Showing posts from February, 2019

Effect of mechanical pruning on vine diseases

Researcher: Francois Halleen

New Winetech funded project 2019 - The objective of this research project is to study the effect of mechanical pruning (MP) on the incidence and severity of grapevine foliar, fruit and trunk diseases compared to conventional pruning. Growth responses, grape composition and morphology, wine quality and labour costs associated with MP have been investigated locally. However, the effect on the incidence and severity of major leaf, fruit and trunk diseases, especially the long-term effect in terms of sustainable production, is unknown.
Apart from an altered canopy structure, MP results in a changed microclimate around the bunch zone, which may favour the development of certain diseases. Depending on the type of MP, a significant increase in the number of pruning wounds can occur as well as wounds with larger surface areas. Trunk pathogens infect susceptible wounds. A build-up of old wood also occurs and even if renewal pruning is practiced on a 3-year rotation…

Screening for potentially novel Pinotage clones generated through irradiance mutagenesis

Researcher: Phyllis Burger

New Winetech funded project 2019 - The aim of this project is to screen and phenotype new Pinotage plants that were generated in a pilot study that focused on developing methods to induce mutations. The intention is that the mutations could lead to potentially novel clones.
In the pilot study, irradiance doses of buds were optimised and associated methods were successfully applied to regenerate viable plantlets. Three clones of Pinotage were used and a significant population of plantlets were yielded. They now need to be further screened for vegetative and reproductive traits that could eventually lead to identification and development of new ‘Pinotage’ clones.
A phased approach will be followed where the initial screening will occur in tunnels or greenhouses to identify a smaller subset with desirable traits that will eventually be transplanted to the field plot for more comprehensive phenotyping. There is high potential for new clones with specific commerc…

Measuring of phenolic compounds during winemaking using a portable spectrometer

Researcher: Jose-Luis Aleixandre-Tudo

New Winetech funded project 2019 - Despite recent advances, the measurement of phenolic compounds during the winemaking process still requires an analytical procedure that involves time, reagents, facilities and dedicated personnel. Due to this fact, the measurement of phenolics is almost absent or limited to a low number of frequencies in commercial cellars. A non-invasive fluorescence spectrometer could provide an efficient solution to measure phenolic composition during the winemaking process. The aim of the project would thus be to investigate the suitability of a fluorescence spectrometer for the quantification of phenolic parameters in wine. Fluorescence emission spectra will in this case be used to build prediction models for the quantification of phenolic composition during winemaking and ageing.

The quantification of phenolic compounds using fluorescence techniques has been widely acknowledged. The idea is to develop a special spectromete…

Cold, soak, whole cluster and stem additions in Pinot noir

By Karien O'Kennedy

The aim of the study was to investigate the chemical and sensory effects of cold soaking and the addition of whole clusters and stems to Pinot noir musts. 

Project layout:

Own rooted Pinot noir grapes from Mendoza were harvested in two consecutive vintages, 2014 and 2015, at 22.8°Brix and 25.2°Brix respectively. The 2014 vintage was much cooler than the 2015 vintage. In 2014 the experimental design consisted of four treatments: control (C), control + 20% whole clusters (C + WC), cold soak (CS) and cold soak + 20% whole clusters (CS + WC).In 2015 two extra treatments were added namely: 3% stems were added to control (C + S) and cold soak wines (CS + S), making it six treatments in total for 2015. Cold soaking was done for five days at 6.7°C on average.Control wines and controls plus either WC or S were all macerated for 10 days in total at 25.5°C on average. Cold soak wines, with and without additions, were macerated for 15 days in total. Wines were all fermented w…