Changes in PAHs levels in edible oils during deep-frying process

Review of polycyclic aromatic hydrocarbons pollution characteristics and carcinogenic risk assessment in global cooking environments

In recent years, research on air pollution in cooking environments has gained increasing attention, particularly studies related to polycyclic aromatic hydrocarbons (PAHs) pollution. Hence, it is crucial and urgent to conduct a comprehensive review of research findings and further evaluate their carcinogenic risks. This study adopts a comprehensive literature review approach, systematically integrating and deeply analyzing the conclusions and data from 62 selected relevant studies. It focuses on the impact of different factors on PAHs concentrations, considers the indoor-outdoor PAHs concentration ratio, and conducts carcinogenic risk assessments for PAHs. The results show that Africa has the highest average PAHs pollution concentration globally at 14.74 μg/m³, exceeding that of other continents by 1.5-160.9 times. Among various influencing factors, fuel type has the most significant impact on PAHs concentrations. Existing research data indicate that cooking with charcoal as fuel produces the highest PAHs concentration at 223.52 μg/m³, with high molecular weight PAHs accounting for 58.16%, significantly higher than when using clean energy. Furthermore, efficient ventilation systems have been proven to substantially reduce PAHs concentrations, with a reduction rate of up to 88.1%. However, cooking methods and food types also have a small but non-negligible impact on PAHs production. Using mild cooking methods such as steaming and selecting low-fat foods can also reduce PAHs to some extent. Additionally, through the analysis of the Indoor/Outdoor ratio, it was found that cooking is the primary source of indoor pollution, and the average concentration of PAHs in cooking environments in Asia and Africa is much higher than in Europe and America. The Total Incremental Lifetime Cancer Risk (TILCR) exceeds 10⁻⁴, indicating a high level of carcinogenic risk.

Investigation of the Frying Fume Composition During Deep Frying of Tempeh Using GC-MS and PTR-MS

This study employed proton transfer reaction mass spectrometry (PTR-MS) and gas chromatography-mass spectrometry (GC-MS) to identify and monitor volatile organic compounds (VOCs) in frying fumes generated during the deep frying of tempeh. The research aimed to assess the impact of frying conditions, including frying temperature, oil type, and repeated use cycles, on the formation of thermal decomposition products. A total of 78 VOCs were identified, with 42 common to both rapeseed and palm oil. An algorithm based on cosine similarity was proposed to group variables, resulting in six distinct emission clusters. The findings highlighted the prominence of saturated and unsaturated aldehydes, underscoring the role of fatty acid oxidation in shaping the frying fume composition. This study not only corroborates previous research but also provides new insights into VOC emissions during deep frying, particularly regarding the specific emission profiles of certain compound groups and the influence of frying conditions on these profiles.

Polycyclic Aromatic Hydrocarbons' Impact on Crops and Occurrence, Sources, and Detection Methods in Food: A Review

Polycyclic aromatic hydrocarbons (PAHs) represent a category of persistent organic pollutants that pose a global concern in the realm of food safety due to their recognized carcinogenic properties in humans. Food can be contaminated with PAHs that are present in water, air, or soil, or during food processing and cooking. The wide and varied sources of PAHs contribute to their persistent contamination of food, leading to their accumulation within these products. As a result, monitoring of the levels of PAHs in food is necessary to guarantee the safety of food products as well as the public health. This review paper attempts to give its readers an overview of the impact of PAHs on crops, their occurrence and sources, and the methodologies employed for the sample preparation and detection of PAHs in food. In addition, possible directions for future research are proposed. The objective is to provide references for the monitoring, prevention, and in-depth exploration of PAHs in food.

