Location: Warmwater Aquaculture Research UnitTitle: Antimicrobial Effect of Water-Soluble Muscadine Seed Extracts on Escherichia coli O157:H7 Author
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2008
Publication Date: 7/1/2008
Citation: Kim, T., Weng, W.L., Stojanovic, J., Lu, Y., Jung, Y.S., Silva, J.L. 2008. Antimicrobial Effect of Water-Soluble Muscadine Seed Extracts on Escherichia coli O157:H7. Journal of Food Protection. 71:1465-1468. Interpretive Summary: Identification of natural products that have antimicrobial properties will be important for maintaining a safe, high quality food supply. We investigated the antimicrobial properties of water soluble extracts prepared from seeds of two muscadine cultivars. One cultivar (Ison) had strong antimicrobial activity against Escherichia coli O157:H7. Extracts from the Ison were more acidic than extracts derived from a less effective cultivar (Carlos). Heating of the Ison extract increased its effectiveness against E. coli. Water soluble muscadine seed extracts have antimicrobial properties and could be useful as natural preservatives in juices and other beverage products.
Technical Abstract: Water-soluble extracts were prepared from purple (cultivar Ison) and bronze (cultivar Carlos) muscadine seeds with or without heating. The Ison extracts had strong antimicrobial activity against a cocktail of three strains of Escherichia coli O157:H7. This extract had higher acidity (pH 3.39 to 3.43), total phenolics (2.21 to 3.49 mg/ml), tartaric acid (5.6 to 10.7 mg/ml), tannic acid (5.7 to 8.1 mg/ml), and gallic acid (0.33 to 0.59 mg/ml) than did the Carlos extracts. Heat treatment on both extracts increased antimicrobial activity, possibly because of increased acidity, tartaric acid, total phenolics, and individual phenolics. Heating of Ison extracts increased ellagic acid up to 83%. Up to 10.7 mg/ml tartaric acid alone was not as effective against E. coli O157:H7 as were water-soluble seed extracts. This finding suggests the involvement of other factors, such as tannic and gallic acids, in inactivation of this pathogen. Water-soluble muscadine seed extracts may be useful for incorporation into juice and other beverage products as natural preservatives.