Unraveling novel umami peptides in beef liver and tendon using high intensity ultrasound and sequential enzymatic hydrolysis: A peptidomics and machine learning approach

The combined effect of high-intensity ultrasound (HIUS) and sequential enzymatic hydrolysis on the umami peptides in beef byproducts is still undiscovered. Therefore, novel umami peptides in the Angus beef livers and tendons were explored by combining HIUS treatment with commercial flavor-generating enzymes. Specifically, the impact of low or high ultrasonication amplitude together with two novel enzyme combinations (Vertera Essence followed by Vertera Flavor or Vertera Savory) on the degree of hydrolysis, molecular structure, and sensory characteristics of the hydrolysates were investigated. Fourier transform infrared spectroscopy results demonstrated the increase in α-helix and decrease in β-turns in both liver hydrolysates and tendon hydrolysates prepared using high amplitude ultrasonication, irrespective of the enzyme combinations. The Nano LC-Q-TOF-MS/MS and electronic tongue evidenced that utilizing low amplitude ultrasonication along with Vertera Essence and Vertera Savory could result in the formation of novel umami peptides in liver and tendon hydrolysates. Parallely, deep learning models (UmamiPreDL and Umami-MRNN) predicted the novel umami peptides in both liver and tendon hydrolysates subjected to low amplitude ultrasonication and exhibited good correlation with the peptidomics and electronic tongue results. Moreover, molecular docking exposed that the key bindings sites of the umami peptides, including the Ser50, Gln 280, and Gly40 in T1R1 subunit, and Asn70, Arg248, and Ser62 in T1R3 subunit. Overall, this study indicates that performing HIUS at low amplitude along with utilizing Vertera Essence and Vertera Savory could result in flavor hydrolysates with umami- and umami enhancing effects.