Properties Of Rice Bran Protein Research Articles

Dynamic rheological behavior of rice bran protein (RBP): Effects of concentration and temperature

The viscoelastic properties of rice bran protein (RBP) and the effect of temperature and concentration were investigated using small amplitude dynamic oscillatory shear measurements (SAOS). Linear viscoelastic region determined at 0.5% strain. Storage modulus (G′) was greater than the loss modulus (G″) at all concentrations and increased by raising RBP concentration. Yield stress value was determined by stress sweep and it increased from 0.038 to 1.80 Pa, when concentration increased from 10% to 15%. Frequency sweep showed that RBP solution had a typical fluid-gel behavior at low frequencies and complex viscosity (η*) had linear correlation with frequency. Phase angle was remained relatively low (>10) over the 1–10 Hz frequency range, confirming weak network of RBP. The effect of temperature on rheological traits was investigated during heating (20–90 °C) and cooling (90–20 °C) phases. RBP has a weak network and storage modulus was increased more during cooling phase. These rheological properties of RBP make it as a good candidate to apply with gelling materials in nutraceutical and food industries.

Production and Physicochemical Properties of Rice Bran Protein Isolates Prepared with Autoclaving and Enzymatic Hydrolysis

The objectives of this study were to increase the protein purity in the rice protein isolate, and to enhance the functional properties of the extracted rice bran protein via enzymatic hydrolysis and/or high temperature treatment. Washing the isolates with 30% ethanol solution achieved significant improvements in the protein contents (77.62%) of the rice bran protein isolates. The highest improvement in solubility was detected in the isolate autoclaved after enzymatic hydrolysis, up to 97.4% at a pH of 10.0. A combined modification of the method involving autoclaving and protease-hydrolysis improved the emulsion activity of the isolate at pH values above 6.0. The autoclaving and enzymatic hydrolysis increased the foaming capacity of the isolate, but reduced the foam stability at all pH ranges except 5.0. Enzymatically hydrolyzed isolates evidenced lower minimum concentrations of gel formation proteins and higher gel strengths than were detected in the other isolates.

Effect of Extraction Temperature on Functional Properties of Rice Bran Protein Concentrates

Protein concentrates were prepared from defatted rice bran at different extraction temperature (30-75°C) and analyzed for their functional properties. Protein yield increased as the temperature of extraction was increased while the protein content of protein concentrate decreased. Water binding capacity was in the range of 1.1-2.27 g/g while oil absorption capacity ranged between 1.64 and 6.89 (g/g). RBPC extracted at 60°C exhibited maximum foam producing capacity of 120% at 1% salt concentration. Emulsifying capacity of protein concentrates ranged between 33.71-70.85%. Emulsion capacity decreased as the temperature of extraction was increased. Emulsions were fairly stable under different pH, salt and sugar concentrations.

Functional properties of rice bran protein concentrates

Protein concentrates were prepared from defatted rice brans and analyzed for their functional properties. Water-binding capacity was in the range of 3.87–5.60 (g/g) while oil absorption capacity ranged between 3.74 and 9.18 (g/g). Basmati 370 had highest bulk density (0.21 g/ml). Rice bran protein concentrates of Basmati 370 exhibited good foam stability with a half-life of 42.6 h at 15% sugar concentration. Emulsifying capacity of protein concentrates ranged between 24% and 74%. Emulsions were fairly stable under different pH, salt and sugar concentrations. Functional properties of rice bran protein concentrates are comparable with casein and have good potential in food industry.

Rice bran proteins: properties and food uses.

Rice bran, a good source of protein and fat, is at present underutilized as a food material. The potential of producing rice bran at the global level is 27.3 million t. The presence of enzyme lipase in rice bran causes rapid deterioration of oil to free fatty acids and glycerol. Various stabilization techniques involving heat treatment, low-temperature storage, chemical treatment, control of relative humidity during storage, and simultaneous milling and extraction were evolved to inactivate lipase. Multiple forms of rice bran lipase have been identified. Fractional classification of proteins reveals a high percentage of albumins and globulins. Proteins can be extracted from full-fat or defatted rice bran by alkaline extraction and acid or heat precipitation. Extraction procedures influence the protein content of concentrates, which ranged from 19.4 to 76.1% in concentrates from full-fat rice bran and 17.5 to 85.0% in concentrates from defatted rice bran. The PER of rice bran ranges from 1.59 to 2.04 and that of protein concentrates from 1.99 to 2.19. Available lysine contents of protein concentrates ranged from 54 to 58.8%. The essential amino acid profiles of protein concentrates indicate that threonine and isoleucine are limiting amino acids. Various functional properties of rice bran protein concentrates have also been investigated that are known to be influenced by drying technique and stabilization treatment of rice bran. Rice bran has been used in food as full-fat rice bran, defatted rice bran, and in the form of rice bran oil and protein concentrates. Full-fat and defatted rice bran have been used in bakery products, breakfast cereals, wafers, as a protein supplement, binder ingredients for meats and sausages, and as a beverage base. Incorporation of protein concentrates have been studied in bread, beverages, confections, and weaning foods.

Solubility, Emulsifying, and Foaming Properties of Rice Bran Protein Concentrates

ABSTRACTRice bran protein concentrates were prepared from full‐fat and defatted raw rice bran. Selected functional properties, viz. nitrogen solubility, emulsification properties, and foaming properties were measured over the pH range 2.0 to 10.5 and in three dispersion media including water, 0.1M NaCl (low salt) and 1.0M NaCl (high salt). Below and above the isoelectric pH (4.5) the nitrogen solubility increased. Higher pH enhanced the nitrogen solubility and, thereby, considerably improved the functional properties. In higher salt concentration, nitrogen solubility was reduced which also altered the properties of emulsification and foaming. Multiple regression analysis showed that pH was the primary determinant of nitrogen solubility, emulsification and foaming properties. Multiple regression models including pH, salt concentration and nitrogen solubility as independent variables were found to be more accurate in predicting other functional properties.