61C-38 |
Determination of antimicrobial properties of anthocyanins naturally stabilized by flavonoids |
D. DEL POZO-INSFRAN1, C. H. Brenes1, S. T. Talcott2, and H. Cantu. (1) Department of Food Technology, ITESM-Campus Monterrey, E.Garza Sada 2501 Sur, Monterrey, 64849, Mexico, (2) Food Science and Human Nutrition/IFAS, University of Florida, 459-C FSHN PO Box 110370, Gainesville, FL 32611
Many spices are known to possess antimicrobial properties attributed to their polyphenolic content. Polyphenolics, particularly flavonoids, with antimicrobial properties are an interest to the food industry and have the added benefit as natural antioxidants and cofactors to anthocyanins. Our objective was to evaluate antimicrobial properties of polyphenolics (flavonoids and anthocyanins) extracted from natural sources and to evaluate their interaction within an optimized range of antimicrobial activity. Anthocyanin extracts from black carrots (BC) and red grapes (RG) along with flavonoid extracts from rosemary (RE) and sage (SE) were exhaustively extracted and purified on reversed phase C18 columns. Antimicrobial properties against Escherichia coli (ATCC 25922) and Salmonella thyphimurium (ATCC 14028) were performed at various concentrations of each extract using hole-plate diffusion, and results classified according to the diameter of the inhibition zone. Selected concentrations were then used to determine growth inhibition by an agar dilution method. Phenolic compounds present in each extract were characterized and quantified spectrophotometrically. Polyphenolic extracts of RE and SE had strong antimicrobial activity compared to anthocyanin extracts, but activity was greatly modulated following anthocyanin copigmentation. Percent microbial inhibition was quantified using selected flavonoid concentrations of 0.5, 1 and 2%, tested alone and in combination with 150 and 300 ppm of BC and RG. Alone, BC and RG inhibited E. coli growth by 29 and 73% respectively at 300 ppm, but inhibition was >90% when RE and SE were added at 2% v/v. At the same concentrations, BC and RG alone were highly effective against S. thyphimurium (90-96%) with only slight increases observed by the addition of 2% RE and SE. Results indicate the polyphenolics investigated have a high degree of specificity against various bacterial strains. This study demonstrates favorable antimicrobial interactions between polyphenolics isolated from various sources and demonstrates potential roles as a multifunctional food additive.
Session 61C, Food Microbiology: General I
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