Project Abstract

Abstract
Yoghurt is a popular dairy product consumed worldwide, known for its nutritional value and probiotic properties. However, the presence of microorganisms in yoghurt raises concerns about food safety and public health. This study aimed to assess the antimicrobial susceptibility pattern of microorganisms present in yoghurt to provide insights into the potential risks associated with consuming this product. A total of 100 yoghurt samples from different brands and sources were collected and analyzed for the presence of bacteria and fungi. The samples were processed using standard microbiological techniques to isolate and identify the microorganisms. Antimicrobial susceptibility testing was carried out using the disc diffusion method against a panel of commonly used antibiotics. The results revealed the presence of a variety of microorganisms in the yoghurt samples, including both Gram-positive and Gram-negative bacteria as well as fungi. The most commonly isolated bacteria were Lactobacillus species, Streptococcus thermophilus, and Escherichia coli. Fungal species such as Saccharomyces cerevisiae and Candida albicans were also identified in some samples. Antimicrobial susceptibility testing showed varying patterns of resistance among the isolated microorganisms. Gram-positive bacteria exhibited higher susceptibility to antibiotics compared to Gram-negative bacteria. Lactobacillus species were generally susceptible to most antibiotics tested, while some strains of E. coli showed resistance to multiple antibiotics. Fungal isolates showed limited susceptibility to antifungal agents, indicating potential challenges in controlling fungal contamination in yoghurt. These findings highlight the importance of monitoring the microbial quality of yoghurt products and implementing appropriate control measures to ensure food safety. The presence of antibiotic-resistant bacteria in yoghurt raises concerns about the potential transfer of resistance genes to human pathogens, posing a risk to public health. In conclusion, this study provides valuable information on the antimicrobial susceptibility pattern of microorganisms in yoghurt, emphasizing the need for continuous surveillance and quality control in dairy products. By understanding the susceptibility profiles of microorganisms in yoghurt, appropriate strategies can be developed to mitigate potential risks and ensure the safety of consumers.

Project Overview

1.0   INTRODUCTION

Yoghurt is a fermented dairy product obtained from the lactic acid fermentation of milk. It is one of the most popular fermented milk products in the world and produced commercially at home. (Willey et al., 2008). In its commercial production, non fat or low fat milk is pasteurized cooled to 43°c and are inoculated with known cultures of microorganisms referred to as starter cultures. The starter cultures may be a pure culture of a particular species of Lactobacillus or a mixed culture of Streptococcus thermophilus and Lactobacillus bulgaricus in a 1: 1 ratio. The coccus which is theStreptococcus thermophilus grows faster than the Rod which is the Lactobacillus bulgaricus and is primarily responsible for acid production while the rod adds flavor and aroma. The growth of these Microorganisms causes the transformation of milk’s sugar, lactose into lactic acid. This process gives yoghurt it’s texture. The associative growth of the two organisms results in acid production at a rate greater than that produced by them individually.

Yoghurt is generally made from a standardized mixture containing whole milk, partially defatted milk, condensed skim milk cream and non fat dry milk. Alternatively milk may be partly concentrated by removal of 15- 20% water in a vacuum pan or by heating. While the microorganisms fermenting milk confers on it certain health benefits inadequate pasteurized milk may contain microorganism of special importance to man. (Boor and Murphy, 2002).