Multispectral fluorescence sensitivity to acidic and polyphenolic changes in Chardonnay wines - The case study of malolactic fermentation

In this study, stationary and time-resolved fluorescence signatures, were statistically and chemometrically analyzed among three typologies of Chardonnay wines (A, B and C) with the objectives to evaluate their sensitivity to acidic and polyphenolic changes. For that purpose, a dataset was built using Excitation Emission Matrices of fluorescence (N = 103) decomposed by a Parallel Factor Analysis (PARAFAC), and fluorescence decays (N = 22), mathematically fitted, using the conventional exponential modeling and the phasor plot representation. Wine PARAFAC component C4 coupled with its phasor plot g and s values enable the description of malolactic fermentation (MLF) occurrence in Chardonnay wines. Such proxies reflect wine concentration modifications in total acidity, malic/lactic and phenol acids. Lower g values among fresh MLF + wines compared to MLF- wines are explained by a quenching effect on wine fluorophores by both organic and phenolic acids. The combination of multispectral fluorescence parameters opens a novel routinely implementable methodology to diagnose fermentative processes.

Automated summary

Statistical and chemometric analysis was conducted on the fluorescence signatures of three typologies of Chardonnay wines to evaluate their sensitivity to acidic and polyphenolic changes. The dataset was built using Excitation Emission Matrices of fluorescence decomposed by PARAFAC and fluorescence decays mathematically fitted. The combination of multispectral fluorescence parameters offers a new methodology to diagnose fermentative processes.