【作者】 郭颖；

【导师】 孟宗；

【作者基本信息】 江南大学 ， 食品科学与工程， 2019， 硕士

【摘要】 植物油脂凝胶化制备的油凝胶具有零反式、低饱和脂肪酸的优点,被认为是代替传统塑性脂肪的新型油脂产品。目前油凝胶商业化应用的关键挑战是寻求无毒、有效、健康营养的食品级凝胶因子。本课题选取单甘油酯（Monoglyceride,MAG）、单双甘油脂肪酸酯（Mono-diglyceride,DS）、聚甘油脂肪酸酯（Polyglycerol fatty acid ester,PGEs）和硬脂酰乳酸钠（Sodium stearoyl lactylate,SSL）四种食品级乳化剂为凝胶因子,以葵花籽油为基料油制备油凝胶,分析了微观结构对宏观物性的影响规律;初步探索了乳液凝胶的相图及其微观结构;最后评价了油凝胶在烘焙产品中的应用性能。主要内容及结论如下:首先,通过直接分散法制备MAG和DS油凝胶,采用物性分析仪、流变仪、核磁共振仪（pulsed nuclear magnetic resonance,pNMR）、偏振光显微镜（Polarizing light microscope,PLM）、X-射线衍射仪（X-ray diffraction,XRD）及傅里叶红外（Fourier transform infrared spectroscopy,FTIR）等对油凝胶体系宏观物性及微结构进行分析,结果表明凝胶因子的脂肪酸组成、含量和结构影响油凝胶中晶体形态和分布,进而对硬度、持油率和热力学性质等产生影响。晶体均匀分布的网络结构能提供较强的机械硬度和液油结合能力;由单甘酯和甘油二酯形成的混晶三维网络结构在硬度和液油结合能力上优于单一组分单甘酯构建的油凝胶。MAG和DS油凝胶均在4.5?左右出现衍射峰,并在3300-3400 cm^-1出现羟基伸缩振动的特征峰,表明氢键可能对反向片层结构的形成和稳定发挥积极作用。其次,分别利用PGEs和SSL构建油凝胶,运用上述分析技术研究了油凝胶体系的晶体特性和宏观物性。结果表明高浓度凝胶因子促进了油脂凝胶网络结构的形成,使得油凝胶中结晶数量增多且分布更密集。热力学性质、液油结合能力、硬度和固体脂肪含量随着凝胶因子添加量的增加而增大。PGEs油凝胶在4.56?和4.15?出现衍射峰,SSL油凝胶分别在37.51?、4.58?和4.12?出现衍射峰,表明凝胶因子以反向片层结构和α-晶体共同存在。离子型乳化剂SSL构建的凝胶中没有发现羟基的吸收峰,而由非离子型乳化剂PGEs构建的油凝胶中出现了羟基伸缩振动衍射峰。再次,探讨了乳液凝胶相图及其微观结构。荧光显微镜图片证实乳液凝胶为水包油型,乳液凝胶中液滴尺寸和流动性均随着水相比例的增加而增大。PLM图片显示油水界面存在晶体的双折射现象,且乳液凝胶在4.4-4.5?出现宽的衍射峰,表明油水界面存在水合双层结构。最后,将油凝胶应用到面包和酥饼的制作中以替代人造奶油和起酥油,并对其质构性能、脂肪酸组成和感官特性进行评价。油凝胶制作的面包和酥饼中的SFA含量在12%左右,而人造奶油和起酥油制作的烘焙产品中SFA含量在50%以上,另外油凝胶面包和酥饼中不含TFA。油凝胶面包具有典型的发酵气泡结构,在硬度、弹性上优于葵花籽油面包,但稍逊于人造奶油和起酥油面包。油凝胶酥饼在外观、色泽、滋味和整体接受度与人造奶油和起酥油酥饼差异不大,表明其具有替代人造奶油和起酥油的潜能。更多还原

