Quantitative evaluation of the alkaline phosphatase activity in industrial and traditional dairy products supplied in Ahvaz as an indicator of pasteurization

Subject Areas : Food Science and Technology

M.  Zarei ¹ (Associate Professor, Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University, Ahvaz)
مهدی  Pourmahdi Borujeni ² (Associate Professor, Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University, Ahvaz)
A.  Manafeian ³ (Faculty of Veterinary Medicine, Shahid Chamran University, Ahvaz)

Received: 2015-11-21 Accepted : 2016-06-12 Published : 2017-05-22

Keywords: alkaline phosphatase, Cheese, Milk products, Pasteurization,

Abstract :

Alkaline phosphatase is an indigenous milk enzyme and is probably, the most important indigenous milk enzyme from a dairy technology viewpoint which is used to determine the efficacy of the pasteurization process. The aim of this study was to assess the alkaline phosphatase activity of 200 samples of industrial and traditional yoghurt, ice cream and cheese, as well as raw and pasteurized milk samples. To achieve this purpose, p-nitrophenylphosphate was used as substrate and the amount of liberated p-nitrophenol was measured spectrophotometrically. The amount of liberated p-nitrophenol in all samples of raw milk was very high (6839±4070 µg/ml) but in pasteurized milk samples, the amount was in the range of 0.75-52.96 µg/ml and 88% of the samples had less than 10 µg p-nitrophenol/ml, the maximum permissible limit of p-nitrophenol in pasteurized products. The amount of liberated p-nitrophenol was in the range of 5.68-1210 µg/ml and 2.61-18.22 µg/ml in traditional and industrial cheese samples, respectively and it was estimated at the range of 0.75-26.67 µg/ml and 0.71- 35.82 µg/ml for traditional and industrial ice cream samples, respectively. The lowest alkaline phosphatase activity was observed in both industrial and traditional yoghurt samples. Meanwhile, p-nitrophenol in 12% of industrial cheese, 44% of traditional cheese and 16% of both industrial and traditional ice cream samples was higher than 10 µg/ml which could be due to the inadequate pasteurization of the product or cross contamination with raw milk. The results of the present study showed a need for more strict attention in the pasteurization of milk and its products.

References:

Aschaffenburg, R. and Mullen, J.E. (1949). A rapid and simple phosphatase test for milk. Journal of Dairy Research, 16: 58-67.

●Britz T.J. and Robinson R.K. (2008). Advanced Dairy Science and Technology. 1^st ed. Blackwell Publishing Ltd, Oxford, pp. 3-18.

●Cassidy, S., Daly, C., Early, J. and Trowe, M. (2014). Alkaline phosphatase activity in United Kingdom cheeses made from bovine pasteurized milk. International Journal of Dairy Technology, 67(2): 297-299.

●Chavarri, F., Santisteban, A., Virto, M. and deRenobales, M. (1998). Alkaline phosphatase, acid phosphatase, lactoperoxidase and lipoprotein lipase activities in industrial ewe’s milk and cheese. Food Chemistry, 46(8): 2926-2932.

●European Union Commission regulation. (2006). EC. No. 1664/2006. Official Journal of the European Union L320/13.

●FAO (2005). http://www.FAO.org/docrep/meeting/008/j2308e.

●Fox, P.F. (2003). Significance of indigenous enzymes in milk and dairy products, In: Whitaker J.R., Voragen, A.G.J. and Wong, D.W.S. (Editors), Handbook of Food Enzymology, Marcel Dekker, New York, pp. 255–277.

●Fox, P.F. and Kelly, A.L. (2006). Indigenous enzymes in milk: overview and historical aspects part 2. International Dairy Journal, 16(6): 517-532.

●Fox P.F. and McSweeney P.L.H. (1998). Dairy Chemistry and Biochemistry, 1^st ed. Blackie Academic and Professional. London, pp. 320-325.

●International Dairy Federation. (1987). Milk and dried milk, buttermilk powder, whey and whey powder. Detection of phosphatase activity. International Standards. Brussels: IDF, 82A.

●Lorenzen P.C., Martin D., Clawin-Radecker I., Barth K. and Knappstein K. (2010). Activities of alkaline phosphatase,ɣ-glutamiltransferase and lactoproxidase in cow, sheep and goat milk in relation to heat treatment. Small Ruminant Research, 89(1): 18-23.

●Payne, C. and Wilbey, R. (2009). Alkaline phosphatase activity in pasteurized milk: A quantitative comparison of fluorophos and colourimetric procedures. International Journal of Dairy Technology, 62(3): 308-314.

● Shakeel-ur-Rehman, P., Fleming, C.M., Farkye, N.Y. and Fox, P.F. (2003). Indigenous phosphatases in milk, In: Fox P.F. and McSweeney P.L.H. (Editors), Advanced Dairy Chemistry, Volume 1, proteins. 3^rd Edition. Kluwer Acaemic-Plenum Publishers. New York, pp. 523-543.

●Vamvakaki, A.N., Zoidou, E., Moatsu, G., Bokari, M. and Anifantakis, E. (2006). Residual alkaline phosphatase activity after heat treatment of ovine and caprine milk. Small Ruminants Research, 65: 237-241.

●Walstra, P., Wouters, J.T.M. and Geurts, T.J. (2006). Dairy Science and Technology. 2^nd ed. CRC Press, pp. 85-95.

●Wright, R.C. and Tramer, J. (1953a). Reactivation of milk phosphatase following heat treatment. Journal of Dairy Research, 20: 177-188.

●Wright, R.C. and Tramer, J. (1953b). Reactivation of milk phosphatase following heat treatment. II. Journal of Dairy Research, 20: 258-273.

●Wright, R.C. and Tramer, J. (1954). Reactivation of milk phosphatase following heat treatment. III. Journal of Dairy Research, 21: 37-49.

●Wright, R.C. and Tramer, J. (1956). Reactivation of milk phosphatase following heat treatment. IV. Journal of Dairy Research, 23: 248-256.

●Yoshitomi, K. (2004). Alkaline phosphatase activity in cheeses measured by fluorometry. International Journal of Food Science and Technology, 39: 349-353.