Preservation of Raw Milk by Hydrogen Peroxide

Abstract

This study was undertaken to investigate the effect of hydrogen peroxide on lengthening the shelf-life of raw milk samples obtained from University of Khartoum farm, Sudan University for Science and Technology farm, Kuku collecting center and vender's milk. The milk samples were inoculated with different levels of hydrogen peroxide (0.01, 0.03, 0.05, 0.07 and 0.08%, w/v). The acidity, coagulation time, potassium iodide (KI) test, protein values and total bacterial count were studied, in six samples from each farm for 24 hours. The results indicated a significant (P<0.0l) reduction in the developing of acidity (expressed as lactic acid percentage) of the hydrogen peroxide treated samples 0.03, 0.05, 0.07 and 0.08% H2O2. However, 0.01% H202 treated milk samples always gave results similar to the control. Coagulation time increased significantly (P<0.0l) with the increase in hydrogen peroxide concentrations. The 0.01% H2O2 obtained results similar to the control. Hydrogen peroxide concentrations slightly affected the nutritive value of milk proteins. The results, however, showed that higher concentration of hydrogen peroxide (0.08%) significantly (P<0.0l) decreased the protein value compared to the other samples. Total bacterial count (TBC) was carried out every six hours for 24 hours and the results indicated that hydrogen peroxide concentrations decreased the total bacterial count, and that was found to be dependent on the increase of hydrogen peroxide concentrations and the initial bacterial count of the raw milk samples. Identification of bacterial genera was carried out for the raw and treated milk samples. The results showed that the staphylococcus spp. was predominant in raw and treated milk samples. The level of 0.03 to 0.05% H2O2 was recommended for the preservation of raw milk for at least 9-12 hours after milking. This time lag will facilitate the safe distribution of hygienic milk in areas where lack of transportation, refrigeration and cooling facilities are predominant