关键词: 植物油；饱和度；脂肪酸；油凝胶；微观结构；理化指标；表征

Abstract: Oleogels were prepared using four vegetable oils with different degrees of saturation (cottonseed oil, almond oil, walnut oil, and pomegranate seed oil) as the oil phase and beeswax and phosphatidylcholine as the gelator, and their physicochemical properties were determined. The aim was to study the effects of different saturation levels of vegetable oils on the physicochemical properties of oleogels. The physicochemical analysis showed that both the acid value (0.19–0.77 mg/g) and peroxide value (0.03–0.06 g/100 g) of the four oleogels met the national standards. Their saturation levels decreased in the order: cottonseed oil > almond oil > walnut oil > pomegranate seed oil. The relative content of pomegranate acid, a polyunsaturated fatty acid with three double bonds, in pomegranate seed oil was as high as 82.59%. The oil retention rates of all four oleogels were greater than 99%, and there was no correlation between the oil retention rate and the saturation degree. Intermolecular van der Waals forces were present in the four oleogels, all of which showed β’ crystal form, and the crystallinity was correlated with the content of polyunsaturated fatty acids with three double bonds in oils. The crystal structure of the oleogels was affected by the type of unsaturated fatty acids, mainly featuring elastic deformation, and these oleogels had solid-like characteristics. Pomegranate seed oil oleogel had the highest elastic modulus, viscous modulus and apparent viscosity, and the thixotropic recovery rate was as low as 49.15%. The content of polyunsaturated fatty acids with three double bonds mainly affected the rheological properties of oleogels. The melting temperature (48.9 ℃) and crystallization temperature (38.6 ℃) of pomegranate seed oil oleogel were higher than those of the other three oleogels. The crystallization and melting temperatures of oleogels was positively correlated with the unsaturation degree of oils. This study provides theoretical references for the development and utilization of vegetable oils and offers a theoretical basis for the preparation of oleogels and their application in the field of food processing.

Key words: vegetable oils; saturation degree; fatty acids; oleogels; microstructure; physicochemical indicators; characterization