A liquid chromatographic method optimization for the assessment of low and high molar mass carbonyl compounds in wines

Abstract

Carbonyl compounds (CC) play an important role in beverage aroma since they may affect flavor of wines, brandies, and beers, among others. For this reason, it is necessary to identify and quantify CC through adequate analytical techniques. This study is a proposal of both developing and optimization of a new analytical methodology that allows investigate C(1)-C(8 )CC in wines simultaneously by quantifying even those ones that are predominantly present in the adduct form hydroxylalkylsulfonic acids (HASA). The HASA dissociation is undertaken by specific alkaline media (pH 11). The developed methodology employed the LC with UV/VIS detection (lambda = 365 nm) technique under gradient elution in the way to reach both free-CC and bound-CC quantification. Results showed that binary gradient system using eluent A (MeOH/ACN/H(2)O 74.5:0.5:25% v/v/v) and eluent B (MeOH) reached the best separation condition of both lower and higher molecular mass CC. This proposed method allowed simultaneous quantification of formaldehyde, acetaldehyde, propanone, furfuraldehyde, butyraldehyde, benzaldehyde, hexanaldehyde, 2-ethyl-hexanaldehyde, E-pent-2-en-1-al, and cyclohexanone--all of them were found in white wine (Moscato Canelli) and red wine (Shiraz) produced in the São Francisco Valley, in the Northeastern Region of Brazil--although this optimized method may probably be suitable for quantification of propionaldehyde, isobutyraldehyde, heptanaldehyde, octanaldehyde, benzaldehyde, and E-hex-2-en-1-al as well. We could not prove if this method is also able to determine the latter CC group since we have not found these substances present in detectable levels in our real samples considered in this study.

Rapid Quantitation of 12 Volatile Aldehyde Compounds in Wine by LC-QQQ-MS: A Combined Measure of Free and Hydrogen-Sulfite-Bound Forms

“…Oxidized wine is characterized by color and aroma deterioration, − such as the formation of brown pigments, the loss of desirable fruity attributes, , and the generation of undesirable oxidation-related odorants, such as carbonyl compounds and, in particular, aldehydes . Depending on their molecular structure and concentration, aldehydes can give either pleasant or undesirable nuances to wine, generally described as hay, old wood, papery, fusel, farm-feed, and cooked vegetables . Acetaldehyde (apple/woody), methional (boiled vegetable/rotten potato), and phenylacetaldehyde (honey) are important examples of aldehyde compounds with the potential to induce off-flavors.…”

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

“…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].…”

“…Depending on their concentration and structure, these carbonyls can contribute pleasant or undesirable notes to wine and other fermented beverages [4,9]. For instance, the saturated shortchain aldehydes significantly affect overall flavor, contributing notes such as nutty, bruised apples, herbaceous, grassy, green, fatty, fruity and pungent [10], while the significance of acetaldehyde to wine aroma is questionable, as no correlation was found between this oxidation product and oxidation flavors in young white wines [11].…”

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

“…For liquid chromatography (LC) the most used derivatisation reagent is 2,4-dinitrophenylhydrazine (DNPH) which improves the UV absorption coefficient of aldehydes and their hydrophobic retention, so they can be easily separated by reverse phase LC and detected by UV spectrophotometry [15]. In contrast to what is previously stated for GC analysis, usually no extraction of aldehydes from wines is performed for LC determinations, i.e., derivatisation is carried out insample, and the mixture is directly injected in the chromatographic system [14, 18,19].…”

“…But when the pH is set below pH 1 (pK a1 01.85) or above pH 8 (pK a2 0 7.2) [13], sulphites are mainly present in other forms (SO 2 and SO 3 2− , respectively), and the adduct bond is broken. Accordingly, for the analysis of total content of AA present in the samples, a hydrolysis step should be performed [14,15]. Whilst above pH 10 a small percentage of HSO 3 − is still present, it is recommended to use higher pH values to guarantee a total dissociation of the species [16].…”