Antimicrobial potential of Ericaria selaginoides extracts against Listeria monocytogenes in “mató”, a Catalan fresh cheese

Abstract

The objective of this work was to assess the antimicrobial effect of crude extracts and non-polar and mid-polar subfractions of the brown macroalga Ericaria selaginoides, using a mid-polarity extraction medium. The activity was evaluated through challenge testing against Listeria monocytogenes in Catalan “mató” (fresh cheese) selected as a food matrix. Three concentrations were tested, representing 2 ×, 4 × and 10 × Minimum Bactericidal Concentration values obtained for crude extract in previous in vitro assays. Ericaria selaginoides extracts inhibited L. monocytogenes growth in a dose-dependent manner. Intermediate concentrations of the three extracts were able to notably reduce the growth rate of the pathogen. Highest concentration of crude extract and non-polar subfraction were able to completely inhibit the growth of L. monocytogenes during the 10 days of storage at 8 °C. Moreover, a slight listericidal effect was observed in presence of the non-polar subfraction, reducing the L. monocytogenes level by ca. 3 log after 10 days of refrigerated storage. These results prove the potential of E. selaginoides extracts as a source of valuable antimicrobial compounds that can be used as natural food ingredients to develop safer fresh dairy food.