Masters Degrees (Viticulture and Oenology)

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Browsing Masters Degrees (Viticulture and Oenology) by Author "Botha, Anri"

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    The use of different oak products during the fermentation and ageing of Chenin Blanc : sensory properties, perceived quality, and consumer preference
    (Stellenbosch : Stellenbosch University, 2015-12) Botha, Anri; Du Toit, Wessel J.; Brand, Jeanne; Stellenbosch University. Faculty of Agrisciences. Dept. of Viticulture and Oenology.
    ENGLISH ABSTRACT: Wooden barrels have been the preferred method for oak maturation for wines, but the use of alternative oak products have increased options of oak maturation for winemakers, since new barrels are expensive and have a limited lifetime. The main aim of this study was to investigate the effect of different oak products used during fermentation and ageing on the sensory profile, degree of liking and perceived quality of Chenin blanc wine. The different wine treatments included an unoaked tank control wine, wines matured in 5th fill barrels, wines matured in new barrels from three different cooperages, and wines matured in 5th fill barrels with stave inserts from two different cooperages. All of the treatments, except for the unoaked tank control, were performed in triplicate, rendering a total of 19 experimental wines. Sensory descriptive data were obtained with Pick-K attributes, using a trained and expert panel at three different intervals of wine maturation. These intervals included 4 months oak maturation, 9 months oak maturation, and 9 months oak maturation with an additional 6 months bottle ageing. At the third maturation interval, an untargeted consumer study was also conducted using CATA questions to obtain descriptive and hedonic data. At this interval the perceived quality of the wines were also investigated using an expert panel. The expert panel received no formal training prior to any of the testing intervals. The trained panel were trained to recognise aromas from a list of 89 descriptors used by sensory scientists and industry experts to describe Chenin blanc wines. The results obtained from the different panels at the different ageing intervals were compared. The biological repeatability of the different treatments were satisfactory from a cooperage point of view. There were clear differences between the sensory profiles of the different wine treatments. Differences between the oak products from the different cooperages used within treatments were less pronounced. There were significant differences in the degree of liking and perceived quality of the different products, but the degree of liking and perceived quality for different products were comparable. The degree of liking and perceived quality of the 5th fill barrels and new barrels were higher than the degree of liking and perceived quality of the stave treatments. The mean degree of liking for the 5th fill barrels and new barrels were higher than for the stave treatments. There were no significant difference between the degree of liking for the unoaked tank wine and the oaked treatments. The sensory descriptive data obtained from the trained, expert and consumer panel were comparable in terms of panel consensus and configurational congruence. This validates the suitability of CATA and its variant, Pick-K attributes, as rapid methods to elicit qualitative information for the sensory profiling of wine. The results from this research made significant contributions towards method validation for CATA as rapid sensory method, and the descriptive and hedonic sensory results from this research can be used by winemakers to both inform and justify the usage of specific oak products.