Evaluation of scorched particles, solubility index and dispersibility of commercial dried milk powder purchased from local markets of Hyderabad Pakistan

Samples of repacked full cream, half cream and skim milk powders, purchased from local markets of Hyderabad, Pakistan, were analyzed for scorched particles, solubility index and dispersibility. For reconstitution of milk, tap water as well as reverse osmosis (RO) water was used at 24 o C., 40 o C. and 60 o C. Scorched particles in skimmed milk powder were 17 ± 2.43mg, which were comparatively higher than those found in half cream milk powder (10.5 ±1.22mg) and full cream milk powder (9.75 ±1.14mg). The optimum solubility index of full cream dried milk was 1.25 ± 0.11ml, which for half cream was 1.2 ± 0.11ml and for skimmed milk powder was 1.5 ±0.12ml, when tap water was used for reconstitution of milk powder. When RO water was used for reconstitution of dried milk, satisfactory results were obtained and optimum solubility index of 0.75 ± 0.11 ml, 0.75 ± 0.11 ml and 1.3 ±0.15ml were recorded for full cream, half cream and skimmed milk powders respectively. It was further observed that water temperature at 60 o C gave better reconstitution results (i.e. least insoluble residues) compared to lower water temperatures of 40 o C and 24 o C. The optimum dispersibility time recorded for skimmed milk powder was 21.3±1.40 sec, for half cream milk powder was 18.2 ± 0.77 sec, and for full cream milk powder was 20.8±1.67 sec when reconstitution was carried out in tap water. Use of RO water for reconstitution of dried milk gave satisfactory results. Optimum dispersibility time observed for skimmed milk powder was 19.3±1.32 sec, for half cream was 16.6±0.92 sec and for full cream was 18.4± 1.55 sec. It was further observed that water temperature at 60 o C gave better dispersibility results as compared to that of at 40º C and 24º C.