Biological properties of LMW-peptide fractions from apricot kernel protein: Nutritional, antibacterial and ACE-inhibitory activities

In this study, angiotensin-converting enzyme (ACE) inhibitory, antioxidant and antibacterial activities, and nutritional quality of low molecular weights (LMWs) peptide fractions (PFs) from apricot-kernel (Prunus armeniaca cv. Tabarzeh) with PFs <3, 3-10, 10-30 and 30-100 kDa were investigated. The ratio of essential to total (E/T) amino acids (similar to 34.5 %) and PER value (1.8-1.9) indicated the high nutritional and digestibility of peptide fractions. Antioxidant indices were affected by enzymatic hydrolysis, molecular weight (Mw) and concentration of peptides. In general, the highest inhibition of DPPH- (89.2 %), ABTS(+) (93.1 %), TEAC (2.52 mM), OH center dot (78.1 %), NO center dot (70.4 %), total antioxidant activity (2.01), reducing power (1.27), ACE inhibitory (75.1 %), chelation of Fe2+ (90.2 %) and Cu2+ (40.2 %) metal-ions were related to low Mw fractions (PF-3 and PF-10). The hydrolysates and primary protein showed enhanced antibacterial effects against Escherichia coli and Bacillus cereus with diameter of inhibition zones of 17 and 14 mm, respectively. Overall, apricot-kernel peptides can be considered as a nutrient source, natural antioxidant and preservative with ACE-inhibitory effect in dietary supplements and food formulations.