Antimicrobial potential of Ericaria selaginoides extracts against Listeria monocytogenes in mato, a Catalan fresh cheese

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 mato (fresh cheese) selected as a food matrix. Three concentrations were tested, representing 2 x, 4 x and 10 x 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 degrees 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.

Automated summary

The study aimed to evaluate the antimicrobial effect of crude extracts and non-polar and mid-polar subfractions of the brown macroalga Ericaria selaginoides. The extracts inhibited the growth of Listeria monocytogenes in a dose-dependent manner. The highest concentration of crude extract and non-polar subfraction completely inhibited the growth of L. monocytogenes during the 10 days of storage at 8 degrees C. Moreover, the non-polar subfraction showed a slight listericidal effect during refrigerated storage.