Influence of ultrasound pretreatment on enzymolysis kinetics and thermodynamics of sodium hydroxide extracted proteins from tea residue

Abstract

The effect of ultrasound pretreatment using Single Frequency Counter Current Ultrasound (SFCCU) on the enzymolysis of tea residue protein (TRP) extracted with sodium hydroxide was investigated. The concentration of TRP hydrolysate, enzymolysis kinetics and thermodynamic parameters after SFCCU pretreatment were determined and compared with traditional enzymolysis. The results indicated that both ultrasound assisted and traditional enzymolysis conformed to first-order kinetics within the limits of the studied parameters. Temperature and sonication had affirmative effect on the enzymolysis of TRP with temperature yielding greater impact. Michaelis constant ( ) in ultrasonic pretreated enzymolysis decreased by 32.7% over the traditional enzymolysis. The highest polypeptide concentration of 24.12 mg ml was obtained with the lowest energy requirement at improved conditions of 50 g L of TRP, alcalase concentration of 2000 U g, time of 10 min and temperature of 50 °C for the ultrasonic treated enzymolysis. The values of reaction rate constant () for TRP enzymolysis increased by 78, 40, 82 and 60% at 20, 30, 40 and 50 °C, respectively. The thermodynamic properties comprising activation energy (), change in enthalpy ) and entropy) were reduced by ultrasound pretreatment whereas Gibbs free energy ) was increased.

Enzymolysis of walnut ( Juglans regia L.) meal protein: Ultrasonication‐assisted alkaline pretreatment impact on kinetics and thermodynamics

“…Largely, the protein digests accumulation in the control and MFSU‐assisted alkaline pretreated hydrolysates progressively increased as substrate concentration and temperature increased with increasing hydrolysis time. These phenomena have previously been reported (Abdualrahman et al, ; Ayim et al, ; Jia et al, ; Zhang et al, ; Zou et al, ). Elevated temperatures have been reported to be detrimental to enzymes and produce a negative effect on hydrolysis processes (Benjakul & Morrissey, ), hence, in this study 313 K maximum was used.…”

“…The nutritional value of plant protein from industrial by‐products has been improved (having a higher solubility) through enzymolysis and more efficiently by application of ultrasound pretreatment to the proteins hitherto were less soluble (Ayim et al, ; Jin, Ma, Qu, et al, ; Qu et al, ; Zhang et al, ). The protein digest (hydrolysate) concentration is a measure of the solubility of protein during enzymolysis (Cheng et al, ).…”

“…Ultrasound technology has been explored as an eco‐friendly and green processing technology requiring no toxic chemical application (Bermúdez‐Aguirre, Mobbs, & Barbosa‐Cánovas, ; Malomo, Onuh, Girgih, & Aluko, ; Uluko et al, ). Several researchers have proven the valuable influence of ultrasonic pretreatment on either extraction, structural, functional, or enzymatic hydrolysis efficiency of food materials like corn gluten meal, rice protein, tea residue, garlic powder, sunflower meal, and rapeseed protein (Ayim, Ma, Alenyorege, Ali, & Donkor, ; Dabbour et al, ; Jin, Ma, Qu, et al, ; Jin, Ma, Wang, et al, ; Jin et al, ; Li et al, ; Ma, Huang, Peng, Wang, & Yang, ; Yagoub, Ma, & Zhou, ). The improved enzymolysis parameters such as the initial rate of reaction ( k ) and energy (enthalpy, entropy, and Gibbs free energy) efficiency were accredited to the impact of ultrasonication (Dabbour et al, ; Uluko et al, ).…”

“…Ultrasound technology has been highly acknowledged to induce structural changes in food material under treatment before enzymolysis. It causes a rapid collision between enzyme and substrates resulting in an upsurge in the rate of enzymolysis with a resultant decrease in thermodynamic parameters with emphasis on activation energy ( E a ) and Gibbs free energy ( G ) (Ayim et al, ; Dabbour et al, ; Jin, Ma, Qu, et al, ; Qu et al, ). Additionally, ultrasound treatment causes a shift of the ultra‐violet visible light absorption and fluorescence emission due to the structure disorganization of proteins.…”

“…The principles underpinning this phenomenon are its thermal (pressure, high temperature) and mechanical (shear forces, shock waves, turbulence) effects produced via cavitation resulting in the improved mass transfer, with improved enzyme and substrate collision rate (Ren, Ma, Mao, & Zhou, ; Zhang et al, ; Zhou et al, ). Also, Mono‐frequency ultrasonication has been applied solely or in combination with alkaline pretreatment in improving the enzymolysis of various food materials, including sugarcane bagasse (Velmurugan & Muthukumar, ), garlic powder (Ma et al, ), wheat gluten (Zhang et al, ), tea residue protein (Ayim et al, ), sodium caseinate (NaCas) (Abdualrahman et al, ), and rice protein (Li et al, ) with positive results. Yet, no or little exploration has been documented on the mechanism and influence of mono‐frequency ultrasound‐assisted alkaline pretreatment on the enzymolysis efficacy relating to the kinetic and thermodynamic mechanisms of WMP.…”