The Contribution of Glycoside Precursors to Cabernet Sauvignon and Merlot Aroma

Abstract

Volatile compounds released from Cabernet Sauvignon and Merlot grape glycoside fractions, isolated from both skin and juice, were studied by sensory descriptive analysis and by gas chromatographymass spectrometry (GC-MS). Both acid-and enzyme-hydrolysates were studied. The contribution to wine aroma of the different fractions was evaluated by sensory analysis of white wines to which the hydrolysates had been added. Acid-hydrolysates from each variety increased the intensity of attributes such as tobacco, chocolate and dried fig. In contrast, glycosidase enzyme-hydrolysates gave no detectable change in aroma. The relationship among the aroma attributes of the hydrolysates and their volatile composition was investigated using partial least square regression analysis (PLS), which indicated that the intensity of the attributes dried fig, tobacco and honey could be related to the concentration of specific compounds of the norisoprenoid, benzene derivative, monoterpene and aliphatic classes. The red-free glycosyl-glucose (G-G) concentration of the skin extracts and juices was correlated with the scores of aroma attributes of the glycoside hydrolysates, suggesting the potential of the G-G assay as a predictor of wine aroma.The awareness that glycosidically-conjugated volatile compounds are present in grape berries and other fruits has stimulated substantial research interest in these constituents. Research on glycosidic flavor precursors has been the subject of several reviews (1-6). In the case of wine grapes, it is becoming evident from sensory studies that grape berry derived glycosidically-bound volatile compounds are capable of making a contribution to varietal wine flavor.For the non-floral white grape varieties Chardonnay, Semillon and Sauvignon

Glycosidically Bound Volatile Aroma Compounds in Grapes and Wine: A Review

“…While the glycosides often have a bitter taste, they do not contribute to bitterness in wine (Noble et al 1987(Noble et al , 1988. However, upon hydrolysis, the released volatile aroma compounds may affect the aroma profile of a wine, as previously suggested (Wilson et al 1986, Günata et al 1985 and shown (Francis et al 1999). Despite being relatively thermodynamically unstable in the acidic environment of a wine, most glycosides remain intact throughout the winemaking process and, to a lesser extent, in the bottle ).…”

Origins of Grape and Wine Aroma. Part 1. Chemical Components and Viticultural Impacts

“…They have been shown to contribute significantly to the dried fig, tobacco, and chocolate aromas in Cabernet Sauvignon and Merlot musts (Francis et al 1998). One of the more interesting grape-derived volatile phenylpropanoids is methyl anthranilate, which is considered to be responsible for the distinctive "foxy" aroma and flavor of the Washington Concord grape (Vitis labrusca) (Wang and De Luca 2005) and may also contribute to the aroma of Pinot noir (Moio and Etievant 1995).…”

Composição da produção e qualidade da uva em videira cultivada sob dupla poda e regime microclimático estacional constrastante

“…Este fato, em combinação com as condições de demanda evaporativa atmosfé-ricas reinantes, no local e época, levaram à captação, no dossel da cultura, de valores mínimos de potencial da água na folha em -1,3 MPa (Tabela 1 Jackson (1994), dentre outros, mostram que as rotas metabólicas, para o acúmulo da pigmentação fenólica (antocianina, polifenóis totais, taninos), são fortemente influenciadas pela dinâmica da água no solo e pela amplitude térmica. Doravante, Francis et al (1999) comprovaram cientificamente a ligação entre pigmentação fenólica e complexidade do vinho em sabor e aroma.…”