A Comparative Study on Extraction and Physicochemical Properties of Soluble Dietary Fiber from Glutinous Rice Bran Using Different Methods

The methods of hot water extraction and ultrasound-assisted enzymatic treatment were applied for extracting the soluble dietary fiber from the glutinous rice bran in the study. Based on the single factor experiment for the hot water method, the optimum parameters of the extraction time of 120 min, solid-liquid ratio 1:20 (w/v), and pH 8.0, as well as the extraction temperature 80 degrees C, were obtained, while the yield and purity of SDF reached 31.83 +/- 0.06% and 93.28 +/- 0.27%, respectively. Furthermore, the SDF yield was improved to 34.87 +/- 0.55% by using the ultrasound-assisted enzymatic treatment under the optimum conditions of cellulase dosage 9 x 10(3) U/g and ultrasonic temperature of 50 degrees C. Similar polysaccharide compositions were detected based on the infrared spectroscopic analysis. Compared with the SDF obtained from hot water extraction, the whiteness, solubility, water holding capacity, and swelling properties of SDF extracted by ultrasound-assisted enzymatic method improved significantly. These results demonstrated that both two strategies could be applied to SDF extraction in practical production, and the ultrasound-assisted enzymatic method might be an effective tool to improve the functional properties of SDF.

Automated summary

The methods of hot water extraction and ultrasound-assisted enzymatic treatment were used to extract soluble dietary fiber (SDF) from glutinous rice bran. The optimum parameters for hot water extraction were determined to be an extraction time of 120 min, a solid-liquid ratio of 1:20 (w/v), pH 8.0, and an extraction temperature of 80°C, resulting in a SDF yield of 31.83% and purity of 93.28%. Ultrasound-assisted enzymatic treatment further improved the SDF yield to 34.87% under optimized conditions of cellulase dosage (9 x 10(3) U/g) and ultrasonic temperature (50°C). The functional properties of SDF extracted by ultrasound-assisted enzymatic method, including whiteness, solubility, water holding capacity, and swelling, were significantly enhanced compared to those extracted by hot water extraction. Both methods can be applied in practical production, and ultrasound-assisted enzymatic method has the potential to improve the functional properties of SDF.