EFFECT OF SPICES, pH AND TEMPERATURE ON THE SURVIVAL AND MULTIPLICATION OF SALMONELLA SPECIES IN ZOBO DRINK

Abstract

This study was carried out to investigate the effects of spices, pH and temperature on the survival and growth of Salmonella species isolated from stream water samples in zobo drink. A total of 12 water samples were drawn from 3 different streams used in Ihiala Local Government Area, Anambra State, and screened for the presence of Salmonella species using pour plate method. The isolate obtained was characterized and identified using their morphological and biochemical characteristics. The effect of spices, pH and temperature on the isolate was determined by subjecting the isolate to 0.25%, 1.25% and 2.5% of spices (Zingiber officinale and Myristica fragrans), different pH ranges (3-10) and different temperatures (4⁰C, 25⁰C and 37⁰C). Eleven water samples out of twelve samples drawn from the streams showed the presence of Salmonella species. The spices showed pronounced activity against the organism in sterilized and non- sterilized samples of which the activity increased significantly (P<0.05) as the concentration increased. The activity of Zingiber officinalewas significantly (P<0.05) higher than that of Myristica fragrans. The maximum growth of the isolate was significantly (P<0.05) observed at pH 6 and 37⁰C. No growth was observed little or no growth at 4⁰C. This study has shown that the growth of Salmonella species in zobo drink could be controlled using Zingiber officinale and Myristica fragrans extracts at pH values other than 6, and should best be sold and consumed at refrigeration temperature (4⁰C).

Key words: Salmonella, zobo drink, Zingiber officinale, Myristica fragrans