Determination of the Levels of Polycyclic Aromatic Hydrocarbons in Toasted Bread Using Gas Chromatography Mass Spectrometry

Concentration of 16 polycyclic aromatic hydrocarbons (PAHs) in eighteen baked bread samples using gas oven toasting were evaluated in this study. Samples were classified into the following categories: (1) bread baked from white wheat flour, (2) bread baked from brown wheat flour, and (3) sandwich bread baked from white wheat flour. Analysis was performed by GC-MS after Soxhlet extraction of the sample and clean up of the extract. The levels of B[a]P was not detected in ten of eighteen samples. In the rest of the samples, B[a]P are varied from 2.83 to 16.54 g/kg. B[a]A, CHR, B[b]FA, B[k] FA, IP, DB[a,h]A, and B[ghi]P concentrations were found to be less than 10.0 g/kg. However, B[a]P are not detected in original white and brown wheat flour. The total PAHs were varied in the range 1.06–44.24 g/kg and 3.08–278.66 g/kg for H-PAH and L-PAH, respectively. Reproducibility and repeatability of the proposed method was calculated and presented in terms of recovery and relative standard deviations (RSD, %). Recoveries were varied from 72.46% to 99.06% with RSD ± 0.28–15.01% and from 82.39% to 95.01% with RSD ±1.91–13.01% for repeatability and reproducibility, respectively. Different commercialized samples of toasted bread were collected and analyzed. 1. Introduction Polycyclic aromatic hydrocarbons (PAHs) are a group of chemicals having aromatic ring. Those containing up to four benzene rings are known as light PAHs (L-PAHs) and those containing more than four benzene rings are known as heavy PAHs (H-PAHs). H-PAH are more stable and toxic than L-PAHs [1]. Some studies have shown that heavy PAHs can induce dioxin-like activity and weakened estrogenic responses [2]. Most PAHs are formed from incomplete combustion of wood, oil, coal, and garbage [3]. Some have been demonstrated to be mutagenic and carcinogenic for humans [4]. Those PAHs that have not been found to be carcinogenic may, however, synergistically increase the carcinogenicity of other PAHs [5, 6]. Human exposure to PAHs does not occur singly, it encountered in complex mixtures of PAHs [7]. The main source of human exposure to PAHs is to be through diet with grains and vegetables, being the major dietary sources [5]. Foodstuffs can be contaminated by PAHs in several ways, such as either direct or indirect contact with smoke. The routes through which PAHs travel include food, air, and water [8]. The highest levels of PAHs are found in foodstuffs, both processed and unprocessed [9]. PAHs have been detected in seafood, beverages, smoked foods, and broiled meat [10]. Several methods for the analysis of B[ ]P