Molds contamination of raw milk and dairy products: Occurrence, diversity and contamination source

Subject Areas : Food Science and Technology

طاهره Moshtaghi Maleki ¹ , شهرام Hanifian ²

1 - - M.Sc Graduate in Microbiology, Ahar Branch, Islamic Azad University, Ahar, Iran
2 - Assistant Professor of Department of Food Science and Technology, Tabriz Branch, Islamic Azad University

Received: 2018-03-21 Accepted : 2018-03-21 Published : 2015-11-22

Keywords: Diversity, dairy products, raw milk, Mold occurrence, Contamination sources,

Abstract :

This study aimed to assess the occurrence and diversity of mold species in raw milk and its products along with the identification of potential contamination sources. For this reason, a total of 260 samples consisting of 80 raw milk, 100 dairy products (i.e., pasteurized milk, yoghurt, cheese and buttermilk) and 80 environmental (i.e. ingredients, packaging materials, surface of processing equipments and air) specimens were collected. Using culture assay and microscopic observation, the occurrence as well as the diversity of mold species was investigated. According to the results, 82.3% of the samples were identified as positive for mold contamination. The percentage of mold contamination for raw milk was estimated as 97.5%. In the case of pasteurized milk, yoghurt, buttermilk, cheese and environmental samples, it was determined as 52%, 76%, 52%, 56% and 96.25%, respectively. Mold diversity among various samples consisted of Aspergillus, Geotrichum, Penicillium, Mucor, Alternaria, Rhizopus, Stemphylium, Cladosporium, and Fusarium. Results revealed a significant (p < 0.01) correlation between kind of mold species isolated from raw milk and dairy products. Similarly, a correlation was observed between dairy products and environmental sources. Regarding the high occurrence of mold contamination in raw milk and environmental sources, it seems that in some instances heat treatment was not effective enough to inactivate all molds; whereas in some other cases, cross contamination may have resulted in mold contamination. Therefore, it is crucial to maintain hygienic conditions during raw milk handling as well as processing steps. These practices could efficiently reduce the occurrence of mold contaminations in dairy products.

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● Erdogan, A., Gurses, M. and Sert, S. (2003). Isolation of moulds capable of producing mycotoxins from blue mouldy Tulum cheese produced in Turkey. International Journal of Food Microbiology, 85(1): 83–85.
● Harrigan, W.F. (1998). Laboratory Methods in Food Microbiology, 3th Edition, Academic Press, pp. 349–375.
● Hayaloglu, A.A. (2007). Microbial quality and presence of molds in Kuflu cheese. International Journal of Food Microbiology, 115(3): 376–380.
● Hoekstra, E.S., Van der Horst, M.I., Samson, R.A., Stark, J., and Van Rijn, F.T.J. (1998). Survey of the fungal flora in Dutch cheese factories and warehouses. Journal of Food Mycology, 1: 13–22.
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● Jay, J.M., Loessner, M.J. and Golden, D.A. (2005). Modern Food Microbiology, 7th Edition, Springer, pp. 38–56.
● Lavoie, K., Touchette, M., St-Gelais, D. and Labrie S. (2012). Characterization of the fungal microflora in raw milk and specialty cheese of the province of Quebec. Dairy Science and Technology, 92: 455–468.
●Mortazavi, S.A., Kashani Nejad, M. and Ziaalhag, H.R. (2005). Food Microbiology. (Translation). Author: Frazier, William and Vesthof, Dennis, 4th Edition, published by University of Mashhad: 36-33. [in Persian]
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● Panelli, S., Brambati, E., Bonacina, C. and Feligini, M. (2013). Diversity of fungal flora in raw milk from the Italian Alps in relation to pasture altitude. SpringerPlus, 2: 405.
● Ranjbar, S., Noori, M. and Nazari, R. (2010). Study of milk aflatoxin M1 and its relationship with feed fungi flora in Markazi Province, Journal of Cell & Tissue, 1(1): 9-18. [in Persian]
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● Walstra, P., Wouters, J.T.M. and Geurts, T.J. (2006). Dairy Science and Technology, 2nd Edition, Taylor & Francis Group LLC, pp. 19–83.