The angiotensin-I-converting enzyme (ACE) inhibitory oligopeptide-enriched hydrolysates from Acetes chinensis by treatment with the protease from Bacillus sp. SM98011 were produced at pilot scale (100 L) and plant scale (1000 L). The pilot and plant scaled hydrolysate products almost had the same properties as that at laboratory scale. Spray-drying had little effect on the peptide composition and bioactivity of the hydrolysates. The plant scaled hydrolysates were used to study its blood pressure-depressing effect in vivo. It caused reduce of 18.3-38.6 mmHg of the blood pressure of spontaneously hypertensive rats in dose-dependent manner in the range of 100-1200 mg/kg/day. Histopathologic study showed that the pathologic changes of heart and brain in SHRs got obvious alleviation after treatment of the hydrolysates. (C) 2007 Elsevier Ltd. All rights reserved.