Minimum inhibitory concentrations of antimicrobials against micro-organisms related to citrus juice

Minimum inhibitory concentrations (MIC) of various cleaner or sanitizer compounds were determined by a Spiral Gradient Endpoint agar diffusion method against four micro-organisms associated with spoilage of orange juice (Lactobacillus plantarum,Leuconostoc mesenteroides,Gluconobacter oxydans, andSaccharomyces cerevisiae) and against eight unidentified micro-organisms isolated from citrus fruit surfaces (two yeasts and six bacteria). Survivor curve testing was conducted on the four known micro-organisms. Compounds that were effective at the lowest concentrations were chlorine dioxide, the iodophor and quaternary ammonium compound. Dimethyldicarbonate, hypochlorite, peracetic acid and a phosphoric acid anionic compound also possessed substantial antimicrobial activity. Citric and lactic acids andd-limonene were less effective as antimicrobial compounds.