Simulation and parameter determination of the net sorption of phenanthrene by sediment particles

The distribution of polycyclic aromatic hydrocarbons (PAHs) in the ocean is affected by the sorption-desorption process of sediment particles. This process is determined by the concentration of PAHs in seawater, water temperature, and organic matter content of sediment particles. Quantitative relationships between the net sorption rates (=the difference of sorption and desorption rates) and these factors have not been established yet and used in PAH transport models. In this study, phenanthrene was chosen as the representative of PAHs. Three groups of experimental data were collected to address the dependence of the net sorption processes on the initial concentration, water temperature, and organic carbon content representing organic matter content. One-site and two-compartment mass-transfer models were tested to represent the experimental data using various parameters. The results showed that the two-compartment mass-transfer model performed better than the one-site mass-transfer model. The parameters of the two-compartment mass-transfer model include the sorption rate coefficients kafand kas (L g-1 min-1), and the desorption rate coefficients kdf and kds (min-1). The parameters at different temperatures and organic carbon contents were obtained by numerical simulations. Linear relationships were obtained between the parameters and water temperature, as well as organic carbon content. kaf, kas and kdf decreased linearly, while kds increased linearly with temperature. kaf, kas and kdf increased linearly, while kds decreased linearly with organic carbon content. The r2 values between the simulation results based on the relationships and the experimental results reached 0.96-0.99, which supports the application of the model to simulate sorption-desorption processes at different water temperatures and organic carbon contents in a realistic ocean.

Analysis of Polycyclic Aromatic Hydrocarbons via GC-MS/MS and Heterocyclic Amines via UPLC-MS/MS in Crispy Pork Spareribs for Studying Their Formation during Frying

This study aims to explore the effects of frying conditions on the formation of HAs and PAHs in crispy pork spareribs, a popular meat commodity sold on Taiwan's market. Raw pork spareribs were marinated, coated with sweet potato powder, and fried in soybean oil and palm oil at 190 °C/6 min or 150 °C/12 min, followed by an analysis of HAs and PAHs via QuEChERS coupled with UPLC-MS/MS and GC-MS/MS, respectively. Both HAs and PAHs in pork spareribs during frying followed a temperature- and time-dependent rise. A total of 7 HAs (20.34-25.97 μg/kg) and 12 PAHs (67.69-85.10 μg/kg) were detected in pork spareribs fried in soybean oil and palm oil at 150 °C/12 min or 190 °C/6 min, with palm oil producing a higher level of total HAs and a lower level of total PAHs than soybean oil. The content changes of amino acid, reducing sugar, and creatinine played a vital role in affecting HA formation, while the degree of oil unsaturation and the contents of precursors including benzaldehyde, 2-cyclohexene-1-one, and trans,trans-2,4-decadienal showed a crucial role in affecting PAH formation. The principal component analysis revealed that HAs and PAHs were formed by different mechanisms, with the latter being more liable to formation in pork spareribs during frying, while the two-factorial analysis indicated that the interaction between oil type and frying condition was insignificant for HAs and PAHs generated in crispy pork spareribs. Both CcdP (22.67-32.78 μg/kg) and Pyr (16.70-22.36 μg/kg) dominated in PAH formation, while Harman (14.46-17.91 μg/kg) and Norharman (3.41-4.55 μg/kg) dominated in HA formation in crispy pork spareribs during frying. The outcome of this study forms a basis for learning both the variety and content of HAs and PAHs generated during the frying of pork spareribs and the optimum frying condition to minimize their formation.

Chemical characterization of volatile organic compounds (VOCs) emitted from multiple cooking cuisines and purification efficiency assessments

