The impact of dosage sugar-type and aging on Maillard reaction-associated products in traditional method sparkling wines

Liqueur d’expedition (dosage) is a final sugar addition made to sparkling wine which determines the sweetness and balance of the finished product. In the present study, the influence of dosage sugar composition on Maillard reaction-associated products and precursors in traditional method (bottle-fermented) sparkling wines was evaluated over 18-months of storage in climate-controlled cellar conditions (14 °C, 70 % relative humidity). Evaluated dosage sugar-types included glucose, fructose, cane-derived sucrose, beet-derived sucrose, maltose, and Must Concentrate Rectified (MCR) Sucraisin®, which were compared to a zero dosage (no sugar added) control. Maillard reaction-associated products were quantified by headspace solid-phase microextraction coupled to gas-chromatography-mass spectrometry (HS-SPME-GC/MS), and precursors including sugars and amino acids, were measured by enzymatic assay and proton (1H) nuclear magnetic resonance (NMR) spectroscopy, respectively. Partial least squares discriminant analysis (PLS-DA) was used to effectively discriminate between wines based on aging duration but did not adequately separate wines treated with different dosage sugar-types. Decreases in alanine and glycine were observed after 18-months of cellar aging, suggesting that Maillard reaction product formation may be partially related to their depletion. Benzaldehyde and ethyl-3-mercaptopropionate were identified as discriminatory Maillard reaction-associated compounds when comparing 0- and 18-month aged wines, with benzaldehyde increasing and ethyl-3-mercaptopropionate decreasing over the aging period. This research contributes to an increased understanding of Maillard reaction pathways in the unique low-temperature and low pH sparkling wine matrix and establishes the relatively greater effect of aging duration compared to dosage sugar-type on the formation of Maillard reaction-associated products. The combined application of HS-SPME-GC/MS and 1H NMR based metabolomics presents new insights into the chemical composition of sparkling wines during aging.