Extraction methods significantly impact physicochemical, amino acid, phytochemical and textural properties of pumpkin seed protein concentrate in Nigeria

Abstract

The increasing interest in sustainable plant-based proteins has driven research into underutilized seeds like pumpkin. This study investigated the physicochemical (colour), functional (bulk density, water and oil absorption capacities, swelling power), phytochemical, textural, and nutritional properties (amino acid) of defatted pumpkin seed protein concentrate obtained using precipitation (PM), solubilization (SM), and aqueous alcohol wash (AM) methods. Analysis were conducted using standard methods. Results showed that protein concentrate varied significantly with the extraction method. AM produced the lightest isolate (L* = 58.25) with reduced redness and yellowness, while PM exhibited superior functional attributes: bulk density 0.69 g/mL, water absorption 2.84 g/g, oil absorption 2.00 g/g, swelling power 4.50 g/g, and enhanced retention of flavonoids (5.15 mg/g), alkaloids (2.10 mg/g), saponins (3.50 mg/g), and tannins (2.85 mg/g). Textural analysis revealed higher hardness (7.20 N), chewiness (40.10 N-mm), and resilience (0.50) in PM. Amino acid profiles confirmed higher essential (leucine 7.03 g/100 g, lysine 6.00 g/100 g) and non-essential (glutamic acid 11.99 g/100 g) amino acids in PM. Thus, precipitation extraction yielded protein concentrate with superior functional, textural, and nutritional qualities, highlighting its potential for use in fortified and functional foods.