Prevalence of Thermophiles and Mesophiles in Raw and UHT Milk

Abdul-Hadi A Abd,Nadia I Abdula?Al,Aysar S Abood

doi:10.19026/ijava.6.5612

Abdul-Hadi A Abd, Nadia I Abdula?Al + Show 1 more

Open Access

https://doi.org/10.19026/ijava.6.5612

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Abstract

The objective of the study was to evaluate the contamination level of cow's raw milk and different brands of UHT milk in Baghdad local market for thermophilic and mesophilic bacteria. The numbers of colony counts in milk samples were determined by the culture method according to bacteriological standards methods. Investigations were carried out for seven weeks in college of veterinary dairy farms from March 2013 to May 2013. Six (29%) positive samples out of 21 samples were tested for thermophiles in raw milk while 36 (100%) milk samples of Ultra High Temperature (UHT) were positive for thermophiles. Twenty one (100%) of mesophiles in raw milk samples were positive while in UHT milk samples only 18 (50%) out of 36 were positive. Overall the means of mesophiles have more significant counts differences (p<0.05) than thermophiles in raw milk samples. In UHT brands indicated that the results revealed high numbers of thermophiles in Nada and KDD which indicated that these brands were low quality. Moreover the values of these brands have significant differences (p<0.05) comparing with the UHT milk brands Al-Maraee and Al-Safi. In the same time the UHT brands were shown high numbers of mesophiles in Nada and Al-Safi which indicated that these brands have significant differences (p<0.05) comparing with Al-Maraee and KDD. This study was concentrated on milk contamination occurred after milk producing as well as processing, transport and store of UHT.

Highlights

An increase in the counts of bacteria in cow’s raw milk is problematic because they produce thermoresistant extracellular proteolytic and lipolytic enzymes that pose a qualitative risk during milk processing and cause the spoilage of the final products during storage (Chen et al, 2003)
Out of 21 samples were examined only 6 (29%) samples were positive for thermophiles from raw milk while all the 36 imported Ultra High Temperature (UHT) milk samples examined (100%) were positive for thermophiles (Table 1). out of 36 were positive imported UHT milk samples examined only 18 (50%) samples were positive for mesophiles while all the 21 raw milk samples examined (100%) were positive for mesophiles
Considering that this group of microorganisms is not eliminated by the thermal treatment of milk before processing to milk foodstuffs, it must be kept in mind, that seemingly low mesophilic counts may have serious negative consequences for quality and storability of milk foodstuffs (Banykó and Vyletělová, 2009)

Summary

Introduction

An increase in the counts of bacteria in cow’s raw milk is problematic because they produce thermoresistant extracellular proteolytic and lipolytic enzymes that pose a qualitative risk during milk processing and cause the spoilage of the final products during storage (Chen et al, 2003). Spore-forming microorganisms were either strictly anaerobic (SPAN)-genus Clostridium, which caused problems mainly in long lasting ripening of cheeses, or they were facultatively anaerobic; it means that they were grown under aerobic as well as anaerobic conditions-genus Bacillus, which was characteristic by broad complex of physiologic variants that were reflected in a variety of mesophilic, thermophilic and psychrophilic species with the high taxonomic diversity (Scheldeman et al, 2006) These spores can survive in products given heat treatment (De-Jonghe et al, 2010) and by undesired growth can cause defect such as sweet curdling, coagulation and diarrhea and emetic toxin production (Stenfors Arnesen et al, 2008)

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