Esters in wine

Perestrelo, R., Nogueira, J. M. F., and Camara, J. S. (2009). Potentialities of two solventless extraction approaches-stir bar sorptive extraction and headspace solid-phase microextraction for determination of higher alcohol acetates, isoamyl esters and ethyl esters in wines. Talanta 80, 622-630. 

Esters in wine have two distinct origins enzymic esterification during the fermentation process and chemical esterification during long-term aging. The same esters may be synthesized in either way. 

Amerine, M. A. 1944. Determination of esters in wines liquid-liquid extraction. Food Research 9, 393-395. 

Table 20.20. Esters in wine with sensory relevance...

Caprylic acid C7H15COOH As a glyceride in butter of cow s milk and coconut oil, as an ester in wine. 

Essential oils are obtained from fmits and flowers (61,62). Volatile esters of short- and medium-chain carboxyHc acids or aromatic carboxyHc acids with short- and medium-chain alcohols are primary constituents of essential oils, eg, ethyl acetate in wines, brandy, and in fmits such as pineapple ben2yl acetate in jasmine and gardenia methyl saHcylate in oils of wintergreen and sweet birch. Most of these naturally occurring esters in essential oils have pleasant odors, and either they or their synthetic counterparts are used in the confectionery, beverage, perfume, cosmetic, and soap industries (see Oils, essential). 

Ferreira V, Jarauta I, Ortega L, Cacho J (2004) Simple strategy for the optimization of solid-phase extraction procedures through the use of solid-liquid distribution coefficients—application to the determination of aliphatic lactones in wine. J Chromatogr A 1025 147 Rettinger K, Karl V, Schmarr HG, Dettmar F, Hener U, Mosandl A (1991) Chirospecific analysis of 2-alkylbranched alcohols, -acids, and -esters chirality evaluation of 2-methylbutanoates from apples and pineapples. Phytochem Anal 2 184... 

For the red wines (82-84), which were injected directly into the HPLC without sample preparation, a ternary-gradient system using aqueous acetic acid (1% and 5% or 6%), and acidified acetonitrile (acetonitrile-acetic acid-water, 30 5 6) was used for cinnamic acid derivatives, catechins, flavonols, flavonol glycosides, and proanthocyanidins. Due to the large number of peaks, the gradient was extended to 150 min for the resolution of many peaks of important phenolics. This direct injection method was able to separate phenolic acids and esters, catechins, proanthocyanidins, flavonols, flavonol glycosides, and other compounds (such as tyrosol, and rrans-resveratrol) in wine in a single analysis. However, use of acetic acid did not permit the detector (PDA) to be used to record the UV spectra of phenolics below 240 nm (84). 

Besides these simple fermentation alcohols, the yeast also forms higher alcohols as side products, "fusel oils," that have intense odors and play a role in wine aroma. Other components are carboxylic acids, such as tartaric and malic acids, that are important as "life-insurance" during aging of the wine. Some of the aromas perceived in wines stem from esters... 

Rojas, V., Gil, J. V., Pihaga, F., and Manzanares, P. (2003). Acetate ester formation in wine by mixed cultures in laboratory fermentations. Int. J. Food Microbiol. 86,181-188. 

Traditionally, large oak barrels are used to facilitate the diffusion of oxygen. This is assumed to play a major role in the many chemical reactions occurring during aging. Oxidation reactions promote desired changes in wine phenolics (e.g., anthocyanins, flavonoids, and tartaric esters of hydrocinnamic acids) as well as oak phenolics extracted from the... 

Some strains of L. brevis cause mannitol taint by enzymatic reduction of fructose to mannitol. Mannitol is a polyol produced in heterofermentative metabolism. Its perception is often complicated as it generally exists in wine alongside other defects, but it is usually described as viscous and ester-like, combined with a sweet and irritating finish (Du Toit and Pretorius 2000). Mannitol is usually produced in wines that undergo MLF with a high level of residual sugars still present. 

Recent work has also indicated that commercially available strains of LAB are also able to synthesize acetates and ethyl fatty acid esters during winemaking (Maicas et al. 1999 Ugliano and Moio 2005), which appear to be in contradiction with early suggestions that the MLF could result in a decrease in wine esters (Davis et al. 1988 Du Plessis et al.2002). More research is required in this area before general conclusions can be drawn regarding the influence of MLF on the ester composition of wine. 

---