Structural characterization of a tetrapeptide from Sesame flavor-type Baijiu and its interactions with aroma compounds.

Abstract The small molecules in Chinese Baijiu have been widely reported, but there is little information on peptides since their low concentrations. A tetrapeptide, Asp-Arg-Ala-Arg (DRAR), was newly identified from Jingzhi Sesame flavor-type Baijiu (SFTB) by high-performance liquid chromatography and quadrupole-time-of-flight-mass spectrometry (HPLC-Q-TOF-MS) with a concentration of 13.159 ± 0.202 μg/L (P > 0.05). Interactions between DRAR and volatile compounds were characterized using headspace solid-phase micro-extraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC–MS), and the results indicated that DRAR could suppress the volatility of aroma compounds by 0.09–39.02 %, especially with respect to esters and alcohols. The involved binding modes of DRAR with esters or alcohols in 46% ethanol/water solutions (v/v) were respectively determined by ultraviolet (UV) absorption spectroscopy. According to the Van't Hoff equation, the thermodynamic parameters (for DRAR - esters complex, ΔH = −34.7 KJ mol−1, ΔS = −66.4 J mol−1 K−1 and for DRAR - alcohols complex, ΔH = −40.8 KJ mol−1, ΔS = −91.8 J mol−1 K−1) indicated that hydrogen bonds and van der Waals forces played major roles in stabilizing the DRAR-esters and DRAR-alcohols complexes. This study will help us to further understand the interaction mechanisms between aroma compounds and peptides, and the important role of peptides on the quality of Chinese Baijiu. Graphical abstract DRAR identified from Chinese Sesame flavor-type Baijiu selectively effect the aroma. Unlabelled Image Highlights • A new tetrapeptide (Asp-Arg-Ala-Arg, DRAR) was separated from Jingzhi Baijiu. • The chemical structure of DRAR was characterized with HPLC-Q-TOF-MS. • Hydrogen bonds and van der Waals forces play major roles in stabilizing the DRAR-esters and DRAR-alcohols complexes. [ABSTRACT FROM AUTHOR]