Abstract:

By using single factor and orthogonal array designs, the optimized hydrolysis conditions of whole apricot kernel employing papain for improved degree of hydrolysis were obtained as hydrolysis temperature of 50 ℃, initial pH of 7.0, hydrolysis time of 8.0 h, and enzyme concentration of 6.0%. Under these conditions, the maximum experimental value of hydrolysis degree of 26.43% was achieved, agreeing with the predicted value of 27.85%. This paper also reports on the antioxidant activity and α-glucosidase inhibitory effect of the enzymatic hydrolysate. The scavenging rates of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), superoxide anion radical (O2-·), and hydroxyl radical (·OH) with the hydrolysate at a concentrationof 10.00 mg/mL were 50.44%, 65.22% and 22.78%, respectively. When the concentration increased to 160.00 mg/mL, the absorbance value for reducing power was 1.072. Four peptides extracted from the hydrolysate were separated by ultrafiltration as ≤ 5, 5–10, 10–30 and ≥ 30 kD. The inhibitory rates of α-glucosidase by the four peptides at 10.00 mg/mL were 3.65%, 4.43%, 7.94% and 10.00%, respectively. Then, the peptide fraction with molecular weight less than 5 kD, the most active against α-glucosidase, was further separated into three components by gel filtration chromatography, with inhibitory rates on α-glucosidase of 11.52%, 10.65% and 9.67%, respectively. The results showed that the peptides derived from enzymatic hydrolysate of whole apricot kernel have good antioxidant activity and α-glucosidase inhibitory effect in vitro, exerting improved health-protective effects than native apricot kernel.

Key words: whole apricot kernel, functional food, papain, response surface methodology, antioxidant activity, α-glucosidase inhibitory activity