Cooking process can produce abundant volatile organic compounds (VOCs), which are harmful to environment and human health. Therefore, we conducted a comprehensive analysis in which VOCs emissions from multiple cuisines have been sampled based on the simulation and acquisition platform, involving concentration characteristics, ozone formation potential (OFP) and purification efficiency assessments. VOCs emissions varied from 1828.5 to 14,355.1 µg/m³, with the maximum and minimum values from Barbecue and Family cuisine, respectively. Alkanes and alcohol had higher contributions to VOCs from Sichuan and Hunan cuisine (64.1%), Family cuisine (66.3%), Shandong cuisine (69.1%) and Cantonese cuisine (69.8%), with the dominant VOCs species of ethanol, isobutane and n-butane. In comparison, alcohols (79.5%) were abundant for Huaiyang cuisine, while alkanes (19.7%), alkenes (35.9%) and haloalkanes (22.9%) accounted for higher proportions from Barbecue. Specially, carbon tetrachloride, n-hexylene and 1-butene were the most abundant VOCs species for Barbecue, ranging from 8.8% to 14.6%. The highest OFP occurred in Barbecue. The sensitive species of OFP for Huaiyang cuisine were alcohols, while other cuisines were alkenes. Purification efficiency assessments shed light on the removal differences of individual and synergistic control technologies. VOCs emissions exhibited a strong dependence on the photocatalytic oxidation, with the removal efficiencies of 29.0%-54.4%. However, the high voltage electrostatic, wet purification and mechanical separation techniques played a mediocre or even counterproductive role in the VOCs reduction, meanwhile collaborative control technologies could not significantly improve the removal efficiency. Our results identified more effective control technologies, which were conductive to alleviating air pollution from cooking emissions.

Formation, migration, derivation, and generation mechanism of polycyclic aromatic hydrocarbons during frying

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and lipophilic, which can be found in frying system. This review summarized the formation, migration and derivation for PAHs, hypothesized the possible mechanism for PAHs generation during frying and presented the research prospects. Some factors like high oil consumption, high temperature, long time and oil rich in unsaturated fatty acids promoted the formation of PAHs and the presence of antioxidants inhibited the PAHs formation. The effect of proteins and carbohydrates in foods on the formation of PAHs is inconclusive. The formed PAHs were migrated into food and air. Moreover, some PAHs transformed into more toxic PAHs-derivatives during frying. The generation of PAHs may be related to low-barrier free radical-mediated reaction and the unsaturated hydrocarbons may be precursors of PAHs during frying. In future, the isotope tracer technology and on-line detection may be applied to discover intermediates and provide clues for studying PAHs generation mechanisms.

Pot study using Chlorophytum comosum plants to biomonitor PAH levels in domestic kitchens

In indoor environments, cooking is a major contributor to indoor air pollution releasing potentially harmful toxic compounds such as polycyclic aromatic hydrocarbons. In our study, Chlorophytum comosum 'Variegata' plants were applied to monitor PAH emission rates and patterns in previously selected rural Hungarian kitchens. Concentration and profile of accumulated PAHs could be well explained by cooking methods and materials used in each kitchen. Accumulation of 6-ring PAHs was characteristic in the only kitchen which frequently used deep frying. It also should be emphasized that applicability of C. comosum as indoor biomonitor was assessed. The plant has proven a good monitor organism as it accumulated both LMW and HMW PAHs.

The effect of in-package cold plasma on the formation of polycyclic aromatic hydrocarbons in charcoal-grilled beef steak with different oils or fats

In-package cold plasma (ICP) pretreatment is an emerging non-thermal food processing methods. In the current study, ICP on the formation of polycyclic aromatic hydrocarbons (PAHs) in grilled beef steaks with different oils and fats was evaluated, the influence of prolonged storage periods (1 d, 2 d) of raw meat after ICP pretreatment on the PAH inhibitory effect was investigated. The results showed that sunflower seed oil had an inhibitory effect on PAH formation; the groups with ICP pretreatment showed a significant decrease in PAH content (p < 0.05) according to the UHPLC results, inhibitory rates were dependent on the original contents in each group without ICP pretreatment, ranging from 35% to 96%. The optimal condition was grilling immediately after ICP pretreatment, and the results indicated that the nonpolar radical scavenging activity (RSA) of ungrilled meat was negatively correlated with PAH8 contents according the DPPH assay, while ICP pretreatment enhanced the RSA_oil of raw meat.

