Antimicrobial Activity of Spice Extracts against Pathogenic and Spoilage Microorganisms

Abstract

The ginger, galangal, turmeric, and fingerroot extracts were determined for their antimicrobial activities against foodborne pathogenic bacteria, spoilage bacteria and fungi by using agar dilution assay. Salmonella enterica serotype Typhimurium and Eschericia coli O157:H7 were resistant to ginger, galangal, turmeric, and fingerroot extracts. Minimal inhibitory concentrations (MICs) of ginger, galangal, turmeric and fingerroot extracts against those gram-negative bacteria were 8–10% (v/v). Fingerroot extract showed stronger inhibitory activity against Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus than ginger, turmeric, and galangal extracts. MICs of fingerroot extract was 0.2–0.4% (v/v). For the spoilage bacteria Lactobacillus plantarum and L. cellobiosus, galangal extract gave the most efficiency of with MIC at 4% (v/v). The results showed that fingerroot and ginger extracts had antifungal activity ranging from 8 to 10 and ≥10% (v/v) against Aspergillus flavus, A. niger, A. parasiticus and Fusarium oxysporum, respectively. Moreover, inhibition over time of E. coli O157:H7 was studied in TSB added with spice extracts at concentrations ranging from 8 to 10% (v/v). The 8% galangal and 10% fingerroot extracts showed bactericidal effect at 36 hours and 9 hours, respectively. While 8% turmeric extract showed bacteriostatic effect. In conclusion, rhizomatous spice extracts had antimicrobial effect against some spoilage and pathogenic microorganisms, thus it has potential to be used as natural preservative agents.