Towards healthier staples: Yellow cassava pasta fortified with African leafy vegetables

Hidden hunger, due to regular consumption of a diet deficient in micronutrients, may persist unabated, especially in low-and-middle-income countries of the world, unless more attention is focused on developing healthy and nutritious foods to alleviate the burden. Several nutritional interventions have been implemented for decades but one of the most sustainable food-based solutions proffered in recent times is the twin-strategy of biofortification and food-to-food fortification. In response to the challenge of combating hidden hunger, the yellow cassava biofortified with pro-vitamin A carotenoids was introduced to sub-Saharan Africa. However, yellow cassava is still low in minerals such as iron and zinc, hence the need to incorporate micronutrient-rich and affordable food ingredients such as the African leafy vegetables. To ensure an adequate intake of the much-needed micronutrients, we developed pasta, a widely consumed, healthy and affordable food product with the yellow cassava with two leafy vegetables, amaranth and fluted pumpkin incorporated. The increasing demand by consumers for gluten-free pasta as a functional food also focused attention on cassava as a gluten-free ingredient. This thesis, therefore aimed at evaluating the nutritional, sensorial, technological and functional aspects of the novel vegetable fortified yellow cassava pasta to gain more insights into its contribution to a healthier living for the consumers.

In Chapter 2, using consumer survey focus group discussions and sensory studies, we evaluated the acceptance of yellow cassava pasta and African leafy vegetables. We found the main driver of intended consumption among the consumers in Nigeria to be related to health concerns. Also, yellow cassava pasta was acceptable to the consumers while fluted pumpkin (Telfairia occidentalis) was the most preferred leafy vegetable followed by amaranth. The low awareness of yellow cassava among the consumers was also highlighted with solutions proffered to boost awareness of the nutritional benefits of the novel food product. The findings of this study highlighted a need to conduct experimental studies on the nutritional composition of the novel pasta products to ascertain the health benefit to consumers.

The main focus of Chapter 3 was to ascertain the nutritional value of the novel cassava pasta product. We conducted experiments to gain insights into the nutritional and functional properties of the cassava- vegetable pasta before and after being processed. We found that the incorporation of amaranth leaf powder boosted the antioxidant capacities of pasta products while the cooking time and gruel solid loss were also reduced upon the addition of the leaf powder. Furthermore, the protein, fibre, iron and zinc contents of the formulated pasta were enhanced with the addition of amaranth leafy vegetables. 

As a follow up to the study in Chapter 3, another popular leafy vegetable, fluted pumpkin was used in food-to-food fortification of yellow cassava pasta in Chapter 4. We conducted experiments on both the white and yellow cassava flours and pasta to evaluate the functional, textural, pasting, thermal, cooking and sensory properties of the novel pasta with the inclusion of fluted pumpkin leaf powder. We found that the inclusion of the leaf powder reduced the cooking time and hardness of cassava pasta products. Also, the pasting temperatures were lowered with leaf powder incorporation. Interestingly, we observed that the provision of nutritional information enhanced the likeness of the leaf powder-fortified cassava pasta products.

In Chapter 5, we focused on the nutritional value of both Amaranth-fortified and fluted-pumpkin-fortified yellow cassava pasta highlighting the added health benefits of the gluten-free cassava pasta. We conducted in-vitro studies to evaluate the impact of leaf powder addition (amaranth and fluted pumpkin leaves) on the retention and bioaccessibility of beta carotene, iron and zinc in the pasta and the impact on the starch digestibility and in-vitro glycemic index of the functional pasta. We found that the estimated glycemic index of yellow cassava pasta was reduced with the inclusion of the leaf powder while the zinc was found most bioaccessible. Also, the functional pasta was estimated to contribute a substantial percentage to estimated average requirements for vitamin A, iron and zinc.

Chapter 6 provided the rundown of all the results presented in the previous chapters and put them into perspective with similar works from literature while enumerating prospects of the novel gluten-free cassava pasta. We demonstrated the potential of the functional food to alleviate micronutrient deficiencies.