Study On Component Analysis And Protein Extraction Of Rice Residue Protein

In China's industry of starch sugar production and monosodium glutamate fermentation, it produces 10 million tons by-products such as rice residue, rice bran and rice germ annually.The protein content in rice residue is between 40%-60%. Rice protein is one of proteins which have the highest nutritional value. However, it is used for animal feed mostly, due to its poor performance in dissolution and emulsification, which makes a large amount of protein resource wasted.In this paper, the rice residue from sugar production was used as raw materials, the protein composition and the conditions of sequential extraction method in the protein extraction process were studied. The results were as follows:(1)Analysis of sugar and protein content in rice residueDNS colorimetry method and phenol sulfuric acid method were used respectively to analyse the total sugar content in rice residue.The measure range of sugar concentration is (0~0.16)mg/mL,(0~0.02)mg/mL.In these rage, the protein in rice residue has no effect on sugar content.Bradford method and Biuret method were used respectively to analyse the protein content in rice residue. The measure range of protein concentration were (0~0.05)mg/mL, (0 ~12)mg/mL; the sugar in rice residue has no effect on protein content in these rage.(2)Then these two methods were used to determine the content of four proteins in rice residue. The effect of extraction conditions on protein content were studied through single factor and orthogonal experiments.(3)The components of rice residue were obtained.The main components of rice residue were carbohydrates, protein and fat. The content were 52%-56%, 25%, 12%, respectively.(4)The extraction condition of protein in rice residue was studied, using step extraction method.The effect of extraction sequence on protein content was studied. The results showed that: the maximum extraction rate of proteins was obtained when the extraction sequence was albumin firstly, globulin secondly, prolamin thirdly, glutelin lastly. At this point, the total protein content was 68.2% (wet basis).(5)The dissolution of these four proteins were been studied.â‘ Albumin can dissolve in ethanol and NaCl solution. During the extraction of albumin, ethanol will facilitate its dissolution when concentration in the extraction solution was below 2%. â‘¡Globulin can dissolve partly in ethanol when ethanol content in the extraction solution was below 4%.â‘¢During the extraction of prolamin, Na+ which existed in the extraction solution can facilitate its dissolution.Finally, the sequential extraction method was used for protein extraction in rice residue.(6)Response surface method was used to analyse the sighificant level of extraction factors which affect glutelin content, and the interaction between these factors were researched.During the extraction of glutelin, the mixture ratio, extraction temperature, NaOH concentration, the interaction between mixture ratio and NaOH concentration and the interaction between NaOH concentration and temperature can affect glutelin content siginificantly.(7)Scanning electron micrograph and IR spectra were used to characterize the structure changes in rice residue after solvent treatment.It showed that the continuous structure on the surface of untreated rice residue changed to sheet skeleton structure, then to gel granular structure, which showed the effect of solvent treatment on protein extraction. IR spectra showed that the composition of rice residue does not change much after extraction, but the content of each component decreased slightly.