Bacteriology of a most popular street food (Panipuri) and inhibitory effect of essential oils on bacterial growth

Abstract

Bacteriology of Panipuri was studied and the antibacterial effect of eight essential oils (EOs) was established on pathogens found in Panipuri. Samples were collected from twelve respective vendors from different locations in Baripada city, Orissa. Samples were fractionated into two parts viz. khatta pani and smashed potato masala used in Panipuri. Total plate count and isolation of pathogenic bacteria were done on both basal and selective media. Coliforms were detected primarily by presumptive test and confirmed subsequently, using Eosine Methylene Blue Agar. Selected colonies were pure cultured and identified through staining and an array of biochemical reactions. Antibiogram pattern of the pathogens and their susceptibility towards eight different EOs were performed. Antibacterial efficacy of four EOs in food sample was studied. Aerobic bacterial load of solid samples was observed to be more than in the liquid samples. Coliform-positive samples were found to be of 80.33%. Pathogenic bacteria like Escherichia coli, Klebsiella sp., Enterobactor sp., Bacillus sp., Enterococcus sp., Micrococcus tetragens, Salmonella paratyphi, Shigella dysenteriae and Vibrio sp. were detected. Antibiogram studies of the isolates showed multiple antibiotic resistance index (MRI;%) ranging from 15 to 92%. Among the EOs studied Cinnamon and Clove oils showed maximum antibacterial activity. Antibacterial efficacy showed that Clove and Cinnamon oils were comparatively of superior quality than Turmeric leaf and Japanese mint oils to kill food borne pathogens. Although it was a preliminary endeavor, the present study is a prerequisite in understanding the significance of pathogenic microorganisms in street foods and use of EOs as both antibacterial agents and food preservatives.