title: Effects of ultrasound and ultrasound assisted alkaline pretreatments on the enzymolysis and structural characteristics of rice protein.
abstract: The objectives of this study were to investigate the effects of multi-frequency energy-gathered ultrasound (MFEGU) and MFEGU assisted alkaline pretreatments on the enzymolysis and the mechanism of two pretreatments accelerating the rice protein (RP) proteolysis process. The results showed that MFEGU and MFEGU assisted alkaline pretreatments improved significantly (P<0.05) the degree of hydrolysis (DH) and the protein elution amount of RP. Furthermore under the same DH conditions, ultrasound and ultrasound assisted alkaline pretreatments were more save the enzymolysis time than the unpretreatment. The changes in UV-vis spectra, fluorescence emission spectra indicated unfolding and destruction of RP by MFEGU and MFEGU assisted alkaline pretreatments. The circular dichroism analysis showed that both pretreatments decreased α-helix but increased β-sheet and random coil of RP. Amino acid composition revealed that MFEGU and MFEGU assisted alkaline pretreatments could increase the protein elution amount and the ratio of hydrophobic amino acids. Atomic force microscopy (AFM) indicated that both pretreatments destroyed the microstructures and reduced the particle size of RP. Therefore, MFEGU and MFEGU assisted alkaline pretreatments are beneficial to improving the degree of hydrolysis due to its sonochemistry effect on the molecular conformation as well as on the microstructure of protein.
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China; School of Food and Biological Engineering, Zhengzhou University of Light Industry, 5 Dongfeng Road, Zhengzhou, Henan 450002, China; Collaborative Innovation Center for Food Production and Safety, Henan Province, 5 Dongfeng Road, Zhengzhou, Henan 450002, China.
authors.forename: Suyun
authors.initials: S
authors.lastname: Li
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Yang
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China. Electronic address: mhl@ujs.edu.cn.
authors.forename: Haile
authors.initials: H
authors.lastname: Ma
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
authors.forename: Qiufang
authors.initials: Q
authors.lastname: Liang
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Qu
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
authors.forename: Ronghai
authors.initials: R
authors.lastname: He
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
authors.forename: Cunshan
authors.initials: C
authors.lastname: Zhou
authors.affiliation: School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang, Jiangsu 212013, China.
authors.forename: Gustav Komla
authors.initials: GK
authors.lastname: Mahunu
mesh_terms: D000468:Alkalies / Q000737:chemistry*; D002942:Circular Dichroism; D012275:Oryza / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry*; D059748:Proteolysis; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014465:Ultrasonics
chemical_list: D000468:Alkalies; D010940:Plant Proteins
keywords: Enzymatic hydrolysis; Multi-frequency energy-gathered ultrasound; Rice protein; Ultrasound assisted alkaline pretreatments