Satisfying Africa's sensory experience

Have you have ever thought about why people prefer one food to another? The obvious answer is the taste, but, if you think about it, the texture, sound, smell and appearance of food also play a fundamental role in our food choices. Together with taste, these four elements are known as the sensory properties of food.

Prof Riëtte de Kock, of the Department of Food Science and the Institute of Food, Nutrition and Well-being (IFNuW), has been involved in Sensory Food Science research since 1990. Over the years, Prof De Kock’s research has focussed on the food security issues facing sub-Saharan Africa, by applying sensory science to indigenous and locally relevant food sources, including cereals, legumes and animal types that are adapted to the African climate and that are potentially nutritious and affordable.  

One nutritional challenge facing developing Africa is urbanisation. On the one hand, this results in an affluent urban lifestyle, where people move away from traditional staples to variants that offer a more satisfying sensory experience. Unfortunately, such dietary changes have the tendency to cause lifestyle diseases, ranging from diabetes and cardiovascular disease to hypertension and obesity. On the other side of the spectrum, many poor urban households’ diets consist mainly of cereal-based porridges, which lack proteins and essential micronutrients. 

Prof De Kock’s team has responded by developing modern foods based on traditional African crops that are highly nutritious and locally available. A challenge the team has faced, however, is that, compared to modern alternatives, traditional African food products generally do not offer the same satisfactory sensory experience as modern foods do. African green leafy vegetables, for example, are rich in vitamins and minerals essential for growth and development, but often taste bitter. A well-growing food staple such as wholegrain sorghum is also nutritious but, because it tends to have a strong flavour and gritty texture, it is often substituted with more refined alternatives. Unfortunately, research shows that if food is not satisfactory in terms of its sensory properties, it will not be consumed, no matter how nutritionally beneficial it is. Food products therefore need to be not only adequately nutritious, but also appealing and appetising. To improve the sensory experiences of foods from these traditional crops, De Kock and her colleagues are using modern food technologies, such as extrusion cooking and micronisation, to develop food products based on traditional foods but that cater to modern tastes. For example, the team has developed new, composited cereal-legume products that have a higher protein content, such as porridges and snacks.

However, as De Kock notes, ‘Very little good scientific documentation of the sense properties of some of the traditional African food products is available.’ So, in order to create modern versions of these traditional foods, researchers have to spend time in rural communities accessing traditional recipes from the ‘gogos’ of the communities. The team also utilises facilities at UP’s Mamelodi Campus to reach a wider group of target consumers.

The UP team’s work has a multi-layered vision: first, it aims to improve the diets of African communities. Second, research focuses on developing ready-to-eat products and products that do not require much cooking time, so as to save the consumer time and the associated costs of high energy use. Furthermore, by developing modern foods made from locally relevant ingredients, the demand for produce from small-scale farmers will increase, in turn empowering and benefitting the farmers as well. This research team is certainly finding viable solutions to both the food and poverty challenges facing Africa.

De Kock and her sensory evaluation research team also assist leading food companies in the development of food products. A special laboratory, where a group of trained and experienced sensory panellists evaluate food products using standardised procedures, is a key part of the research. The Sensory Research Division at UP conducts contract research for the food industry, consults, and develops and presents short courses as part of Business Enterprises at UP (Pty Ltd.) (BE@UP).

Prof De Kock has a C2 NRF rating, with several postgraduate students under her supervision. She is also the author of numerous publications in international peer-reviewed journals, serves as the current Research Chair of the European Sensory Network (www.esn-network.com), and is a member of several internationally recognised bodies.

Researchers

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  Professor Riëtte de Kock

  Professor Riëtte de Kock completed her undergraduate studies at the University of Pretoria (UP) and has been doing research at the institution for 25 years. She says that research does not happen in isolation and that it is important to build a network of researchers in various parts of the world that can share knowledge and co-create ideas to solve modern-day problems.
  
  Prof De Kock conducts research to optimise the sensory properties of foods; this contributes to the nutrition status and well-being of consumers in sub-Saharan Africa. Her research involves gaining an understanding of the factors that impact consumers’ food choices by developing and applying suitable measurement instruments; food product development to meet the demands of a growing, more urbanised African population; and the exploration of Africa’s bio-diverse food sources to improve the nutritional value, appeal and taste of the products.
  
  Agricultural, biotechnological and nutritional food innovations require skilful consideration of the sensory aspects of food. Given a choice, all people prefer to eat tasty food that fit their culture, values and traditions. UP researchers like Prof De Kock scientifically listen to, look at, smell, feel and taste the products of their research efforts to build a more sustainable, food-secure future for people in sub-Saharan Africa.
  
  “Whether foods are produced and consumed in affluent or poor conditions, sensory food science can contribute to better understanding the reasons for acceptance or rejection of foods and help to anticipate long-term preferences,” say researchers Prof Erminio Monteleone and Prof Hely Tuorila, two scientists that Prof De Kock holds in high regard. In fact, at the 2007 Pangborn Sensory Science Symposium in Italy, a statement by these academics promoted Prof De Kock to refocus her research efforts. “Sensory scientists should do more to address the needs of the developing world,” they said. “Since that time, and more formally since 2018, Prof Tuorila has become a mentor and a role model to me and my postgraduate students,” says Prof De Kock.
  
