Study On The Emulsification Characteristics And Application Of Rice Bran Extract

Current research on rice bran extract mainly concentrates on the extraction and purification of single component,with little focus on the mixed components.In this project,defatted rice bran is used as raw material to prepare rice bran extract solution by ultrasound,ultrasound-assisted enzymatic and ultrasound-assisted alkaline methods,and the emulsification characteristics of the rice bran extract solution prepared by different methods were compared.The rice bran extract solution with the best emulsification property was selected.After freeze-drying the rice bran extract solution,it and the commercially available rice protein were added to oat milk separately,and the extent of the improvement on the stability of the oat milk was then compared,which provided a certain reference basis for the rice bran concentrate as a natural emulsifier.The main research contents and results are as follows:(1)Research on the preparation method of rice bran extract solution.Taking the rice bran protein extraction rate as evaluation index,the extraction rate of protein in rice bran extract solution extracted by ultrasound,ultrasound-assisted enzymatic and ultrasound-assisted alkaline methods were comparatively studied,the solubility and molecular mass of the protein in the obtained product and the microscopic morphology of the defatted rice bran after different treatments were analyzed.The results showed that the extraction rate of rice bran protein was 30.2% under the conditions of ultrasonic power at 260 W and treatment time at20 min.After ultrasonic pretreatment,cellulase enzymolysis,papain enzymolysis and alkaline extraction were used to extract rice bran protein,and the extraction rates were 50.3%,65.0%,and 75.7%,respectively.Scanning electron microscopy(SEM)results showed that ultrasonic pretreatment destroyed the rigid structure of rice bran,and enzymatic hydrolysis and alkaline conditions further destroyed the structure of rice bran,making the fiber structure loose and porous,thereby increasing the dissolution of rice bran protein.(2)Research on the emulsification characteristics of rice bran extract solution.The difference between the storage stability and freeze-thaw stability of the emulsion prepared from rice bran extract solution obtained by different extraction methods was compared and studied.The storage stability results showed that the order of the layering index of the emulsion was UPS?UAPS?UCPS?UPPS(UPS: rice bran extract solution prepared by ultrasound method,UAPS: rice bran extract solution prepared by ultrasound-assisted alkaline method,UCPS: rice bran extract solution prepared by ultrasound-assisted cellulase enzymolysis method,UPPS: rice bran extract solution prepared by ultrasound-assisted papain enzymolysis method),which was consistent with the ?-potential of the rice bran extract solution and the interface protein adsorption rate,emulsification activity,and emulsion stability of the emulsion.Within 1 week of storage,the volume weighted size of emulsion droplets prepared by UPS,UAPS,UCPS,UPPS increased from 4.59,4.86,6.01,7.82 ?m to10.37,11.87,14.50,16.15 ?m,respectively,the emulsion droplets prepared by UAPS,UCPS,and UPPS had a larger particle size distribution range,while the emulsion droplets prepared by UPS had a more concentrated particle size distribution.The microscopic images also showed that the emulsions prepared by UAPS,UCPS,and UPPS had larger aggregates,while the emulsions prepared by UPS had a small amount of flocculation and aggregation and had the best storage stability.The freeze-thaw treatment results showed that after the emulsion was freeze-thaw three times,the order of the stratification index was UPS?UAPS?UCPS?UPPS.The volume weighted size of emulsion droplets prepared by UPS,UAPS,UCPS,UPPS increased from 3.39,5.83,3.76,6.73 ?m to 13.27,22.30,18.54,34.4 ?m,respectively.The particle size distribution range of emulsion droplets prepared by UPS had the smallest change,and the average particle size was in the range of 0.1?100 ?m.The particle size distribution range of emulsion droplets prepared by UAPS,UCPS and UPPS was enlarged,and the average particle size was in the range of 0.1?1000 ?m.The microscopic images also showed that the emulsions prepared by UAPS,UCPS,and UPPS had larger aggregates,while the emulsions prepared by UPS formed a small amount of flocculation and aggregation and had the best freeze-thaw stability.(3)Research on the effects of ultrasonically prepared rice bran concentrate(RBPC)and commercially available rice protein(RP)on the stability of oat milk.With the increase in the addition of RBPC and RP,the turbidity and stability coefficient of oat milk stabilized by RBPC are significantly greater than those of oat milk stabilized by RP.The centrifugal precipitation rate,fat floating index,light transmittance,p H reduction rate,stratification index and average particle size of oat milk stabilized by RBPC are all significantly smaller than oat milk stabilized by RP.At the level of 0%,0.2%,0.8%,and 1.6% addition,the volume weighted size of oat milk stabilized by RBPC was 4.30,4.12,1.70,and 1.32 ?m,respectively,and the droplet size distribution gradually concentrated.The volume weighted size of oat milk stabilized by RP was 4.30,5.18,7.28,8.89 ?m,respectively,and the droplet size distribution range was enlarged.The microscopic images also showed that the addition of RP caused the oil droplets in the oat milk to gradually form large aggregates;the addition of RBPC significantly reduced the droplet size of oat milk,the particle size distribution was more uniform,and the stability of oat milk was significantly improved.