Antimicrobial action of natural bioactive compounds for the development of functional packaging systems

Fresh fruit and vegetables are biologically dynamic foods, due to their metabolic activity and associated microflora, and therefore fragile in terms of integrity and hygiene. The intensity of degenerative processes depends on both biological factors and environmental conditions. Natural bioactive compounds incorporated in innovative packaging represent an extremely promising alternative for preventing food microbial contamination and spoilage and for extending shelf-life. They show antimicrobial and antibiofilm activity with low toxicity and allergenicity, also providing the advantage of reducing the use of petroleum-derived polymers and the related environmental pollution. The evaluation of the individual and synergistic antimicrobial action of bioactive compounds is essential for the development of innovative and bioactive packaging. Moreover, probiotic strains (e.g. Lactobacillus Plantarum) and natural bioactive compounds tested together can display a potential in terms of beneficial effect against microbial pathogens. Although classical microbiology techniques are widely used to study the antimicrobial action of numerous substances, these tests show limitations overcome by the integration of flow cytometry (FCM). FCM allows monitoring the cell physiological state and proves to be a promising tool for real-time analysis of the treatment response of each microbial strain.

Evaluation of the antimicrobial and antibiofilm activity of selected natural compounds (e.g. natural extract and essential oils):

• application of traditional microbiological methods: disk diffusion test, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), crystal violet assay and growth in microtiter plates;
• assessment of the effect on planktonic and sessile culturable cells;
• FCM analysis: cellular physiological response following the applied treatments.

Evaluation of the individual and synergistic antimicrobial action of bioactive compounds. 

Selection and application of probiotics in combination with natural bioactive compounds as potential enhancers of antimicrobial and antibiofilm effect on microbial pathogenic and spoilage strains.

The evaluation of the individual and synergistic action of natural bioactive compounds will allow the development of innovative and compostable packaging in which these compounds can be incorporated. Moreover, probiotic strains and natural bioactive compounds tested together will exert a potentiated action in terms of beneficial effect against microbial pathogenic and spoilage strains. Based on the selection of the most performing compounds and their synergy, in vivo test on bioactive packaging might be assessed.