Summary In this study, the ultrafine grinding (UG) and high pressure homogenization (HPH) treated slurry on the particle size and rheological property of slurry, texture, in vitro starch digestibility, and multiscale structure of steamed rice bread (SRB) were investigated. Then, it was found that the average particle size of slurry treated by UG and HPH reduced from 84.6 to 38.6 μm and 22.6 μm, respectively. The rheological properties results demonstrated that G′ resulted in higher values than G″, and that the values of G′, G″ and tan δ of slurry decreased obviously after UG and HPH treatment. Obviously, the hardness and viscidity of SRB made by UG and HPH were lower, while the elasticity and specific volume were higher. The determination of in vitro starch digestibility revealed that UG treated on slurry accelerated the starch hydrolysis rate of SRB, resulting in an increase in the pGI from 76.17 to 79.36, while HPH treatment reduced the pGI from 76.17 to 73.49. Furthermore, XRD and FTIR demonstrated that both UG and HPH increased the intermolecular hydrogen bonds, and both treatments also assisted in starch arrangement for increasing the ordered crystallization of starch, which may contribute to the increasing amylose content.
Yu Chen,Qingxuan Fu,Weiping Jin,Wangyang Shen,Jinling Li
In this study, micro-cellulose (15–250 μm) was selected as fillers to replace rice flour for the preparation of steamed rice bread, a type of traditional gluten-free bread in China. The effects of particle size, surface charge, and hydrophobicity on the textural properties of the steamed rice bread were investigated. The results showed that the 2 % substitution of rice flour with micro-cellulose significantly increased the chewiness of the steamed rice bread. The particle size of micro-cellulose was positively correlated with hardness and negatively correlated with specific volume. The surface charge of micro-cellulose was positively correlated with crumb structure and negatively correlated with springiness, cohesiveness, and resilience. When the micro-cellulose content ranged from 3 to 5 %, the steamed rice bread achieved optimal quality, and the specific volume was improved from 1.62 mL/g to 1.83–1.87 mL/g. Notably, micro-cellulose with a size of 15 μm served as an active filler for rice paste and significantly increased its viscosity, enhancing gas retention capacity. At a high concentration (5–7 %), all the micro-celluloses acted as active fillers in starch gel, increasing the Young’s modulus. This study provides an effective method for improving the quality of gluten-free bread through the addition of colloidal particles.
Starch structure and digestibility strongly depends on food composition during rice bread processing. This study investigates the effect of okara (0%, 7%, 14%, 21%) on the texture, in vitro starch digestibility, and multiscale structure (i.e. granule, crystallites, and short-range order) of steamed rice bread (SRB). Texture profile analysis results demonstrated that okara increased the elasticity and viscidity and reduced the hardness, cohesiveness, and chewiness of SRB. The addition of okara increased amylose content, slowly digestible starch (SDS), and resistant starch (RS) of SRB significantly, thereby reducing the predicted glycemic index (pGI) from 79.14 to 74.17–68.91. Meanwhile, SEM results showed that addition of 7% okara promoted the formation of the porous space starch–gel network structure in the SRB while 21% okara produced rougher surfaces and increased bread matrix density. XRD and FTIR revealed that suitable amounts of okara (<14%) assisted in starch arrangement while others (21%) reduced the ordered crystallization of starch. Results showed that the enhanced intermolecular hydrogen bonding between okara and water enhanced the viscosity and gas retention of SRB, thereby enabling the starch to retain more gas and form a loose starch gel structure spatial network. Furthermore, the addition of okara changed the multiscale structural and amylose contents when the SDS and RS contents are high and the pGI is low. As a result, the action sites of amylase can be shielded effectively to restrict the interaction of amylase with starch. Thus, this research suggests a potential approach in which rice complexed with okara can modify the texture and starch digestibility of SRB.
危险品化学品经营许可证（带存储）