Properties Of Rice Germ Protein And Researh On Oil Refining Technology

Rice germ as a byproduct of rice processing, which contains a lot of protein and fat, and also contains a variety of vitamins and trace elements of human body needs, its nutritional value is similar to soybean, so it is a good food ingredients. In this paper, rice germ was raw material, got rice germ protein fractions by using Osborne method, researched on physicochemical properties and functional properties of each fraction of rice germ protein, provided a theoretical basis for the usage of rice germ proteins in food; besides, dewaxing, degumming, bleaching, deodorization processing of rice germ crude oil and established the optimal refining conditions of refining to make the oil accord with food standards after refining.Extracted rice germ albumin, globulin, prolamin, glutelin four proteins according to the Osborne method and determinated amino acid composition of four proteins, and assessed on its nutritional properties and vitro digestibility. Results showed that amino acid fractions of rice germ protein were accorded with FAO/WHO recommended mode, amino acid score of albumin was the highest61.9, content of tryptophan and lysine was low, compared with albumin, globulin and glutelin, prolamin was in poor quality. Vitro digestibility of albumin was highest78.45%in the four proteins, then were globulin and glutelin, prolamin was relatively poor59.62%. Analysis on rice germ protein of physicochemical properties and functional properties, and analysis on solubility, foaming and effect of pH on foam stability, results showed that:with the increase or decrease of pH, solubility and foaming increased, but foam stability was opposite, which reached the maximum at pH5. Studied on the effects of pH, ionic strength, protein concentration on emulsibility and emulsification of each fraction in rice germ protein, got the optimal emulsification conditions:pH11, NaCl concentration was0.1mol/L, protein concentration was1mg/mL,3mL soybean oil. Surface hydrophobicity of prolamin was the highest1570by determination surface hydrophobicity of the four protein fractions. Secondary structure of each component of rice germ protein was mostly α-helix,β-folding, content was about45%. Results of DSC showed that denaturation temperature of four protein fractions was high, respectively was74.03℃,86.38℃, 83.29℃,82.36℃.Natural oil always contains impurities, only refining on natural oil can it achieves edible standards. Determined the optimum degumming process by designing L9(34) orthogonal experiment of rice germ crude oil:reaction temperature was45℃, addition of phosphoric acid was to0.4%, addition of water was6%, reaction time was40min, degummed oil yield was94.45%; and screened decolorizing agent and solvents in decoloring process, and determined the optimal amount of decolorizing agent and solvent:hexane200mL, activated charcoal20g, color absorption rate was85.72%, decolorization oil yield was94.21%Odor, color, physical and chemical indicators of rice germ oil has reached the vegetable oil health standards after refining, AV value decreased from70.9mg/g to0.69mg/g, POV value reached132.52mmol/kg, IV value was90.2g/100g, saponification value was162mg/g, and content of unsaponifiable matter was0.82%, refractive index was1.4709. Fatty acid composition of rice germ oil before and after refining didn’t change much, mostly was oleic acid, linoleic acid and palmitic acid, and content of unsaturated fatty acid was higher.