微波预处理对黑芝麻乳稳定性的影响

Effect of microwave pretreatment on stability of black sesame milk

以黑芝麻为研究对象,探究了微波预处理时间(0~12 min)对黑芝麻物性特征和全籽乳稳定性的影响。结果表明:微波预处理会诱导黑芝麻体积膨胀,外种皮呈凹凸不平状,其中微波预处理12 min时,外种皮发生破裂;微波预处理显著降低了黑芝麻的硬度、弹性、胶黏性和回弹性(P<0.05),其中微波预处理9 min时,均达到最小值;随着微波预处理时间的延长,黑芝麻乳的平均粒径从1.21μm增加至1.52μm(P<0.05),Zeta-电位从-26.90 mV降低至-31.91 mV(P<0.05),并伴随着物理稳定性的明显提升,以微波预处理9 min时效果最佳,表现为Turbiscan稳定性指数(TSI)曲线斜率明显降低,以及背散射(ΔBS)曲线底部和顶部的轻微变化;微波预处理使黑芝麻乳静态体系的弹性行为增强、流动性减弱,表观黏度逐渐降低,动态黏弹性增加,其中微波预处理9 min时最为明显;微波预处理使黑芝麻乳中脂滴数量和粒径明显增加,连续相中贮藏蛋白构成的多孔片层结构减少,提示优先参与乳体系中脂滴重构。因此,适宜时长微波预处理能够改善黑芝麻物性特征和全籽乳稳定性,拓宽黑芝麻的应用场景。

The effects of microwave pretreatment time(0~12 min)on the physical properties of black sesame seed and whole seed milk stability were investigated.The results showed that microwave pretreatment induced the volume expansion of black sesame seed,and uneven outer seed coat,which was further ruptured when the microwave pretreatment further reached 12 min.The hardness,elasticity,adhesion and resilience values of black sesame seed were significantly reduced upon microwave pretreatment(P<0.05),achieving the minimum values when the microwave pretreatment extended for 9 min.With the gradual prolongation of microwave pretreatment time,the average particle size of black sesame milk increased from 1.21μm to 1.52μm(P<0.05),and the zeta potential values decreased from-26.90 mV to-31.91 mV(P<0.05),accompanied by the obvious improvement of physical stability.In particular the black sesame milk exhibited an optimal physical stability when microwave pretreatment increased for 9 min as manifested by the obvious decrease in the curve slope of the Turbiscan Stability Index(TSI)values,and a slight change in the bottom and top of theΔBS curves.Microwave pretreatment,particularly for 9 min,enhanced the elasticity behavior and weakened the fluidity of black sesame seed milk in the static system,decreased the apparent viscosity,and increased the viscoelasticity in dynamic system.Microwave pretreatment caused an obvious increase in the particle size of emulsion droplets,and adecrease in the lamellar porous storage proteins in bulk aqueous phase of black sesame seed milk,suggesting the preferential participation in the reproduction of emulsion droplets.Therefore,suitable microwave pretreatment could remodel the physical properties of black sesame seed and physical stability of whole seed milk,thereby broadening their application scenarios.