Abstract #T106
Section: Dairy Foods (posters)
Session: Dairy Foods VI
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Exhibit Hall A
Session: Dairy Foods VI
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Exhibit Hall A
# T106
Development of a rapid detection method of lactoperoxidase in milk.
Weiying Du1,5, Yangdong Zhang1,2, Nan Zheng1,2, Fadi Li5, Jiaqi Wang*1,2, 1State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China, 2Key Laboratory of Quality & Safety Control for Dairy Products of Ministry of Agriculture, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China, 3Milk Product Risk Assessment Laboratory of China Ministry of Agriculture (Beijing), Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China, 4Milk and Milk Product Inspection Center of China Ministry of Agriculture (Beijing), Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China, 5State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, China.
Key Words: milk, lactoperoxidase, enzyme activity
Development of a rapid detection method of lactoperoxidase in milk.
Weiying Du1,5, Yangdong Zhang1,2, Nan Zheng1,2, Fadi Li5, Jiaqi Wang*1,2, 1State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China, 2Key Laboratory of Quality & Safety Control for Dairy Products of Ministry of Agriculture, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China, 3Milk Product Risk Assessment Laboratory of China Ministry of Agriculture (Beijing), Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China, 4Milk and Milk Product Inspection Center of China Ministry of Agriculture (Beijing), Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China, 5State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, China.
Lactoperoxidase (LPO) is one of the most heat resistant enzymes in milk, and is used as an indicator of heat load of dairy products, especially for overpasteurization of milk. The aim of this study was to develop a rapid detection method of LPO activity of overpasteurization milk, which could be used to qualitatively determine the degree of heat load of milk in practice. Based on the principle of enzymatic reaction, LPO activity was determined by color change using potassium iodide and p-phenylenediamine assay. LPO could oxidize iodide ions to iodide when hydrogen peroxide existed in milk, the LPO activity could be assayed according to the color reaction between iodide and starch. Similarly, p-phenylenediamine could also be oxidated in this way. Samples for the tests were raw and different heat treated milk of 72.5°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, and 120°C for 15 S. Three kinds of reagent solutions (starch soluble, potassium iodide, and hydrogen peroxide) were mixed together by shaking. P-phenylenediamine solution and hydrogen peroxide would be mixed in another assay to determine the LPO activity. The results showed that there were noticeable color changes from blue to light blue for raw and heat treated milk from 72.5°C to 80°C, and the color of heat treated milk above 80°C did not change. It was inferred that LPO lost its enzyme activity in the heat-treated milk above 80°C for 15 S. This study contributed new information to developing a LPO activity assay kit for overpasteurization milk test in practice.
Key Words: milk, lactoperoxidase, enzyme activity
