title: Enzymolysis reaction kinetics and thermodynamics of defatted wheat germ protein with ultrasonic pretreatment.
abstract: This research explores the mechanism of ultrasonic pretreatment on enzymolysis of defatted wheat germ protein (DWGP). The enzymolysis reaction kinetics and thermodynamics were studied after ultrasonic pretreatments using a probe-type sonicator and an ultrasonic cleaning bath, and the results were compared with traditional enzymolysis. The results showed that both the traditional and ultrasonic pretreated enzymolysis fit well to first-order kinetics. Both the temperature and ultrasound had a positive effect on the enzymolysis of DWGP, with temperature playing a dominant role. Under the optimized conditions of DWGP concentration of 1% (w/v), Alcalase concentration of 2000 U/g, time of 10 min and temperature of 50 °C, both the probe and cleaning bath ultrasonic pretreated enzymolysis showed high polypeptide concentrations (231.019 and 231.320 μg/mL) and low energy requirements. In comparison with traditional enzymolysis, these methods significantly increased the reaction rate constant (k) by 166.7% and 144.4%, 92.9% and 85.7%, 28.0% and 28.0%, 16.1% and 12.9% at 20, 30, 40 and 50 °C, and decreased the activation energy (Ea), enthalpy of activation (ΔH), Gibbs free energy of activation (ΔG) and entropy of activation (ΔS) by 68.6% and 62.4%, 74.1% and 67.5%, 34.3% and 31.2%, 1.4% and 1.3%. It can be concluded that ultrasonic pretreatment of DWGP can remarkably improve the enzymolysis efficiency and consequently leads to the production of higher polypeptide yield.
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.forename: Haile
authors.initials: H
authors.lastname: Ma
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Ronghai
authors.initials: R
authors.lastname: He
authors.forename: Zhongli
authors.initials: Z
authors.lastname: Pan
authors.forename: Ernest Ekow
authors.initials: EE
authors.lastname: Abano
mesh_terms: D007700:Kinetics; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D013381:Subtilisins / Q000737:chemistry / Q000378:metabolism*; D013816:Thermodynamics; D014908:Triticum / Q000737:chemistry / Q000378:metabolism*; D014465:Ultrasonics
chemical_list: D010940:Plant Proteins; D013381:Subtilisins