PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Rice bran (RB) is a major by-product of the rice industry, and the high proportion (~90%) of insoluble fibre (IF) is the main reason limiting its applications in foods. Thus, the objective of this research is to enhance the solubility of rice bran fibre and decrease the molecular weight (MW) of the soluble fibre (SF) fraction through ultrasound (US) and steam explosion (SE) treatments. The main sugars in the RB fibre were xylose and arabinose, with glucose, galactose, and mannose present in the side chains. The ratio of Ara/Xyl was 0.92 for the un-purified and 1.02 for the purified RB, reflecting the high degree of substitution of the xylan backbone. The highest amount of SF was obtained from RB treated at 60% US amplitude, 20 min treatment, where 7.8% (un-purified) and 35.2% (purified), respectively. For SE treatments, the amount of SF in un-purified RB increased as the pressure increased from 0.3 and 0.6 MPa, which were 6.10±0.34 and 8.83±0.56%, respectively. Meanwhile, the highest SF fraction (35.2%) of purified RB was obtained from the SE treatment at 0.6 MPa. The SF produced from both treatments mainly contained oligosaccharides with MW <1 kDa, with those produced by the SE treatment generally smaller than those by the US treatment. Purification of RB significantly enhanced the efficiency of the US and SE treatments in breaking down the IF into the SF.

• Álvarez, C., González, A., Negro, M. J., Ballesteros, I., Oliva, J. M., & Sáez, F. (2017). Optimized use of hemicellulose within a biorefinery for processing high value-added xylooligosaccharides. Industrial Crops and Products, 99, 41–48. https://doi.org/10.1016/j.indcrop.2017.01.034

• Brodeur, G., Yau, E., Badal, K., Collier, J., Ramachandran, K. B., & Ramakrishnan, S. (2011). Chemical and physicochemical pretreatment of lignocellulosic biomass: A review. Enzyme Research, 2011, e787532. https://doi.org/10.4061/2011/787532

• Daou, C., & Zhang, H. (2012a). Oat beta-glucan: Its role in health promotion and prevention of diseases. Comprehensive Reviews in Food Science and Food Safety, 11(4), 355–365. https://doi.org/10.1111/j.1541-4337.2012.00189.x

• Daou, C., & Zhang, H. (2012b). Study on functional properties of physically modified dietary fibres derived from defatted rice bran. Journal of Agricultural Science, 4(9), 85–97. https://doi.org/10.5539/jas.v4n9p85

• Ebringerová, A., & Hromádková, Z. (2002). Effect of ultrasound on the extractibility of corn bran hemicelluloses. Ultrasonics Sonochemistry, 9(4), 225–229. https://doi.org/10.1016/S1350-4177(01)00124-9

• Ebringerová, A., & Hromádková, Z. (2010). An overview on the application of ultrasound in extraction, separation and purification of plant polysaccharides. Open Chemistry, 8(2), 243–257. https://doi.org/10.2478/s11532-010-0006-2

• Englyst, H. N., Quigley, M. E., Hudson, G. J., & Cummings, J. H. (1992). Determination of dietary fibre as non-starch polysaccharides by gas-liquid chomatography. Analyst, 117(11), 1707–1714. https://doi.org/10.1039/an9921701707

• Gong, L., Huang, L., & Zhang, Y. (2012). Effect of steam explosion treatment on barley bran phenolic compounds and antioxidant capacity. Journal of Agricultural and Food Chemistry, 60(29), 7177–7184. https://doi.org/10.1021/jf301599a

• Han, G., Deng, J., Zhang, S., Bicho, P., & Wu, Q. (2010). Effect of steam explosion treatment on characteristics of wheat straw. Industrial Crops and Products, 31(1), 28–33. https://doi.org/10.1016/j.indcrop.2009.08.003

• Hromádková, Z., & Ebringerová, A. (2003). Ultrasonic extraction of plant materials - Investigation of hemicellulose release from buckwheat hulls. Ultrasonics Sonochemistry, 10(3), 127–133. https://doi.org/10.1016/S1350-4177(03)00094-4

• Hu, R., Zhang, M., Adhikari, B., & Liu, Y. (2015). Effect of homogenization and ultrasonication on the physical properties of insoluble wheat bran fibres. International Agrophysics, 29, 423–432. https://doi.org/10.1515/intag-2015-0048

• Ismail, N. A., & Zhao, J. (2022). Effects of ultrasound and steam explosion treatments on the physicochemical properties of rice bran fibre. Pertanika Journal of Tropical Agricultural Science, 45(4), 893–918. https://doi.org/10.47836/pjtas.45.4.04

