title: Binding of tea catechins to rice bran protein isolate: Interaction and protective effect during in vitro digestion.
abstract: Rice bran protein isolate (RBPI) was prepared from defatted rice bran and used to deliver tea catechins. RBPI had the high adsorption selectivity for tea catechins over caffeine. The adsorption characteristics of tea catechins onto RBPI were determined over a range of time (0-300min), concentration (0.25-3.5gL-1) and temperatures (5°C, 20°C and 35°C). The adsorption kinetic data of EGCg and total catechins (TC) onto RBPI showed excellent fitness with the pseudo-second-order model, indicating that chemisorption is the dominating process. Langmuir and Freundlich models adequately described the isothermal adsorption of tea catechins onto RBPI, and the maximum adsorption of EGCg and TC were achieved at 5°C. SDS-PAGE profiles indicated that globulin and albumin were the major soluble proteins in RBPI to bind tea catechins. Fourier transforms infrared spectroscopy analysis showed that the protein secondary structures of RBPI were altered upon interaction with catechins, with a great increase in random coil and β-antiparallel, a minor increase in α-helix and a reduction in large loop and turn. Binding tea catechins to RBPI respectively increased the recovery% of EGCg and TC from 10.5% and 17.7% to 29.5% and 31.6% after in vitro intestinal digestion. Thus, RBPI is a promising food matrix for delivering tea catechins to gastrointestinal tract.
authors.affiliation: Zhejiang University Tea Research Institute, Hangzhou 310058, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Shi
authors.affiliation: Zhejiang University Tea Research Institute, Hangzhou 310058, China.
authors.forename: Long-Yue
authors.initials: LY
authors.lastname: Huang
authors.affiliation: Zhejiang University Tea Research Institute, Hangzhou 310058, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Nie
authors.affiliation: Zhejiang University Tea Research Institute, Hangzhou 310058, China.. Electronic address: jx0515@163.com.
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Ye
authors.affiliation: Zhejiang University Tea Research Institute, Hangzhou 310058, China.
authors.forename: Xin-Qiang
authors.initials: XQ
authors.lastname: Zheng
authors.affiliation: Zhejiang University Tea Research Institute, Hangzhou 310058, China.
authors.forename: Jian-Liang
authors.initials: JL
authors.lastname: Lu
authors.affiliation: Zhejiang University Tea Research Institute, Hangzhou 310058, China.
authors.forename: Yue-Rong
authors.initials: YR
authors.lastname: Liang
mesh_terms: D000327:Adsorption; D055592:Biophysical Phenomena; D002110:Caffeine / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives / Q000378:metabolism*; D004063:Digestion; D041981:Gastrointestinal Tract / Q000378:metabolism; D007700:Kinetics; D012275:Oryza / Q000737:chemistry*; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism*; D012639:Seeds / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D010940:Plant Proteins; D002110:Caffeine; D002392:Catechin; C045651:epigallocatechin gallate
keywords: Adsorption; Catechins; Food matrix; Gastrointestinal digestion simulation; Protein secondary structure; Rice bran protein isolate