Managing the hazardous waste cooking oil by conversion into bioenergy through the application of waste-derived green catalysts: A review

Waste cooking oil (WCO) is a hazardous waste generated at staggering values globally. WCO disposal into various ecosystems, including soil and water, could result in severe environmental consequences. On the other hand, mismanagement of this hazardous waste could also be translated into the loss of resources given its energy content. Hence, finding cost-effective and eco-friendly alternative pathways for simultaneous management and valorization of WCO, such as conversion into biodiesel, has been widely sought. Due to its low toxicity, high biodegradability, renewability, and the possibility of direct use in diesel engines, biodiesel is a promising alternative to mineral diesel. However, the conventional homogeneous or heterogeneous catalysts used in the biodiesel production process, i.e., transesterification, are generally toxic and derived from non-renewable resources. Therefore, to boost the sustainability features of the process, the development of catalysts derived from renewable waste-oriented resources is of significant importance. In light of the above, the present work aims to review and critically discuss the hazardous WCO application for bioenergy production. Moreover, various waste-oriented catalysts used to valorize this waste are presented and discussed.

Impact of different cooking methods on polycyclic aromatic hydrocarbons in rabbit meat

The influence of a variety of cooking methods (poaching, boiling, grilling (charcoal or gas)), frying (pan, deep frying, and stir frying) with a variety of oils (vegetable oil, extra virgin olive oil, sesame oil, extra light olive oil, and sunflower oil), microwaving, and oven roasting on polycyclic aromatic hydrocarbons (PAHs) formation in rabbit meat samples was investigated. Meat samples (including three replicates) were prepared without additives or spices. PAHs extraction was carried out by saponification method with potassium hydroxide in methanol which was followed by a silica gel column technique and the samples were quantified by using gas chromatography with mass spectrometry (GC-MS). PAHs standards, fluorene, naphthalene, anthracene, phenanthrene, pyrene, acenaphthalene, fluoranthene, and benzopyrene, were used for this study. The other PAHs except fluorene were not observed (detection limit-0.009 µg/g) in all the samples. Among traditional processing techniques, higher PAH contents were observed as a result of frying. Frying with vegetable oil produced higher fluorene content (0.06-0.13 µg/g) in the deep-fried sample, although sesame oil is the best oil which produces lowest PAH contents in fried samples. Among all the processing techniques, lower fluorene (0.01-0.02 µg/g) content was noticed in poaching. Benzo(a)pyrene was not observed in all the investigated samples which is viewed as a reliable strategy of the cooking process for human consumption. After processing, the cooking loss was determined and oven roasting and grilling exhibited greater moisture loss.

Polycyclic and nitro-polycyclic aromatic hydrocarbon pollution characteristics and carcinogenic risk assessment of indoor kitchen air during cooking periods in rural households in North China

Medium-flow atmospheric samplers were used to collect particulate (PM_2.5) and gaseous samples from the indoor kitchen of each of 35 randomly selected rural houses in North China while a meal was being cooked. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) and 9 nitro-PAHs (NPAHs) in the samples were quantified by high-performance liquid chromatography (HPLC). This study provided the real PAH and NPAH pollution characteristics and carcinogenic risk produced by cooking in rural indoor kitchens in North China. The mean PAH and NPAH concentrations in air in the indoor kitchens during cooking periods were 4049.1 and 1741.6 ng/m³, respectively. The PAH and NPAH concentrations were lower in the particulate phase than the gaseous phase. The mean PAH and NPAH concentrations were much higher for cooking using coal than for cooking using liquefied petroleum gas (LPG) or electricity. The PAH and NPAH benzo[a]pyrene toxic equivalent (TEQ_BaP) concentrations for cooking using coal were 1823.3 and 2760.9 ng/m³, respectively. Lower PAH and NPAH concentrations were found in kitchens with than without range hoods. Range hoods decreased the PAH and NPAH TEQ_BaP concentrations by 68.8% and 61.9%, respectively. Appropriate fuel and ventilation choice will improve air pollution in indoor kitchens during cooking. The results provide important evidence for changing cooking habits and developing policies for cooking in rural China.

