Pinotage ripening – an overview

by | Mar 1, 2020 | Winetech Technical, Practical in the vineyard

Harvesting of Pinotage grapes, Welgevallen Experimental Farm, Stellenbosch University.

The aim of this compact overview of existing technical information is to create context for forthcoming articles discussing the impact of grape ripening on wine composition and potential wine styles of Pinotage.

Introduction

Pinotage was developed by Prof. A.I. Perold of the University of Stellenbosch in 1925, when he successfully crossed Pinot noir and Cinsaut. Since its development and commercialisation in the 1950’s, Pinotage has seen a steady acceptance by the South African wine industry and by 1979 there were 660 639 Pinotage vines planted in the Cape. Demand for the variety increased when wine export sanctions were lifted in 1994, paving the way for a unique South African offering. Currently, there are 20 814 088 Pinotage vines planted in South Africa, amounting to 6 979 ha of vineyard, thereby ranking 3rd with regard to total vineyard area planted to red varietals (1st Cabernet Sauvignon – 10 360 ha and 2nd Shiraz/Syrah – 9 735 ha) (SAWIS, 2017). Plantings have also spread across the world as recognition of Pinotage wine quality has grown. Pinotage can now be found in Australia, Brazil, Canada, France, New Zealand, Switzerland and the United States of America (OIV, 2017). Yet, despite the recent popularity of Pinotage, varietal specific information is sparse and limited to a handful publications.

Viticulture

Cultivation

Plant material in the form of clones with specific attributes linking to specific productions goals has become an important part of modern viticulture. In a comparative study (Kriel, 1983), seven clonal selections (grafted to Jacquez rootstock) were evaluated (1970 – 1981) on the basis of shoot mass, sugar content, acid concentration, occurrence of viruses and Botrytis cinerea resistance. Three clones were selected (PI 45, PI 48 and PI 50) and made available to the industry. Since then PI 50 has been removed due to virus infection of the source material and have been replaced by field selections PI 6 and PI 7 (Table 1). Due to its youth, Pinotage clonal material is limited. However, recent DNA sequencing advances has aided the understanding of the genetic make-up of Pinotage and will prove valuable to future breeding programs (Coetzee, 2018).

Traditionally, Pinotage has been cultivated as a bush vine, with local belief that it produces wines of higher quality when cultivated in this way. A long term investigation into the impact of vine training (bush vine versus vertical shoot positioning – VSP) on Pinotage wine quality displayed no consistent trends regarding this perceived relationship (Van Schalkwyk & Schmidt, 2009a, 2009b, 2009c, 2009d), rather pointing to vineyard site, vintage, ripeness level, grapevine water status and bunch microclimate as complex drivers to wine quality. Practices such as regulated deficit irrigation (Myburgh, 2011 & Serra Stepke, 2014) and canopy management have shown to improve bunch microclimate and subsequent grape composition and wine quality of Pinotage. Although much remains unknown with regard to the effects of bunch microclimate and key Pinotage qualitative components. The negative impact of management practices which are prone to deliver fruit with heterogeneous maturity, sunburn, extensive shrivelling and general over-ripeness have been documented (Van Schalkwyk & Schmidt, 2009b).

Planting of Pinotage vines at the foot of Simonsberg, Stellenbosch.

Ripening

Pinotage is an early ripening variety, with a relatively short growth cycle, ripening up to eight weeks before Cabernet Sauvignon in Stellenbosch, and often avoids several heat waves by being harvested before the warmest month (February) of the season. Due to its rapid sugar accumulation, determining the correct ripeness level is critical to avoid over-ripeness. Research regarding Pinotage ripeness levels was first published by Du Plessis and Van Rooyen (1982) in which they proposed a maturity index of °Brix:TA ratio and identified a value of 3.9 as “optimum ripeness” for highest wine quality. In a follow up work an additional maturity index, namely sugar content (°B) x pH with values ranging between 85 and 95 was proposed for highest quality (Van Rooyen et al., 1984). Grape colour/pigmentation was also identified as a potential ripeness level indicator for Pinotage, but results were not consistent due to the extremely high colour/pigmentation values found in Pinotage compared to other cultivars (Marais & October, 2005). Despite these recommendations, modern era Pinotage producers still mainly use sugar level (°B) to make harvest decisions. Admittedly early studies (Marais et al., 1979; Du Plessis & Van Rooyen, 1982; Van Rooyen et al., 1984) assessed a wide range of ripeness levels (17 – 25°B), while nowadays vintners are picking in a narrower band at higher sugar levels. Internationally this trend has seen a major drive in grape compositional research and analyses in the search for improved ripening indicators and links to wine attributes. This field is unexplored for our most important local variety.

