Investigation of bisphenol a (BPA) level changing in şavak brined cheese stored in polyethylene terephalate (PET) packaging

This study was carried out to examine the change in BPA level during storage in Şavak brined white cheese made from raw cow milk in which BPA was added experimentally. For this purpose, two groups cheeses were produced as control group and BPA-added group. BPA was added to the milk at 1 ml/L concentration to produce the experimental cheese group. The cheeses were placed in PET containers and 18 % brine was added on it, and then stored at 4oC for 270 days. The cheese and brine were analyzed for the level of BPA, fat, dry matter, salt, and pH and % acidity on days 120, 150, 180, 210, 240, and 270 during the storage. In the study, a total of 132 samples including 36 cheeses, 39 brine samples, 36 PET package samples, 6 raw milk samples, 6 cheese curd samples, 6 whey and 3 rennets were evaluated for BPA. BPA levels were detected as 0,340±0,170 µg/L in the control group raw milk, as 992,37±1,65 µg/L in the raw milk of the experimental group, as 1,677±0,28 µg/kg in the control group curd, as 5589,70±265 µg/kg in the curd of the experimental group, as 0,349±0,12 µg/L in control whey, as 821,67±128 µg/L in the whey of the experimental group. On the other hand, BPA was detected in the rennet and in the brine solution as 0,837±0.20 µg/L and 0,246±0.21 µg/L, respectively. During the storage, BPA levels in the control brine were detected between 0,443±0,064 and 0,747±0,314 µg/L, in brine of BPA-added group were detected between 1387±298,71 and 1894±179,801 µg/L, the control group cheeses were detected between 0,927±0,285 and 1,237±0,25 µg/kg, in the cheeses made with added-BPA were detected between 3702±2070,237 and 4205±325,267 µg/kg. BFA amounts of polyethylene terephthalate (PET) packages were detected between 0,000-0,040 µg/L in unused PETs (A), 0,032-0,094 µg/L in PETs containing control group cheeses (B), and 0,080 - 0,197 µg/L PETs containing cheese made from milk with BPA added (C). pH values were 5,947±0,488-6,082±0,512 in control group cheeses and 5,333±0,205- 5,527±0,363 in the control group brine. Cheeses added-BPA were 5,873±0,296- 6,290±0,551 and in the brine solutions added-BPA were detected between 5,233±0,214 and 5,698±0,394. The % acidity in the control group cheeses were 0,200±0,055–0,477±0,247 and it was 3,432±1,113- 4,312±0,970 in the control group brine. On the other hand, the acidity were 0,200±0,068–0,320±0,073 % and 3,333±1,419–4,463±0,593 % in cheese and brine solution in which made from BPA added milks, respectively. The dry matter % values were 34,000±0,414 – 37,850±0,373 in the control group cheese and 17,150±0,261– 19,180±0,507 in the control group brine. On the other hand, cheese and brine which is added BPA were detected between 36,170±0,677 – 38,100±0,473 and 17,230±0,444 –19,250±0,363, respectively, The fat % were 15,40±0,42- 18,21±2,148 and 4,25±0,333– 6,50±0,447 % in the control group cheese and brine, respectively. It was detected between 15,3±0.687– 17,65±0.536 % in BPA added group cheese and 4,433±0,242 – 6,383±0,075 % in BPA-added cheese's brine. The salt % in the control group cheese and brine were 4,52±0,344-7,240±0,386 and 10,52±0,391–13,110±0,849, respectively. On the other hand, salt percentages were 4,440±0,644– 6,690±0,853 in the cheeses made with BPA added milk and 11,100±0,475 – 13,450±1,508 in the brine made with BPA added milk. Low level of positive correlation was determined between BPA migration and pH, fat % and dry matter %, while, a low level of negative correlation was determined between BPA migration and acidity % and salt %. As a result, it was observed that pH, acidity, dry matter, fat and salt had a low effect on BPA migration in brine solution and cheese. It was determined that the brine solution and cheese deformed the structure of the PET packages. Hereby, BPA migrate from the cheese and brine solution to the PET packages by negative migration. Key Words: Şavak Brine Cheese, PET, Bisphenol A, Migration