Modelling the growth inhibition of common food spoilage and pathogenic micro-organisms in presence of solvent extract from Irish York cabbage

Preservatives are required to maintain the quality, extend shelf life, and ensure safety of fresh and processed food products. Although chemical preservatives form an essential part in food preservation, legislation has restricted their use in different foods. Vegetables in the Brassica family (Cabbage, Broccoli, Brussels sprouts) are a rich source of a number of bioactive compounds such as flavonoids, glucosinolates and their breakdown products which may have antimicrobial, antioxidant and anticancer properties. The present study investigates the antimicrobial activities of solvent extract from Irish York cabbage, Brocolli and Brussels Sprouts on the growth inhibition of common food spoilage (Listeria monocytogenes and Salmonella abony) and food pathogenic (Pseudomonas aeruginosa and Enterococcus faecalis) bacteria. Out of the three vegetables, extracts from York Cabbage showed the best results. Brocolli and Brussels sprouts, at a concentration of 2.8%, showed a weak inhibition in the range of 47-50% and 20-40%, respectively, against the different organisms. The extracts from York cabbage showed a broad spectrum of antimicrobial activity for the different organisms and the activity was found comparable to common synthetic food preservatives such as sodium benzoate and sodium nitrite. Extracts at a concentration of 2.8% showed varying level of inhibition against Listeria monocytogenes (100%), Salmonella abony (75%), Pseudomonas aeruginosa (65%) and Enterococcus faecalis (31%). Growth/survival of the micro-organisms in presence of extract was mathematically modelled using Baranyi model equations. The lower concentrations of cabbage extract prolonged the lag phase and reduced both the maximum specific growth rate and final population densities. Thus, the present study brings a new insight into the use of a commonly available vegetable such as York cabbage to provide an innovative measure as a natural antimicrobial agent with potential to enhance food safety.