Browsing by Author "Mafata, M."

Now showing 1 - 4 of 4
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    The effect of grape temperature at pressing on phenolic extraction and evolution in Méthode Cap Classique wines throughout winemaking
    (South African Society for Enology and Viticulture, 2018) Mafata, M.; Buica, A. S.; Du Toit, W. J.; Van Jaarsveld, F. P.
    Maintaining the chemical composition of a wine is essential for the wine industry. Although the sugar-acid balance of a wine is of primary sensory importance, individual acids and oenological parameters are equally important. The main focus of this study was to investigate the impact of grape temperature at harvest, on the oenological volatile acidity (VA), titratable acidity (TA), pH and alcohol levels and organic acid (citric, malic, pyruvic and succinic) characteristics of Méthode Cap Classique (MCC) wines during winemaking, produced from grape cultivars obtained from two regions. Chardonnay and Pinot noir grapes were obtained from Robertson (warmer) and Elgin (cooler) regions and were subjected to different temperature treatments, i.e. 0, 10, 25 and 30oC before further processing, including pressing, primary fermentation, blending, tirage, secondary fermentation, riddling and disgorging. Grape temperature was mostly responsible for a significantly higher pH of Robertson (0 and 10ºC) and lower pH (0ºC) of Elgin post-tirage wines. Chardonnay base wines from both regions that were vinified from grapes at lower temperatures (0 and 10oC) were richer in malic- and succinic acid, while Pinot noir wines from both regions were characterised by higher malic-, citric- and pyruvic acid. Pyruvic acid was only detected after the secondary fermentations in wines from both regions. To our knowledge, this study is the first to investigate the influence of grape temperature on the oenological and organic acid characteristics of MCC wines in different regions, and throughout different production stages.
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    The effect of grape temperature on the sensory perception of Méthode Cap Classique wines
    (South African Society for Enology and Viticulture, 2017) Mafata, M.; Buica, A. S.; Du Toit, W.; Panzeri, V.; Van Jaarsveld, F. P.
    The production process of South African bottle-fermented sparkling wine, the Méthode Cap Classique (MCC), follows the traditional French method (méthode champenoise), although each cellar has its own unique additions to the method. South African winemakers use different techniques and blends to achieve their award-winning MCCs, but there have not been many scientific investigations of the science behind these wines. This project is one of the first scientific studies on MCC. MCC wines were made using Chardonnay and Pinot Noir grapes harvested over two vintages (2014 and 2015) from two regions (Robertson and Darling) and stored at 0°C, 10°C, 25°C and 30°C before processing. The study was aimed at investigating the effect of grape storage temperature on the sensory characteristics of MCCs. The aroma and taste of the final nine-month old MCCs were evaluated, with each region analysed separately. The study showed a grouping of the MCCs according to temperature treatments for both vintages. There were vintage differences in terms of the attributes cited and the frequency of citations. Based on the frequency of citation, the MCCs made 2014 from grapes stored at 0°C and 10°C were described by the judges as having a fruity, fresh and crisp aroma, whilst those made from grapes stored at 25°C and 30°C were described as having oxidised fruit, volatile acidity and solvent-like aromas. The judges perceived less oxidation and volatile acidity (VA) (in terms of the frequency of citation) in the aroma of the 2015 MCCs, although treatments at higher temperatures were still associated with less desirable attributes compared to treatments at lower temperature. This study shown that the temperature of the grape at the time of processing has a significant effect on the aroma of MCCs aged nine months, and not so much of an effect on the taste.
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    Impact of grape temperature at pressing on organic acids and oenological characteristics of Méthode Cap Classique wines
    (South African Society for Enology and Viticulture, 2018) Chidi, B. S.; Mafata, M.; Notshokovu, N. Z.; Van Jaarsveld, F.
    Maintaining the chemical composition of a wine is essential for the wine industry. Although the sugar-acid balance of a wine is of primary sensory importance, individual acids and oenological parameters are equally important. The main focus of this study was to investigate the impact of grape temperature at harvest, on the oenological volatile acidity (VA), titratable acidity (TA), pH and alcohol levels and organic acid (citric, malic, pyruvic and succinic) characteristics of Méthode Cap Classique (MCC) wines during winemaking, produced from grape cultivars obtained from two regions. Chardonnay and Pinot noir grapes were obtained from Robertson (warmer) and Elgin (cooler) regions and were subjected to different temperature treatments, i.e. 0, 10, 25 and 30oC before further processing, including pressing, primary fermentation, blending, tirage, secondary fermentation, riddling and disgorging. Grape temperature was mostly responsible for a significantly higher pH of Robertson (0 and 10ºC) and lower pH (0ºC) of Elgin post-tirage wines. Chardonnay base wines from both regions that were vinified from grapes at lower temperatures (0 and 10oC) were richer in malic- and succinic acid, while Pinot noir wines from both regions were characterised by higher malic-, citric- and pyruvic acid. Pyruvic acid was only detected after the secondary fermentations in wines from both regions. To our knowledge, this study is the first to investigate the influence of grape temperature on the oenological and organic acid characteristics of MCC wines in different regions, and throughout different production stages.
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    Investigating the concept of South African old vine Chenin blanc
    (South African Society for Enology and Viticulture, 2020) Mafata, M.; Brand, J.; Panzeri, V.; Buica, A. S.
    Although South African vineyards are still young by European standards, there is a belief in the industry that vines aged 35 or more years produce grapes and wines with specific characteristics (“old vine wines”). The aim of this study was to investigate the existence of the concept of old vine Chenin blanc wines using a typicality rating and sorting tasks. Chenin blanc wines were made from grapes harvested from vines aged five to 45 years old. Winemaking was standardised, with no wood contact. Typicality rating and sorting tasks were performed on young (first-stage) and two-year bottle-aged (second-stage) wines. Principal component analysis (PCA) on rating data demonstrated judge consensus, but no correlation was found between vine age and typicality rating. Sorting results were submitted to agglomerative hierarchical clustering (AHC) performed on the correspondence analysis (CA) and multidimensional scaling (MDS) results for grouping and attributes resulting from the sorting task. The clusters were different for the young wines and two-year bottle-aged wines. The verbal aspect of the sorting demonstrated the judges’ agreement on the concept of old vine Chenin blanc, shown by the annotation of the old vine group as ‘complex’, ‘balance’, ‘rich’ and ‘good mouthfeel’. However, because the judges did not sort the wines according to vine age, the perceptual aspect of the concept could not be confirmed, its features could not be tested further, and the sensory space could not be built.