• Izydorczyk, M. S., & Biliaderis, C. G. (1995). Cereal arabinoxylans: Advances in structure and physicochemical properties. Carbohydrate Polymers, 28(1), 33–48. https://doi.org/10.1016/0144-8617(95)00077-1

• Jiang, S.-T., & Guo, N. (2016). The steam explosion pretreatment and enzymatic hydrolysis of wheat bran. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 38(2), 295–299. https://doi.org/10.1080/15567036.2012.744118

• Ma, J., Adler, L., Srzednicki, G., & Arcot, J. (2017). Quantitative determination of non-starch polysaccharides in foods using gas chromatography with flame ionization detection. Food Chemistry, 220, 100–107. https://doi.org/10.1016/j.foodchem.2016.09.206

• Ramos, L. P. (2003). The chemistry involved in the steam treatment of lignocellulosic materials. Quimica Nova, 26(6), 863–871. https://doi.org/10.1590/s0100-40422003000600015

• Sfalcin, P., Lunelli, F. C., Maleski, T. P. S., Foletto, V. S., Souza, M., Zimmermann, E., Prá, V. D., Foletto, E. L., Kuhn, R. C., & Mazutti, M. A. (2015). Glucose obtained from rice bran by ultrasound-assisted enzymatic hydrolysis. Ingeniería e Investigación, 35(2), 61–66. https://doi.org/10.15446/ing.investig.v35n2.49710

• Shibuya, N., & Iwasaki, T. (1985). Structural features of rice bran hemicellulose. Phytochemistry, 24(2), 285–289. https://doi.org/10.1016/S0031-9422(00)83538-4

• Shiiba, K., Yamada, H., Hara, H., Okada, K., & Nagao, S. (1993). Purification and characterization of arabinoxylan of two from wheat bran. Cereal Chemistry, 70(2), 209–214.

• Sun, R. C., & Tomkinson, J. (2002). Characterization of hemicelluloses obtained by classical and ultrasonically assisted extractions from wheat straw. Carbohydrate Polymers, 50(3), 263–271. https://doi.org/10.1016/S0144-8617(02)00037-1

• Truong, K. T. P., & Rumpagaporn, P. (2019). Oligosaccharides preparation from rice bran arabinoxylan by two different commercial endoxylanase enzymes. Journal of Nutritional Science and Vitaminology, 65, S171–S174. https://doi.org/10.3177/jnsv.65.S171

• Uraipong, C., & Zhao, J. (2016). Rice bran protein hydrolysates exhibit strong in vitro α-amylase, β-glucosidase and ACE-inhibition activities. Journal of the Science of Food and Agriculture, 96(4), 1101–1110. https://doi.org/10.1002/jsfa.7182

• Wang, J., Sun, B., Liu, Y., & Zhang, H. (2014). Optimisation of ultrasound-assisted enzymatic extraction of arabinoxylan from wheat bran. Food Chemistry, 150, 482–488. https://doi.org/10.1016/j.foodchem.2013.10.121

• Yilmaz, T., & Tavman, S. (2016). Ultrasound assisted extraction of polysaccharides from hazelnut skin. Food Science and Technology International, 22(2), 112–121. https://doi.org/10.1177/1082013215572415

• Ying, Z., Han, X., & Li, J. (2011). Ultrasound-assisted extraction of polysaccharides from mulberry leaves. Food Chemistry, 127(3), 1273–1279. https://doi.org/10.1016/j.foodchem.2011.01.083

• You, Q., Yin, X., & Ji, C. (2014). Pulsed counter-current ultrasound-assisted extraction and characterization of polysaccharides from Boletus edulis. Carbohydrate Polymers, 101(1), 379–385. https://doi.org/10.1016/j.carbpol.2013.09.031

• Zhang, L.-H., Li, D., Wang, L.-J., Wang, T.-P., Zhang, L., Chen, X. D., & Mao, Z.-H. (2008). Effect of steam explosion on biodegradation of lignin in wheat straw. Bioresource Technology, 99(17), 8512–8515. https://doi.org/10.1016/j.biortech.2008.03.028

• Zhang, L., Ye, X., Ding, T., Sun, X., Xu, Y., & Liu, D. (2013). Ultrasound effects on the degradation kinetics, structure and rheological properties of apple pectin. Ultrasonics Sonochemistry, 20(1), 222–231. https://doi.org/10.1016/j.ultsonch.2012.07.021