Optimization of Protein Extraction from Red Lima Bean (Phaseolus lunatus L.) and Its Application as a Binder in Chicken Nuggets

Abstract

Red lima bean (Phaseolus lunatus L.) is an underutilized legume that is well adapted to marginal environments and possesses high nutritional value. However, its application remains limited due to the presence of antinutritional compounds, particularly hydrogen cyanide (HCN). This study aimed to optimize protein extraction from red lima beans and to evaluate the functional performance of the resulting protein concentrate as a binder in chicken nuggets. Protein extraction was optimized using alkaline solubilization followed by isoelectric precipitation. A soaking pre-treatment for 24 h reduced the HCN content to 6.40 ppm. Optimal extraction was achieved at pH 10, with subsequent precipitation at pH 4, yielding a protein concentrate containing 49.32% protein. The functional properties of the protein concentrate were evaluated through partial to full substitution of soy protein isolate as a binder in chicken nuggets. In addition, physicochemical and sensory properties were analyzed. The results demonstrated that red lima bean protein concentrate exhibited effective binding functionality in chicken nuggets. A substitution level of 50% (w/w) with soy protein isolate resulted in the highest sensory acceptance without compromising product quality. These findings highlight the potential of red lima bean protein as a sustainable and functional ingredient in meat products, supporting the valorization of underutilized legumes and the development of alternative plant-based binders.