Cassava leaves as an alternative protein source: Effect of alkaline parameters and precipitation conditions on protein extraction and recovery

Alternative protein sources have been required to meet the significant plant protein demand. Agro-industrial by-products such as leaves have considerable potential as a source of macromolecules once they are mostly discarded as waste. The current study evaluated dried cassava leaves as a protein source. First, alkaline extraction parameters (solid-liquid ratio, pH, and temperature) were optimized and the run that result in the highest protein yield were acidified at pH 2.5 or 4. The influence of carbohydrate solubilized on protein precipitation was also evaluated by removing it via alcoholic extraction prior to precipitation. The experimental design showed that high pH and temperature conditions associated with a low solid-liquid ratio led to increased protein yields. The presence of carbohydrates in the supernatant significantly influenced protein precipitation. The protein concentrate had around 17.51% protein when it was obtained from a supernatant with carbohydrates, while protein content increased to 26.88% when it was obtained from carbohydrate-free supernatant. The precipitation pH also influenced protein content, whereas protein content significantly decreased when pH increased from 2.5 to 4. The natural interaction between carbohydrates and proteins from cassava leaves positively influenced the emulsion stability index and the foaming capacity and stability. Thus, the presented results bring insights into challenges in extracting and precipitation proteins from agro-industrial by-products.