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PAHs in foods prepared in the home and from catering outlets to determine effects of frying, grilling and barbecuing.

Project Code: C02069

29/09/2006

Central Science Laboratory
Fernandes, A ; Rose, M; White, S

Cooking techniques such as grilling and barbecuing can result in the presence of polycyclic aromatic hydrocarbons (PAHs) in food. Direct contact with flames or very high cooking temperatures may result in the formation of PAHs on the food itself. Pyrolysis of fat dripping from food onto hot charcoal, or a similar heat source, can also be a significant source of PAHs in grilled or barbecued food.

Approach

The effects of frying, grilling, roasting, toasting, using domestic cooking appliances, and barbecuing, were investigated by carrying out controlled cooking experiments for a range of foods including sausages, beef burgers, beef, chicken and salmon. The effects of different types of fuel were systematically investigated for the barbecuing experiments. PAH levels in pre-cooked food samples from retail or catering outlets were also tested. Gas chromatography was used to analyse 28 PAHs, including the 16 PAHs identified as mutagenic/genotoxic by the European Food Safety Authority.

None of the controlled cooking experiments using domestic cooking appliances caused significant PAH formation in food but barbecuing did result in raised PAH levels to varying degrees depending on the type of food and fuel and the cooking duration.

Overall, barbecued beef burgers contained the highest levels of PAHs, with benzo(a)pyrene concentrations of up to 29 ppb. By comparison, benzo(a)pyrene concentrations were 17- to 125-fold lower in beef steak than in burgers barbecued for a normal time. For all food types except burgers, barbecuing over charcoal plus wood-chips resulted in the highest PAH concentrations. For example, the maximum benzo(a)pyrene concentration in sausages barbecued over charcoal plus wood chips was about 10-fold greater than for sausages cooked over charcoal alone.

The majority of the pre-cooked retail samples contained low PAH concentrations. However, PAH levels were raised in three beef burger samples, from catering outlets.

Key Findings

Frying, grilling and toasting using domestic cooking appliances did not cause significant PAH concentrations in any of the cooked food samples. The maximum benzo(a)pyrene (BaP) concentration and the maximum total concentration of the 16 PAHs identified by European Food Safety Authority as being mutagenic/genotoxic (the EFSA 16) were less than 0.09 ppb and 1.0 ppb respectively for these food samples
The maximum BaP concentrations in barbecued beef burgers and pork sausages were 29.1 and 30.6 ppb, respectively. The median BAP concentrations for barbecued beef burgers and pork sausages were 12.2 and 1.9 ppb. The maximum BaP concentrations in other types of barbecued food were considerably lower than for sausages or beef burgers.
The highest and median oncentrations for the ‘EFSA 16’ PAHs in barbecued beef burgers were 566 and 221 ppb. For barbecued pork sausages, the highest and median concentrations for the ‘EFSA 16’ PAHs were 446 and 30.7 ppb, respectively.
In general, barbecuing with charcoal plus wood chips gave the highest levels of BaP, but barbecuing over charcoal alone gave the highest BaP concentrations in the case of beef burgers.
Extended cooking time resulted in moderate increases in PAH levels for some types of barbecued food, but for beef burgers cooked over charcoal or charcoal plus wood chips, there was a decrease in PAH levels when cooking time was extended by 50% or 100%. Thorough cooking to prevent food poisoning remains the most important food safety consideration.
For the barbecued food samples, there was no clear correlation between fat content in the food prior to cooking and the PAH levels found following barbecuing.
BaP concentrations were negligible in the majority of pre-cooked food composite samples from retail and catering outlets but the highest three BaP concentrations – all in beef burger samples – were 8.4, 9.8 and 20.4 ppb.

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