Effect of alkali concentration on digestibility and absorption characteristics of rice residue protein isolates and lysinoalanine

• Published in: Food chemistry Vol. 289; pp. 609 - 615
• Main Authors: Zhang, Zhaoli, Wang, Yang, Li, Yihe, Dai, Chunhua, Ding, Qingzhi, Hong, Chen, He, Yuanqing, He, Ronghai, Ma, Haile
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.08.2019
• Subjects: Absorption; Alkali concentration; alkali treatment; Amino acid release; arginine; cysteine; Digestibility; in vitro digestibility; intestinal absorption; lysine; Lysinoalanine (LAL); molecular weight; Molecular weight (MW); peptides; phenylalanine; protein isolates; rats; rice; Rice residue protein isolates (RPI); small intestine; sodium hydroxide; threonine; tyrosine; Amino acid release; RPIPs; RPI; MW; Molecular weight (MW); NRR; BSA; NPU; Rice residue protein isolates (RPI); RPIPTs; Alkali concentration; Absorption; LAL; Lysinoalanine (LAL); HPLC; Digestibility
• ISSN: 0308-8146; 1873-7072; 1873-7072
• DOI: 10.1016/j.foodchem.2019.03.085

•As NaOH exceeded 0.03 M, in vitro digestibility of rice protein isolates decreased.•There was a release in lysinoalanine with 2.65–9.28% via in vitro digestibility.•The high alkali concentration reduced the absorption rate of rice protein isolates.•Lysinoalanine was not available for intestinal absorption. The effect of alkali concentration on the digestibility and absorption characteristics of rice residue protein isolates (RPI) and lysinoalanine (LAL) was studied. When NaOH concentration was 0.03 M, the in vitro digestibility of RPI reached a maximum, and when NaOH concentration was higher than 0.03 M, the in vitro digestibility decreased. Alkali treatment reduced the release of all amino acids, especially arginine, lysine, phenylalanine, tyrosine, cysteine, and threonine. LAL only released 2.65–9.28% of the total LAL content, which was mainly combined with longer peptide chains, and the molecular weight was mostly accumulated between 1000 Da and 3000 Da. The experimental model of rats in the small intestine perfusion showed that the high alkali concentration significantly reduced the absorption rate of RPI, and LAL had no specific absorption site in the small intestine of rats, and was not available for intestinal absorption.