The development of alkaline phosphatase based paper bioreporter for evaluation of milk pasteurization

Karakaş, Ceren
Alkaline phosphatase (ALP) is a natural milk enzyme. It has been used as reporter for process controls in food industry. Since ALP denatures at pasteurization temperature (at 63°C or 72°) its detection in milk confirms the unproper pasteurization. There are different detection procedures such as colorimetric, fluorometric methods and immunoassays for ALP in milk. However, they are time consuming processes and require specific instruments and qualified staff. In this study, new, semiquantitative, disposable, cheap and practical paper bioreporter have been developed for ALP detection. In optimization studies, 1mg/mL p-NPP in 0.1 M glycine buffer at pH 9.5 and 0.5 mg/mL bromocresol green in 1.0 M Tris-HCl buffer at pH 9.5 were determined as optimum for ALP bioreporter as a result of visual inspection and green color intensity analyses.The effects of samples temperature and pH of on the response of bioreporter were tested. Milk samples at pH 5.0, 5.5, 6.0 and 6.5 and milks stored at 37°C, room temperature and 4°C did not affect the response of bioreporter. Also the response of bioreporter against milk samples from different animals (cattle, sheep and goat) and cow’s milk from different location in Turkey were evaluated. The appropriate responses were observed by bioreporter. Whatman filter papers, cotton and bandage were used as support materials to construct bioreporter and Whatman filter papers were selected as the most applicaple support material. Finally, stability tests were carried out at 4°C and room temperature and 40 days at 4°C was determined as shelf life of bioreporter.


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Citation Formats
C. Karakaş, “The development of alkaline phosphatase based paper bioreporter for evaluation of milk pasteurization,” M.S. - Master of Science, Middle East Technical University, 2009.