Recently, researchers from the National Dairy Technology Innovation Center published scientific research results in the journal " LWT - Food Science and Technology ". The article proposes that using saccharified casein as the wall material can improve the protection and controlled release effect of flaxseed oil microcapsules.

　　Linseed oil is rich in unsaturated fatty acids, mainly composed of α - linolenic acid, oleic acid and linoleic acid, and is one of the best sources of ω -3 polyunsaturated fatty acids. However, the oxidation of flaxseed oil limits its practical application.

　　Oxidized flaxseed oil can produce unpleasant flavors and toxic substances such as aldehydes, ketones, hydrocarbons and epoxides that can adversely affect human health. Therefore, how to effectively solve this problem has become the research focus in the field of flaxseed oil development.

　　Microencapsulation of oils has been considered one of the most effective ways to preserve their nutrients and sensory properties. Microcapsules are an effective delivery medium that targets oil release and absorbs in the intestine, improving oil bioavailability. At present, different types of wall materials such as whey protein, plant protein, maltodextrin have been used in the preparation of oil microcapsules, but their oil carrying capacity is relatively low. Studies have shown that linseed oil microcapsules are prepared using denatured starch as wall materials, and their oil carrying capacity is 40% , encapsulation efficiency is 75% , but their oxidation stability is poor. Therefore, it is a great challenge to achieve high packaging efficiency and good oxidation stability of microcapsules under high oil-carrying conditions.

　　As a surfactant in emulsions, proteins are widely used as wall materials for milk-based microcapsules. However, natural proteins are unstable at the oil / water interface and cannot provide sufficient stability to the emulsion. Compared with proteins, polysaccharide molecules can dominate the attraction interaction between oil droplets and provide better emulsification due to their sufficient spatial repulsion. The Maillard reaction can enhance the function of proteins, thereby producing smaller and more stable emulsions. In addition, glycosylated proteins as microcapsule wall material can enhance the integrity of microcapsules, delay oxygen entering microcapsules, and improve core storage stability. Previous studies have shown that the embedding rate of vitamin E microcapsules prepared by soy protein isolate - chitosan conjugate is 74.74% , which has stronger water-soluble resistance and better storage stability. Therefore, glycosylated proteins are more suitable as wall materials for microcapsules than their parent proteins. Studies have shown that glycosylated protein products prepared by the Maillard reaction, such as casein - pectin conjugate ( CA-CP conjugate) and casein - Arabinogalactan conjugate ( CA-AG conjugate), have good thermal stability, solubility and foaming properties, and are ideal for microcapsule wall materials.

　　In order to explore the feasibility and effectiveness of CA-CP conjugate and CA-AG conjugate as linse oil microcapsule wall materials, this study prepared CA-CP conjugate and CA-AG conjugate emulsions, and used them as microcapsule wall materials, the emulsification properties and antioxidant activities of CA-CP conjugate and CA-AG conjugate were studied, and the oil carrier amount and encapsulation efficiency of the two linse oil microcapsules were compared. Finally, the oxidative stability and in vitro digestive properties of microcapsules were investigated.

The study found that both the CA-CP conjugate and the CA-AG conjugate exhibit higher emulsification and antioxidant properties 　　compared to casein , thus having the potential to be a microencapsulated wall material. To this end, linseed oil microcapsules were prepared by spray drying using CA-CP conjugate or CA-AG conjugate as wall materials. When the mass ratio of wall material to core material is 1:1 , the encapsulation rates of prepared CA-CP conjugate + flaxseed oil microcapsules ( CPM ) and CA-AG conjugate + flaxseed oil microcapsules ( AGM ) reached 72.23% and 83.44% respectively . Fourier infrared spectroscopy ( FT-IR ) and scanning electron microscopy ( SEM ) results show that the microcapsules are smooth on the surface and spherical in the overall shape, and the inner wall material successfully encapsulates flaxseed oil. In vitro simulated gastrointestinal digestion and antioxidant analysis showed that microcapsules achieved controlled release of flax oil in the gastrointestinal tract and improved the storage stability of flax oil. Therefore, microencapsulation of flaxseed oil using Maillard reaction products is a promising method of preservation and provides a new way to develop flaxseed oil products.