Application of gas-diffusion microextraction to the analysis of free and bound acetaldehyde in wines by HPLC–UV and characterization of the extracted compounds by MS/MS detection

Abstract

In wines, the presence of high levels of acetaldehyde (AA) not only is responsible for undesirable characteristic odours but can also cause health adverse effects. Such sensorial activity of AA can be overcome by adding sulphites during winemaking, due to the formation of adducts between AA and sulphites, which lower the sensorial impact of AA. Nevertheless, bound AA can be released during wine storage; therefore, the knowledge of its total amount can be important to estimate the long-term wine quality. The proposed methodology is based on the extraction of AA from wines using gas-diffusion microextraction and determination by liquid chromatography. Free and bound forms of AA could be differentiated and determined using an alkaline hydrolysis step to dissociate the sulphites-AA adducts. This methodology was successfully applied to different wine types, with free AA values ranging between 5 and 26 mg L(-1) and total form between 154 and 906 mg L(-1). Bound AA was above 90% of the total content determined for all samples analysed, and higher amounts were obtained for white wines (around 98%). Other carbonyl compounds were also identified in the extracts using mass spectrometry.

Electrochemical sensing of total sulphites in beer using non-modified screen-printed carbon electrodes

“…The basic extraction principles of GDME have been described previously (10)(11)(12)(13)(14). Analytes were extracted from the sample by a gas-diffusion process through a gas-permeable hydrophobic membrane with a porosity of 5.0 μm (Mitex PTFE, Millipore).…”

A rapid, one step preparation for measuring selected free plus SO 2 -bound wine carbonyls by HPLC-DAD/MS

“…2). This process used 1.8% sulfuric acid, at 65 1C, and 0.57 g L À 1 DNPH solution, with additions of SO 2 that would provide concentrations of 0, 60, 80, Reaction Time (min) 5 1 100 and 240 mg L À 1 in the reactions solutions. In reactions without added SO 2 , a significant (po 0.05) increase in acetaldehyde concentration was observed.…”

“…They are frequently cited as volatile organic compounds in wines that can play a major role in the aroma character of fermented beverages [4]. In some cases, the levels of these compounds in beverages can be an indicator of deterioration caused by pasteurization, storage or even an indicator of contamination [5]. To date, well-characterized carbonyl substances found in the wine include acetaldehyde, pyruvic acid, 2-ketoglutaric acid, glyceraldehyde, formaldehyde, acetoin, glucuronic acid, sugars and diacetyl [6,7].…”

Copper(II) and Sulfur Dioxide in Chardonnay Juice and Shiraz Must: Impact on Volatile Aroma Compounds and Cu Forms in Wine

“…Aldehyde and hence readily form addition products that are odorless (non-volatile) [10][11][12]. However, as SO 2 can be gradually depleted during aging [13,14], the addition products can progressively dissociate and release free aldehyde compounds [15,16] and the accompanying off-flavors. In contrast to the aldehyde compounds, low molecular weight sulfur compounds (LMWSCs) can contribute significant 'reductive' off-flavors to wine [17].…”