QUALITY ASSESSMENT OF VARIOUS MILK SAMPLES AVAILABLE IN NIGERIA
Milk is an important source of all basic nutrients required foraals including human beings. Milk from various mammals such as cow, buffalo, goat, sheep, camel is uses for different nutritional purposes e.g. feeding to young ones and preparation of some nutritional products such as milk cream, butter, yoghurt, ghee,sour milk ( Webb et al.,1994; Hassan, 2005). Nutritionally enriched milk and its products with enhanced biological potential and without health risks are generally demanded (Khan and Zeb, 2007; Baloch et al., 2006; Rahman et al., 2006). The major chemical components of milk include water, fats, proteins, carbohydrate, minerals, organic acids, enzymes and vitamins. In order to assess the quality of milk, milk samples including infant formulas, milk powder, milk fromarkets, raw milk (unprocessed human milk and animal milk) from various countries such as Canada, Lithuania, Italy, USA, UK, and Nigeria have been extensively studied.
The content of 38 micro and trace elements in raw milk of cows in the Silesian region, Poland were studied by Dorzanski et al.(2005). They found that the location if cows has a significant impacts on the contents ofany micro and trace elements in milk. In another study, infant formula samples sold in Nigeria, UK, USA were analyzed for various essential elements ( Can, Co Cu Cr, Fe, Mg, Mn Mo, Na and Zn) and non essential elements (Ag, Al,As, Ba, Be, CD, Hg, Ni, Pb, Sb, Sn, Sr, Ti, Tl, U and V) (Ikem et al., 2002). They found that soy based powder infant formulas generally had higher element levels than milk based powder formulas. Some brands also had low nutritional contents when compared with the recommended dietary allowances (RDAs) and dietary reference intakes (DRIs) for use in North America.
Commercial production of dried milk dates back to 1832 and was pioneered by Russian chemist M. Dirchoff (Hunzike, 1920). Since then the powdered milk has been produced using different techniques. The production method and stages employed makes the whole milk susceptible to contamination and /or having the required essential element. Most of the powdered milk available in the market is produced from Cow's milk. However, the breed of cow and its environment, method of manufacture and storage, all combined, affect the quality and quantity of essential and trace elements present (Salah et al., 2013). A review on the sources and defuency diseases of mineral nutrients in human health and nutrition can be found in Gupta and Gupta (2014). Powdered milk is widely consumed in Nigeria. In fact most of tea served during breakfast in Nigeria consists of powdered milk.
1.2 Problem Statement
Milk is frequently used in the manufacture of infant formulas recipes for bakes products, beverages and confectionary. However, storage conditions and high temperature can degrade the nutritive value of milk powder. Hence, there is need to periodically assess the milk quality for both food safety and nutritional considerations.
1.3 Objectives of the Study
The major objective of the study is to assess the quality of various milk samples available in Nigeria which is to be achieved through the following specific objectives:
(i) Assessment of the physical characteristics of the milk.
(ii) The chemical analysis of the various milk samples and
(iii) The bacteriological examination of the milk samples.
1.4 Research Questions
1. What are the various milk samples available in Nigeria?
2. Do the various milk samples conform with the standard provides by regulatory authorities?
3. Why the need to assess the quality of milk available in Nigeria?
1.5 Significance of the study
This research is a prelinary study to ascertain the physiochemical characteristics and nutritional quality of the various milk samples available in Nigeria market. The findings of this research will help to know if the milk brands are within the recommended nutritional levels. The findings may also be helpful for the concerned goverental parties to monitor the quality of the milk products in the market in Nigeria.
1.6 Scope of the study
The research focuses on the quality assessment of various milk samples available in Nigeria.
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