Influence of processing and structure on the digestibility of Bambara groundnuts (Vigna subterranea (L.) Verdc)
A wide variety of legumes have been cultivated by humans for thousands of years. Today, legumes increasingly continue to form an essential part of the human diet as they provide a rich source of nutrients including proteins, carbohydrates, minerals and some vitamins. In addition, they provide appreciable amounts of dietary fibre and bioactive compounds which improve human health. An example is the Bambara groundnut (Vigna subterranea (L.) Verdc) which is one of the important legumes in sub-Saharan Africa. From a macronutrient point of view, Bambara groundnut contains on average about 63% carbohydrates, around 20% protein and about 7% of oil.
Although they possess a good nutrient profile they are an underutilised crop partly because of the long hours required for their cooking due to the described “hard to cook” phenomenon, which develops when storing the dry pulse grain as a function of time at ambient temperature. It is known that a range of structural changes are linked to the development of the hard to cook phenomenon in pulses. However, this phenomenon has not been mechanistically documented for the case of Bambara groundnut.
It is generally known that the food matrix structure may positively or negatively influence the digestibility and bioaccessibility of nutrients. For instance, some digestive barriers (e.g. antinutritional factors; intactness of the plant cell wall; physical state of the polymers) contribute to the particular digestibility of the proteins and hinder minerals from being absorbed in the body. Processing can be used to tailor food structure in various ways and can either promote or hinder the digestibility of the nutrients.
The objective of this work is twofold: (i) to obtain mechanistic insight in the development of hard to cook in Bambara groundnut; (ii) to investigate the influence of processing and food structure on the in vitro digestibility of macronutrients (protein and starch) and micronutrients (minerals) in Bambara groundnuts and derived food products.