Influence of amino acids, and their interaction with volatiles and polyphenols, on the sensory properties of red wine

<p><b>Background and Aims</b> The effect of amino acids, and their interactions with volatiles and other non-volatiles, on in-mouth sensory properties of red wines is not known. This knowledge gap has been studied in a series of comprehensive sensory experiments.</p> <p><b>Methods and Results</b> A solvent-assisted flavour evaporation extract of Shiraz wine volatiles, a de-aromatised polyphenolic extract and amino acids were added to model wine and wine systems. Using full factorial designs, samples were evaluated by sensory quantitative descriptive analysis. Volatiles enhanced Viscous mouthfeel (<i>F</i> = 20.0, <i>P</i> < 0.001), Sweetness (<i>F</i> = 26.5, <i>P</i> < 0.001) and Body (<i>F</i> = 81.4, <i>P</i> < 0.001), while the phenolic extract directed Astringency (<i>F</i> = 170.5, <i>P</i> < 0.001) as well as Bitterness (<i>F</i> = 7.3, <i>P</i> < 0.001) and suppressed Sweetness (<i>F</i> = 16.5, <i>P</i> < 0.001). An amino acid by volatile interaction (<i>F</i> = 4.2, <i>P</i> < 0.05) was found, and further experiments showed that L-proline enhanced Viscosity (<i>F</i> = 5.0, <i>P</i> < 0.05), Sweetness (<i>F</i> = 14.4, <i>P</i> < 0.001), Red fruit flavour (<i>F</i> = 7.8, <i>P</i> < 0.001) and suppressed Astringency (<i>F</i> = 6.1, <i>P</i> < 0.05) and Bitterness (<i>F</i> = 7.0, <i>P</i> < 0.01), while L-glutamic acid imparted an Umami taste (<i>F</i> = 5.0, <i>P</i> < 0.05) at wine-like concentration.</p> <p><b>Conclusions</b> For the first time, these causal experiments showed that amino acids can influence the taste, mouthfeel and flavour of red wine.</p> <p><b>Significance of the Study</b> This work provides insight into a new class of wine compounds of sensory significance that can be targeted by producers to directly influence wine flavour.</p>