In cheese-making, a starter culture composed of adequately
chosen lactic acid bacteria (LAB) may be suitable to ensure the
rapid acidification of milk, improve textural and sensory characteristics,
and avoid pathogen proliferation. In this work, 232 LAB isolates
collected from artisanal goat’s raw milk cheeses produced in
Portugal were evaluated for their antimicrobial capacity (at 10 and
37°C), as well as their acidifying and proteolytic properties.
Among the 232 isolates, at least 98% of those isolated in De Man-
Rogosa-Sharpe (MRS) agar presented antagonism against Listeria
monocytogenes, Salmonella Typhimurium, or Staphylococcus
aureus, whereas less than 28.1% of M17-isolated LAB showed
antagonism against these pathogens. M17-isolated LAB displayed
better results than MRS ones in terms of acidifying capacity. As for
the proteolytic assay, only 2 MRS isolates showed casein hydrolysis
capacity. Principal component analyses and molecular characterization
of a subset of selected isolates were conducted to identify
those with promising capacities and to correlate the identified
LAB genera and species with their antimicrobial, acidifying,
and/or proteolytic properties. Lactococcus strains were associated
with the highest acidifying capacity, whereas Leuconostoc and
Lacticaseibacillus strains were more related to antimicrobial
capacities. Leuconostoc mesenteroides, Lactococcus lactis, and
Lacticaseibacillus paracasei were the predominant organisms
found. The results of this work highlight various strains with
pathogen inhibition capacity and suitable technological properties
to be included in a customized starter culture. In future work, it is
necessary to appropriately define the starter culture and implement
it in the cheese-making process to evaluate if the in-vitro capacities
are observable in a real food system.
