Nutritional, functional, biological and antibacterial properties of wild pistachio (P. khinjuk) nuts peptides

Pistachio khinjuk is a rich and high-quality source of protein. This work aimed to investigate the characteristics of P. khinjuk protein (PKP) and P. khinjuk protein hydrolysates (PKPHs), prepared by application of different proteases (pepsin, alcalase, pancreatin, trypsin), in terms of structural, nutritional, functional, biological and antibacterial properties. Amino acids analysis showed the occurrence of antioxidant (16%), hydrophobic (36%) and essential (41%) amino acids in the obtained hydrolysates with a protein efficiency ratio of 1.75. Compared to PKP, all hydrolysates exhibited the highest antioxidant activity in terms of DPPH (55.57–64.2%), ABTS⁺ (70.87–89.93%), nitric-oxide (21.6–35.13%), hydroxyl (45.43–59.3%) radicals scavenging, reducing power (0.99–1.38), total antioxidant (1.01–1.34) and Fe²⁺ (27.7–39.23%) and Cu²⁺ (9.83–17.63%) chelating activities. PKP showed the highest antibacterial activity against Escherichia coli and Bacillus cereus with diameter of inhabitation zones (DIZ) of 11.2 mm and 22.7 mm, respectively compared to that of PKPHs. Among the hydrolysates, pepsin hydrolysate, however, had the most enhanced antibacterial activity against E. coli and B. cereus with DIZ of 10.3 mm and 34.0 mm, respectively. Considering the appropriate nutritional, functional, antioxidant and antibacterial properties of PKP and PKPHs, their application as food supplement could improve health-promoting and nutritional properties of foods.

Graphical Abstract