Enhanced Antibacterial Activity of Lactoperoxidase-Thiocyanate-Hydrogen Peroxide System in Reduced-Lactose Milk Whey

Abstract

The product of the lactoperoxidase system (LPOS) has been developed as a preservative agent to inhibit foodborne bacteria, but its action was, heretofore, limited to several original compounds in milk. This research was conducted to analyze the application of the lactoperoxidase system against Escherichia coli in fresh bovine milk and its derivative products to determine the strength of antibacterial activity. Lactoperoxidase was purified from bovine whey using the SP Sepharose Big Beads Column. The enzymatic reaction involving lactoperoxidase, thiocyanate, and hydrogen peroxide was used to generate the antibacterial agent from LPOS. This solution was then added to milk, skimmed milk, untreated whey, reduced-LPO whey, reduced-lactose whey, and high-lactose solution containing E. coli at an initial count of 6.0 log CFU/mL. LPOS showed the greatest reduction of bacteria (1.68 ± 0.1 log CFU/mL) in the reduced-lactose whey among the products tested. This result may lead to a method for enhancement of the antimicrobial activity of LPOS in milk and derived products.

Figure 1

LPO activity in nine fractions obtained from the elution of 0.4 mM NaCl in 0.1 mM phosphate buffer of pH 7.0 through column containing Sepharose™ Big Beads.

Figure 2

SDS-PAGE profile of nine fractions that were eluted from column packing Sepharose™ Big Beads. Lanes 1 to 8 were the samples from fractions 1 to 8.

Figure 3

Antibacterial effect of LPOS against E.coli in milk and derivative products. This number was calculated from the initial population of 7.0±0.10 log CFU/ml. The solution containing E. coli and LPOS was incubated for 1 and 4 hours in 30°C. Values are means ± SE (n = 3).