Microbiological quality of carbonated and non-carbonated mineral water stored at different temperatures

Abstract

The microbiological quality of five brands of carbonated and non-carbonated mineral water sold in Poland was studied. The study was carried out on the survival of heterotrophic bacteria at 22 and 37 degrees C (pour plate technique) in the samples of mineral waters stored at 4 and 22 degrees C. The one hundred ten bottles (twenty two bottles of each of the five brands) of carbonated and uncarbonated mineral waters with different levels of dissolved solids and organic content were chosen to microorganisms study. Ten bottles of mineral water were studied initially. Fifty bottles were stored at 4 degrees C, the other fifty were kept at 22 degrees C. The haemolysing bacteria in 1 cm3; E. coli, P. aeruginosa and A. hydrophila in 250 cm3 of mineral water were unidentifiable. Total viable count of heterotrophic bacteria at 22 and 37 degrees C in 1 cm3 of mineral water was the highest respectively for brand T and for brands T and M; the lowest for brand Z. Initially, approximately 29% of 110 water samples (respectively 4% of carbonated and 55% of uncarbonated) had bacterial counts greater than Ministry of Health's standards, notwithstanding the number of water samples which doesn't perform requirements grew up to 47% (respectively 36% of carbonated and 58% of uncarbonated) when the time of TVC 37 and 22 degrees C incubation was elongated from 1 and 3 days to 3 and 14 days respectively. The temperature of storage was inessential for the numbers of studied microorganisms. The most important factors were the brand, time of storage and the carbonating or non-carbonating of water. The highest numbers of the bacteria analysed were detected in non-carbonating water, irrespective of the water brand and temperature of storage.