Processing Vernonia amygdalina Delile to Reduce Competition for Food Between Humans and Livestock

This study evaluated and endorsed optimal processing methods for Vernonia amygdalina Delile with the dual objective of producing a palatable, de-bittered vegetable (ndole) for human consumption and a nutrient-rich co-product (Vernonia amygdalina Wash-water-VaWW) for livestock feed. What distinguishes this study is its comprehensive, side-by-side evaluation of both edible and co-product streams from 21 debittering protocols, a level of comparative detail not presented in prior research. Nutritional values and antioxidant trade-offs are quantified for the first time across washing, abrasion, boiling, and potash-based methods. Twenty-one traditional processing methods from existing literature were first standardized under laboratory conditions and then scaled up to household conditions. Six most suitable methods—selected for their de-bittering effectiveness and efficiency—were subsequently evaluated for their impact on nutrient and antioxidant retention in both the final product and the wash-water. Results revealed a significant trade-off between processing time and nutrient retention. While Method 21 (heating with potash and water) was significantly (P < 0.05) the most time-efficient, requiring just 5 minutes to process 1000g of leaves, it resulted in significant (P < 0.05) nutrient and antioxidant loss in the final product. Conversely, Method 4 (ordinary abrasion until foaming stops) was found to be the superior (P < 0.05) processing method for nutrient retention. Method 4 consistently resulted in the highest retention of protein (content statistically similar (P > 0.05) to unprocessed leaves), Vitamin C, and minerals in the de-bittered ndole. Boiling methods (Methods 9 and 14) led to a greater loss (P < 0.05) of nutrients in the ndole but, consequently, produced VaWW with a higher nutrient content, confirming the transfer of these compounds from the leaves to the VaWW. In conclusion, this research identifies a superior processing method that maximizes nutrient retention for human food while simultaneously generating a valuable co-product for livestock. The utilization of Vernonia amygdalina wash-water as an animal feed additive provides a sustainable strategy to mitigate competition for this valuable food source. Policy adoption of abrasion-based protocols is recommended for communities prioritizing nutritional retention. Wash-water co-products should be promoted as sustainable livestock supplements, reducing feed costs and food competition.