|SENSORY PROFILING AND CHANGES IN COLOUR AND PHENOLIC COMPOSITION PRODUCED BY MALOLACTIC FERMENTATION IN RED MINORITY VARIETIES
Olga Martínez-Pinilla, Leticia Martínez-Lapuente, Zenaida Guadalupe, Belén Ayestarán*
Instituto de Ciencias de la Vid y del Vino (Universidad de la Rioja, Gobierno de La Rioja y CSIC), C/ Madre de Dios 51, 26006, Logroño, La Rioja, España. *Corresponding author, Tel.: +34 941 299725, Fax: +34 941 299721, E-mail address: firstname.lastname@example.org
This research studies the sensory properties and chemical composition of varietal wines made with minority varieties from La Rioja (Spain) and it analyses the transformations in phenolic compounds and colour parameters occurring during the malolactic fermentation. In this sense, all the analysed parameters underwent changes of the same magnitude during this stage and both anthocyanin and hydroxycinnamic acid distribution was found to be dependent on the grape variety and not on the winemaking process. Wines made with these varieties showed high values of resveratrol that could lead to healthier wines, and the variety Maturana Tinta de Navarrete was found to share quite similarities in the chemical parameters with Tempranillo, studied as a reference variety. In the sensory analysis, and although all the wines obtained good punctuations, Monastel and Maturana Tinta de Navarrete were the best valued. Monastel had the highest color intensity and both varieties showed high aromatic intensity and great complexity. In mouth, Monastel showed the greater persistence, mount length and structure and Maturana Tinta de Navarrete was described as fresh and pleasant. In conclusion, this research shows the first characterization of these wines and provides data to be used as a chemotaxonomic tool to fingerprint them. Moreover, it opens the door to the use of minority varieties providing a viable alternative to traditional grape varieties cultivated in La Rioja and favouring consumer offer and wine differentiation.
Keywords: red minority varieties, polyphenols, colour, sensory analysis, alcoholic fermentation, malolactic fermentation.
Over the last few decades the introduction and spread of world recognized varieties has caused a massive loss of indigenous grapevine varieties traditionally grown in various grape-growing regions. Initiatives has been ongoing in recent years to safeguard biodiversity in the oenological sector via a process of enhancement of ancient varieties, under a pressure of a market strongly oriented towards production deriving from native vines of specific geographical zones. In that sense, La Rioja (Spain), an autonomous community with a large vitiviniculture tradition, has raised the need to preserve and characterize its minority vine varieties in order to maintain the authenticity and quality of its wines. This community has different vine-growing zones with an important number of minority grape varieties, which are perfectly adapted to these zones.
Previous studies of local and minority varieties from La Rioja were carried out in experimental plots in order to know their possibilities of production and winemaking (Martínez de Toda, Martínez, Sancha, Blanco & Martínez, 2004a; Martínez de Toda, Martínez, Sancha, Blanco & Martínez, 2004b). The results of these works highlighted for their oenological interest red Maturana Tinta, Monastel and red Maturana Tinta de Navarrete. These minority varieties could be able to provide differentiation of red wines from La Rioja and be a good complement to the widespread and most representative variety of the area, Tempranillo, which implies 85% of the surface of red grapes cultivated in La Rioja.
Although there are a few studies on the growing potential of these minority varieties (Martínez de Toda et al., 2004a), studies on the oenological potential are limited to measures of general oenological parameters and sensory analysis in experimental microvinifications after alcoholic fermentation (Martínez de Toda et al. 2004b). No scientific researches have been carried out to study the composition, behaviour and evolution of these wines during the winemaking. Therefore, we aimed to evaluate the oenological characteristics of these minority varieties during the winemaking by analyzing their behaviour both after the alcoholic fermentation and malolactic fermentation, necessary to elaborate high quality wines that could be aged.
It is obvious the influence of monomeric and polymeric phenolic compounds in the colour parameters and sensory quality of the wines. Grape and wine phenolics belong to two main groups: flavonoid and nonflavonoid compounds. Flavonoids, located in grape skins, seeds and stems, include anthocyanins, flavan-3-ol monomers, oligomeric and polymeric proanthocyanidins, flavonols, flavanonols and flavones. Nonflavonoids, which derive primarily from the pulp and skins of grape berries, include hydroxycinnamic and hydroxybenzoic acids and resveratrol and its derivatives. All are important constituents of both grapes and wine due to their direct and indirect contribution to wine sensorial properties such as colour, flavour, astringency, bitterness and structure of the wines (Garrido & Borges, 2011). The content and profile of these polyphenols have not yet been studied in these minority varieties, hence the importance of its knowing, that could provide information about their oenological potential. Moreover, researches on the effect of malolactic fermentation on phenolics or colour parameters are limited and they are frequently aimed at the study of aromas, biogenic amines or microbiological researches (Pramateftaki, Metafa, Karapetrou & Marmaras, 2012; Bartowsky & Borneman, 2011; López et al., 2011; Miller, Franz, Cho & du Toit, 2011; Pan, Jussier, Terrade, Yada & Mira de Orduña 2011; Mendoza, Manca de Nadra & Farías, 2010; Hernádez-Orte et al., 2009; Terrade, Noël, Couillaud & Mira de Orduña, 2009).
Therefore, the aim of this work was to evaluate the oenological characteristics of the selected varieties by analyzing the sensory profiling of the wines obtained as well as the changes occurring in the colour parameters and polyphenolic composition during the malolactic fermentation. Wines were elaborated in an industrial wine cellar Tempranillo was also studied as a reference variety.