Contents

• Research and focus areas
• Publications

Research and focus areas

The main objective of the research activities within the DVO is to contribute to enabling the South African industry to produce wines and vineyard products of a high quality with the aid of environmentally friendly technology in the most cost-effective manner. Industry-linked research that can be implemented by means of technology transfer to the industry is undertaken at all times.

Research activities according to the niche fields of the academic staff of the DVO, as well as the Institute for Wine Biotechnology, are as follows:

# Involved in both the DVO and Institute for Wine Biotechnology (IWBT)
* From the IWBT

Viticulture

Dr Albert Strever

Specialisation:   Grapevine cultivation
Focus area:        Plant management and remote sensing
His research is focused on the use of remote-sensing technology for monitoring variability in vineyard blocks. He also manages projects on climate and GIS studies for grapevine, as well as a study on alternative vineyard practices for optimising yield and grape composition for specific price points. Previous work includes a PhD study on non-destructive assesment of leaf composition (structure and pigment content) for Shiraz

Prof Alain Deloire

Specialisation: Ecophysiology of grapevine berry composition
Focus area: Grapevine physiology and berry ripening
Managing harvest potential of grapes to obtain a desired wine style is complex. The first step requires a scientific understanding of grapevine functioning in its environment (mainly in relation to influences of light, water, temperature and wind). Physiological and biochemical studies with regards to the plant’s source-sink relationships and the dynamic of berry development and ripening enable us to develop a comprehensive understanding that assists in the definition of practical rules for vineyard management. Decision-making tools and indicators of plant functioning which are derived from research, are necessary to help professionals to make a decision at vineyard level.

Prof Kobus Hunter

Specialisation: Grapevine physiology
Focus area: Grapevine cultivation and metabolism
Research is aimed at the integration of grapevine physiology, cultivation, and grape and wine quality. The main field of interest is the study of vine physiology, particularly the understanding of source:sink ratios (communication and control), canopy and root system dynamics, and grape development and composition, and the interaction of these with short- and long-term cultivation practices and the environment (climate, soil, topography). Focus is on the establishment of practically applicable principles to improve grape and wine quality and obtain different wine styles. The improvement of plant material and the effect of cultivation practices and the environment on that also receives attention.

Dr Pieter Raath

Specialisation: Table grape production
Focus area: Table grape cultivation and nutrition
Research addresses aspects relevant to the table grape industry. The focus falls on improving table grape quality and levels of production. Investigations into the physiological development of Thompson and Red Globe berries are conducted. The aim is to understand the factors promoting crispy grape berries and to incorporate them in a vineyard management strategy. The impact of gibberellic acid applications on vine fertility and the physiology of berry colour development are also being addressed.

Mrs Erna Blancquaert

Specialisation: Ecophysiology of grapevine berry composition
Focus area: Berry ripening
Research addresses the environmental factors that have a significant impact on wine grape composition and quality. Research are currently being conducted on the influence of abiotic factors (light,temperature) on tannin and phenolic development in the berry and the mouthfeel characteristics of the wines.

Mrs Anneli Bosman

Specialisation: Grapevine architecture and alternative trellis systems
Focus area: Alternative grapevine trellis systems and sustainable practices
Her research is focused on the use of alternative trellis systems in order to optimise productivity in vineyards whilst preserving or improving grape quality, relative to a specific production goal and price point. This involves observing the vine’s compensation mechanism in reaction to the modification of its balances. Sustainable practices which includes the altercation of grape vine architecture in order to be amongst other more environmentally friendly and cost effective, whilst improving product marketability is also investigated.

Grapevine molecular biology and biotechnology

Dr John Moore

Specialisation: Grapevine biochemistry and metabolism
Focus area: Grapevine biotechnology
His research area forms part of the Grapevine Biotechnology Programme (within the framework of the NRF-supported Wine Science Research Niche Area (RNA)) of the IWBT in collaboration with Professor Melané Vivier. The goals of the programme are to improve the disease resistance, fruit quality and abiotic stress (i.e. drought) tolerance of Vitis vinifera (grapevine) cultivars utilising transgenic technology. His specific research aims are to understand the biochemical and metabolic aspects of berry development, plant pathology and abiotic stress tolerance in grapevine, with a focus on the role of the cell wall. He also maintains an interest in the chemistry and biology of plant polyphenols, with particular reference to their functional significance in planta as well as being key constituents of grapes and wine.

