疏水化淀粉微粒对Pickering乳状液界面稳定机理的研究

Particle emulsifier attracted more attention in the food, drug release, and chemical industry, etc. Compared with the thaditional emulsifier, particle emulsifier has the advantages of strong interfacial stability, non-toxic, eco-friendly and low cost. The latest research showed that the hydrophobic modified starch can be used as particle emulsifier to stabilize oil-in-water emulsions. However, the interfacial stability mechanism are nuknown. Based on our previous work, the octenyl succinic anhydride modified rice starch particles with high amylose content will be used as emulsifier to stabilize soybean oil-in-water Pickering emulsions. The factors affecting the stability of emulsion will be studied. The contacting interfaces, arrangement model, net structure and other adsorption behaviors of the hydrophobic modified starch particles on the oil/water interfaces will be investigated by means of confocal laser scanning microscopy, scanning electron microscopy, etc. The shear viscosity, elasticity modulus and viscous modulus of the interfacial films will be studied using interfacial rheometer. The relationships among interfacial adsorption behavior, rheological behavior and emulsion stability will be analysed to elucidate the stability mechanism of the emulsion. This investigation is very important for the developmente of new functional starch-based particle emulsifiers which can be used in the food industry and related industries.

颗粒乳化剂因其具有强界面稳定性、无毒、环保和成本低等特性，在食品乳状液、药物缓释、化工等领域具有重要潜在应用价值而备受关注。最新研究表明，淀粉经疏水化修饰后，可以作为食品级颗粒乳化剂，稳定水包油型乳状液，但其界面稳定机理尚未明确。本项目在前期研究基础上，以辛烯基琥珀酸酐疏水化修饰的高直链大米淀粉微粒为乳化剂，以大豆油／水体系为研究模型，构筑Pickering乳状液，研究各因素对乳状液稳定性的影响规律；并利用激光共聚焦显微镜、扫描电镜等分析技术研究乳状液中油/水界面疏水化淀粉微粒的吸附位点、排布规律、网络结构等吸附行为；采用界面流变仪研究乳状液中油/水界面膜的剪切粘度、弹性模量和粘性模量的动态变化规律；将界面吸附行为、界面膜流变学特性与乳状液稳定性进行关联分析，揭示疏水化淀粉微粒稳定乳状液的机理。该研究有助于开发新型功能性淀粉基颗粒乳化剂，为其在食品工业及相关行业的应用提供理论依据。

本课题以特糯2072、特优2035、Ⅱ优838和冈优188四种不同直链淀粉含量（AC: 1.90 - 26.98%）的疏水化大米淀粉微粒为乳化剂，制备Pickering乳状液，研究各因素对乳状液稳定性的影响规律，并对淀粉微粒在油/水界面的吸附行为和所形成界面膜的流变学特性进行研究，探讨淀粉微粒稳定乳状液的机理。结果表明：淀粉颗粒吸附于油/水界面，包裹住油滴，通过物理屏障作用及三维空间位阻作用稳定乳状液，抑制油滴聚结。疏水化淀粉微粒稳定的乳状液液滴平均粒径在32.99~71.82 µm之间，乳状液贮存100 d无絮凝。. 同时研究了各因素对Pickering乳状液稳定性的影响规律。结果表明：淀粉颗粒浓度增加，乳相体积增加，乳状液液滴粒径减小。乳状液的液滴粒径随着油相浓度的增加而增大，且当油相浓度大于50 %时，净乳相体积明显降低。当pH 4~8时，乳化稳定性高；pH > 9时，乳状液的稳定性急剧下降。不同NaCl浓度下，乳状液的Dav在20.22~25.08 µm 之间，体系NaCl浓度对乳状液的稳定性无显著影响。乳状液液滴粒径随蔗糖浓度的增加先增大后减小。Dav从20.22 µm增加至32.08 µm，再减小为16.30 µm。. 静态剪切流变实验表明：随着剪切速率的增加，乳状液黏度下降，具有剪切稀释行为，为假塑性流体。动态黏弹性分析表明，淀粉颗粒浓度为4.0 %时，乳状液弹性模量（G′）最高，损耗角正切（Tanδ）最小；随油相浓度的增加，乳状液弹性模量降低，损耗角正切增加；pH值增加，乳状液弹性模量无显著性变化，但损耗角正切降低，具有典型的凝胶流变学行为；且G′越高，Tanδ越小，乳状液体系液滴间相互作用力越强，抵抗形变能力越强。. 该研究构建淀粉基颗粒乳化剂，用于稳定水包油型乳状液，突破了以往对食品乳化剂的思维局限；并重点研究了界面吸附行为和界面膜流变学特性，阐明淀粉基颗粒乳化剂稳定乳状液的机理，实现了食品学科与界面化学的交叉与融合，为淀粉基颗粒乳化剂在食品工业和相关行业中的应用提供理论与技术依据。