Effect of Different pHs and Temperatures on Stability and Mode of Action of Ethanolic Kayu Manis Hutan (Cinnamomum iners) Extract Against Foodborne Pathogens

Pathogenic bacteria found in raw foods have the potential to contaminate processed goods and cause them to deteriorate. Processed foods are divided into groups based on the necessary degree of heat treatment and pH levels in order to provide quality and safety. This study aims to evaluated the effect of different pHs and temperatures on the stability and mode of action of ethanolic Cinnamomum iners leaves extract against foodborne pathogens. Two different stages of leaf maturity were selected, namely young and old. The susceptibility activities of extracts after treated with different pHs (5, 7 and 9) and temperature (30oC, 50oC and 80oC) against foodborne pathogens ranged between 8.33 ± 0.76 to 11.33 ± 0.58 mm and 8.67 ± 0.58 to 12.67 ± 0.58 mm, respectively. Young leaves showed better susceptibility toward foodborne pathogens than old leaves against P. mirabilis (10.33 ± 0.58 and 11.33 ± 0.58 mm) at pH 5 and pH 9, while E. coli (10.33 ± 0.58 mm) at pH 7. In terms of temperature for foodborne pathogens, B. cereus showed the highest inhibition zone (12.67 ± 0.58 and 10.00 ± 0.00 mm) at 30oC and 50oC, while B. megaterium (11.00 ± 1.00 mm) at 80oC. The MIC and MBC from both extracts tested showed at the ranged between 0.31 to 5.00 after being treated at different pHs and temperatures. The SEM analysis showed morphological features in selected treated microorganisms namely, B. cereus and K. pneumoniae changed in the cell wall shape, ruptured, and the cytoplasm leaked. Meanwhile, untreated cells assume normal rod with a smooth surface. In conclusion, C. iners leaf extract exhibited antibacterial activity particularly young leaf, which showed stability after being subjected to different pHs and temperatures and can be developed as natural food preservatives.