WINETECH Technical Yearbook 2019

FIGURE 4. Reduced and oxidised GSH at the initial testing stage (racked juice) for the two cultivars and all three vintages. The results are from four biological (vineyard) repeats each.

the viticultural and winemaking level to produce wines with more desirable sensory attributes. REFERENCES Bruwer, F.A., 2018. Effect of foliar nitrogen and sulphur spraying on whi te wine composition ( Vitis vinifera L. cv. Chenin blanc and Sauvignon blanc). MSc dissertation, Stellenbosch University. Juhasz, A., 2015. Effect of foliar fertilization on wine aroma for white wine cv. Sauvignon blanc ( Vitis vinifera L.). MSc dissertation, Geisenheim University.

Gutiérrez-Gamboa, G., Garde-Cerdán, T., Gonzalo-Diago, A., Moreno-Simunovic, Y. & Martinez-Gil, A., 2017. Effect of different foliar nitrogen applications on the must amino acids and glutathione composition in Cabernet Sauvignon vineyard. Elsevier 75: 147-154. Doi: 10.1016/j.lwt.2016.08.039. Lasa, B., Menendez, S., Sagastizabal, K., et al. , 2012. Foliar application of urea to “Sauvignon blanc” and “Merlot ” vines: Doses and time of application. Plant Growth Regulation 67(1): 73-81. Doi: 10.1007/ s10725-012-9667-5.

Lacroux, F., Tregoat, O., Leeuwen, C.V.A.N., Pons, A. & Dubourdieu, D., 2008. Effect of foliar nitrogen and sulphur application on aromatic expression of Vitis vinifera L. cv. Sauvignon blanc. Journal International des Sciences de la Vigne et du Vin 42(3): 1-8. Doi: 10.1007/s11032-013-9938-5. Hannam, K.D., Neilsen, G.H., Neilsen, D., Rabie, W.S., Midwood, A.J. & Millard, P., 2014. Late-season foliar urea applications can increase berry yeast-assimilable nitrogen in wine grapes ( Vitis vinifera L.). American Journal of Enology and Viticulture 65(1): 89- 95. Doi: 10.5344/ajev.2013.13092.

Dienes-Nagy, Á., Vuichard, F., Spring, J-L. & Lorenzini, F., 2017. Evolution of major N containing substances in response to the foliar urea treatment (poster).pdf. Switzerland. Lavigne, V., Pons, A. & Dubourdieu, D., 2007. Assay of glutathione in must and wines using capillary electrophoresis and laser- induced fluorescence detection. Changes in concentration in dry white wines during alcoholic fermentation and aging. Journal of Chromatography A. 1139(1): 130-135. Doi: 10.1016/j.chroma.2006.10.083.

– For more information, contact Astrid Buica at abuica@sun.ac.za.