Study on Citric Acid Production and Antibacterial Activity of Kombucha Green Tea Beverage during Production and Storage

Abstract

Aims: The aim of this study was to determine the amount of citric acid production and antibacterial activity of Kombucha green tea during its production and storage. Study Design: Experimental study. Place and Duration of Study: Department of Public Health, Maragheh University of Medical Sciences, between December 2016 and May 2017. Methodology: The amount of citric acid at two temperatures of 20°C and 30°C was determined using the HPLC technique during 21 days. To survey the antibacterial effect of Kombucha on the growth of Staphylococcus aureus, Salmonella typhimurium and Lactobacillus rhamnosus bacteria, two processes of well and the disc were used. Results: Production of citric acid undergone a change at 20°C from 5.92 on day 1 to approximately 31.75 on day 21, and this difference was significant. Additionally, the amount of this organic acid at 30°C changed from 5.57 on day 1 to 15.43 on day 21. The amount of citric acid produced during storage at 20°C was significantly greater than that at 30°C (p<0.05).  In the well method, for Staphylococcus aureus and Salmonella typhimurium at both temperatures of 20°C and 30°C, the diameter of the formed halo between different days was significantly different (p<0.05). In the disc method, for Staphylococcus aureus at 20°C and 30°C the halo diameter in all experimental days were significantly greater (p<0.05) than day 1. For Lactobacillus rhamnosus bacteria, no halo was formed around the discs and wells. Conclusion: By time increase, the pH decreased the amount of citric acid increased, and the halo diameter around the well and disk (in all positive cases) increased.