuclear magnetic resonance (p-NMR) spectroscopy, respectively. The data of DSC showed that the peak temperatures (Tps) and enthaplies of the oleogels in melting and crystallization process were affected by the ratio of MP to CW, the Tps of the oleogels in the 1st melting process were higher than those of the corresponding peaks in the 2nd melting process, the Tps of the oleogels in the melting process were higher than those of the corresponding peaks in the crystallization process. In the melting and crystallization process, with the CW content increasing, the Tps with lower temperature decreased first and then increased, the Tps with higher temperature increased, the melting and crystallization enthaplies of the oleogels declined first and then increased. The crystallization kinetics of the oleogels was fitted using Gompertz model. The maximum solid fat content when crystallization time approached infinity (SFCmax), crystallization rate (μ) and induction time (λ) was affected greatly by the ratio of MP to CW. With CW content in the gelators increasing, SFCmax and μ decreased first and then increased,λ increased first and decreased.

       

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