Change of benzo(a)pyrene during frying and its groove binding to calf thymus DNA

Benzo[a]pyrene (BaP), a prototype of polycyclic aromatic hydrocarbons (PAHs) with potential mutagenicity, toxicity and carcinogenicity, is ubiquitous in deep-fried foods. Herein, the changes in eight specific PAHs (PAH8) concentration in sunflower oil during frying were investigated by gas chromatography-triple quadrupole-mass spectrometry (GC-QqQ-MS). PAH8 concentrations in sunflower oil were 23.92-27.82 μg kg^-1 and increased with increasing frying time. The detected BaP levels were 3.64-4.00 μg kg^-1, exceeding the upper limit (2 μg kg^-1) set by European Union (EU), though below the limiting value (10 μg kg^-1) in China. The interaction between BaP and calf thymus DNA (ctDNA) was explored through various spectroscopic methods and molecular docking. Melting studies, denaturation experiments, ionic strength effects and viscosity measurements indicated that BaP interacted with ctDNA primarily via groove binding as evidenced by circular dichroism analysis and molecular docking. Further gel electrophoresis assays suggested that DNA was damaged at high levels of BaP.

Determination of polycyclic aromatic hydrocarbons in olives exposed to three different industrial sources and in their respective oils

Atmospheric contamination of plant raw material with Polycyclic Aromatic Hydrocarbons (PAHs) helps explain their presence in edible vegetable oils. This study compared PAH contamination of Turkish olive fruits during their growing period on the tree and their respective oils from three different industrial sources (petroleum refinery, thermal power plant and heavy industry site). The method included liquid-liquid extraction solid-phase extraction for cleanup followed by HPLC with fluorescence detector. There were statistically significant differences between the three industrial sources in benzo[a]pyrene content, the sum of light, total PAHs and PAH4 (p˂0.05), but only slight differences in PAH profiles. The highest level of PAH compounds was measured in samples exposed to pollution from the petroleum refinery, nearly twice as high as samples exposed to the thermal power plant which showed the lowest contamination levels. None of the samples analysed exceeded the limits stipulated by current legislation. The transfer ratios of PAH compounds from olives to olive oil were 22.8-73.2%. This indicates that PAHs either diffuse directly from skin to oil within the fruit or transfer during oil extraction.

Barbecued desi chicken: an investigation on the impact of polluted milieu upon formation and ingestion of polycyclic aromatic hydrocarbons (PAHs) in commercial versus laboratory barbecued organs along with stochastic cancer risk assessments in people from an industrial district of Punjab, Pakistan

8∑PAHs in 2- and 4-month-old desi chicken organs collected from Faisalabad district, Punjab, Pakistan, were examined via high-performance liquid chromatography (HPLC). Exposure doses (A_VDD) of PAHs with consequential lifetime excess cancer risks (L_tECR) were also estimated in people ingesting laboratory barbecued (L_b) and commercially barbecued (C_b) desi meat organs. The results exposed the presence of 8ΣPAH in 2- and 4-month-old L_b and C_b chicken organs: drumsticks (D_s), breast (B_S), and wings (W_s) (0.45, 3.10, 0.97 ng g^-1; 2.52, 4.31, 1.22 ng g^-1; and 10.09, 15.04, and 9.06 ng g^-1 respectively). BαP was found only in C_b organs with the highest concentrations (5.08 ng g^-1) in B_s. It was above the EU's tolerable limit, while it was not detected in all L_b organs. The lowest level of 8ΣPAH was found in 2-month-old desi W_s. A comparative percentage increase in 8ΣPAH levels between all L_b and C_b organs was found in the range of 1500-2416.67%. L_tECR for males and adults were ranging from 1.35 × E^-13 to 4.49 × E^-5 at different consumption rates with A_VDD ranging from 1.08 E^-6 to 6.01 E^-5. In contrast to 2- and 4- month-old chicken meat, 2-month-old desi meat is better having less PAH load. Comparing different organs, W_s of former one displayed abridged PAH levels. In conclusion, L_b desi meat is less carcinogenic relative to C_b. More PAH levels are due to secondary smoke in C_b samples collected from the metropolitan. Ingestion of L_b 2-month-old desi chicken organs could be safe to dine as compared with 4-month-old desi and C_b organs. Graphical abstract.

