IBMP-Polypenol interactions: Impact on volatility and sensory perception in model wine solution

Abstract

3-Isobutyl-2-methoxypyrazine (IBMP) is one of the key molecules in wine aroma with a bell pepper aroma and a very low threshold in wine, 1-6 ng/L for white wine and 10-16 ng/L in red wine1. The differences in these thresholds are likely due to IBMP-non volatile matrix interactions. It has indeed been shown that polyphenols may influence the volatility of flavor compounds2. In the present study, we focus on IBMP-polyphenols interactions in relation to volatility and sensory perception in model wine solution. Methods: 1. GC-MS Static Headspace Analysis: Samples were analyzed by Static headspace analysis with an Agilent 7890A gas chromatograph coupled to HP 5975C mass spectrometry detector (Agilent Technologies, Santa Clara, CA, USA). The analyses of polyphenols and IBMP in model wine were all performed in 10ml vial flasks with volumes of 1ml of model wine volume. IBMP was quantified in Single Ion Monitoring (SIM) mode. The ions used for SIM mode were m/z 94, 121, 154. All the solutions were at fixed pH and ethanol concentration (pH 3.5, 12% Ethanol). For each experiment a control of IBMP, polyphenol, a blank and a mix between IBMP and polyphenol were prepared. 2. Sensory Analysis: Triangular tests were performed by trained panelists (n=26) to orthonasally differentiate between IBMP on its own and IBMP in the presence of a polyphenol. 3. NMR Spectroscopy : Spectra were performed on an Agilent 500 MHz DD2 NMR spectrometer (Agilent Technologies, Santa Clara, CA, USA).Titrations of polyphenols were obtained by addition of IBMP solubilized in CD3OD (~200mM) to quercetin or polydatin (~20mM) CD3OD solution. Absolute concentrations of both aroma and polyphenols were accurately determined from the surface integration of well-separated 1D 1H signal using qNMR method. Results: 1. The headspace analysis showed that polydatin and quercetin decreased the volatility of IBMP. 2. Compared to the control (IBMP without polyphenol), significant results were found in sensory analysis (triangular tests) for polytadin (P < 0030) and quercetin (P < 0000) in presence of IBMP at 8 ng/L in model wine solution 3. Variations in NMR 1H chemical shifts were observed in titration experiments which suggest different possible sites for the interactions of IBMP with the polyphenols

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