Study On The Extraction,Physical-chemical Characteristics And Antioxidant Activity Of Active Ingredients From Rice Bran

Rice bran is an important byproduct of rice processing industry,which accounts for about 6%-8% of the total weight of rice.China produces the largest rice bran of about 14,000,000 tons annually,ranking first in the world.However,most of the rice bran produced is used as animal feed and only a small part are utilized for the extraction of oil and preparation of phytin,inositol,oryzanol and other high valued products.With the development of science and technology,the high valued nutrients contained in rice bran will be graduely developed.In the modern resource-saving society,the application and comprehensive utilization of rice bran has been continuely focued at home and abroad.The gradient extraction technology and properties of active substances extracted from rice bran were studied in this paper.The active ingredients of rice bran oil,rice bran protein,rice bran polysaccharide and etc in the whole rice bran as raw material were studied.The main contents of their processing conditions optimization and physical-chemical properties analysis were studied as follows:1.The extraction of rice bran oil using hexane,ethanol,and instant low temperature compression method from different water containing rice bran under different conditions were studied,and the physical-chimcial properties and antioxidant characteristics extracted by the 3 extraction methods were analysised.The results showed that highest oil extraction rate was got by the hexane extraction method and the lowest one was of the instant low temperature compression method,while the oil extracted by the instant low temperature compression method had the lowest acid value,peroxide value and high quality comparing with other two methods.the rice bran oil extracted by the three methods all showed antioxidant properties,in which instant low temperature compression method showed the highest inhibition rate of DPPH free radicals and the optimal antioxidant activity.The fatty acid compositions of the rice bran oils extracted by the 3 methods maily were palmitic acid,linoleic acid and oleic acid,repectively,and these fatty acids varied in their quantities,while the ratio of saturated fatty acids and unsaturated fatty acids is about 1:1 in the rice bran oil extracted by the instant low temperature compression method.2.The solubility,amino acid composition,DSC denaturation temperature and antioxidant properties of the extracted protein were compared with the methods of ultrasonic assisted cellulase extraction method and alkali extraction method.The main results are as follows:The extraction parameters were optimized by the single factor and orthogonal experiments,the results showed that the extraction temperature was 60 ?,the extraction time was 5h,the ratio of material to liquid was 1: 9,the p H value was 5,and the amount of enzyme was 0.5%,the extraction rate of rice bran protein reached 63.11%A total of 17 amino acids were isolated from the rice bran protein extracted from the ultrasonic-assisted cellulase method and the rice bran protein extracted by the alkali method.The composition was basically the same,and mainly are glutamic acid,aspartic acid and arginine,but the amino acid content varied.The results showed that the concentration of aspartic acid,glutamic acid,leucine and lysine in the protein extracted by water enzymatic method was about 27%,followed by serine,glycine,alanine,Phenylalanine and arginine,the sum of the content is about 22%.Differential scanning calorimetry?DSC?analysis showed that the thermal denaturation temperature of rice bran protein was 66.98 ? by ultrasonic assisted cellulase extraction method,and the thermal denaturation temperature of alkali extraction method was 71.06 ?.With the increase of the rice bran protein concentration,the ability of rice bran protein to remove · OH radicals and the ability to scavenge DPPH free radicals were stronger,and the ability of rice bran protein to scavenge DPPH free radicals was better.The solubility of rice bran protein extracted by ultrasonic assisted cellulase and the solubility of rice bran protein extracted by alkaline method showed that the solubility of rice bran protein extracted by different methods varied and the former one showed better solubilityOn the basis of ammonium sulfate precipitation and dialysis,the separation of rice bran protein by gel filtration chromatography showed that the chromatographic peaks of the protein with high molecular weight dialysis bag were relatively small,and with the decrease of molecular weight of dialysis bag,more protein were separated,which may be due to the degradation of cellulase,and the study of separation and purification of the rice protein should be further carried out.3.The rice bran material without lipid and protein was extracted by ultrasonic assisted extraction method and the results showed that under the optimal contidios of 90 ?,material to liquid ratio of 1:20,extraction time of 2h,ultrasonic power of 300 W and 20 min,the extraction rate of rice bran polysaccharide was 1.423%.The effects of Sevag method,trichloroacetic acid method and papain method on the removal of protein from rice bran polysaccharide were compared,and the results showed that the effect of papain was better than that of Sevag and trichloroacetic acid method.The results showed that the removal rate of protein was 54.89%,and the polysaccharide loss rate was of 3.26%.The antioxidant activity of the rice bran polysaccharide was studied.The results showed that the antioxidant activity of the rice bran polysaccharide increased with the increase of the polysaccharide concentration and the polysaccharide is able to remove the free radicals,and the scavenging rate of DPPH · and · OH radicals reached 32.7% and 31.6%,respectively.The composition of the monosaccharides of the crude rice bran polysaccharide and the polysacchariede after purification were determined by gas chromatograph after hydrolysis and derivatization.The results showed that the crude polysaccharide contained mannose,Glucose and galactose.The purified 6^th and 13^th parts of the rice bran polysaccharide were composed of mannose and galactose,respectively.The results showed that the scavenging ability of DPPH radical and · OH radicals were effective by the purified 6^th,10^th and 13^th fractions of the purified rice bran polysaccharide.