Comprehensive analytical workflow for fermented and non-fermented grape-based beverages volatile profiling: higher resolution and reliability for a wide range of molecular structures

Abstract

The increasing demand for no/low-alcohol beverages (< 5 % v/v) has intensified the need for technological innovation in grape-based products within this category. Such innovation must be supported by robust analytical data to guide process monitoring. Although advanced analytical techniques, such as Headspace Solid-Phase Microextraction (HS-SPME) combined with Comprehensive Two-Dimensional Gas Chromatography (GC×GC), are already well stablished for the study of beverages volatile composition, studies are usually focused on one type of beverage and not on comparative studies involving fermented and non-fermented beverages with different ethanol contents and compositional complexity. Chemical complexity arises from compounds generated during fermentation, such as esters and higher alcohols that become major compounds in beverages and difficult analysis (1), while rising ethanol concentrations alter the partitioning behaviour of volatile compounds in the headspace. Therefore, optimizing sample preparation parameters and selecting an appropriate gas chromatographic method are fundamental steps in the development of a workflow for the characterization of volatile composition of grape-based beverages with different chemical complexity and ethanol content. This research aimed to develop a solvent-free and high throughput approach based on HS-SPME/GC×GC that enables a comparative profiling of grape-based beverages with and without ethanol (from 0 % to ca. 10%). To fulfil this objective three main aspects were considered: a) HS-SPME parameters, namely fiber coating and extraction time, to ensure balanced sensitivity and selectivity across a wide range of volatile compounds, b) chromatographic conditions, namely columns configuration and secondary-oven temperature offset, to enhance resolution and peak capacity, and c) chromatographic data normalization to reduce variability and enhance results reliability. A reverse column configuration combined with a triple-phase fiber coating combined with selected extraction time (5 pre-equilibrium followed by 15 min of extraction) and internal standard normalization provided improved compound coverage, enhanced separation of structurally diverse volatiles, and reduced analytical variability across matrices with different ethanol contents. These findings establish an analytical workflow for comprehensive volatilome characterization of grape-based beverages, supporting innovation in no- and low-alcohol product development.

References

1. Villamor, R. R., & Ross, C. F. (2013). Wine Matrix Compounds Affect Perception of Wine Aromas. Annual Review of Food Science and Technology, 4(1), 1–20. https://doi.org/10.1146/annurev-food-030212-182707