The study was carned out to assess the inhibitory effect of phenyllactic acid (PLA) against several pathogenic bacteria of food-borne disease and fruit-spoiling fungi. The used bacteria cultures included Escherichia coli EPEC, Salmonella typhi and Vibrio cholerae 01, while the fungus cultures were Aspergillus Davus DT, Aspergillus niger DLl and Penicilnum digitatum Saccardo. The inhibition activity of PLA was investigated using the well diffusion method, while the minimal inhibitory concentration (MIC) was determined using the liquid culturing media. Results showed that PLA has strong antimicrobial and antifungal activity against all kinds of tested microorganisms. However, the inhibitory concentration range required against fungi (40-50 mg/ml) was higher than that against bacteria (25-30 mg/ml). Among three fungal cultures tested, Penicillium digitatum was the most sensitive with the lowest MIC value (40 mg/ml) compared to two Aspergillus strains (50 mg/ml). For the pathogenic bacteria cultures tested, both Vibrio cholerae and Salmonella typhi had MIC values (25 mg/ml) lower than that of E. coli (30 mg/ml). In experiment of preserving bottled pineapple juice, the antimicrobial effect of PLA was investigated in concentrations ranging from 0.05 to 0.25 percent. Results revealed that PLA added in bottled pineapple juice with concentration of 0.2 percent remarkably reduced microbial contamination, leading to longer shelf-life of product Other experiment with PLA for preservation of fresh cut pineapple provided the best result of microbial quality when pre-treated products in PLA 2 percent.
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