Preparation And In Vitro Simulated Release Of Borage Oil Microcapsules

Borage oil is widely used in food,medicine and cosmetics due to its high content of γ-linolenic acid and polyunsaturated fatty acids.However,the high content of polyunsaturated fatty acids causes borage oil to be oxidized and rancid,and the fat-soluble functional active ingredient is difficult to dissolve in aqueous solution,which greatly limits the application range of borage oil.Microencapsulation of functional oils can effectively solve this problem,delay the oxidation rate of borage oil,reduce the nutrient loss during industrial production,and expand the application range of borage oil.In this paper,three different wall materials were used to microencapsulate borage oil,and its basic physicochemical properties,stability and release behavior were studied.The protein component gelatin was selected from the wall material formula,and whey protein was used as the control protein.To study the interaction of proteins with polysaccharides and the interfacial properties of oil-water emulsions.Provide scientific theoretical basis for the application development and development of borage oil microcapsules.The main findings obtained are as follows:(1)The borage oil microcapsules were prepared by spray drying method,and the physicochemical properties and thermal stability of the three groups of borage oil microcapsules were evaluated.The results showed that the embedding rate of the three groups of borage oil reached more than 85%.The microcapsules had good dispersibility,high solubility and good thermal stability.The microstructure of borage oil microcapsules was observed by SEM.It was found that the three groups of microcapsules were relatively intact.Among the three groups of formulas,the borage oil microcapsules prepared by formulating sodium caseinate and gelatin combined with corn syrup as the wall material had the best effect,and the embedding rate was 95.7%,and the particle size was 264.09 nm.The structure is more complete and evenly distributed,with outstanding thermal stability.(2)The borage oil and borage oil microcapsules were stored at 60°C for 18 days.The oxidative stability of the three groups of borage oil microcapsules was studied.The results showed that the POV value of the free borage oil reached the highest in 12 days.77.92 meq/kg,while the TBA value increases with storage time.After storage,the POV and TBA values of the three groups of borage oil microcapsules were significantly smaller than the free borage oil,while the microcapsules prepared by Formulation showed the best antioxidant properties after storage.SEM observation showed that the microscopic morphology of microcapsules after accelerated storage showed that although the three groups of microcapsules showed different degrees of depression or aggregation,they still maintained intact microcapsule morphology,and the microencapsulation of oil provided an effective barrier for borage oil.protection.(3)The in vitro release of borage oil microcapsules was observed by inverted fluorescence microscopy.After 5 hours of digestion,the released oil accumulated and emitted strong red fluorescence,and the red fluorescence of Formula 1 in the field of view was stronger than Formula 2 and Formula 3.After the end of digestion,the total release rate of the microcapsule core material prepared by Formula 1 was 82.47%,which was significantly higher than that of Formulation 2(59.34%)and Formula 3(61.02%),while the intestinal release rates of the three groups of microcapsule core oil were respectively 45.05%,47.88% and 44.28%.The microencapsulation of borage oil can release most of the borage oil in the intestinal digestion stage,while the Formula 1 is more suitable for embedding borage oil to achieve the purpose of effective delivery of the functional gastrointestinal tract.(4)X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),optical contact angle and rheometer were used to study the conformational changes of proteins and complexes before and after protein-polysaccharide interaction in a wall material.The nature of the characteristics,while establishing a control group of whey protein and polysaccharide interaction,the results show that: whey protein has a richer amino acid species than gelatin.Under neutral conditions,the addition of corn syrup hinders the formation of the crystal triple helix,but promotes the formation of the left helix of the crystal.Atomic force microscopy showed that the added corn syrup significantly changed the nanostructure of gelatin to form a stable polyion complex with compatibility,and the surface of the whey protein also changed into a spherical agglomerate.The whey protein alone has a greater negative charge than gelatin,and as the amount of corn syrup added increases,the potential of the whey protein complex solution continues to decrease,while the gelatin complex solution first decreases and then increases.The addition of corn syrup facilitates the expansion and diffusion of proteins at the oil-water interface,while the spherical whey protein has more prominent interfacial activity.In the rheology,the rheological coefficient fitting degree of the two protein-polysaccharide complex solution systems is high,and n>1.When the shear rate increases,the kinetic energy of the particles in the system increases and the shear stress increases.The viscosity increases.The addition of polysaccharides promotes shear thinning and improves system stability.