【Abstract】 Oleogelsation prepared by gelatinization of vegetable oil has the advantages of zero trans and low saturated fatty acid,and is considered as a new oil product to replace the traditional plastic fat.Searching for effective,healthy and food-gradeo leogelators was a key challenge in the commercial application of oleogels.In this study,monoglyceride（MAG）,mono-diglyceride fatty acid ester（DS）,polyglycerin fatty acid ester（PGEs）and sodium stearoyl lactylate（SSL）were used as oleogelsators to prepare oleogels.The macroscopic properties and microscopic structure of oleogelss were evaluated.In addition,the effects of oil-water ratio and addition of oleogelators on the construction and microstructure of emulsion gel were explored.Finally,the application of oleogelss in baking products was evaluated.The main contents and conclusions are as follows:First of all,direct dispersion method was used to prepare MAG and DS oleogels.The macroscopic properties and microstructure of oleogels were investigated by physical property analyzer,rheometer,pulsed nuclear magnetic resonance（pNMR）,polarizing light microscope（PLM）,X-ray diffraction（XRD）and fourier transform infrared spectroscopy（FTIR）.The results showed that the structure,fatty acid composition and content of the organogelators affected the crystal morphology and distribution in the organogels which affected the hardness,oil retention rate and thermodynamic properties.The network structure with uniform crystal distribution can provide strong mechanical hardness and oil-binding ability.Three-dimensional network structure formed by mixed crystal of monoglyceride and diglyceride is superior to organogels prepared by single component monoglyceride in hardness and oil-binding ability.Both MAG and DS organogels appeared a diffraction peak around 4.5?,and a characteristic peaks of hydroxyl stretching vibration appear at 3300-3400cm^-1,indicating that hydrogen bonding may play a positive role in the formation and stability of the reverse sheet structure.Secondly,the above analytical techniques were used to investigate crystallization characteristics and macroscopic properties of oleogels prepared by PGEs and SSL.Results showed that the high concentration organogelors promoted the formation of the network structure,and increased the number of crystals and made the distribution of crystals more dense.The thermodynamic properties,oil-binding ability,hardness and solid fat content increase with the addition of the organogelators.Diffraction peaks of PGEs oleogels appeared at 4.56?and 4.15?,while diffraction peaks of SSl oleoglels appeared at 37.51?,4.58?and 4.12?.Results indicated that the lamellar crystals structural andα-crystal coexists in organogels.The absorption peak of stretching vibration of–OH were observed in FTIR spectra of PGEs oleogels,while not appeared in FTIR spectrum of SSL oleogels.Thirdly,phase diagrams and the microstructure of the emulsion gel were investigated.Pictures of fluorescence microscope showed that the emulsion gel was oil-in-water.The droplet size and fluidity of emulsion gel increased with the increase of the water ratio.The PLM images showed that there is crystal birefringence at the oil-water interface,and the emulsion gel has a broad diffraction peak at 4.6?indicating a hydrated two-layer structure at the oil-water interface.Finally,oleogels were applied in bread and puff pastry in order to replace the margarine and shortening.The properties including fatty acid composition,sensory properties and physical properties of the bread and puff pastry produced by the oleogel,sunflower oil,margarine and shortening were measured and compared,respectively.The bakery products produced by the oleogel contained low content of saturated fatty acids（around 12%）and no trans fatty acids,while the baking content of margarine and shortening has a SFA content of more than 50%.The bread produced by oleogel have typical fermented bubble structure,and whose hardness and elasticity were better than those of bread made by sunflower oil but slightly worse than bread made by margarine or shortening.In the sensory evaluation,the score of sunflower oil puff pastry at appearance,color,taste and taste were lower,while the appearance,color,taste and overall acceptance of puff pastryt produced by oleogels were not much different from those of puff pastryt produced by margarine and shortening.It was found that the oleogel has the potential to replace margarine or shortening used in bakery products.更多还原