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ABSTRACT
The Microbiology of three different samples of yogurt from mile 1 area of Port-Harcourt was evaluated using standard plate count and most probable number (MPN) techniques. This was carried out by analyzing for total aerobic heterotrophic bacteria court (THBC) range from 4.5 x 102 to 3.8 x 106 CFUM/ml. The results of the mean values of pH of the samples were green field yoghurt (pH 5.0), Home victory yoghurt (pH 7.5), and Mary Gold natural yoghurt (pH 5.0). Generally, the bacteria coliform counts were highest in the Mary God samples which had an acidic pH, thus shows that the isolates are acidophiles on the other hand the bacterial counts were lowest in Green field sample with a neutral pH, while the home Victory sample C had the least colony counts. The total number of bacterial isolated were Lactobacillus SP, Staphylococcus sp, Bacillus sp, Pseudomonas sp, and Bifidobacteria sp. The presence of these bacteria especially enteric organisms such as Escherichia Coli is of public health concern as they pose serious health hazards to the unsuspecting consumers.
CHAPTER ONE
1.0 INTRODUCTION
MICRO-ORGANISMS: These are microscopic organisms which may be single called or multicellular (Madigan et al, 2006).
YOGHURT: Yoghurt is a custard – like food with a tart flavor prepared from milk curdled by bacteria especially Lactobacillus bulgaricus and Streptococcus thermophilus and often sweetened or flavoured with fruit (American Heritage, 2000).
Yoghurt is derived from a Turkish word “Jau-urt” which means curdled milk. It is a soured milk product known for ages, The oldest data about yoghurt are found in the middle east.
The two bacteria responsible for converting milk to yogurt are Lactobacillus bulgaricus and Strephtococcus thermophilus, both bacteria are thermophiles which means they live best at a temperature between 300C and 500C and their optimal temperature is 430C. The Streptococcus thermophilus forms the milk sour while Lactobacillus bulgaricus proceduces the typical Yogurt aroma. Both bacteria grow symbiotically hence they need each other to grow in milk. The Lactobacillus Bulgaricus produces amino acid which stimulate Streptococcus bacteria to produce formic acid which is essential for the growth and survival of the lactobacillus bacteria Yoghurt can be made from goat, cow, ewe and buffalo or a combination of these milk (Alderton, 2000).
1.1 AIM / SCOPE OF THE STUDY
The aim / scope of this work (microbiology analysis) was to ascertain the following.
- To determine the standard plate count of total bacteria of yoghurt samples.
- To isolate, characterized bacteria that are pathogenic and those that are non pathogenic.
- To ascertain the microbial load of yoghurt.
- To check the sanitary level of yoghurt producers or handlers.