Dual optically responsive paper-membrane for simple, portable, and versatile control of total and volatile acidity in wines

Abstract

Background: The high consumption of expensive and polluting reagents and the use of tedious reactions with long analysis times are key problems in the quantification of total (TA) and volatile acidity (VA) in wine by official methods (titration with sodium hydroxide and enzymatic method).

Results: We have exploited the advantages and versatility of our optically responsive paper-membrane (PaperFM) to perform the dual simultaneous determination (fluorescent and colorimetric) of TA and VA in wine. The technology was tested by performing the simultaneous double quantification (fluorescence and colorimetry) of TA and VA of wine samples from different origins, obtaining an excellent correlation between the results obtained by colorimetry and those obtained by fluorescence. Furthermore, the results were successfully validated using official reference methods (titration with sodium hydroxide and enzymatic method) in an accredited laboratory. Significance: We have developed the first optical sensing method that allows the quantification of the TA and VA in wine. The results presented in this work demonstrate that our optical sensing technology enables direct, simple, reversible, reusable, fast, cost-effective, and environmentally friendly simultaneous dual quantification (fluorescent and colorimetric) of TA and VA in wine samples without the use of additional reagents.