Study on chemical compounds and antibacterial activity of Anethum graveolens L. essential oil as a natural preservative and flavoring in celery juice

Abstract

Nowadays, considering the side effects of chemical preservatives and the attention of food manufacturers to the natural preservatives, it seems necessary to evaluate the antimicrobial effects of natural preservatives in the laboratory and food models. In this study, the stems and leaves essential oil of Anethum graveolens L. was extracted by Clevenger apparatus and its compounds were identified using GC-MS. The fresh celery juice was stored for 7 days at the room temperature until it was rotten, then the serial dilution was prepared and the bacterial culture was performed using pour plate method. The different bacterial isolates were purified and the antibacterial effect of different essential oil concentrations was investigated by disk diffusion method on the dominant bacteria. The sensitive bacteria to the dill essential oil were identified by the standard microbiological methods and 16S rRNA gene amplification method. Then the effective concentration was added to the celery juice and the effect of essential oil on the population of total and dominant bacteria was investigated. The sensory acceptance of different essential oil concentrations among the population groups was assessed by a five-point hedonic questionnaire. This research was conducted in a completely randomized design with three replications. Based on the GC-MS results, dillapiole (21.2%), α-phellandrene (37.2%), and β-phellandrene (9.2%) were the most important constituents of dill essential oil. The results of sequence blasting showed that Bacillus cereus and Acetobacter fabarum were the most dominant putrefactive bacteria in the celery juice. Based on the results, there was a significant difference between the five concentration groups in terms of halo diameter in the bacteria. The highest halo diameter in both bacteria was obtained at the concentration of 1000. In general, the results of the present study showed that dill essential oil is a suitable additive for the celery juice based on the results of sensory evaluation and in terms of controlling the putrefactive bacteria.