Investigation of the effects of yogurt cultures on polycylic aromatic hydrocarbons

It is known that cultures using yogurt making can degrade polycyclic aromatic hydrocarbons (PAHs). There is limited research on how these cultures behave during yogurt making. It was aimed to determine whether different yogurt making can degrade PAHs that may be present in milk. Firstly, the presence of PAHs pH, dry matter and acidity were determined in raw cow milk. The milk found to be PAH-free was divided into 4 groups; (1) obtained from village yeast, (2) yeast from yogurts sold in markets, (3) prepared with Lactobacillus delbrueckki ssp. bulgaricus, Lactobacillus acidophilus, Streptococcus thermophilus, Bifidobacterium animalis ssp. lactis, Bifidobacterium infantis M-63, Bifidobacterium bifidum BGN4 and GOS, (4) prepared with Lactobacillus delbrueckki ssp. bulgaricus, Lactobacillus acidophilus, Bifidobacterium lactics ve Streptococcus thermophilus. Each group was divided into 4 subgroup and first group was kept as control while the other groups were treated with 50, 100, 200 µg/kg of a mixture 4 PAH [Benzo(a)pyrene, chrycene, benzo(b)floranthen, benzo(a)anthracene] respectively. Yogurts were obtained with traditional method. After the PAH mixture was added and yogurt process of formation was completed, PAH analyzes were determined by gas chromatography- mass spectrometer using previously validated method. When reduction data are analyzed according to 4 PAH concentrations in the analysis results; the highest reduction was seen in 3rd group at 200 µg/kg with 21,7%, the lowest was seen in the 1st group at 200 µg/kg with 8.05%. It was concluded that yogurt cultures can inhibit. PAHs in milk at a very low level and cannot completely degrade them.