Prof Melané Vivier

Specialisation: Grapevine molecular and cellular biology
Focus area: Biotechnology product development and molecular biology of grapevine stress
Her research programme is focused on the biology of grapevine (Vitis vinifera). The genetic potential and molecular mechanisms underlying V. vinifera's reaction towards some of the biotic and abiotic stresses typically appearing in vineyards are studied. Two main themes form part of the programme: (i) Understanding and manipulating disease resistance and (ii) Metabolic engineering of grapevine towards enhanced abiotic stress resistance and improved quality parameters. The programme is supported by grapevine transformation and regeneration technologies, basic molecular biology and some systems biology technologies and an increasing list of analytical methods to evaluate grapevine and model plant tissues.

Dr Philip Young

Specialisation: Grapevine molecular biology and biotechnology
Focus area: Molecular biology of grapevine, with the focus on carotenoid biosynthesis
The main focus of the grapevine biotechnology research programme is on the development of genetically improved grape cultivars with outstanding fruit quality, reduced susceptibility to diseases, pests and other stress conditions, and an increased nutritive value (in the case of table grapes). The specific focus of this research is the contribution of the carotenoid biosynthetic pathway to these aspects of grape quality, especially with reference to their role in flavour and aroma development and abiotic stress tolerance.

Oenology and wine biotechnology

Prof Florian Bauer

Specialisation: Wine biotechnology
Focus area: Molecular and cellular biology of yeast
His research is focused on the yeast Saccharomyces cerevisiae and other wine-related yeast species, and investigates the molecular processes that regulate gene expression, carbon flux (ethanol yield and transfer of activated acyl residues), aroma compound production and cellular adhesion properties. The research projects make use of all standard microbiological and molecular biology techniques, as well as genomics-, transcriptomics- and metabolomics-based approaches. Insights gained from these projects are applied to improve wine yeast strains through the use of traditional breeding, mutagenesis, directed evolution and genetic engineering.

Dr Benoit Divol

Specialisation: Wine microbiology and biotechnology
Focus area: Enzyme production by wine yeasts; molecular biology of lactic acid bacteria; interactions between microorganisms
His research focuses on three main fields: enhancing enzyme production by wine yeasts, understanding microbial interactions in order to control spoilage, and understanding the positive contribution of wine lactic acid bacteria during malolactic fermentation. The addition of enzymes has become a common step during the winemaking process. We aim to unravel and enhance the production of enzymes by Saccharomyces cerevisiae or other wine yeasts during alcoholic fermentation by means of genetic engineering tools or co-inoculation. Malolactic fermentation is a major step of the winemaking process, even though it remains poorly understood. Moreover, most of the starter cultures used by the winemakers are not adapted to South African wines. We aim to understand the influence of South African conditions on the efficiency of malolactic fermentation and the production of aroma compounds by Oenococcus oeni . Another aspect of the work is to understand the dominance of Oenococcus oeni and Lactobacillus plantarum after alcoholic fermentation through their potential production of bacteriocins.

Prof Maret du Toit

Specialisation:   (i) Wine microbiology (oenology) and (ii) wine biotechnology
Focus area:        (i) Lactic acid bacteria, microbial spoilage and MLF and (ii) Molecular biology of lactic acid bacteria
Microorganisms form an integral part of the winemaking process and can have a positive or negative influence on wine quality. Lactic acid bacteria (LAB), especially O. oeni, are responsible for malolactic fermentation in wine. Apart from performing this fermentation, they can also contribute to wine aroma compounds that will improve wine quality. The focus is on the following enzymes; ß-glucosidases, esterases, citrate lyase, proteases and phenolic acid decarboxylases. LAB is also regarded as a spoilage microorganism and the focus is on bitterness, biogenic amines and volatile sulphur compounds. LAB also produce bacteriocins, which are investigated in terms of being used as an alternative to chemical preservatives.  Research is currently being conducted on the omics of wine LAB, especially the metabolome produced by commercial MLF starter cultures. Furthermore, infrared spectroscopy is evaluated as a rapid tool with which to identify wine microbes

