QUALITY ASSESSMENT OF VARIOUS MILK SAMPLES AVAILABLE IN NIGERIA

Milk is an important source of all basic nutrients required for all 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 from markets, 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 of any 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 of 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 deficiency 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 confectionery. 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 preliminary 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 governmental 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.

References
Baloch MS, Awan IU, Hassan G. Growth and yield of rice as affected by planting dates and seedlings per hill under high temperature of Dear Ismail Khan, Pakistan J Zhejiang Univ. Sci B. 2006; 7(7): 572-579
Dobrzanski Z, Kolarz R, Gorecka H, Chojnacka K, Bartkowiak A. The content of micro elements and trace elements in raw milk feo. Cows in the Silesian region. Polish J Environ Stud, 2005, 14(5): 685-689.
Gupta, U.C and Gupta, S.C 2014. Sources and deficiency diseases of mineral nutrients in human health and nutrition. A review. Pedosphere 24(1): 13-58.
Hassan SS. Quality Assurance of various Dairy Products Pakistan: Department of Chemistry, University of Peshawar; 2005.
Hunziker O.F. 1920. Condensed milk and milk powder Prepared for the use of milk condenser, dairy students and pure food departments. 3rd end. LaGrange II. P. 277.
Khan I, Zeb A. Nutritional composition of Pakistani wheat varieties J. Zhejiamg Univ. Sci.B. 2007; 8(8): 555- 559.
Rahman S, Khalid N, Zaidi JH, Aad S, Iqbal MZ, Non occupational lead exposure and hypertension in Pakistani adults. J zhejiang Univ. Sci. B, 2006; 7(9): 732-737.
Salah, F.A.A.E, Esmat, I.A. and Mohammed, A.B. 2018. Heavy metals residues and trace elements in milk powder marketed in Dakahlia Governorate. International Food Research Journal 20(4): 1807-1812.
Webb BH, Johnson AH, Alford JA. Fundamental of Dairy Chemistry 2nd End. Westport. CT: AVI Publishing

QUALITY ASSESSMENT OF VARIOUS MILK SAMPLES AVAILABLE IN NIGERIA