ARS | Publication request: Identification of Natural Animicrobial Substances in Red Muscadine Juice against Cranonbacter sakazakii

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2009
Publication Date: March 15, 2010
Citation: Kim, T.J., Weng, W.L., Silva, J.L., Yung, Y.S., Marshall, D.A. 2010. Identification of Natural Animicrobial Substances in Red Muscadine Juice against Cranonbacter sakazakii. Journal of Food Science 75(3) M150-M154.

Interpretive Summary: Cronobacter sakazakii is considered an emerging opportunistic pathogen, causing rare but life threatening meningitis, bacteremia, and necrotizing enterocolitis in infants. Outbreaks of C. sakazakii have been associated with the ingestion of contaminated (less than 1 cell per 100 g) infant formula. Due to C. sakazakii resistance to various organic acids and disinfectants , it is necessary to find novel anti-C. sakazakii ingredients which could be formulated in baby foods. Muscadine grape (Vitis rotundifolia Michx.) juice with natural organic, phenolic acids and polyphenol compounds identified in red muscadine juice (‘Noble’) were tested against Cronobacter sakazakii. Commercial baby juices with high polyphenol content (176.7~347.7 mg/mL), showed poor antimicrobial activity, reducing less than 1-log C. sakazakii in juice samples for 2 h at 37°C. ‘Noble’ muscadine juices, regardless of processing methods (filtration, pasteurization and sterilization), achieved a 6-log reduction of C. sakazakii in the same time period (2 h). The mixture of synthetic organic acids (malic and tartaric acids) and polyphenolic acid (tannic acid) showed strong antimicrobial activity against C. sakazakii. Among synthetic organic acids, tannic acid was undetected in the commercial baby juices. Tannic acid showed the highest antimicrobial activity (1.4 ~ 3.8-log reduction) against C. sakazakii, while malic and tartaric acids showed less than 0.5-log reduction. These results suggest that red muscadine juice could be utilized as a natural antimicrobial in baby food formulations to inhibit C. sakazakii. Data showed that regardless of their pH (3.2 ~ 3.8) or processing method (sterilization, filtration etc.), tannic acid (1.7 mg/mL) was the most active antimicrobial compound among the three polar compounds, showing approximately 4-log reduction on C. sakazakii within two hours In conclusion, muscadine juice, a rich source of phenolic acids and organic acids, including the important tannic acid, showed strong antimicrobial action against C. sakazakii. This result suggests that muscadine juice may have the potential to be used in baby foods as a natural C. sakazakii inhibitor.

Technical Abstract: Muscadine grape (Vitis rotundifolia Michx.) juice with natural organic, phenolic acids and polyphenol compounds identified in red muscadine juice (‘Noble’) were tested against Cronobacter sakazakii. Commercial baby juices with high polyphenol content (176.7~347.7 mg/mL), showed poor antimicrobial activity, reducing less than 1-log C. sakazakii in juice samples for 2 h at 37°C. ‘Noble’ muscadine juices, regardless of processing methods (filtration, pasteurization and sterilization), achieved a 6-log reduction of C. sakazakii in the same time period (2 h). The mixture of synthetic organic acids (malic and tartaric acids) and polyphenolic acid (tannic acid) showed strong antimicrobial activity against C. sakazakii. Among synthetic organic acids, tannic acid was undetected in the commercial baby juices. Tannic acid showed the highest antimicrobial activity (1.4 ~ 3.8-log reduction) against C. sakazakii, while malic and tartaric acids showed less than 0.5-log reduction. These results suggest that red muscadine juice could be utilized as a natural antimicrobial in baby food formulations to inhibit C. sakazakii.