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

Abstract

To improve the utility of walnut meal protein, influences of ultrasonication on the kinetic and thermodynamic constraints of enzyme (trypsin) hydrolysis were assessed using a multi‐frequency counter current S‐type ultrasound machine. Results revealed that both the ultrasonication treatment and control hydrolysis obeyed the first‐order kinetics within the study constraints. After 90 min hydrolysis time, the uppermost percentage conversion rate (57.5%) of substrate to product and the percentage increase (25.42%) in hydrolyzed protein concentration were obtained at 323 K and 10% substrate concentration, respectively. The Michaelis constant (KM) in ultrasonic enzymolysis declined by 58.66% over the control. The reaction rate coefficient (k) for the proteolysis improved by 84.75%, 52.43%, 48.25%, and 37.79% at 219, 303, 313, and 323 K, correspondingly. Generally, the bond energy (Ea), enthalpy change (ΔH), entropy change (ΔS), and Gibbs free energy (ΔG) were reduced by the ultrasound pretreatment with 36.61%, 28.05%, 18.22%, and 5.24%, respectively. Practical applications Walnut meal protein has a well‐balanced amino acid profile and its economic utilization could be increased practicably as a food ingredient via production of hydrolysates/peptides for the production of improved food ingredients instead of being cast off as animal feed. This study demonstrated a positive bearing of ultrasonication‐assisted alkaline pretreatment on proteolytic reaction characteristics and its energy efficiency for walnut meal protein, which makes this technique applicable to the enhancement of plant proteins for inclusion in food products, especially tree nut and oil seed waste products from the oil industry.

Ultrasound-assisted alkaline proteinase extraction enhances the yield of pecan protein and modifies its functional properties

“…Therefore, the acceleration of protein extraction was connected with the changes of protein microstructure induced by ultrasound. And this effect was also observed in ultrasound-assisted treatment systems involving walnut protein [42] . Microstructure influenced the chemical and physical properties, and functionality of the protein.…”

Ultrasonication as an innovative approach to tailor the apple seed proteins into nanosize: Effect on protein structural and functional properties

“…Jambrak et al [33] reported same trend of foaming properties for ultrasonically treated soy protein and wheat gluten [34] . The increase in surface hydrophobicity values may also be responsible for improving the foaming capacity and stability which might be due to the exposure of hydrophobic groups to accelerated adsorption at the gas/water interface [35] .…”

Effect of multi‐frequency countercurrent ultrasound treatment on extraction optimization, functional and structural properties of protein isolates from Walnut (Juglans regiaL.) meal

“…The mechanical and shear force produced during ultrasound cavitation opens up the protein structure resulting in the molecular unfolding via peptide bond disruption (Ren, Zhang, Liang, Hou, & Zhou, 2017). These increased surface area coupled with tissue porosity, loosening/sponginess and unfolded protein structure could prove beneficial in further processing and subsequent increase in the bioactivity of the WMPs via peptide production (Golly et al, 2019).…”

“…The multi‐frequency countercurrent S‐type ultrasound apparatus (MFSU) (WKS 300/6S) employed in this study was developed by our research group in Jiangsu University and produced by Jiangsu Jiangda Wukesong Biotechnology Co., Ltd., China. This equipment has been fully described in our previous work (Golly et al, 2019). The device is equipped with five distinct frequencies; 20, 28, 35, 40, and 52 kHz and powered from five ultrasonic generators.…”

“…The UAE process was in similitude with the traditional method, but with ultrasonic treatment. The ultrasound treatment was performed as described in our previous work (Golly et al, 2019). Single, double and triple frequency combinations were used in the ultrasound treatment.…”