Purpose: The objective of this research was to investigate the antimicrobial efficacy of a commercial naturally-derived citrus flavonoid and organic acid blend (CFA) against the foodborne pathogenic and spoilage microorganisms, Escherichia coli, Salmonella enterica, Enterobacter spp., Bacillus spp. and Staphylococcus aureus.
Methods: The antimicrobial was added to bacterial cultures in broth at 7.8-125 ppm, and growth was monitored for 48h at 22°C. Apple juice and milk were used as model food systems to observe the commercial antimicrobial efficacy against tested microorganisms.
Results: At 22°C, CFA inhibited the growth of all tested microorganisms. Greater than a 1-log reduction of S. aureus and B. cereus was observed within the first 4h exposure at 7.8 and 31.25-ppm CFA, respectively, and inactivation to undetectable levels (>4.5-log reduction) was achieved at 31.25 ppm for both bacteria by 48h. CFA at 62.5 ppm extended the lag-phase of E. coli for up to 24h. At 125 ppm, CFA caused continuous reduction of viable S. enterica over 24h. For E. aerogenes, 31.25-ppm CFA resulted in 1, 2.5 and 4-log reduction after 8, 24 and 48h exposure, respectively.
In apple juice, 120-ppm CFA reduced viable E. coli and Enterobacter spp. by at least 2 log CFU/ml, while S. enterica was reduced to undetectable levels (>4-log reduction) in the presence of 180-ppm CFA in 48h at 22°C. When CFA was applied to milk at 150-18,000 ppm, no inhibition was observed in any tested microorganisms.
Significance: These findings suggest that the commercial CFA is an effective antimicrobial against the foodborne bacteria tested and has potential to enhance food safety and extending product shelf life of high carbohydrate, low fat and protein foods, such as fruit-based products.