Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt Short communication High-speed shearing of soybean flour suspension disintegrates the component cell layers and modifies the hydration properties of okara fibers Chenzhi Wang a,1 , Lin Li a,1 , Xin Sun a , Wen Qin a , Dingtao Wu a , Bin Hu a , Dele Raheem b , Wenyu Yang c , Hongmin Dong d , Thava Vasanthan d , Qing Zhang a, ⁎ a College of Food Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya'an, 625014, Sichuan, China b Northern Institute for Environmental and Minority Law (NIEM), Arctic Centre, University of Lapland, Rovaniemi, 96101, Finland c Key Laboratory of Crop Ecophysiology and Farming System in Southwest, Ministry of Agriculture/Sichuan Engineering Research Center for Crop Strip Intercropping System, Chengdu, 611130, Sichuan, China d Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada ARTICLE INFO Keywords: X-ray diffraction Crystal structure Cell wall Cellulose Solubility ABSTRACT This study evaluated the feasibility of high-speed shearing (HSS) on the modification of okara fibers. Scanning electron microscope analysis suggested that HSS disintegrated and degraded the component cell layers at the cellular level. X-ray diffraction analysis showed that the reflection intensity of crystalline plane (I 002 ) and the amorphous contribution (I AM ) declined after HSS, confirming that the degradation of okara fibers was accom- panied with the disintegration of crystalline as well as amorphous area. Moreover, the reflection intensity of cellulose's triclinic structure went up after HSS, which might be attributed to the breakdown of β-1, 4-glycoside bond. The swelling capacity and water holding capacity extensively declined (p < 0.05) from 5.5 mL/g and 8.5 g/g to 2.2 mL/g and 4.9 g/g after shearing, which was caused by the degradation of porous structure and the decrease of pore volume. HSS empowered okara fiber better solubility as well, and it might be achieved by breaking the cellulose-cellulose hydrogen bonds and redistributing the fiber composition from the insoluble to the soluble fraction. Consequently, HSS provided a cost-efficient way to disintegrate substrates and modify hydration properties of okara fiber, which possessed considerable application prospects in soy industry. 1. Introduction As a main byproduct in soy industry, okara (soybean residue) is usually removed due to its coarse particle size and adverse effect on sensory properties of soy products (Aravind, Sissons, Fellows, Blazek, & Gilbert, 2012). Nevertheless, okara is also regarded as a crucial resource of nutrients which contains about 500 g/kg of dietary fiber and 200 g/ kg of protein (in dry weight), plus considerable isoflavone, oligo- saccharides, saponin, minerals and other functional ingredients (Li et al., 2019; Mateos-Aparicio, Mateos-Peinado, Jiménez-Escrig, & Rupérez, 2010a; Vong & Liu, 2016). However, the use of okara, whose dominant fraction is insoluble dietary fibers, is difficult for its poor solubility and rough texture (O'Toole, 1999). Existing studies that centre on the modification of okara fibers mainly take three types of ways namely, physical, chemical, and enzymatic methods (Chau, Wang, & Wen, 2007; Kasai, Murata, Inui, Sakamoto, & Kahn, 2004; Mateos- Aparicio, Mateos-Peinado, & Rupérez, 2010b), of which physical methods are proved to be economical (compared with enzymatic methods), eco-friendly (compared with chemical methods) and effec- tive (Paakko et al., 2007). Being one of the physical methods, high- speed shearing (HSS) allows materials to be cut, compressed and folded in a shear gap by the strong shearing, dispersing, impacting, and tur- bulent flow. Consequently, materials are well micronized, emulsified, mixed and homogenized in a short time. Based on above advantages, HSS has been successfully applied in food industry for the degradation of chitosan, disaggregation of pectin and structural modification of tomato fibers (Chen et al., 2014; Hua et al., 2017; Rong, Jin, Min, Lan, & Chu, 2011). In China, soybean product industry produces about 280 million tons of okara every year (Li, Qiao, & Lu, 2012) but most of them are pro- cessed into animal fodders or directly discarded. Commercial HSS equipment possesses advantages in energy-saving and effectiveness. Thus, it could be considered a potential technology to micronize the particle and enhance hydration properties of okara fibers. https://doi.org/10.1016/j.lwt.2019.108505 Received 24 April 2019; Received in revised form 8 August 2019; Accepted 10 August 2019 ⁎ Corresponding author. College of Food Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya'an, 625014, Sichuan province, China. E-mail address: zhangqing@sicau.edu.cn (Q. Zhang). 1 Author contribution statement: Chenzhi Wang and Lin Li contributed equally to this study. LWT - Food Science and Technology 116 (2019) 108505 Available online 11 August 2019 0023-6438/ © 2019 Published by Elsevier Ltd. T