WINETECH Technical Yearbook 2019

ASTRID BUICA, MPHO MAFATA, VALERIA PANZERI & JEANNE BRAND: Department of Viticulture and Oenology, Stellenbosch University, Stellenbosch KEYWORDS: Storage conditions, Chenin blanc wine, Sauvignon blanc wine, sensory evaluation. DECEMBER 2019 STABILITY OF YOUNG CHENIN BLANC AND SAUVIGNON BLANC WINE DURING STORAGE (PART 2): SENSORY ASPECTS

The aim of this study was to evaluate the stability of commercial white wines aroma using both analytical chemistry and sensory evaluation approaches, with a focus on the stability of thiols. Part 2 is focused on the evolution of the sensory perception of the aroma of the wines during storage. EXPERIMENTAL LAYOUT The sensory evaluation of the wines after storage was done using Pivot © Profile (Thuillier et al ., 2015), a method that employs a reference (in this case, the control, T0) and compares the rest of the samples in the set to it, while generating a series of attributes for both the reference and the

samples. Unwooded Chenin blanc (CB) and Sauvignon blanc (SB) wines were sourced from six wineries. The wines were stored at room temperature (RT), 15°C and 25°C for three and nine months (T3 and T9), after which they were transferred into a -4°C cooling room until analysis. The control for each winery (T0) was stored at -4°C until analysis. Therefore, each sample set consisted of seven samples (T0, T3/15, T3/25, T3/RT, T9/15, T9/25 and T9/RT) per winery for each cultivar, 12 sets in total. The data analysis began with the capture of 180 forms for each SB and CB. A total of 240 attributes were generated with little redundancies. Semantic grouping led to 170

attributes from which frequency of citations were calculated for CB and SB separately. Further condensation based on how many judges used a certain descriptor resulted in 29 attributes for CB and 33 for SB. The results from the Pivot © Profile allowed us to map the changes with storage time and conditions for each set. We have evaluated the changes from two perspectives: • How the wines have changed during storage (which attributes disappeared/appeared) and • how much the wines changed. Heat maps are a very useful tool for visualising the sample sets