BACTERIOLOGICAL QUALITY OF PASTEURIZED LIQUID MILK SAMPLES SOLD AT DIFFERENT SHOPS

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ABSTRACT

The present study was carried out to determine the bacteriological quality of pasteurized liquid milk samples sold at different shops in students market located at Imo state University front gate. A total of four samples were collected. The present cross sectional study was conducted to assess microbial quality of pasteurized liquid milk and to determine antimicrobial susceptibility of the selected common milk-borne bacteria in Uyo and Abak Local government areas, Akwa Ibom state. A total of 56 respondents were interviewed and subsequently, milk samples were collected for laboratory analysis including microbial quality assessment and antimicrobial susceptibility tests. Results showed that, majority of smallscale livestock keepers were males with no formal education, managing their cattle in dirty environments, practicing extensive grazing system on communal grazing area and treat sick animals themselves. Common antimicrobial agents used were antibiotics. Several factors were observed to predispose milk to microbial contamination. Furthermore, results indicated that 33.9% of respondents consume milk from animals that are under medication, 94.6% of them did not adhere to withdrawal periods, 76.8% of respondents consume raw milk while 78.6% consume milk products made from raw milk. Generally, 85.7% of milk samples had significantly (P < 0.05) higher total bacterial count than the recommended level of 2.0 x 106 cfu/ml by EAC standards. Isolated bacteria included Listeria spp., Staphylococcus aureus, Escherichia coli, Salmonella spp., Pseudomonous aeruginosa and Proteus spp. All isolates were resistant to ampicillin but susceptible to gentamycin, and 91.2% of isolates showed multi-drug resistant to more than two antibiotic drugs. This study concludes that the quality of pasteurized liquid milk was poor; unhygienic practices and poor animal husbandry at farm level predispose farmers, consumers and the public to risk of contracting milk-borne infections and associated bacterial resistances. It is recommended that veterinarians, extension officers and all stakeholders should play their roles in order to ensure safe quality milk delivery to consumers.

CHAPTER ONE

1.0 INTRODUCTION

1.1 Background Information

Milk is an important food of diet of vast population on earth, due to its high nutritional value for human beings. Milk is an excellent growth medium of microorganism when suitable temperature exists. If it is produced unhygenically and handled carelessly, it gets contaminated very easily leading to its early spoilage (Oliver et al., 2005). Many milk-borne epidemics of human diseases have been spread by contamination of milk by spoiled hands of dairy workers, unsanitary utensils, flies and polluted water supplies. The same thing can be said for improper handling of foods in the home, restaurants, hospitals and other institutions.

Milk is an important source of nutrients to human and animals. It is meant to be the first and the only food for the offspring of mammals as is almost complete food (Pandey and Voskuil, 2011). Almost 87% of milk is composed of water and the remaining part comprises total solids (carbohydrates, fat, proteins and minerals) contained in a balanced form and digestible elements for building and maintaining the human and animal body. Other milk ingredients include immuno-globulins which protect the newly born against a number of diseases (Pandey and Voskuil, 2011). Milk has a complex biochemical composition and its high water activity and nutritional value serves as an excellent medium for growth and multiplication of many kinds of microorganisms when suitable conditions exists (Parekh and Subhash, 2008).

Milk meant for human consumption must be free from any pathogenic organisms (Bertu et al., 2010). Microbial contamination in milk may cause milk-borne diseases to humans while others are known to cause milk spoilage. Many milk-borne epidemics of human diseases are spread through milk contamination. Sources of microbial contamination in milk include primary microbial contamination from the infected or sick lactating animal. The secondary causes of microbial contamination occurs along the milk value chain which may include contamination during milking by milkers, milk handlers, unsanitary utensils and/or milking equipments and water supplies used in sanitary activities. Other secondary sources of microbial contamination occur during milk handling, transportation and storage. There is tertiary microbial contamination which occurs mainly due to re-contamination of milk after being processed due to unhygienic conditions and/or poor or improper handling and storage of milk during consumption (Parekh and Subhash, 2008). The quality of milk is determined by its composition and overall hygiene. However, consumption of contaminated food like milk may lead to food-borne diseases (FBDs).