Detection of some preservatives and neutralizers in raw milk traded in Khartoum state

Abstract

A study was conducted in Khartoum State, to investigate and detect the presence of some preservatives in raw milk and their effect on bacterial growth and chemical composition of milk. 120 milk samples were collected from four sales points in Khartoum and Khartoum North. 60 milk samples were transported by cars and 60 milk samples were transported by Donkeys in both States (Khartoum and Khartoum North). Khartoum 60 samples from (Alsalama, street 60), Khartoum North samples from Hliat kuku and Halfaia ) milk venders .Then the milk samples were preserved in a cool cracked ice and transported immediately to the Laboratory and analysis. The results revealed that boric acid was used as preservative in five samples of Khartoum sale points and two samples of Khartoum North sale point, while formaldehyde was used as a preservative in two samples of each Khartoum North and Khartoum milk sale points. Sodium carbonate and sodium bicarbonate were not found in raw milk samples collected from sale point of Khartoum and Khartoum North states. The calcium hydroxide showed one positive case in Khartoum. The data indicated that the mean values of the pH of the milk samples collected from street 60, Elsalama, Hilat kuku and Halfaia were 6.57, 6.65, 6.57 and 6.57, respectively, while the means percentages of the fat content were 4.59, 4.60, 4.60 and 4.60 respectively and the mean percentages of the ash content were 0.54, 0.50, 0.58 and 0.54 respectively. For all samples the differences were not significant in those contents. The results revealed that addition of boric acid, formaldehyde and calcium hydroxide to milk significantly (p<0.01) affected the pH of preserved milk the recorded values were 6.08, 7.12 and 7.05 respectively. While addition of boric acid and calcium hydroxide to milk had no significant effect on fat percentage of preserved milk the record values were 3.97% and 4.2 % respectively. However addition of formaldehyde to milk significantly (p<0.01) affect the fat percentage of preserved milk 3.48 %. The addition of boric acid, Formaldehyde and calcium hydroxide to milk had no significant effect on ash content. The results indicated that the presence of formaldehyde in milk samples prevents growth of bacteria, while bacterial growth was not affected by the presence of boric acid and calcium hydroxide in milk samples. The results revealed that donkey carried milk contained more bacteria than car carried milk. It could be concluded that milk distributed in Khartoum State contain some chemical preservatives, and to minimize use of these preservatives establishment of cooling station system in milk sale points is needed.