Protein Production and Characterisation from Sengkubak Leaves (Albertisia papuana Becc.)

Abstract

Leaf protein concentrate (LPC) is among the rising trends in plant-based protein. Sengkubak (Albertisia papuana Becc.) leaves exhibit protein source potential for LPC development owing to their initial protein content of 21.53% on a wet basis (wb), as a low-fat flour. This study aimed to utilise sengkubak leaves for LPC production and characterise their nutritional, functional, and structural properties. Sengkubak leaf protein was isolated using alkaline extraction and isoelectric precipitation. The produced sengkubak LPC (SLPC) was analysed for its macronutrients, amino acid profile, antioxidant properties, bulk density, water-and oil-holding capacity, solubility, and structural properties. SLPC contained 45.25% protein (wb) with carbohydrate as the main impurity (44.50% wb). The amino acid profile demonstrated a notable cysteine content (chemical score of 136.67%) and umami amino acids (43.60%) with a taste-active value of 90.26. SLPC has functional properties resembling those of commercial lentil protein isolates, with comparable oil-holding capacity. Structural spectroscopy of SLPC resulted in the clear identification of amides A, I, II, and III. Overall characterisation suggested the potential of plant-based, oil-in-water emulsifiers with flavour-enhancing properties. However, process improvement and optimisation are still required to enhance properties in relation to functionality, particularly to improve appearance and maintain antioxidant activity.