Ultrasound Pretreatment Increases the Bioavailability of Dietary Proteins by Dissociating Protein Structure and Composition

Abstract

Bioavailability is an important indicator for evaluating the nutritional value of protein. In this study, we investigated the effect of ultrasound on improving the bioavailability of daily-consumed dietary proteins (rice, oat, corn, and soy protein). The results indicated that there was a significant difference (P < 0.05) in in vitro simulation digestibility between the ultrasound pretreatment group and the control (without ultrasound pretreatment) group. After ultrasound pretreatment, the digestibility of four proteins increased 9.49% (rice), 9.97% (oat), 8.19% (corn), and 9.84% (soy), respectively. There was a significant difference (P < 0.01) in Caco-2 cell model absorption between the ultrasound pretreatment group and the control group. After ultrasound pretreatment, the Caco-2 cell model absorption increased 5.59% (rice), 4.16% (oat), 8.78% (corn), and 18.69% (soy), respectively. The results of CD (Circular Dichroism) and fluorescence spectroscopy indicated that ultrasound pretreatment changed the protein’s secondary structures and tertiary structure, and more hydrophobic residues were exposed. The results of molecular weight distribution indicated that ultrasound increased the content of 200–1000 Da peptides. The conclusion is that ultrasound pretreatment can effectively improve the bioavailability of these dietary proteins by changing protein structure and composition.