  Prof De Kock collaborates with various research teams and colleagues in food, consumer and nutrition sciences. She is the project leader of a research team from UP and the University of Venda that is part of a project funded by the Long-term EU-Africa research and innovation Partnership on food and nutrition security and sustainable Agriculture (LEAP-Agri). The project – the title of which is Nutrifoods: Innovative Approaches to Value-Addition and Commercialisation of Climate-Smart Crops for Enhanced Food Security and Nutrition in Africa and Beyond – also includes Wageningen University & Research in the Netherlands, Uganda’s Makerere University, the Kenya Industrial Research and Development Institute and the Technical Research Centre of Finland. Various commercial entities are also involved, such as Bake Five in the Netherlands, two enterprises from Kenya and Uganda, and the Bakery and Food Technology Incubator of South Africa.
  The Nutrifoods project began in 2018 and will continue until 2022. It aims to develop novel gluten-free bread products where alternatives to wheat flour ¬– which African countries import at huge cost ¬¬– can be used. Target crops include sorghum, cowpeas and cassava. Manufactured foods such as bread made from imported raw materials like wheat flour are popular but limit local agricultural activity and subsequent economic growth. Success with this project could stimulate value addition all along the value chain and create employment for many.
  
  A research programme is also underway to develop instruments to segment food users in African countries (SA, Lesotho, Botswana, Uganda, Kenya and Ethiopia) in order to structure and apply healthy food intervention strategies. Common to all the countries is the rapid change of food consumption patterns. By understanding the factors that drive consumers’ food choices and preferences, researchers are better able to design acceptable food product options.
  
  Prof De Kock says a recent highlight was her participation in the Pangborn Sensory Science Symposium, which was held online. The first workshop that she participated in – Consumer Sensory Research in Africa: the Africa Country Profile Project – provided an opportunity to present the progress of this project to grow and develop the discipline of sensory and consumer science in Africa. She says that the quest to improve food security in Africa requires the involvement of researchers from various disciplines to investigate challenges from many perspectives. Understanding people’s attitude to food is part of the process.
  
  The second workshop was titled How to Create Inclusive Models for Sensory and Consumer Research. Prof De Kock presented research on challenges faced when testing food products with consumers of low socio-economic status in Africa. “Sensory and consumer scientists should work in symbiosis with nature and the research should leave a positive impact on society,” she says.
  
  Prof De Kock founded the African Network for Sensory Evaluation Research (ANSWER) in 2019 and is the current Chair. ANSWER was created to build capacity, and to transfer knowledge and skills in order to help sensory and consumer science researchers in African countries to adapt and apply global best-practice principles to the specific circumstances and challenges faced in Africa’s product value systems. “My dream is that my academic work and research endeavours will align food choice determinants with product development and intervention strategies to reduce food insecurity on the continent,” she says.
  
  Prof De Kock credits Prof Hildegarde Heymann – a Distinguished Professor and the Ray Rossi Endowed Chair in Viticulture and Enology at the University of California Davis, who is originally from Stellenbosch – for inspiring her career choice. Prof Heymann presented a short course on the sensory evaluation of food during a visit in 1994. “She has a special gift of transferring knowledge in a practical, meaningful manner, and that short course kick-started my research career,” says Prof De Kock. “Prof Heymann encouraged me to attend the Pangborn Sensory Science Symposium the following year in Davis, California. My participation in the event over the years has helped me to build an extensive international network of research colleagues.”
  
  Her research matters, she says, because while food products contain wonderful nutrients, if they are not appealing to consumers, then they have no value. Sensory scientists are part of the food product development teams who engineer the needs and preferences of consumers into acceptable food products. The look, feel and taste of foods provide key inputs for consumers and affect their choices, emotional responses and well-being. Food waste can be reduced if the shelf life of products can be optimised and positively contribute to enhanced food experiences.
  About her current students she has this to say: “Our students are the future, and it is vital for me to assist and empower them to carry on and expand the research that I was part of and which I had started during my career.” As for school learners and undergraduate students interested in her field, she advises them to use their senses and to heed the sensory properties of their food. “Develop a sensory language to describe what you see, hear, smell, taste and feel. I do not like routine; sensory science allows me to solve a variety of problems every day. It involves so many different aspects that I am constantly learning: I have to understand human physiology, the psychology behind food choices and consumer behaviour; the chemical, physical and microbiological properties of food ingredients; and the influence of processing and technology.”
  
  For recreation, Prof De Kock loves swimming because “so many muscles have to work simultaneously”. While she swims, she relaxes, thinks and plans her day. She enjoys travelling, and her research work has given her wonderful opportunities to travel, meet people and enjoy incredible experiences and adventures.
  

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  Satisfying Africa's sensory experience