2,8S0
Pre-selection
on skim milk of dairy lactic acid bacteria to
improve antioxidant
activity and shelf life of cheeses
A. Caridi, A. Piscopo, A. Zappia, M. Poiana
Department of AGRARIA, Mediterranea University of Reggio Calabria, Reggio
Calabria, Italy
It has been shown that some lactic acid bacteria possess antioxidant activity [1].
The using of lactic acid bacteria to increase the antioxidant activity in cheese [2]
is a good way to improve its shelf life. Consequently, the aim of this work was to
perform the clonal isolation, identification and selection of lactic acid bacteria to
produce compounds with the property to improve the antioxidant activity and the
shelf life of cheeses. Seventy-three strains of lactic acid bacteria, belonging to the
strain collection of the Unit of Microbiology of the Department AGRARIA of Reggio
Calabria and isolated from dairy products during different years, were tested on
skim milk for their pH and antioxidant activity. Each strain was first precultured in
MRS broth (lactobacilli) or in M17 broth (coccal-shaped) at3rC for 24 h.These
cultures were then used in inoculation (1 %, v/v) of 15 ml of skim milk treated at
121°C for 5'. Each strain was inoculated in triplicate for 44 h at 3rC. Then the
pH was determined and the antioxidant activity was measured by analysing the
radical scavenging activity using a spectrophotometric decolourization assay
(ABTS) according to Virtanen et al. [3]. In addition, also DPPH assay was
performed. The pH values were distributed in 34 homogeneous groups showing
a mean value of 4.88, with a minimum of 3.49 and a maximum of5.89. The ABTS
values (expressed as%of inhibition) were distributed in 32 homogeneous groups
showing a mean value of 51.56, with a minimum of 24.40 and a maximum of 71.52.
These results confirm that the development of antioxidant activity is a
strain-specific characteristic. In detail, the tested strains exhibit a high degree of
biodiversity. Six strains [3 Lactobacillus, 2 Enterococcus, and 1 Lactococcus],
exhibiting the highest radical scavenging activity, were selected for further
investigation. Research will go on testing the best strains in cheese-making, in
order to validate these results.
Keywords: Antioxidant activity, cheese, lactic acid bacteria pre-selection, shelf life, skim milk.
This research was supported by Ministero dell'/struzione, dell'Universite e delia Ricerca (Prot. 9S7/ric, 28/12/2012), through the Project 2012ZN3KJL "Long Life, High Sustainability".