β-carbolines norharman and harman in vegetable oils in China

The beta-carbolines norharman and harman, two heterocyclic aromatic amines with potential mutagenicity, have been determined in vegetable oils. Identification and analysis were carried out by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-MS/MS). In 88 samples analysed, the concentrations of norharman and harman were < LOD to 336.22 ng/g and < LOD to 505.14 ng/g, respectively. A high variability of norharman and harman levels among different oil types was observed. Sesame-, flaxseed-, sunflower seed-, peanut- and rapeseed oils were most contaminated. Both β-carbolines were most likely formed during roasting of the oilseeds. Oil consumption, especially of oils obtained after roasting of the seeds, was a major dietary source of the β-carbolines norharman and harman. Under existing oil risk factors, this investigation contributes to the unprecedented and essential information for dietary assessments associated with oil consumption.

Substantial Decrease in Contaminant Concentrations in the Sediments of the Venice (Italy) Canal Network in the Last Two Decades—Implications for Sediment Management

The Venice canal network requires periodic intervention to remove sediments that progressively accumulate. The most recent dredging operation was carried out in the second half of the 1990s and early 2000s. These sediments had accumulated over a period of more than 30 years and were highly contaminated with Cd, Cu, Hg, Pb, Zn and PAHs. Sediments deposited after the dredging work were investigated in 2005, 2009, 2014 and 2017 by analysing sediment cores collected from three sites in the canal network. Arsenic, heavy metal and PAH concentrations were observed to be much lower than past values, although Cu, Hg and PAH levels were still relatively high. The high Cu concentrations (mean 161 mg kg−1) are partly due to the widespread use of Cu-based antifouling paint. Current Italian regulations forbid the disposal of dredged sediments with these concentrations inside the lagoon, thereby increasing the cost of canal network maintenance.

Polycyclic aromatic hydrocarbons in edible oils and fatty foods: Occurrence, formation, analysis, change and control

Numerous studies have demonstrated that dozens of polycyclic aromatic hydrocarbons (PAHs) are mutagenic, genotoxic and strongly carcinogenic. PAHs are found to be widely present in foods contaminated through multiple paths. Due to their lipophilic nature, these compounds easily accumulate in edible oils and fatty foods where they can range from no detection to over 2000μg/kg. Compared to precursor PAHs, researchers have seldom studied the presence of PAH derivatives, especially in food matrices. This chapter includes the physical and chemical characteristics of PAHs and their types, occurrence, sample pretreatment and instrumental determination methods, and their formation, change and control in edible oils and fatty foods. The occurrence and formation of PAH derivatives in foods are much less investigated compared to those of their precursor PAHs. Although the removal of matrix effects and accuracy remain difficult for current rapid determination methods, a prospective research direction of PAH analysis for large-scale screening is in demand. To date, physical absorption, chemical oxidation and biodegradation have been widely used in PAH removal techniques. Specific types of bacteria, fungi, and algae have also been used to degrade PAHs into harmless compounds. However, most of them can only degrade a range of LPAHs, such as naphthalene, anthracene and phenanthrene. Their ability to degrade HPAHs requires further study. Moreover, it is still a great challenge to maintain food nutrition and flavor during the PAH removal process using these methods.