Practical implications

Research conducted locally on Shiraz displayed a strong relationship between progressive ripening and changes in wine style (Hunter et al., 2007). This suggests that there are multiple “optimum ripeness” points during ripening, each associated with a specific style, contrary to the notion of a sole optimal point. This theory, however, remains un-investigated for rapid ripening Pinotage. What is the possible scope of stylistic diversity? The ability/flexibility to manipulate wine style in the vineyard will allow producers to harness the potential of a given terroir, while also adhering to changing consumer preferences and market trends. Thus, understanding the development and progression of flavours and its eventual implications in wine style will serve as a valuable tool to Pinotage producers in day-to-day harvest decisions.

References

Du Plessis, C.S. & Van Rooyen, P.C., 1982. Grape maturity and wine quality. South African Journal of Enology and Viticulture 3, 2, 41 – 45.

Coetzee, B., 2018. PhD thesis: Genome and transcriptome sequencing of Vitis vinifera cv. Pinotage. Stellenbosch University.

Hunter, J.J., Nadal, M. & Volschenk, C.G., 2007. Grape ripeness and wine style of Shiraz. Winetech Technical, November.

Kriel, G.J. le R., 1983. KWV-Plantverbeteringskema: Watter kloon moet ek plant? Wynboer Technical Yearbook 2, January, 51 – 56.

Marais, J. & October, F., 2005. Verband tussen druifkleur en wynkwaliteit. Winetech Technical 191, 15 – 17.

Myburgh, P.A., 2011. Possible adjustments to irrigation strategy and trellis system to improve water use efficiency of vineyards (Part 6): Yield and quality of Pinotage. Winetech Technical, June.

OIV, 2017. 2017 World viticulture situation. In: OIV Statistical Report on World Vitiviniculture, 1 – 20.

SAWIS, 2017. SA Wine Industry 2017 Statistics 42, 1 – 31.

Serra Stepke, I.M., 2014. Grapevine (Vitis vinifera L., cv. Pinotage) responses to water deficit modulated by rootstocks. Stellenbosch University.

Van Rooyen, P.C., Ellis, L.P. et al., 1984. Interactions between grape maturity indices and quality for Pinotage and Cabernet Sauvignon wines from four localities. South African Journal of Enology and Viticulture 5, 1, 29 – 34.

Van Schalkwyk, D. & Schmidt, A., 2009a. Cultivation of Pinotage in various climatic regions (Part 1): Climatic differences. Wynboer Technical Yearbook 1, 1, 7 – 11.

Van Schalkwyk, D. & Schmidt, A., 2009b. Cultivation of Pinotage in various climatic regions (Part 2): The influence of canopy management, vine frame and cordon height on viticultural and oenological performance of Pinotage in climate region 2. Wynboer Technical Yearbook 1, 1, 12 – 17.

Van Schalkwyk, D. & Schmidt, A., 2009c. Cultivation of Pinotage in various climatic regions (Part 3): The influence of canopy management, vine frame and cordon height on the viticultural and oenological performance of Pinotage in climate region 3. Wynboer Technical Yearbook 1, 1, 18 – 24.

Van Schalkwyk, D. & Schmidt, A., 2009d. Cultivation of Pinotage in various climatic regions (Part 4): The impact of canopy management, vine frame and cordon height on the viticultural and oenological performance of Pinotage in climate region 4. Wynboer Technical Yearbook 1, 1, 25 – 30.

– For more information, contact Etienne Terblanche at etienne@vinpro.co.za.

 

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