Preparation and Stability Analysis of Torreya grandis Seed Oil Microcapsules Using Ovalbumin and Fructooligosaccharide as Wall Materials

To broaden the functional applications of Torreya grandis seed oil in the food industry, mixtures of ovalbumin (OVA) and fructooligosaccharides (FOS) in varying proportions were employed as wall materials to prepare microcapsules of Torreya grandis seed oil via spray drying. The emulsions were characterized in terms of particle size, ζ-potential, micromorphology, and storage stability. The physicochemical properties, micromorphology, oxidative stability, thermal stability, and in vitro simulated digestion behavior of the microcapsule powders were also analyzed. The results indicated that stable oil-in-water (O/W) emulsions could be formed using OVA-FOS as wall materials with Torreya grandis seed oil as the core. Notably, a wall material ratio of 2 % (w/w) OVA and 18 % (w/w) FOS enabled the successful encapsulation of 20 % (w/w) Torreya grandis seed oil. Encapsulation efficiency of 71.96 % was achieved with a dense structure of Torreya grandis seed oil microcapsules, along with excellent solubility (61.78%), flowability (angle of repose 36.83°) and storage stability (moisture content 3.72%). Accelerated oxidation tests confirmed that the microcapsules effectively protected Torreya grandis seed oil. The peroxide value and thiobarbituric acid value were reduced by 53.30% and 66.06% respectively, compared with the unencapsulated oil, indicating a significant improvement in oxidative stability. Thermogravimetric analysis demonstrated that the microcapsules exhibited excellent stability below 200 ℃, meeting the thermal processing requirements for food applications. Furthermore, the microencapsulated Torreya grandis seed oil showed superior slow-release characteristics during simulated in vitro digestion. This study provides a theoretical reference for the development of microencapsulated Torreya grandis seed oil products and the effective protection of functional oils, offering new perspectives for the development of functional oil-based foods.