Abstract: Intact Chinese chestnut kernels were enzymatically hydrolyzed to develop functional products with antihypertensive and antioxidant activities. Enzyme screening was investigated for different purposes. Papain could result in higher short-chain peptide yield and degree of hydrolysis (DH) than other five proteases investigated. A higher short-chain peptide yield was obtained by papain + α-amylase than papain + pullulanase and papain alone. Compared with papain alone, the combination of papain and each of the other five proteases increased the DH of Chinese chestnut kernels, especially in combination with Flowryme. Improper protease amount was unfavorable for the hydrolysis of Chinese chestnut kernels. The appropriate amount of α-amylase was 0.35 g/100 mL hydrolysate. The appropriate ratio of papain to Flowryme was 2:1 (m/m). The DH of Chinese chestnut kernels was 26.27% and the short-chain peptide yield was 43.62% under the following hydrolysis conditions: protease amount of 8000 U/g protein, hydrolysis temperature of 55 ℃ and hydrolysis time of l5 h. The resultant hydrolysate exhibited excellent ACE inhibitory activity with an IC50 of 4.70 mg/mL and antioxidant activity. The IC50 vales for inhibiting linoleic acid oxidation and scavenging superoxide anion, hydroxyl, DPPH free radicals were 4.26, 2.77, 7.78 mg/mL and 4.30 mg/mL, respectively.

Key words: chestnut kernel, functional food, peptide, ACE inhibition, antioxidation