ACE-inhibitory activity of milk fermented with Saccharomyces cerevisiae K7 and Lactococcus lactis subsp. lactis NBRC 12007

Abstract

The angiotensin-I converting enzyme (ACE)
inhibitory activity of the milk fermented with Lactococcus lactis
subsp. lactis NBRC 12007 and Saccharomyces cerevisiae K7 in
monoculture and co-culture was evaluated. Bovine full-fat milk
was fermented with each strain in monoculture and co-culture
at 30 ºC for 72 h, and the in vitro ACE inhibitory activity (%)
of each milk sample was determined by a fluorogenic assay
using H-(2)Abz-Acp(6)-Ala-Phe(4-NO2)-Leu-OH as the
substrate. The ACE inhibitory percentages of the milk samples
fermented with L. lactis subsp. lactis NBRC 12007 and
S. cerevisiae K7 monocultures and the co-culture was 33, 27
and 25 %, respectively, which varied significantly (p < 0.05).
Each milk sample was fractionated by semi-preparative HPLC
analysis and the ACE inhibitory activity (%) of each fraction
was determined using the same substrate, which varied from
20 - 47 %, 16 - 37 % and 16 - 31 % in the milk fermented with
L. lactis subsp. lactis NBRC 12007, S. cerevisiae K7 and the
co-culture, respectively. The highest ACE-inhibitory activity
(47 %) was observed in fraction-2 of the milk fermented with
L. lactis subsp. lactis NBRC 12007. The results concluded that
the two strains tested were able to hydrolyze milk proteins into
ACE-inhibitory peptides in order to produce fermented milk
products with ACE-inhibitory activity, both in monoculture and
co-culture. Therefore, it can be suggested that these strains can
be successfully utilized in the dairy industry in manufacturing
fermented milk products with ACE-inhibitory activity as
a dietary supplement and/or as an alternative approach for
antihypertensive medication.