| There is about 60.075 million mu of walnut cultivation area in China,with an annual output of about 3.287 million tons,ranking first around the world,mainly distributed in Xinjiang,Shaanxi,Hebei,Shandong,Shanxi,Henan,Gansu,Guizhou,Yunnan and other places.Walnut oil has been widely used as a walnut deep-processing product.Walnut oil is rich in unsaturated fatty acids such as?-linolenic acid,linoleic acid,and oleic acid,which has higher edible and medicinal value and is popular among people,however,it is not readily stored in production becouse of its susceptibility to oxygen,light,moisture,etc.Microencapsulation of fats can prevent oxidation,prolong the shelf life,and enhance nutritional value.The work investigated the production technology and mechanism of microencapsulation in walnut oil.Different types of materials and emulsifiers were screened and walnut oil microcapsules with high embedding rate and oil load were prepared by optimizing emulsification and drying process.Two drying methods that spray drying and vacuum drying effected microcapsules of walnut oil on the physical indicators,storage stability,in vitro simulated digestion,thermal stability,Fourier infrared spectral characteristics,and microstructure were studied,the technical parameters of production in walnut oil microencapsulation were optimized and the physiological functions of walnut oil and its microcapsules were evaluated.The main results are as follows:1.We found that the best carbohydrates wall is malt dextrin,the protein wall material is soybean protein isolate,the hydrocolloid wall material is acacia,where they were mixed in an optimum ratio of 7:9:4,through screening various wall materials and dosages for preparing walnut oil microcapsules as well comparing the emulsification stability of emulsions prepared by different wall materials and the embedding rate of microcapsules.By screening the emulsifiers,it was found that the non-ionic emulsifier was sucrose oil and fat,the amount was 0.80%,and the anionic emulsifier was glyceryl monostearate,the amount was 0.60%.2.In this part,the technological parameters of emulsion preparation were optimized by statistical analysis of emulsifying time,wall core material ratio,soluble solid content,emulsifying temperature.We found that the best emulsification was performmed in the state of 75? and 60 min,solid content of 10%,wall core material ratio of 1.5.3.The process parameters of spray drying were optimized by statistical analysis of namely inlet air volume,inlet temperature,optimal inlet flow rate and homogeneous pressure.It was found that the preparation of walnut oil microcapsule by spray drying was bestly worked out at the air inlet volume of 50 m3·h-1,inlet temperature of 168?,feeding of 0.5 L·h-1 and the average pressure of 25 MPa.Under this condition,the embedding rate of walnut oil microcapsules was 80.29%.4.The comparative analysis of spray drying and vacuum freeze drying was worked out.In terms of physical indicators,the moisture content(2.40%±0.21%),the angle of repose(37.22±0.47°),the embedding rate(81.91%± 2.75%)of walnut oil microcapsules prepared by spray drying were better than that of vacuum freeze-drying.In the accelerated oxidation test,both spray-drying and vacuum freeze-drying microcapsules can inhibit the oxidation of walnut oil,and have the best spray-drying effect.Comparing to the vacuum freeze-drying,the walnut oil microcapsules prepared by spray drying has a better oil release effect in vitro simulated digestion test,which is more conducive to the digestion and decomposition of oil in the body.Thermogravimetric analysis(TGA)results showed that the thermal stability of the microcapsules prepared by the two drying methods was not significantly different.However,the weight loss was increased after 400?,which indicated the wall material was easily disintegrated at this temperature.Fourier transform infrared spectroscopy(FTIR)plots indicate that the spray-drying effect is better than vacuum freeze-drying.The SEM observation showed that the microcapsules prepared by spray drying had uniform particle size,uniform shape,and regular distribution.5.The obese mice model was successfully established through continuous 4 weeks feeding with high-fat diet.The obese mice body weight and liver index,serum HDL-C levels,serum LDL-C,TC,and TG levels,liver MDA content as well liver GSH-PX and T-SOD activities were effectively improved after the intervention of different doses of walnut oil and its microcapsules. |
PDF Full Text Request