Effect of frying and storage on oxidative quality of conjugated linoleic-acid-rich soybean oil produced by photoisomerization using plantain as a model system

BACKGROUND

Conjugated linoleic acid (CLA) is known to have beneficial properties to health. Naturally, in foods it is found in very low concentrations, and so these beneficial properties cannot be obtained. This study investigated the enrichment of soybean oil by photoisomerization, as well as assessing its oxidative stability during the frying process using plantain slices as a model system and after a storage period of 20 days at 60 °C.

RESULTS

The oxidative stability of soybean oil enriched with CLA by photoirradiation was measured based on the peroxide, p-anisidine, and Totox values, as well as by the polyphenol content, tocopherol content and DPPH^· scavenging capacity. The results obtained showed that a substantial amount of CLA was obtained by photoirradiation (31.73%). The oxidative stability values of the oil enriched with CLA showed good stability during a frying cycle; however, this stability decreased when it was stored and during the final frying cycles.

CONCLUSIONS

The results obtained indicated that photoirradiation is a good technique for obtaining oils enriched with CLA, and in this way CLA can be incorporated into foods; however, it is necessary to add antioxidants to improve their stability. © 2019 Society of Chemical Industry.

Quality of Lipid Fractions in Deep-Fried Foods from Street Vendors in Chile

Deep-fried foods sold by unlicensed street vendors are a health concern for various reasons, but oil quality is particularly important considering known links between fat consumption and cardiovascular disease. To diagnose the exact gravity of this situation in Chile, a country where street vendors are proliferate, the physicochemical parameters of fat fractions from fried food samples were assessed. Fat quality was assessed through the acidity index, peroxide index, extinction coefficient, TOTOX index, polar compounds percentage, and fatty acid profile. Most food samples (80%) had at least a 10% fat content. Many samples also had high peroxide values (1.7–103.3 meqO2/kg) and extinction coefficients (K232 and K270), findings indicative of advanced oil deterioration. These results were supported by values for para-anisidine (100.2–311.0), TOTOX (>103.6), and polar compounds (14.2–49.7%). All assessed food samples contained saturated, monounsaturated, and polyunsaturated fatty acids, as well as trans-fatty acids (0.6–1.7%). According to national regulations on polar compounds, 50% of the assessed food samples are unfit for human consumption. When applying national limits for C18, all food samples should be discarded. These findings stress the urgent need to strictly control deep-fried foods sold by street vendors.

Characteristics of polycyclic aromatic hydrocarbons in food oils in Beijing catering services

The concentrations and characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in 48 oil samples randomly collected from 30 catering services that employ six cooking methods were quantified via high-performance liquid chromatography (HPLC). These 16 PAHs were detected in almost all of the samples. The levels of Σ16PAHs, Σ4PAHs, benzo[a]pyrene (BaP), and total BaP equivalents (ΣBaP_eq) for the six cooking methods exceeded the legal limit. The concentrations of Σ4PAHs were approximately 9.5 to 16.4 times the legal limit proposed by the European Commission (Off J Eur Union 215:4-8, 2011), and the level of BaP exceeded the national standard in China by 4.7- to 10.6-fold, particularly in oil from fried foods. Low molecular weight PAHs (LMW PAHs) were predominant in fried food oil from different catering services and accounted for 94.8 % of these oils, and the ΣBaP_eq of the high molecular weight PAHs (HMW PAHs) was 11.5-fold higher than that of the LMW PAHs. The concentrations of Σ16PAHs (3751.9-7585.8 μg/kg), Σ4PAHs (144.6-195.7 μg/kg), BaP (79.7-135.8 μg/kg), and ΣBaP_eq (231.0-265.4 μg/kg) were highest in the samples from fast food restaurants/buffets (FB), followed by those from fried food stalls (FS) and then cooking restaurants/cafeterias (RC). The results of this study suggest that the government should strengthen control and supervision of PAH contamination in food and edible oils.