Research by Dr Clarity Ropafadzo Mapengo, who recently graduated from the University of Pretoria (UP) with a PhD in Food Science, has found that infrared energy can be used to make starch in foods like maize meal less digestible, thereby promoting satiety and potentially decreasing the risk and incidence of diabetes and obesity.
“Communities that are threatened by such diet-related diseases are often encouraged to shy away from staple foods [like pap] in an attempt to stay healthy,” Dr Mapengo explains. “[My research] shows the potential of green technology in improving the nutritional quality of starchy foods, such as maize meal, so that its consumption does not promote such lifestyle diseases.”
In her doctoral thesis, titled ‘Nutritional, structural and functional properties of infrared heat-moisture-treated maize starch and maize meal with added stearic acid’, Dr Mapengo maps out how infrared heat-moisture treatment promotes the formation of new crystallites, which are less digestible and therefore release glucose slowly into the bloodstream. Essentially, people can eat smaller portions and feel satisfied for longer.
Dr Clarity Ropafadzo Mapengo is continuing her journey as a postdoctoral researcher in UP's Department of Consumer and Food Sciences, working on developing functional foods and ingredients using indigenous grains.
“The modified starch has the ability to bulk foods, increase viscosity in the stomach and ferment in the gut,” Dr Mapengo explains. “This means that when one consumes starchy foods, due to the increased viscosity, there will be a slower gastric emptying, which may, in turn, slowly release glucose into the bloodstream, thereby reducing satiety hormonal response and leading to lower energy intake over the course of the day. This aids in compliance with healthy eating and weight management strategies, by lessening the effect of hunger sensations. The infrared treatment makes normal starch behave more like dietary fibre [in that it becomes less digestible].”
Starch modified in this manner could also help to balance gut flora and has the potential to decrease the risk of colon cancer.
Dr Mapengo says the modifying treatment is 100% safe because it is done using green chemistry/technology. “There is no addition of synthetic chemicals – the stearic acid added is a naturally occurring saturated fatty acid – so the food and ingredients developed using this treatment can be classified as ‘clean label’. The infrared energy that is used is classified as mid-infrared, which does not promote the formation of free radicals in food and is therefore safe. Also, no chemical effluent is produced during the modification process, meaning it is safe for the environment too.”
Communities in the sub-Saharan region, she says, are the immediate beneficiaries of this modification process, “as our staple food is a high-GI starchy food (pap). Consumers from communities with diets that are rich in starch are most likely to benefit from the low-GI starchy foods developed by the treatment. Following a low-GI diet can improve blood sugar control in people with type 2 diabetes. Overall, slowly digestible and resistant starch benefits everyone in promoting good health and well-being.”
Dr Mapengo is grateful for the mentorship of Professor Naushad Emmambux of UP’s Department of Consumer and Food Sciences, and to Prof Sinha Ray of the Council for Scientific and Industrial Research’s National Centre for Nano-Structured Materials.
She continues her journey as a postdoctoral researcher in the department, working on developing functional foods and ingredients using indigenous grains.
“My parents taught me that the most significant achievement in life is not just attaining education or science, but rather making that education or science contribute towards improving lives,” she says.