To investigate the molecular mechanism of ultrasound-induced phenolic synthesis in fresh-cut fruits and vegetables, transcriptome sequencing and bioinformatics analyses were carried out on fresh-cut red cabbage washed with and without the assistance of ultrasound at different storage periods. The results showed that at the early storage stage (day 2), 1142 differentially expressed genes (DEGs) were identified between the control and treatment groups, of which 689 were up-regulated and 453 were down-regulated. At the late storage stage (day 6), 1166 DEGs were identified, with 480 of them being up-regulated genes and 686 being down-regulated. Bioinformatics analyses revealed that ultrasound significantly modulated metabolic pathways related to reactive oxygen species (ROS) metabolism, energy metabolism, signal transduction, and phenolic biosynthesis. It was further hypothesized that ultrasound washing disrupted ROS homeostasis in fresh-cut red cabbage, promoted ROS production and activated the ROS scavenging system during the initial storage period, thereby inducing phenolic synthesis. Ultrasonic stimulation may induce the expression of genes involved in the conversion of carbohydrate to phenolics by modulating the signal transduction system of fresh-cut red cabbage. Meanwhile, ultrasound washing enabled fresh-cut red cabbage to maintain high levels of energy charge during storage, thus providing energy for this series of reactions. In conclusion, this study provides a theoretical basis for further research on the molecular mechanism of phenolic biosynthesis in fresh-cut fruits and vegetables under ultrasound stress.

The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques. The combination of aspartic acid (D) and glutamic acid (E), or peptide fragments composed of arginine (R), constitute the characteristic taste structural basis of salty peptides of S. rugosoannulata. The taste intensity of the salty peptide positively correlates with its concentration within a specific concentration range (0.25–1.0 mg/mL). The receptor more easily recognizes the first amino acid residue at the N-terminal of salty peptides and the aspartic acid residue in the peptides. GLU513, ASP707, and VAL508 are the critical amino acid residues for the receptor to recognize salty peptides. TRPV1 is specifically the receptor for recognizing salty peptides. Hydrogen bonds and electrostatic interactions are the main driving forces for the interactions between salty peptides and TRPV1 receptors. KSWDDFFTR has the most potent binding capacity with the receptor and has tremendous potential for application in sodium salt substitution. This study confirmed the taste receptor that specifically recognizes salty peptides, analyzed the receptor-peptide binding interaction, and provided a new idea for understanding the taste receptor perception of salty peptides.