Detection of microbial load in Imported UHT milk in Baghdad Markets

The aim of this study was concerned on the evaluation of microbial load of imported UHT milk sold in different markets and stores in Baghdad. A total of 50 milk samples were collected, analyzed and processed during February till March 2011. A methylene blue reduction time, resazurin reduction time and 2,3,5-triphenyltetrazolium chloride (TTC) reduction test were used for detection and enumeration of microbial loadaccording to the standard protocols of Food and Drug Administration (FDA) and International Organization for Standardization (ISO) with some modifications.In this study, TTC was added to Plate Count Agar (PCA) for enumeration of microorganisms in UHT milk samples, with the aim to verify the frequency of microorganisms that are unable to reduce TTC.Milk samples were decimally diluted in phosphate buffered saline and pour-plated in PCA plus 0.015% TTC. Colonies were counted after 24h and 48h of incubation at 35oC. From a total of 50 samples, a 7 (14%) were contaminated with many types of bacteria according to results of tests used in this study especially gram negative rods such as Escherichiacoli as well as high percentage of microorganisms unable to reduce TTC in UHT milk, which cannot be detected by laboratory procedures based on the formation of red colonies. These findings suggest presence of high microbial load that contaminates some UHT or sterilized milk samples in Baghdad city, so it is strongly recommended that these imported products are monitored carefully.