Dr Wessel du Toit

Specialisation: Wine chemistry
Focus area: Wine ageing, oak aroma, wood and phenolics, oxidation
The changes undergone by red wines in wooden barrels change the style and taste of the wine, as well as its quality. Research is currently being conducted to determine the effect of this on red wine, as well as to find alternative wood maturation products. Micro-oxygenase, whereby small quantities of oxygen are added to the wine to hasten desirable polymerisation reactions, is closely related to this. Oxygen additions to red wine at different winemaking stages are also investigated. Fundamental oxidation reactions between O2 , SO2 and phenolics are investigated, and this will support the more applied research. The phenolic composition of different vineyard blocks, and how this reflects in the corresponding wines, is looked at. This will provide a large database for the colour and phenolic development of South African wines. Reductive and oxidative treatments of Sauvignon blanc juice is also investigated.

Mrs Marianne McKay

Specialisation: Wine chemistry,  teaching methodology
Focus area: Wine aroma, faults and sensory evaluation. Service learning in the wine industry, graduate attributes and other teaching research.
Previous research focused on identifying and quantifying white oakwood aroma compounds. The present series of projects focuses on contamination of wine by environmetal pollutants and sources of taint in wine.  Also involved in research into the use of service learning and internships,  in order to enhance professionalism, employability and ‘graduate attributes’ in our students.

Prof Pierre van Rensburg

Specialisation: Wine biotechnology
Focus area: Molecular biology of yeasts
Wine yeasts ( Saccharomyces cerevisiae ) cannot degrade/utilise polysaccharides and certain grape must proteins and are also not able to destroy contaminating spoilage organisms. For these reasons, most winemakers add enzyme preparations (pectinases, glucanases, hemicellulases, proteases) and bentonite to remove filter-blocking, polysaccharide-rich particles and haze-forming proteins from the must, as well as chemical preservatives to prevent wine spoilage. However, these practices are cost-ineffective, time-consuming and contrary to the principle of environmental friendliness. Therefore, attempts are made in this laboratory to isolate new yeasts, prepare mutants and generate hybrids that will secrete these polysaccharide-degrading enzymes during fermentation. In addition, heterologous pectinase, cellulase, xylanase, protease and chitinase genes are cloned from other microorganisms, manipulated and then expressed in wine yeasts. In all of these projects, sophisticated recombinant DNA techniques are finely interwoven with the strong genetic system of S. cerevisiae in the search for answers to questions in basic biology, but also with the aim of establishing industrially applicable and improved processes.

Mr Riaan Wassüng

Specialisation: Cellar technology
Focus area: Winemaking and wine apparatus
He is responsible for the basic management operations and maintenance of the Welgevallen Cellar, including the production and ageing of wines for the Department and for third-party (external) clients. He is involved in the education of under graduate students and providing assistance to postgraduate students regarding cellar technology and wine practices. Assistance is given to research projects conducted at Welgevallen Cellar (e.g. micro-oxygenation (doctoral project) and barrel ageing experiments (undergraduate)).

Analytical chemistry

Prof Marius Lambrechts

Specialisation: Analytical chemistry
Focus area: Advanced chemical-analytical techniques in viticulture, oenology and biotechnology
His research focuses on the optimisation of the brandy process. This includes the study of the aroma components as well as the corresponding sensory quality. The effects of cultivar, time of harvesting, yeast strain and the age of the barrels used for maturation are investigated. This information is used to determine which of the above factors are important to quality. Lastly, the project attempts to determine which aroma compounds are important and to explain stylistic differences. Further research looks at the optimum ripeness of Cabernet Sauvignon grapes in relation to wine quality. This project focuses specifically on the development of phenols as an indicator of optimum ripeness. Various other parameters are also investigated.

Dr Helénè Nieuwoudt

Specialisation:   Biospectroscopy, bioprocess monitoring and chemical, sensory and consumer preference profiling of  wine
Focus areas:    (i)    Application of infrared spectroscopic techniques in viticulture, oenology and biotechnology, as well as monitoring of bioprocesses. (ii) Chemical, sensory and consumer preference profiling of wine, with particular focus on the effect of winemaking techniques on wine quality.
Her research focuses on both the quantitative and qualitative profiling of grape and wine composition

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Publications

Publications 2007-2011

See complete list here

Publications are currrently being updated.

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