Milk is a complex mixture of fat, proteins, carbohydrates, minerals, vitamins and other miscellaneous constituents dispersed in water. Milk production in flush season is much more than the requirement. Milk production and supply fluctuate through out the year and during winter it is surplus to its demand. Dairy is one of the expanding industrial sectors in Pakistan; about 17 units are engaged in the production of various dairy products. Surplus milk is available in winter and this is the normal practice of dairy industry in Pakistan that surplus milk is converted in to different types of milk powders. The objectives of the study were to evaluate the physico- chemical and keeping quality of whole milk powder commercially available in the market and comparative study of functional properties among different brands of whole milk powders, evaluate the storage stability of different brands of whole milk powder atl5°C, 25°C and 40°C temperature and study the effects of processing conditions indicator like Hydroxymethyl Furfural (HMF) during storage.

Project was undertaken to study the effect of storage temperatures (15, 25 and 40°C) and processing conditions on physico chemical and sensory characteristics of whole milk powder. Statistical analysis of whole milk powder samples indicated during storage non significant changes in protein, ash, fat, lactose, acidity, burnt particles within the treatments as a function of storage was observed. Significant changes were recorded in free fatty acids, solubility index and per oxide value within the treatments and during storage period of 120 days. At 120 days of storage minimum increase in free fatty acids and peroxide value was noted in T3. Acidity, free fatty acids and peroxide value increased throughout the storage period of 120 days but at 15 °C the effect of storage on free fatty acids and peroxide value was comparatively less than 25 and 40 °C.

Hydroxy methyl furfural was found significant within the treatments and effect of storage period and temperature was also significant. Hydroxy methyl furfural almost remained same at 15 °C, with the increase of temperature it increased significantly. Sensory evaluation was carried out by a panel of six trained judges it was noted that score for color, taste; smell and mouth feel decreased with the increase of temperature and storage period. The highest score for color, smell, taste and mouth feel was obtained by T3 during 120 days of storage. Chemical analysis of whole milk powder samples showed that whole milk powder samples stored at 40 °C were most affected in terms of physico chmeical and sensory quality.

Overall results indicated that physico chemical quality and sensory properties of T3 was found best and it was comparatively less affected by storage temperatures. On the basis of this study it is recommended that for proper storage of whole milk powder 15 °C temperatures is suitable.