Pilot-scale production of low molecular weight peptides from corn wet milling byproducts and the antihypertensive effects in vivo and in vitro

A pilot-scale production was developed to enhance the value of proteins from corn gluten meal (CGM). Corn protein isolate (CPI) with high protein content (90.68%) was obtained through heat treatment of CGM (150 kg) in aqueous alkaline solution. Two-step enzymatic hydrolysis and multistage separation were applied to enrich corn oligopeptides (COP) with low molecular weights, 96.77% of which were less than 1000 Da. The greatest antihypertensive effect of COP treatment in spontaneously hypertensive rats (SHR) was observed at a dose of 0.45 g/kg. One major ACE-inhibitory peptide, Ala-Tyr, was identified and quantified (9.16 +/- 0.08 mg/g) from COP. The ACE inhibitory activity of Ala-Tyr (IC50 = 0.037 mg/ml) was over 27 times higher than that of COP (IC50 = 1.020 mg/ml). The results indicate that COP may be a source of natural antihypertensive compounds that could be used for drugs or functional food ingredients. (C) 2010 Elsevier Ltd. All rights reserved.