Enzymatic modification of cold pressed coconut meal protein: nutritional, functional and biological properties

Bioactive peptides (BPs) generated by hydrolysis of food proteins exhibit a broad spectrum of biological properties in both in vitro and in vivo models. In this research, variations in amino acid composition, solubility, emulsifying, foaming and water/oil-holding properties and antioxidant capacity of hydrolysates obtained from coconut meal protein (CMP) were investigated. The solubility of hydrolysates was significantly increased (P < 0.05) from 11% (in CMP at pH = 4) to 79.7% (t = 180 min, pH = 4). Emulsifying activity (EAI) and emulsion stability (ESI) indices of different hydrolysates ranged between 43.7 and 70.7 m² g⁻¹ and 38.7–82.7%, respectively at pH = 3–9. Primary CMP showed the lowest EAI, ESI, and foaming capacity at pH = 5 (near pI). Limited hydrolysis (t = 30 min) of CMP resulted in the highest water-holding (WHC, 6.0 g g⁻¹) and oil-holding (OHC, 5.0 g g⁻¹) capacities. Increasing hydrolysis led to a significant decrease in WHC and OHC values. The extent of hydrolysis significantly increased the amount of essential, antioxidant, hydrophobic, and negatively charged free amino acids in the hydrolysates. Generally, the antioxidant activity of CMP reached the maximum value (DPPH = 74.1%, ABTS = 64.5%, OH = 66.7%, reducing power = 0.87, total antioxidant = 1.29, Fe = 63.7% and Cu = 24.3% chelation) after 90 min of hydrolysis. Overall, improved techno-functional, antioxidant and nutritional indicators of CMP hydrolysates consider these polypeptides as natural sources of antioxidants in the food and pharmaceutical industries.