Abstract
D.Tech. (Food Technology)
Drought and challenges related to climate change are some of the issues facing sub-Saharan Africa countries, with dire consequences on agriculture and food security. Due to this prevailing situation, drought and climate resistant crops like sorghum (Sorghum bicolor (L) Moench) can adequately contribute to food security. The versatility and importance of sorghum is well reflected in its use as a major food source for millions of people in sub-Saharan Africa. Recent interest in gluten free food products has equally positioned this crop as a potential substitute for wheat, with numerous studies attesting to this possibility. Although other food processing techniques for the transformation of these sorghum grain exists, fermentation is an important and dominant technique for processing sorghum into other food products particularly in the developing world. Porridge and gruels are commonly and usually consumed in developing countries. A form of this sorghum fermented food is ting, referred to as mabele, bogobe (when processed to hard porridge) or motogo (when processed to soft porridge). It is commonly consumed in South Africa, Botswana and other neighbouring Southern African countries. Although ting is conventionally processed using refined grains, the role of whole grain meals with regards to the provision of desirable health benefits is emphasized in recent literatures. Their composition yields better contents of bioactive, health promoting and beneficial compounds in subsequent products as compared to products from refined grains.
The composition of fermented foods depends on such factors as fermentation time and temperature, meaning that changes and choice of these conditions would influence the quality of the final product. Such differences in fermentation conditions would thus affect ting quality, necessitating an optimization of these conditions. Accordingly, a response surface methodology (RSM) optimization technique was employed in this study to optimize fermentation conditions of ting from two whole grain sorghum types: high tannin sorghum (Avenger) and low tannin sorghum (Titan). The effect of fermentation time and temperature on whole grain-ting parameters such as pH, titratable acidity (TTA), total viable bacteria count (TBC), total lactic acid bacteria count (TLABC), total fungal and yeast count (TFYC), tannin content (TNC), total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities (AA) was investigated. Scanning electron microscopy (SEM) was also used to investigate possible morphological changes in the samples during fermentation...