Thesis Abstract

Abstract
Yoghurt is a popular dairy product consumed worldwide for its nutritional benefits and taste. However, the quality and safety of yoghurts can be compromised by microbial contamination. This research project aimed to investigate the level of microbial contamination of yoghurts sold in various markets. A total of 100 yoghurt samples from different brands and sources were collected and analyzed for microbial contamination. The samples were tested for the presence of bacteria such as Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes, as well as yeast and mold. The microbial load in the yoghurt samples was determined using standard microbiological techniques. The results revealed varying levels of microbial contamination in the yoghurt samples. Escherichia coli, a common indicator of fecal contamination, was detected in 25% of the samples, indicating poor hygiene practices during production or handling. Staphylococcus aureus, a potential pathogen, was found in 15% of the samples, posing a risk to consumer health. Listeria monocytogenes, known for causing severe foodborne illnesses, was present in 5% of the samples, highlighting the need for strict quality control measures in yoghurt production. Yeast and mold were also prevalent in the yoghurt samples, with 40% of the samples testing positive for these microorganisms. While some level of yeast and mold may be expected in dairy products, high counts can affect the sensory attributes and shelf-life of yoghurts. Overall, the findings of this study suggest that microbial contamination is a common issue in yoghurts sold in the market. The presence of pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes raises concerns about the safety of these products for consumers. It is essential for yoghurt manufacturers to implement strict hygiene practices, quality control measures, and regular monitoring of microbial levels to ensure the safety and quality of their products. Further research is needed to investigate the sources of microbial contamination in yoghurts and develop strategies to mitigate these risks. Consumer awareness and education on proper storage and handling practices of dairy products are also crucial in preventing foodborne illnesses associated with microbial contamination.

Thesis Overview

1.0   INTRODUCTION         Yoghurt is a cultural diary product produced by lactic fermentation of milk (Hui, 1992). Yoghurt is produced by the controlled fermentation of milk by two species of bacteria; Lactobacillus bulgaricus and Strptococcus thermophilus.         These two species of bacteriae have now been established as the yoghurt starters.         Any sort of milk may be used to make yoghurt, but modern production is dominated by cow milk. It is the fermentation of the milk sugar (Lactose) into lactic acid that gives yoghurt its gel-like texture and characteristics tang (Davis, 1974).

Milk is often regarded as being nature’s most complete food. It earns this reputation by providing many of the nutrients which are essential for the growth of the human body. It is an excellent source of protein, vitamins, minerals particularly calcium