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Analysis of Formaldehyde in Shiitake Mushrooms


Formaldehyde is found naturally at low levels in a wide range of foods such as fruit, vegetables, mushrooms and seafood. It is a normal product of human metabolism.
The current study is being undertaken to verify the formaldehyde levels found in Shiitake mushrooms in a very limited study conducted previously by the Pesticides Safety Directorate (PSD). The aim of the study is to provide additional information on the possible formaldehyde levels in Shiitake mushrooms to enable an assessment to be made of any possible health implications.

A further aim of the study is to determine whether formaldehyde is produced naturally by Shiitake at the levels reported. The effects of cooking and storage on formaldehyde levels in Shiitake are also being investigated.

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Research Approach: <BR> The levels of formaldehyde in raw UK and Chinese Shiitake mushrooms will be quantified using liquid chromatography mass spectrometry (LC-MS) analysis and confirmatory analysis with LC-MS/MS. The formaldehyde levels in mushrooms fried for 3 or 6 minutes or stored for up to 10 days will also be quantified.

Results and findings: <BR> Key Facts:
<UL> <LI> This study investigated the levels and origins of formaldehyde in Shiitake mushrooms, as well as the effects of cooking and storage on formaldehyde levels.
<LI>This study indicates that the levels of formaldehyde observed were the result of natural production by the Shiitake mushrooms.
<LI>Cooking for 6 minutes caused a significant reduction in formaldehyde levels, whereas storage for up to 10 days had no effect on formaldehyde levels.
<LI>Maximum consumer intakes of formaldehyde from Shiitake mushrooms cooked for 3 minutes were below an established safety limit.
<LI>Shiitake are eaten infrequently in the UK. The findings of this study do not indicate any appreciable risk to human health from exposure to formaldehyde through consumption of Shiitake mushrooms. Consumers do not need to change their diet as a result of the findings of this study.
<LI>In the light of the results and interpretation of the current study, it is no longer considered necessary to set a limit for formaldehyde in Shiitake mushrooms.
Overall the mean concentrations detected in raw UK and Chinese mushrooms analysed on days 1 to 3, were 199 mg/kg and 238 mg/kg respectively. The highest level of formaldehyde (323 mg/kg) was reported in a sample of Chinese mushrooms measured on day 3. Frying the mushrooms for 3 minutes did not have a significant effect on formaldehyde levels, although the results were suggestive of a decrease. Frying for 6 minutes, however, caused a significant reduction in the levels observed. No consistent difference was seen in the levels of formaldehyde following storage of UK Shiitake for 6 or 10 days.
The results of this study provide evidence that fresh Shiitake mushrooms can naturally give rise to formaldehyde concentrations in the order of 100-300 mg/kg, as measured under the analytical conditions described. The estimated intakes of formaldehyde from UK and Chinese Shiitake from this study were 0.15 and 0.16 mg/kg bodyweight, respectively. However, this exposure is likely to be an overestimate because the conditions used to extract formaldehyde were relatively harsh and therefore the analysis may overestimate the amount of formaldehyde that would be released by mushrooms on consumption. These intake levels are unlikely to pose an appreciable risk to human health.
<p>Find more about this project and other FSA food safety-related projects at the <a href="; target="_blank">Food Standards Agency Research webpage</a>.

Central Science Laboratory
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