There were four full-time staff members of the Faculty of AgriSciences at the University of Stellenbosch among the group of 30 students in the faculty who received doctorates.  They are: Dr Marianne McKay, oenologist; Dr Jan Greyling, agricultural economist; Dr Jeanne Brand, expert in the sensory qualities of wine, and Dr Phillip Crafford, wood production scientist.

During the 2018 academic year (which includes December 2018 and April 2019) 45 doctorates were awarded in the field of agriSciences – a new record for the faculty.

This week, 184 students from the Faculty of AgriSciences graduated. Of these, 46 successfully completed master’s degree studies in various fields.

Timber as a sustainable building material

Dr Phillip Crafford, a lecturer in the department of forest and wood science, received a PhD in wood product science by comparing the environmental sustainability of certain building practices in South Africa. Dr Crafford found that timber and other wood-based construction generally has a far lower environmental impact than buildings that use cement, brick and steel. “Our green building rating tools do not sufficiently reflect the well-documented environmental benefits of using wood,” said Crafford.

He hopes that prospective South African homeowners will increasingly turn to timber as the preferred green building material, as it is a renewable resource. Crafford regards timber building as a way for households to reduce their dependency on fossil fuels, and to reduce global warming in general.

Maize politics and history

Dr Jan Greyling of the department of agricultural economics reviewed the development of South Africa’s maize industry during the 20th century, focusing on how changing policies have shaped the industry.

“During the 20th century, changes in agricultural policies had a definite influence on the production and productivity of maize farming in the country. It influenced where people decided to grow maize,” said Greyling.

Between the 1940s and the 1980s, favourable policies stimulated an expansion in maize production into relatively lower yielding marginal production areas in the Western Free State and North West province.

“This spatial reallocation of production lowered productivity but investments in improving plant material, farming practices and infrastructure increased the suitability of the drier production areas,” he explained. “It enabled production to remain in some of the marginal areas after the supportive policies were removed. “

The influence of smoke taint on red wines

Dr Marianne McKay of the department of viticulture and oenology has lectured to prospective winemakers at Stellenbosch University since 2007 and has been commended as a scholar and a teacher.

Given the frequency, scale and financial implications of veld fires in the traditional wine regions of the Cape in recent years, the subject of her PhD is topical.

If wines are produced from the grapes of vineyards that have withstood veld fires, the grapes absorb certain compounds from the smoke, and these may cause off-odours, or the so-called smoke taint, in the wine. In her sensory study, McKay looked at how these compounds interact to produce olfactory effects, or smell, in red wine.

“This sensory information helps to clarify the effects on the wine’s aroma that cannot be understood if the wine is only analysed chemically,” McKay said.

She hopes her findings will help winemakers with their decisions on whether to use smoke-affected grapes, and will increase awareness of these issues in the wine industry.

Sensory profiles of wines

Dr Jeanne Brand manages the sensory laboratory of the department of viticulture and oenology, and regularly guides sensory tasting panels through their work.

Brand said wine was not easy to describe because of its complexity. She compared four rapid methods that sensory panels commonly used to test and describe wines and evaluated each method in terms of its cost-effectiveness and usefulness to the industry and to research.

“It’s important to choose the right wine profiling method, based on the experiment you want to do,” she said. “One must also weigh up each method’s practical limitations.”

Her findings highlighted two methods that help tasting panels to best distinguish between products: the CATA method and sorting.

The CATA (check-all-that-apply) method gives a list of attributes to people who serve as judges on sensory tasting panels. They must then make their choices accordingly. The sorting method gives all the products to a tasting panel; members must then sort them according to the differences and similarities between the products in terms of sensory properties such as taste and aroma. – Press release