The food microbiology theme focuses on the detection and identification of a diversity of microbial populations present in food products, including fruits, fruit juices, vegetables, cheese and other dairy products, cereals, meat and fermented foods. Traditional microbiological isolation and identification methods, as well as molecular techniques, are used to identify these microbes. Research is focused on spoilage microbes, food-borne pathogenic microbes and the microbes present during food fermentation (with a specific focus on milk fermentation), often using a non-culturing approach to ensure the detection of all viable, although often not culturable, microbes. (Prof P Gouws)
The environmental theme focuses on the impact of food processing operations on water usage, wastewater characteristics and treatment options. The application of anaerobic digestion technology and the use of ozone and other pre-treatment techniques to improve the efficiency of wastewater treatment systems are also researched.
Water wastage – either the excessive use of water or the unnecessary disposal of large volumes of polluted wastewater – has been a research focus for many years because South Africa is increasingly becoming water scarce, while its population is steadily increasing. Sustainable food production to ensure food security means that more food needs to be produced and preserved, despite ever-dwindling water resources. Therefore research on water minimisation in food processing, wastewater treatment and recycling, and energy recovery from waste and wastewater is becoming increasingly important. Sustainable food and beverage processing, especially in the Western Cape, is crucial for job security, as this sector is a major economic contributor in terms of foreign exchange and job creation.
The research done in the Department focuses on minimising the water used in food-processing environments, although much research is also done on treating various food-processing wastewaters due to the fact that food processing cannot really be done without generating some wastewater. Anaerobic digestion technology, which utilises bacterial consortiums to degrade the organic pollution in the wastewater to carbon dioxide and methane, is a focus of study. The methane generated in this way can be recovered and is a valuable energy source that can offset some energy expenditure. Ozone and other advanced oxidation processes, like UV, can be used as a pre-treatment to anaerobic digestion. A benefit of ozone use is that it leaves no chemical residue in the water.(Prof GO Sigge & Prof P Gouws)
The food safety theme researches the occurrence, identity, survival and control of spoilage and potential pathogens in the pre- and post-harvest processing environment of a variety of foods. Emphasis is placed on the impact of water quality on the safety of agricultural products.
The research focussed on investigating the links between irrigation water quality and food safety in commercial and subsistence agriculture. There is growing concern about the safety of agricultural produce that is consumed raw or after minimal processing. If irrigated products are contaminated by microbes they will affect the health of the consumer and have a negative impact on the country's national and international trading status. A better understanding of the presence, survival and decay rates of contaminating microbes is essential for the development of an efficient strategy that will assure the delivery of safe agricultural products to the local and export markets.
Our research over the last six years has shown clear evidence of poor-quality irrigation water and the risk of pathogens being carried over to agricultural produce. The health risks emanating from the use of such water are setbacks South Africa can ill afford in the present economic climate. The social consequences of the increased risk of disease are equally devastating, especially to the substantial proportion of the population living in poverty.
The success of the abovementioned national study has given rise to further funding from the Water Research Commission to do a scoping study on different on-farm treatment options to reduce the high microbial contaminant loads of irrigation water in order to reduce the related food safety risk. This project commenced in 2012 and will continue until 2016. (Prof GO Sigge & Prof P Gouws)
The vibrational spectroscopy theme focuses on the evaluation of bulk near infrared (NIR) spectroscopy and NIR hyperspectral imaging in conjunction with chemometric techniques for quantitative, qualitative and authentication studies of food and food products. NIR hyperspectral imaging research is possible at the Department due to researcher exchanges being funded by a South Africa-Sweden bilateral agreement. The work is done in collaboration with Prof Paul Geladi of the Swedish University of Agricultural Sciences (SLU).
NIR hyperspectral imaging is similar to taking a picture with a digital camera, which shows pixels and colours. In the case of hyperspectral imaging, however, each pixel is also linked to the sample's chemical composition, which provides a chemical map of the sample. This makes it possible to identify plant material that is visually similar but chemically different. Ongoing studies include the evaluation of the potential of NIR hyperspectral imaging to distinguish between different maize kernel hardness categories, as well as the detection of fungi on whole maize kernels before they are visible visually. This work has been extended to also include X-ray micro computed tomography which is performed in collaboration with Dr Anton du Plessis (CT-Scanner, Central Analytical Facility). (Prof M Manley & Dr P Williams)
Between 25 and 33% of the total gross value of agricultural production in SA is from grain. The quality of grain determines profitability; hence economic growth requires the improvement of cereal cultivars. The improvement of quality monitoring is achieved through the optimisation of existing methods and the implementation of new techniques.
In the cereal quality theme we aim 1) to develop greater understanding of the underlying factors determining cereal quality parameters, and 2) to develop rapid methods for the early identification of superior breeding lines. Cereal quality research projects are funded by the Winter Cereal Trust. The trust also supports students by providing grants for students working on cereal-related topics.
(Prof M Manley & Dr P Williams)
Within the sensometrics theme, which entails mathematical and statistical methods of analysis, research projects are usually multidisciplinary: chemical, sensory and physical attributes of food products are correlated.
In experimental sensometric studies, three pieces of information need to be linked to each other: information about the samples tested (sensory or extrinsic product attributes), consumer liking of the same samples (liking, choice or ranking) and additional information about the consumers (demographics, attitudes and habits). In this regard, fruitful research collaboration was established in 2013 between SU and Prof Tormod Næs, principal statistician at Nofima, an international food research institute in Norway. This collaboration resulted in novel research in which residual analysis was performed on preference data, resulting in new insights into the analysis of consumer preference data, as well the establishment of a new research project focussing on the development of rapid sensory profiling methodologies. (Ms Nina Muller)
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