The Effect of Seasonal Variation on the Chemical and Microbial Quality of Raw Milk Samples Used in Qazvin, Iran

Document Type: Original Article


1 Department of Food Hygiene and Safety, School of Health, Qazvin University of Medical sciences, Qazvin, Iran

2 Medical Microbiology research Center, Qazvin University of Medical sciences, Qazvin, Iran

3 Health products safety research Center, Qazvin University of Medical sciences, Qazvin, Iran

4 PhD student in molecular medicine, Department of medical, Qazvin University of Medical Sciences, Qazvin, Iran


Although milk and dairy products are considered as nutritious food for human, it serves as a beneficent medium for the growth of many microorganisms such as psychrotrophic microorganisms (PMs). PMs can be affected by the milk quality and dairy products by production thermostable enzymes. The present study aimed to evaluated the psychrotrophic microorganisms count (PMsC) of raw cow milk samples in milk collection centers. A total of 60 raw cow milk samples were collected from 15 main milk collection centers located in Qazvin, Iran for a period of one year (four seasons). The mean±SD of PMs, Ph, and acidity levels for a period of one year was 4.83±0.43 Log10 CFU/ml, 6.30±0.41, and 20.13±3.21°D, respectively. PMsC, Ph, and acidity levels in cold seasons (autumn and winter) were greater than warm seasons (spring and summer). It may be expected that PMs values can affect the pH and acidity levels while no significant relationship (P>0.05) was found among PMs, Ph, and acidity levels. Seasonal variations had a significant effect (P<0.05) on PMs values while seasonal variations had no significant effect (P>0.05) on the pH and acidity levels. 55% (33 out of 60) of milk samples were in the accepted limit. Milk quality properties in Qazvin in terms of PMs were relatively within the hygienic standards limit. 


1. Mahmoudi R., Norian R., Pajihi M.R., Aliakbarlo J., 2014. Effect of season on microbial and chemical characteristics of milk and yoghurt from sheep. Animal Prod Sci. 54(8), 1091–1094.

2. Angulo F.J., LeJeune J.T., Rajala-Schultz P.J., 2009. Unpasteurized milk: a continued public health threat. Clinical Infectious Dis. 48(1), 93-100.

3. Anonymous., 2004. Regulation (EC) No 853/2004 of the European parliament and of the council of 29 April 2004 laying down specific hygiene rules for on the hygiene of foodstuffs. Official J. of the European Union L139/55.

4. Barbano D., Ma Y., Santos M., 2006. Influence of Raw Milk Quality on Fluid Milk Shelf Life1, 2. J Dairy Sci. 89, 15-19.

5. Bava L., Zucali M., Sandrucci A., Brasca M., Vanoni L., Zanini L., Tamburini A., 2011. Effect of cleaning procedure and hygienic condition of milking equipment on bacterial count of bulk tank milk. J Dairy Res. 78(2), 211-219.

6. Beales N., 2004. Adaptation of microorganisms to cold temperatures, weak acid preservatives, low pH, and osmotic stress: a review. Comprehensive Rev in Food Sci Food Safety. 3(1), 1-20.

7. Bonizzi I., Buffoni J., Feligini M., Enne G., 2009. Investigating the relationship between raw milk bacterial composition, as described by intergenic transcribed spacer–PCR fingerprinting, and pasture altitude. J Appl Microbiol. 107(4), 1319-1329.

8. Buehner K.P., Anand S., Garcia A., 2014. Prevalence of thermoduric bacteria and spores on 10 Midwest dairy farms. J Dairy Sci. 97(11), 6777-6784.

9. Burdova O., Baranova M., Laukova A., Rozanska H., Rola J.G., 2002. Hygiene of pasteurized milk depending on psychrotrophic microorganisms. Bulletin-Vet. Institute In Pulawy. 46(2), 325-330.

10. Cempírková R., 2002. Psychrotrophic vs. total bacterial counts in bulk milk samples. Vet Med Praha. 47(8), 227-233.

11. Cempírková R., Mikulová M., 2009. Incidence of psychrotrophic lipolytic bacteria in cow’s raw milk. Czech J Animal Sci. 54(2), 65-73.

12. Chen L., Daniel R.M., Coolbear T., 2003. Detection and impact of protease and lipase activities in milk and milk powders. Int Dairy J. 13(4), 255-275.

13. Chye F.Y., Abdullah A., Ayob M.K., 2004. Bacteriological quality and safety of raw milk in Malaysia. Food Microbiol. 21(5), 535-541.

14. Coorevits A., 2008. Comparative analysis of the diversity of aerobic spore-forming bacteria in raw milk from organic and conventional dairy farms. Systematic and Appl Microbiol. 31(2), 126-140.

