The use of natural extracts in the food industry in order to combat pathogens present in food has been the object of study in recent years. Consequently, this work aimed to test the antimicrobial activity of different natural extracts against pathogens targeted by the food industry. The extracts with the highest activity were used in a solution to marinate a meat matrix and evaluate their ability to inhibit or reduce the microbial load of three food pathogens. Initially, the antimicrobial capacity of different natural extracts was evaluated: Microalgae (Chlorella spp., Chlorococcum spp., Nannochloropsis), peptides and plants and fungi (Rosemary, Oleuropein, Shiitake), against different strains of pathogens Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, Yersinia enterocolitica, Pseudomonas spp., Bacillus cereus, Enterococcus faecalis, Campylobacter spp. and Clostridium spp. The antimicrobial capacity of Chlorella spp., Chlorococcum spp. and Nannochloropsis was evaluated using bacterial growth curves, but without reductions in the microbial load over time. Two of the peptides (3.1 and CA-M) inhibited the growth of all pathogens, with minimal inhibitory concentrations less than 25.00% (V/V) for all bacteria tested. Oleuropein extract inhibited all pathogens to values below the detection limit of the enumeration technique (<1.3 log CFU/mL), and Rosemary and Shiitake extracts also demonstrated high antimicrobial capacity for tested pathogens, having been observed, respectively, reductions of 3,77 ± 0,32 and 3,81 ± 0,32 log cycles for E. coli, 3,97 ± 0,98 and 3,54 ± 0,67 log cycles for L. monocytogenes, 3,64 ± 0,32 and 3,57 ± 0,17 log cycles for Salmonella spp., and 4,02 ± 0,82 and 4,44 ± 0,08 log cycles for Campylobacter spp. The high inhibitions recorded have led to the use of these extracts to marinate an artificially contaminated meat food matrix. However, despite some reductions seen in the pathogens tested, none of these reductions was significant. This study demonstrated the promising antimicrobial capacity of natural extracts against foodborne pathogens. Future studies of the synergy between the studied extracts would be interesting, as well as their incorporation in different food matrices, which we believed would lead to new beneficial discoveries for the food industry
| Date of Award | 24 Jan 2022 |
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| Original language | Portuguese |
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| Awarding Institution | - Universidade Católica Portuguesa
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| Supervisor | Joana Barbosa (Supervisor) & Paula Teixeira (Co-Supervisor) |
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