芝麻油体的稳定性及油体膜蛋白结构分析

Stability of sesame oil bodies and structure analysis of oil body proteins

油体是天然存在于油料作物种子中的储油器官,了解其稳定性和表面膜蛋白结构对油体的应用至关重要。选取白芝麻油体为研究对象,考察不同加工与贮藏条件(如pH、离子强度、温度)对芝麻油体稳定性的影响,并对芝麻油体膜蛋白进行结构表征。结果表明:酸性环境(pH≤5.0)和高盐离子浓度(≥0.2mol/L)会加速油体的聚集和失稳,而碱性条件、高热处理和低盐离子浓度则有助于维持其稳定性。通过聚丙烯酰胺凝胶电泳(SDS-PAGE)、红外光谱(FTIR)及差示扫描量热法(DSC)分析,发现白芝麻的油体膜蛋白主要由12~14ku的油体蛋白(Oleosin)和27ku的油体钙蛋白(Caleosin)组成,油体膜蛋白的热变性温度约为55℃,α-螺旋为其主要二级结构。这些参数为开发基于芝麻油体和油体膜蛋白的产品提供了理论参考。

Oil bodies are the natural oil storage organ in crop seeds.To understand the stability and oil body proteins structure are key factors for application.In this study,oil bodies and proteins extracted from white sesame seeds were served as research objects.Influences of processing and storage conditions such as pH,ionic strength and temperature on stabilities of sesame oil bodies were investigated,the structure of oil body proteins was characterized.Results showed that acidic pH (pH≤5.0) and high ionic strength (≥0.2 mol/L) promoted the aggregation and coalescence instability of oil bodies.Meanwhile, alkaline conditions,low NaCl concentration and heating treatment had positive effects on the stability of oil bodies.Structural information of oil body proteins was characterized using polyacrylamide gel electrophoresis (SDS-PAGE),infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Two types of oil bodies proteins were obtained.One of them was oleosin with the molecular weight around 12~14 ku,and another was caleosin (27 ku).Denaturation temperature of oil bodies protein was close to 55 ℃ and α-helix was the major secondary structure.These parameters provided the important reference for the development and application of sesame oil body and its proteins.