15. Costello M., 2003. Eleven-year trends of microbiological quality in bulk tank milk. Food Protection Trends. 23(5), 393-400.

16. Cousin M., 1982. Presence and activity of psychrotrophic microorganisms in milk and dairy products: a review. J Food Protec. 45(2), 172-207.

17. Cousin M., Marth E., 1977. Psychrotrophic bacteria cause changes in stability of milk to coagulation by rennet or heat. J Dairy Sci. 60(7), 1042-1047.

18. Cowhx N., Morisetti M., 1969. Microbiological techniques‐some statistical aspects. J Sci of Food and Agric. 20(10), 573-579.

19. De Jonghe V.,  2011. Influence of storage conditions on the growth of Pseudomonas species in refrigerated raw milk. Appl Environ Microbiol. 77(2), 460-470.

20. De Santana EHW. Beloti V., Mülle E.E., de Aguiar Ferreira M., de Moraes L.B., Pereira, M., Gusmã, V.V., 2004. Milk contamination in different points of the dairy process. ii) mesophilic, psychrotrophic and proteolytic microorganisms. Semina: Ciências Agrárias. 25(4), 349-358.

21. Dunstall G., Rowe M.T., Wisdom G.B., Kilpatrick  D., 2005. Effect of quorum sensing agents on the growth kinetics of Pseudomonas spp. of raw milk origin. J Dairy Res. 72(3), 276-280.

22. Elmoslemany A.M., 2010. The association between bulk tank milk analysis for raw milk quality and on-farm management practices. Preventive Vet Med. 95(1-2), 32-40.

23. Eneroth Å., Christiansson A., Brendehaug J., Molin G., 1998. Critical contamination sites in the production line of pasteurised milk, with reference to the psychrotrophic spoilage flora. Int Dairy J. 8(9), 829-834.

24. Foltys V., Kirchnerová  K., 2006. Mesophilic and psychrotrophic aerobe sporulating microorganisms in raw cow’s milk. Open Life Sci. 1(4), 545-560.

25. Gargouri  A., Hamed  H., ElFeki  A., 2013. Analysis of raw milk quality at reception and during cold storage: combined effects of somatic cell counts and psychrotrophic bacteria on lipolysis. J Food Sci. 78(9), M1405-M1411.

26. Garrow J., James W., Ralph A., 2000. Human Nutrition and Dietetics. Pup. British library. pp. 552.

27. Hantsis-Zacharov E., Halpern M., 2007. Culturable psychrotrophic bacterial communities in raw milk and their proteolytic and lipolytic traits. Appl Environ Microbiol. 73(22), 7162-7168.

28. Haryani S., Datta N., Elliott A.J., Deeth H.C., 2003. Production of proteinases by psychrotrophic bacteria in raw milk stored at low temperature. Australian J Dairy Technol. 58(1), 15-20.

29. ISIRI, 2006. Institute of Standards and Industrial Res. of Iran, Milk and milk products- Determination of titrable acidity and pH value- Test method. National Standard No 2852.

30. Júnior J.R., 2018. The main spoilage-related psychrotrophic bacteria in refrigerated raw milk. J Dairy Sci. 101(1), 75-83.

31. Keefe G.P., Elmoslemany A., 2007. A consumer acceptance of fluid milk after raw milk selection using bulk tank bacteriologic and somatic cell count criteria, Proceedings of the National Mastitis Council.

32. Kim I.S., 2017. Comparative analysis of the microbial communities in raw milk produced in different regions of Korea. Asian-Australasian J Animal Sci. 30(11), 1643-1650.

33. Kumaresan G., Annalvilli R., Sivakumar K., 2007. Psychrotrophic spoilage of raw milk at different temperatures of storage. J Appl Sci Res. 3, 1383-1387.

34. Leitner G., 2008. The influence of storage on the farm and in dairy silos on milk quality for cheese production. Int Dairy J. 18(2), 109-113.

35. Liu M., Wang  H., Griffiths  M., 2007. Regulation of alkaline metalloprotease promoter by Nacyl homoserine lactone quorum sensing in Pseudomonas fluorescens. J Appl Microbiol. 103(6), 2174-2184.

36. Marchand S., 2009. Seasonal influence on heat‐resistant proteolytic capacity of Pseudomonas lundensis and Pseudomonas fragi, predominant milk spoilers isolated from Belgian raw milk samples. Environ Microbiol. 11(2), 467-482.

