Sample determination
Twenty-two bread products were randomly sampled from three areas outside Bangkok. Manufacturing information such as mailing address, manufacturing date, expiration date, and food compositions of several samples were not presented. Amounts of calcium propionate in these samples were determined by the developed colorimetry and HPLC methods. From the results shown in Table 2, it could be seen that the results obtained from colorimetry were in agreement with the HPLC method. It was also noticed that 19/22 samples were found to have calcium propionate higher than the recommended concentration of 2000 mg/kg.
Table 2. Assay results of calcium propionate in bread samples obtained from the developed colorimetric method and high-performance liquid chromatography (HPLC) method.