Production of leaf protein concentrates from cassava: Protein distribution and anti-nutritional factors in biorefining fractions

Nowadays, cassava leaves are mostly treated as a byproduct of cassava root production, yet this readily available biomass is rich in protein with a balanced content of amino acids. Cassava leaves therefore represent a promising, underutilized biomass for extraction of proteins. The purpose of this study was to provide updated information on the feasibility of producing cassava leaf protein concentrate for use in feed and food. In this context, protein concentrates were refined from cassava leaves using different precipitation methods and the refining process evaluated with focus on protein, amino acids and selected antinutritional factors. Crude protein was mainly distributed to the press cake and protein concentrates during the two processing steps, i.e., pressing and precipitation, and between 21% and 26% (w/w) of leaf crude protein was recovered in the concentrates. After drying, these contained 40–45% crude protein with an amino acid profile comparable to soybean and tolerable levels of tannins (>1% of TS) for feed purposes. However, the refining process did not significantly reduce the cyanogenic potential, i.e., the total amount of releasable HCN, which accumulated in the dried protein product to around 150–250 ppm. This lies significantly above the 10–50 ppm deemed safe for food and feedstuff by several food safety authorities. Based on these results, extraction of leaf protein from cassava appears promising, but additional research is required to evaluate its full potential, especially in relation to its use in food products.