Effect of Lactoperoxidase Enzyme System in Improving Shelflife of Raw Milk from Dairy Farms in Khartoum State, Sudan

Abstract

Lactoperoxidase enzyme (LP) is a natural component in milk with broad spectrum of antimicrobial activity applications in in vivo and in vitro. LP system (LPS) was developed to eliminate the growth of bacterial pathogens and augment the shelf life of raw milk. The aim of this study was to evaluate the effect of activation of LPS on the growth and survival of bacterial pathogens and preserving raw milk quality. A checklist was developed and filled in ten farms at the time of milking to detect the hygienic measures in these farms. Two liters of milk were collected in sterile containers and warmed to 37°C/15min. LPS was activated by dissolving 40mg and 30mg of sodium thiocyanate and sodium percarbonate, respectively, in one liter of milk and followed by thorough mixing. 50ml from this liter of milk was added to two new containers and designated as group B and C. Moreover, group C was supplied with E. coli (106-107 cfu/ml). While milk in group D, LPS was not activated, instead milk was only supplied with E. coli (106-107 cfu/ml). Group A was considered as the control group (neither activated nor supplied with Escherichia coli). Tenfold serial dilution was performed to determine the bacterial total viable count (TVC) and milk clotting time (per seconds) in each group for 2, 4, 6, 8 and 10 hrs. The TVC and the milk clotting time in each group were statistically expressed as pairs between the groups (A versus B; C versus D) with significance probability of P≤0.05. The checklist analysis reflected the bad hygiene measures in the dairy farms. For TVC, in 2hrs incubation; no significant difference was observed between group A versus group B. While group C versus group D showed high significant difference. After 4hrs incubation, TVC showed prominent significance difference between the control compared to group B. While group C versus group D showed no statistical significance differences. At 6hrs time period, a significant difference was observed between the compared groups. However, no significance differences were observed between the groups after 8hrs and 10hrs of incubation. For clotting time, in 2hrs incubation, a significant difference between the compared groups was observed. After 4hrs incubation, a significant difference between the control compared to group B was prominent, while group C versus group D showed no statistical differences in clotting time. However, no significant differences were observed between the groups after 6, 8 and 10hrs of incubation in the clotting times. Taken together these results indicated that the LPS system was efficient until 6hrs and could prolong milk shelf life and prevent milk clotting.