The level of microbial contamination of yoghurts

Project Abstract

Yoghurt is a popular dairy product consumed worldwide, known for its nutritional benefits due to its high protein and probiotic content. However, the level of microbial contamination in yoghurts is a critical factor that can impact product quality and safety. This study aimed to investigate the microbial contamination levels of various types of yoghurts available in the market. A total of 100 yoghurt samples, including natural, flavored, and probiotic yoghurts, were collected from different supermarkets and local stores. Microbiological analysis was conducted to determine the total viable count (TVC), coliform count, yeast, and mold count in the samples. Additionally, specific pathogens such as Salmonella spp., Escherichia coli, and Staphylococcus aureus were also investigated. The results revealed that the majority of the yoghurt samples had acceptable levels of microbial contamination according to international standards. The TVC ranged from 10^3 to 10^7 CFU/g, with the highest counts observed in flavored yoghurts. Coliform counts were within the permissible limits in most samples, indicating good hygienic practices during production. Yeast and mold counts were generally low, suggesting proper storage and handling of the products. Specific pathogen analysis showed that all samples tested negative for Salmonella spp. and E. coli, indicating the absence of fecal contamination. However, low levels of Staphylococcus aureus were detected in a few samples, highlighting the importance of maintaining strict hygiene practices throughout the production process. Overall, the findings suggest that the microbial contamination levels in yoghurts are generally within acceptable limits, indicating that the products are safe for consumption. However, continuous monitoring and adherence to good manufacturing practices are essential to ensure the quality and safety of yoghurts. This study provides valuable information for consumers, regulatory authorities, and industry stakeholders regarding the microbial quality of yoghurts. Further research is recommended to explore the factors influencing microbial contamination in yoghurts and to develop strategies to improve product safety and quality.

Project Overview

<p> &nbsp;INTRODUCTION &nbsp; &nbsp; &nbsp; &nbsp; 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; <em>Lactobacillus bulgaricus </em>and<em>&nbsp;Strptococcus thermophilus</em>. &nbsp; &nbsp; &nbsp; &nbsp; These two species of bacteriae have now been established as the yoghurt starters. &nbsp; &nbsp; &nbsp; &nbsp; 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). &nbsp; &nbsp; &nbsp; &nbsp; 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 and also some anti-bacterial substances such as lysozyme, ladoferin (transferin) and lactoperoxidases. In addition to the major constituent, milk contains a large amount of lactose sugar, phosphate, peptone and nitrogenbase enzyme (Clurance et al., 1963). Yoghurt has practically the same food value as the basic milk product (Ruud and Bert, 2004). &nbsp; &nbsp; &nbsp; &nbsp; Fermented milk products such as yoghurt contain bacteria from the lactobacilli group. These bacteria occur naturally in the digestive tract and have a cleansing and healing effect. Therefore, the introduction of fermented products like yoghurt into the diet can help prevent certain pathogenic bacteria, which may cause illness. Many people suffer from a condition known as “LACTOSE INTOLERANCE”. This means that they are unable to digest the milk sugar (lactose). Such people can however, tolerate milk if it is fermented to produce foods such as yoghurt. During fermentation, lactic acid producing bacteria breakdown lactose and in doing so eliminate the cause of irritation (Ruud and Bert, 2004). &nbsp; &nbsp; &nbsp; &nbsp; In countries where food borne illness are investigated and documented, the relative importance of pathogens like <em>Staphylococcu aureus </em>and<em>&nbsp;Escherichia coli</em>&nbsp;in yoghurt borne infection is well known (Obende, 1999). Diary foods are frequently contaminated with staphylococci and cases of staphylococcal contamination of milk and milk products like yoghurt have been recorded (Umoh et al., 1985). More than 50% of the strains of <em>S</em>. <em>aureus</em>&nbsp;are able to produce enterotoxin associated with food poisoning. The most important source of contamination by <em>S</em>. <em>aureus</em>&nbsp;is the human. (Payre and Wood, 1974). &nbsp; &nbsp; &nbsp; &nbsp; The coli forms bacteria are also reported to be contaminants of yoghurt. The study of Obende, (1999) shows that 60% of yoghurt samples analyzed in Enugu Urban are contaminated with coli forms. The source of contamination of coli forms bacteria is through water used or through the workers or utensil used in processing (Gillies and Bodds, 1973). &nbsp; &nbsp; &nbsp; &nbsp; Interestingly, most of the yoghurts are produced in little less than the cottage industries at homestead level under different brand names and are found in stalls, or more commonly hawked along the streets, motor parks and in the market. In view of this, the objective of this study was to investigate the level of microbial contamination of yoghurts sold in Enugu Urban. <br></p>