ISOLATION AND CHARACTERIZATION OF BACTERIA ASSOCIATED WITH SELECTED PASTEURIZED DRY MIL POWER
ABSTRACT
The bacteria quality of four (4) commercially available dry sachet milk powder (peak, cowbell, Blue boat and Nunu) were analysed in this study usinf the pour plate method. The result showed that peak, cowbell and blue boat were free of all forms of bacteria which Bacillus and Lactobacillus species were isolated from the Nunu brand. Although the microbial count was low, the fact remains that their presence in the product would certainly compromise it shelf life and there by constituting an health hazard especially to children and lactase intolerance people. In view of this result , there is need for the manufacturers to tighten in –process quality control checks and for government food regulatory agencies such as National Agency for food and Drug Administration and Control (NAFSAC) to carry out routine checks from time to time on these milk producing companies to ensure consumer safety standards are not compromised.
CHAPTER ONE
1.0     INTRODUCTION
milk is nearly white liquid secreted by the mammary glands of female mammals for nourishinf their young ones. Milk contains all the nutrients needed for foods of the adult mammal. Several kinds of mammals are raised to produce milk for human consumption. Of these, daily cattle are of greatest commercial importance, but milk is also obtained from water buffalo, goats, sheep, Camel, reindeer, mares and other mammals (Harper and Hill, 1986).
 Milk is a natural source of energy and natural scource of fifteen essential nutrients. Besides these nutrients, milk also co ntian compounds that have been found to be anti-carcinogen, such as conjugated linoleic acid (CLA) and butyric acid. It is essential therefore to understand the make –up of this extraordinary, wholesome and safe source of goodness that provides so many health giving factors. It is important to remember that the consumption of milk varies according to the type and bread of animal, its state of health and  the diet on which it is reared.
Milk
Milk is unique nutritious and a major source of protein and calcium. Milk powder (dry milk) is a powder-like food product received by means of drying previously condensed milk. Powdered milk has a far longer shelf than liquid milk and does need to be refrigerated due to its low moisture content. It is less expensive and easier to store than fresh milt, but ha a disadvantage is that it never tastes quite like the real thing. Powdered milk was first made in 1802 by Russian doctor Osip Krichevsky. It is found abundantly in many developing countries because of reduced transport and storage cost (as it does not require refrigeration) like other dry foods. It is considered non- perishable and is favoured by survivalist, hikers and other people in need of nonperishable easy to prepare food stuff.
 Powdered milk is often used in baking, in recipes where adding liquid milk would render the product too thin to be used. It is a common sight in UN food aid supplies, fallout shelter, warehouses and wherever fresh milk is not a viable option. Powdered milk is also used in western blosts as a blocking agent to prevent non-specific protein interactions
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The body needs Vitamin D to absorb calcium. Good sources of vitamin are sunshine, Cod liver Oil, Multivitamins, liver and ofcourse milk.
 Milk drawn from a healthy animal already contains some bacteria. Most of the changes which take place in the flavour and appearance of milk, after it is drawn from udder and the resultd of the activities of microbes. The favourable microbes bring favourable changes in flavour and appearance and are carefully propagated while the pathogenic (Unfavourable) which may cause diseases are destroyed to make the milk and its products safe for human consumption. The following are the important microbes found in milk.
(a)      Bacteria – These are microscope, Unicellular organisms which occur inform of spherical, cylindrical or spiral cells. The size ranges from I to 5N. spore forming bacteria post problem in dairy industry because of its resistance to pasteurization and sanitation procedures. The greater the bacteriological count in milk, the lower its quality.
(b)     Moulds- These are multi-cellular organisms, at maturity are as mycelium and is useful in cheese making. It is responsible for defect in butter and other milk products.
©       Yeasts- Unicellular organisms that are larger than bacteria.
(d)     Viruses – these are ultra-microscopic forms of organisms.
 Bacteria inevitable enter milk during milking (production) and handling. They multiply depending on the storage time and condition. Milking is normally followed immediately by cooling to retard bacterial growth. The changes that take place in the physio-chemical properties of milk are as result of the activities of individual microbial cells during their period of growth and reproduction or substances produced during such activity.
 Product of microbial growth in milk are enzymes, decomposition products (fats, protein, sugars), pigments toxins, miscellaneous changes (cousins, 1982).
 Biochemical changes in foods when perceived as undesirable are called spoilage. Sour milk is examples of food considered spoiled as a result of microbial growth. The souring of milk however, involes microbial processes analogous to those that cause agreeable acidic flavour of sour cream
 Raw milk is pasteurized to destroy potentially harmful bacteria it may contain and to disable certain natural enzymes. It also increases the shelf life of milk pasteurization involved the heating of raw milk to 1450F for 30munites or heating it to 1610F for 15munites. During this process, the pathogenic bacteria will be killed while the non pathogenic will survive. The pasteurized milk Is then rapidly cooled to 380F. pasteurization has negligible effect on the taste and nutritive characteristics of milk.
1.1        AIMS OF THE STUDY
The aim of the study is to
1.       Acquaint the individuals and public with precise information and techniques commonly used to assess the bacteria that is associated with pasteurized dry milk power.
2.       Determine the microbial load of pasteurized dry milk powder.
1.2STATEMENT OF PROBLEMS
milk drawn from a health animal already contains some bacteria. After pasteurization, the milk is considered safe for consumption. However, during package process, there may be contamination through handling and preservation of the products and this can leads to change in flavour and appearance of the milk due to the activities of the microbes. It is therefore necessary to acknowledge and understand the possibility of assessing the bacteria that is associated with pasteurized dry milk powder.
1.2        SIGNIFICANCE OF STUDY
To determine the level of bacterial contamination of dry milk powder in sachet packages in view of the fact that they have been pasteurized and are supposed to be sterile.