Modification of fermented whey protein concentrates: Impact of sequential ultrasound and TGase cross-linking

This study aimed to examine the impact of fermentation process on whey protein and improve the general properties of fermented whey protein concentrate (FWPC) recovered by a combined ultrafiltration-diafiltration (UF-DF) operation. Impacts of sequential ultrasound (US) pretreatment and transglutaminase (TGase) cross -linking on structural, functional, and physicochemical properties of FWPCs were investigated. Partially dena-tured and hydrolyzed fermented whey protein could replace heat denaturation prior to the TGase addition to a whey protein system. Sequential treatment increased the molecular weight of FWPCs as exhibited by both SEM and SDS-PAGE, which demonstrates that modification can lead to the polymers and oligomers production. The zeta potential value increased significantly after US treatment and enzyme catalysis, and all the modified FWPCs were strongly negatively charged. Compared with the secondary structure of untreated FWPCs, the percentage of alpha-helix and random coil in modified FWPCs significantly increased, while the percentage of beta-sheet and beta-turns reduced. Solubility, free sulfhydryl groups, and surface hydrophobicity of all FWPCs were significantly improved compared to non-fermented WPC (P < 0.05). Sequential treatment induced a substantial impact on the emul-sifying activity and stability of modified samples in comparison with untreated FWPCs. Scanning electron mi-croscope pictures confirmed the positive effects of sequential treatments on texture and void size reduction. Therefore, the application of recovering modified FWPCs is fully recommended as a commercially viable approach for enhanced protein production at the industrial scale.

Automated summary

The study aimed to investigate the impact of fermentation process on whey protein and improve the properties of fermented whey protein concentrate (FWPC) recovered by ultrafiltration-diafiltration operation. The effects of ultrasound pretreatment and transglutaminase cross-linking on the structural, functional, and physicochemical properties of FWPCs were examined. The sequential treatments resulted in increased molecular weight, improved zeta potential, enhanced solubility, and improved emulsifying activity and stability of FWPCs.