Antagonistic action of watermelon juice probioticated using different strains of lactobacilli against Salmonella typhimurium

Background: The aim of this study was to compare the antimicrobial activity of watermelon juice probioticated using different strains of lactobacilli against Salmonella typhimurium. Methods: Probioticated watermelon juice was produced using four strains of lactobacilli (Lactobacillus casei, L. acidophillus, L. fementum and L. plantarum). The watermelon juice was pasteurized for 30 minutes at 63° C and was inoculated with a 24 h culture of individual lactobacilli and incubated at 37° C. All of the lactobacilli were capable of growing in watermelon juice and reached a cell density of 108 CFU/ml after 48 h incubation at 37° C. Overnight culture of S. typhimurium was added to probioticated watermelon juice and reduction of the viable cells were assayed, on bismuth sulfite agar medium for 24 h. Antimicrobial activities of the lactobacilli cells against the test strain of Salmonella were also determined by measuring the diameter of growth inhibition zone in agar spot test. Results: All of the lactobacilli could inhibit growth of S. typhimurium with L. casei being the most potent. S. typhimurium was totally eradicated in probioticated watermelon juice after 2-6 h. Conclusion: The probioticated watermelon juices could differ in their antagonistic activities against Salmonella which could be due to the metabolite secreted by the lactic acid bacteria specially type of organic acids

Antimicrobial effect of cinnamon (Cinnamomum verum J. Presl) bark essential oil in cream-filled cakes and pastries

Background and objectives: Food poisoning has been always a major concern in health system of every community and cream-filled products are one of the most widespread food poisoning causes in humans. In present study, we examined the preservative effect of the cinnamon oil in cream-filled cakes. Methods: Antimicrobial activity of Cinnamomum verum J. Presl (Cinnamon) bark essential oil was examined against five food-borne pathogens (Staphylococcus aureus, Escherichia coli, Candida albicans, Bacillus cereus and Salmonella typhimurium) to investigate its potential for use as a natural preservative in cream-filled baked goods. Chemical constituents of the oil were determined by gas chromatography/mass spectrometry. For evaluation of preservative sufficiency of the oil, pathogens were added to cream-filled cakes manually and 1 μL/mL of the essential oil was added to all samples except the blank.  Results: Chemical constituents of the oil were determined by gas chromatography/mass spectrometry and twenty five components were identified where cinnamaldehyde (79.73%), linalool (4.08%), cinnamaldehyde para-methoxy (2.66%), eugenol (2.37%) and trans-caryophyllene (2.05%) were the major constituents. Cinnamon essential oil showed strong antimicrobial activity against selected pathogens in vitro and the minimum inhibitory concentration values against all tested microorganisms were determined as 0.5 μL/disc except for S. aureus for which, the oil was not effective in tested concentrations. After baking, no observable microorganism was observed in all susceptible microorganisms count in 72h stored samples.  Conclusion: It was concluded that by analysing the sensory quality of the preserved food, cinnamon oil may be considered as a natural preservative in food industry, especially for cream-filled cakes and pastries