37. Martins M.L., Pinto C.L., Rocha R.B., De Araujo E.F., Vanetti M.C., 2006. Genetic diversity of Gram-negative, proteolytic, psychrotrophic bacteria isolated from refrigerated raw milk. Int J Food Microbiol. 111(2), 144-148.

38. McPhee J., Griffiths M., 2011. Psychrotrophic Bacteria| Pseudomonas spp.

39. Nörnberg M.F., Friedrich R.S., Weiss R.D., Tondo E.C., Brandelli A., 2010. Proteolytic activity among psychrotrophic bacteria isolated from refrigerated raw milk. Int J Dairy Technol. 63(1), 41-46.

40. Oliveira G.B.d., Favarin L., Luchese R.H., McIntosh D., 2015. Psychrotrophic bacteria in milk: How much do we really know? Braz J Microbiol. 46(2), 313-321.

41. Oliver S.P., Boor K.J., Murphy S.C., Murinda S.E., 2009. Food safety hazards associated with consumption of raw milk. Foodborne Pathog Dis. 6(7), 793-806.

42. Perkins N.R., Kelton D.F.,  Hand K.J., MacNaughton G., Berke O.,  Leslie K. E.,  2009. An analysis of the relationship between bulk tank milk quality and wash water quality on dairy farms in Ontario, Canada. J Dairy Sci. 92(8), 3714-3722.

43. Pinto G.C., Martins M.L., Vanetti M.C.D., 2006. Qualidade microbiológica de leite cru refrigerado e isolamento de bactérias psicrotróficas proteolíticas. Sociedade Brasileira de Ciência e Tecnologia de Alimentos.

44. Psoni L., Tzanetakis N., Litopoulou-Tzanetaki E., 2003. Microbiological characteristics of Batzos, a traditional Greek cheese from raw goat's milk. Food Microbiol. 20(5), 575-582.

45. Quigley L., O'Sullivan O., Stanton C., Beresford T.P., Ross R.P., Fitzgerald G.F., Cotter P.D., 2013. The complex microbiota of raw milk. FEMS Microbiol Rev. 37(5), 664-698.

46. Reguillo L., Hernández M., Barrientos E., Perez-Rodriguez F., Valero A., 2018. Evaluation of the Influence of Frequency of Milk Collection and Milking Dayshift on the Microbiological Quality of Raw Milk. J Food Quality. 2, 1-7.

47. Samaržija D., Zamberlin Š., Pogačić T., 2012. Psychrotrophic bacteria and milk and dairy products quality. Mljekarstvo. 62(2), 77-95.


48. Thomas S., 1966. Sources, incidence and significance of psychrotrophic bacteria in milk. Milchwissenschaft. 21, 270-275.

49. Vacheyrou M., Normand A.C., Guyot P., Cassagne C., Piarroux R., Bouton Y,.2011. Cultivable microbial communities in raw cow milk and potential transfers from stables of sixteen French farms. Int J Food Microbiol. 146(3), 253-262.

50. Villar A., Garcia J., Iglesias L., Garcia M., Otero A., 1996. Application of principal component analysis to the study of microbial populations in refrigerated raw milk from farms. Int Dairy J. 6(10), 937-945.

51. Vithanage N.R., Dissanayake M., Bolge G., Palombo E.A., Yeager T.R, Datta N., 2016. Biodiversity of culturable psychrotrophic microbiota in raw milk attributable to refrigeration conditions, seasonality and their spoilage potential. Int Dairy J. 57, 80-90.

52. Vithanage N.R., Dissanayake M., Bolge G., Palombo E.A., Yeager T.R, Datta N.,2017. Microbiological quality of raw milk attributable to prolonged refrigeration conditions. J Dairy Res. 84(1), 92-101.

53. Vyletělová M., Hanuš O., Urbanová E., Kopunecz P., 2000. The occurrence and identification of psychrotrophic bacteria with proteolytic and lipolytic activity in bulk milk samples on storage in primary production conditions. Czech J Animal Sci. 45(8), 373-383.

54. Yakubchak O., Galaburda M., 2012. Contamination of bulk milk by psychrotrophic microorganisms’during milking and milk processing. Int. Scientific Electronic J. Earth Bioresources and Life Quality Founded by National University of Life and Environmental Sci. of Ukraine (NUBiP of Ukraine) and Global Consortium of Higher Education and Res. for Agricul. (GCHERA). 1(1), 1-10.

55. Lei Yuan L., Sadiq F.A., Liu T., Flint S., Chen J., Yang H., Jingsi Gu J.,  Zhang G.,  He G., 2017. Psychrotrophic bacterial populations in Chinese raw dairy milk. LWT-Food Sci Technol. 84, 409-418.