The Quality of Raw Cow`s Milk Preserved By Activation Of Lactoperoxidase System

Abstract

The study was conducted to investigate the keeping quality of raw cow`s milk preserved by activation of the lactoperoxidase system in Tsaeda-Christian, found in the sub zone Berik, Zoba Maekel. Three levels of sodium thiocyanate 10, 14, 18 and sodium percarbonate 20, 30 and 40 mg/L were respectively used to activate the raw milk samples and stored at incubation temperature (300C). Chemical composition, pH, total bacterial counts (TBC) were evaluated. Moreover, alcohol test and clot- on- boiling tests were performed. Activation of LPs in raw milk leads to improve the keeping quality. There were significant variations (P<0.001) in pH and TBC among the treatments throughout the storage period. The milk in all treatments remained fresh during the first 12 hours but the control became spoiled by the 14th hour. LPs treatment extended milk shelf life by 6, 8 and 8 hours, for 10+20mg/L (LP1), 18+30mg/L (LP2) and 20+40mg/L (LP3) sodium thiocyanate and sodium percarbonate, respectively as compared to control under storage temperature conditions (30°C). From all parameters measured, LP2 and LP3 were the last treatments to spoil. Clot-on-boiling test detected milk deterioration 2 hours later than the other quality tests. The results revealed that no difference in milk composition (fat, protein, lactose, SNF, TS, and density) among the control and treatment samples. Therefore, this extension in the shelf-life of milk provided sufficient time for milk to be stored, transported and sold in its fresh state in the local markets without refrigeration and may encourage dairy farming in collection of more milk of high quality.