Effects of Ultrasonic-Assisted Extraction on the Physicochemical Properties of Different Walnut Proteins

Abstract

The effects of ultrasonic-assisted extraction (UAE, 200 W, 20 min) on the yield and physicochemical properties of different walnut proteins (WNPs, including albumin, globulin, and glutelin) were investigated. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated that UAE could result in protein molecular fragmentation of albumin, but did not affect the major bands of globulin and glutelin. The CD spectra demonstrated that different WNPs obtained by UAE had different changes in their secondary structure. Under UAE, there was an increase in surface hydrophobicity (H0) of albumin and gluten and no change in the fluorescence intensity, while decreases were observed in the H0 and fluorescence intensity of globulin; and the contents of total and surface free sulfhydryl in albumin dramatically decreased. UAE reduced the size of the particles and the dimension of the microstructures in albumin and gluten, indicating that ultrasound could unfold protein aggregates. In addition, UAE increased the solubility, emulsifying activity (EA), foaming capacity (FC), and foam stability (FS) of the obtained proteins. The above results indicate that ultrasound extraction is a promising approach to improve the extraction yield and properties of walnut proteins.

Elucidation of Antioxidant Compounds in Moroccan Chamaerops humilis L. Fruits by GC–MS and HPLC–MS Techniques

“…A value of 0.6 ± 0.0 mg/g was attained for the MeOH-H 2 O extract, whereas they were absent in the EtOAc fraction. The low levels of protein content can be caused by the ultrasonic extraction, which leads to protein denaturation, as proven by some researchers [ 22 ].…”

Ultrasound‐microwave assisted extraction of proteins from Moringa oleifera leaves: Comparative optimization study and LC‐MS analysis of the protein concentrate

“…oleifera leaves than conventional solvent extraction. The shear force and cavitation effect produced by ultrasonic can destroy the plant cell membrane, increase the contact surface with the solvent, and cause protein fragmentation (Lv et al., 2019). Also, microwaves generate heat inside the material, which contribute to a quick heating in less time compared to the traditional heating methods, thereby disrupting the cells and facilitate release the protein inside the cell wall into the solvent (Djilani et al., 2006).…”

“…Nevertheless, when microwave power exceeded a certain value, the high microwave energy would disturb the interactions of molecular (Xu et al., 2018) and led to partial protein denaturation. Likewise, higher temperature or longer irradiation time for ultrasound and microwave extraction will destabilize the aqueous envelope of the proteins, destroy the hydrogen bond and structure of the protein, which could accelerate protein denaturation and precipitation, thus made the leaf protein solubility worse (Lv et al., 2019). Also, large amount of solvent can result in insufficient energy diffusion in the reaction field, thereby hindering cell rupture and protein dissolution.…”

Bioactive Peptides from Walnut Residue Protein

“…The natural walnut protein has a compact stereostructure, and most of its cleavage sites are contained in the protein, which makes it difficult to be hydrolyzed by protease. In order to solve this problem, Lv et al [27] and Li et al [28] studied the effect of ultrasonic assistance on the enzymatic hydrolysis of walnut residue. The results showed that ultrasonic-assisted hydrolysis of walnut protein had a positive effect on the reaction characteristics and energy efficiency.…”