Effects and mechanism of dual-frequency power ultrasound on the molecular weight distribution of corn gluten meal hydrolysates

The impact of dual-frequency power ultrasound (DPU) on the molecular weight distribution (MWD) of corn gluten meal (CGM) hydrolysates and its mechanism were investigated in the present study. The mechanism was studied from aspects of structural and nano-mechanical characteristics of the major protein fractions of CGM, viz. zein and glutelin. The results of molecular weight distribution indicated that DPU pretreatment of CGM was beneficial to the preparation of peptides with molecular weights of 200-1000 Da. Moreover, FTIR spectral analysis and atomic force microscopy characterization showed that the DPU pretreatment changed the contents of secondary structure of proteins, decreased the particle height and surface roughness of glutelin, reduced the Young's modulus and stiffness of zein while increased its adhesion force. In conclusion, DPU pretreatment of proteins before proteolysis is an efficient alternative method to produce short-chain peptides because of its positive effects originating from acoustic cavitation on the molecular conformation, nano-structures and nano-mechanical properties of proteins as well.