Unravelling the Impact of Diverse Fermentation Techniques on Key Nutrient Absorption in Bambara Groundnut and African Yam Bean: A Review

Amid growing concerns about climate change and its potential impacts on food security and malnutrition, there is a need for climate-smart crops to help mitigate these challenges. African yam bean (Sphenostylis stenocarpa) and Bambara groundnut (Vigna subterranea) are considered climate-smart neglected or underutilised species (NUS) in sub-Saharan Africa (SSA). These legumes are rich in nutrients, comprising fats, carbohydrates, and protein, as well as essential micronutrients. However, their use is constrained by the presence of antinutritive factors (ANFs) such as oxalates, tannins, and phytates, which reduces mineral bioaccessibility and protein digestibility. Fermentation provides a cost-effective means of effectively reducing these antinutrients, thereby making these crops more mainstream due to their enhanced bioavailability and bioactivity. This review summarises the impact of diverse microbes and fermentation techniques on the bioavailability of essential nutrients in Bambara groundnut and African yam bean. The importance of pre-treatment steps such as soaking, germination, dehulling, and thermal treatment will also be discussed. By synthesising recent studies, the review explores the mechanisms by which fermentation degrades the ANFs, enhances nutrient bioavailability and improves protein digestibility from these crops. This review explores the pivotal roles of fermenting microbes, such as species of Lactobacillus and Bacillus, during the process of biotransformation.