Effect of adding Water on Physical Properties of Raw Milk

Abstract

This research was conducted to study the effects of adding different levels of water to milk on certain physical properties. Ten (10) liters of raw milk were purchased from the farm of the College of Animal Production Science& Technology. One sample was used as control sample without added water (0%) added water while the other samples were divided into four groups samples with 3%, 10%, 20% and 30% added water. Then laboratory tests on color, taste, density, VIII boiling and freezing point were carried out. The experimental treatments were repeated 5 times for the different treatments. The results obtained for the density were (1.033 ± .00) for the control sample and (1.030 ± .00.54) (1.026 ± .0013) (1.025 ± .0083) and (1.024 ± .0084) for samples with 3%, 10%, 20% and 30% added water respectively. A decrease in density is very clear in the samples with added water. The statistical analysis is showed a high significant difference between the control sample and the other samples (3%, 10% 20% and 30%) added water (P≤0.01). . Also a high significant difference was found between the means of the samples with added water (P<0.05). The freezing points detected were (-0.53 ± 0.00˚C) for the control sample and (-0.25 ± .050), (-0.22 ± .057), (-0.20 ± 0.029) and (-0.19 ± .052) ˚C for samples 3%, 10%, 20% and 30% added water respectively. Also in this case arise in the freezing point with increasing added water, was noticed. The statistical analysis indicated a high significant difference between the values of the control sample and the rest of the samples for this property (P≤0.01). Also a high significant variation was recorded between the means or the milk samples with added water (P<0.05). Concerning the boiling point the obtained results for the control sample was (100.17 ± 0.00 ˚C), and (100.10 ± .732) (99.5 ± 1.46) (95.4 ± 1.516) and (94.5 ± 1.525)˚C for 3%, 10%, 20%, and 30% added water samples respectively. The boiling point decreased by increased amount of added water. The statistical analysis in dictated high significant difference between the values of the boiling point of the control sample and the samples of added water. (P≤0.01). .Also a significant difference was found between the means of samples with added water. (P<0.05) The color was extremely normal for the control sample (4.0 ± .00), extremely normal for 3% added water samples, (3.8 ± .42), extremely normal for 10% added IX water samples (3.6± .51), normal for 20% added water samples (2.7 ± .48) and abnormal for 30% added water samples (1.7 ± .82).Remarkable change in color was associated with percentage of the added water. No significant difference was recorded between color of control and 3% added water samples (P>0.05), while a high significant difference was recorded between above-mentioned samples and the rest of the other samples with added water. Also a high significant difference was found between the means of all samples with added water (P≤0.01). The taste of the control sample was extremely palatable (4.0 ± 0.00), for 3% samples extremely palatable (3.9 ± 0.31), for 10% samples extremely palatable (3.5 ± .49), for 20% samples palatable (2.9 ± .73) and for 30% samples unpalatable (1.8 ± .78). Also the taste was not stable, when different levels of water were added to the milk. No significant difference was detected between values of control and 3% and10% added water samples (P>0.05), while a high significant variation was recorded between the means of samples with added water. (P≤0.01). Finally certain recommendations were given.