Studies on the antimicrobial activities of extracts from Eupatorium lindleyanum DC against food spoilage and food-borne pathogens

Antimicrobial activity of extracts from Eupatorium lindleyanum DC (EEL), a traditional Chinese medicine, was screened against eight selected food spoilage and food-borne pathogens. The EEL was observed to show effective antimicrobial effects with a remarkable dose–response relationship and broad antimicrobial spectrum on all test Gram-positive bacteria and Gram-negative species. Acid environment or medium helps enhance the antimicrobial activity. The activity remains rather stable under conventional food sterilization conditions and normal shelving temperature. The EEL obtained by water decoction exhibited the maximum inhibitory effect on test strains with its MIC (minimum inhibitory concentration) and/or MBC (minimum bactericidal concentration) value of 0.4–0.8 mg ml−1. When the EEL was used in commercial orange juice at a concentration of 0.4 mg ml−1, a similar antimicrobial effect to potassium sorbate at the level of 0.2 mg ml−1 was observed. In conclusion, in addition to use as a functional food ingredient, the EEL may be selected as an inhibitor to preserve food products where a natural preservative is desired.