Proteolytic and ACE-inhibitory activities of Dutch-type cheese models prepared with different strains of Lactococcus lactis

Abstract

The proteolytic activity of three Lactococcus lactis strains used as adjunct cultures and their capability to produce peptide inhibitors of the angiotensin-converting enzyme (ACE) in cheese models was studied. Initial and overall proteolytic activity of L. lactis strains were determined. Over the ripening period, water-soluble extracts of cheese models were analyzed for overall proteolytic activity and ACE-inhibitory activity. The ACE-inhibitory capability, increased over the 5 wk period of cheese models ripening (from 40.6 to 94.3%), in contrast to the IC50 value (from 0.84 to 0.32 mg mL-1). After 5 wk of ripening, all cheese models were characterized by a high capability for ACE inhibition >80%. The use of the Lactococcus bacteria led to lower IC50 values (0.32–0.44 mg mL-1) compared to the value determined for the control cheese model (0.49 mg mL-1) after 5 wk of ripening. The proteolytic activity of the three Lactococcus strains analyzed in cheese models varied throughout the ripening period.