Improvement of Ultrasound-Assisted Enzymatic Treatment and Exogenous Amino Acids on Structural, Antioxidant, and Instrumental Taste Profile of Maillard Reaction Products from Potato Protein Hydrolysates.

Potato protein hydrolysates (PPHs) produced by ultrasound-assisted enzymatic hydrolysis exhibit strong antioxidant activity. However, their inherent bitterness limits their application in food sectors. Therefore, this research investigated the effects of energy-divergent ultrasound (EDU)- and energy-gathered ultrasound (EGU)-assisted enzymatic treatment and exogenous amino acids (alanine (Ala), phenylalanine (Phe), and valine (Val)) on the peptide structure, antioxidant activity, and instrumental taste profile of Maillard reaction products (MRPs) prepared from PPHs. It was found that EDU and EGU significantly promoted the progress of the Maillard reaction (MR). All MRPs presented remarkable changes in the peptide structure compared to their PPH counterparts. Under the equal-mass addition of exogenous amino acids, MRPs from EDU with Ala at 120 min (EDU-Ala-120) presented the highest percentage of molecular weight (MW) <2 kDa fractions (68.55%), and a markedly improved oxygen radical absorption capacity value of 108.44 µg Trolox equivalent (TE)/mL. MRPs from EDU revealed significantly stronger umami taste and lower bitterness, while MRPs from EGU exhibited stronger sweetness. The umami taste of the MRPs was strongly negatively correlated with bitterness (-0.9517, p < 0.001) and positively correlated with esters (0.7293, p < 0.01), whereas the sweetness of the MRPs was positively associated with specific volatile components but negatively correlated with <1 kDa peptides (-0.6039, p < 0.05). Thus, the EDU-assisted enzymatic treatment and MR with the addition of appropriate exogenous amino acids could be a prospective way to produce natural flavor with enhanced antioxidant activity.