| China is a primary country who consumes and artificially cultivates edible fungi.Edible fungi have the biological characteristics of absorbing heavy metallic elements;therefore,the contents of heavy metal in fungi will be high during growth.Hazardous side effects will be brought about and the quality and safety condition of fungi are affected accordingly.This study selected the four most commonly consumed edible fungi in Guangdong Province of agaric,ganodorma lucidum,lentinan and agrocybe cylindracea as the research subjects.111 samples were collected from 63 districts or counties in Guangdong Province where edible fungi are planted.Every sa mple weighed 1kg respectively.The samples were selected randomly from all batches.The same types of fungi from different areas were mixed together.Advanced instrumental analysis methods such as AFS and GFAAS were adopted to test the five hazardous heavy metals of Pb,As,Cd,Hg and Al;heavy metal solution with different concentrations were added in edible fungi media,for the discussion of absorption performance of the studied edible fungi;hazardous risk assessment was undertaken to compare with PTWI value proposed by JECFA;the collected data was analysed with Microsoft Excel(Microsoft Office 2010).The research results showed that,the contents of the five analysed heavy metal varied greatly among the different edible fungi studied herein: the contents of Pb(0.712mg/kg)and As(0.950mg/kg)in ganodorma lucidum were higher than the other samples,and Cd,Hg and Al were also relatively higher;Cd(0.324mg/kg)in lentinan was evidently higher,and its Pb,As,Hg and Al were at a high level;Hg(0.190mg/kg)and Al(227.3mg/kg)in agaric were higher than the other samples and its As was relatively high;comparing with other samples,contents of the five heavy metal in agrocybe cylindracea were the lowest in the studied four edible fungi.The sequence for the average content level of heavy metal was agaric > ganodorma lucidum > lentinan > agrocybe cylindracea.In the four edible fungi,Pb was within the limit;Cd in ganodorma lucidum and lentinan exceeded 27.2% and 62.0% of the limit separately;As and Hg in ganodorma lucidum and Hg were beyond the limit,with As(90.0%)and Hg(30.0%)in ganodorma lucidum and As(6.0%)and Hg(90.0%)in agaric.In the absorption experiment for edible fungi,lentinan was found to boast the highest Cd absorption ability of 126 times as its highest and a weaker absorption towards Al;ganodorma lucidum was found to tend to absorb Pb the most with a high absorption factor of 576.4 times during the experiment,while its ability to absorb Hg was weak;agaric was found to strongly absorb Al,and 716.3 times of absorption factor was reached during experiment,while its absorption towards Cd was weak;agrocybe cylindracea 's absorption performance towards the five heavy metal was not significant.The result of hazardous risk assessment for the five heavy metal exposure in the four edible fungi displayed that the daily dietary intake of the five heavy metal elements from the four edible fungi was lower than the PTWI value stipulated by JECFA.Main conclusions: A.The contents of Pb,As,Cd,Hg and Al in ganodorma lucidum and agaric were relatively high,followed by lentinan,while the contents of heavy metal in agrocybe cylindracea were relatively low;ganodorma lucidum,agaric and lentinan were relatively darker,and it is therefore a good aspect for future research to study whether a stronger absorption performance is held in edible fungi with darker colours.B.The absorption performance of ganodorma lucidum,agaric and lentinan towards Pb,As,Cd and Al was significant,and the accumulated amount of heavy mental was related to their concentrations.Heavy metal in mycelium increased along with higher concentration.The data also showed that the contents of heavy metal increase and the absorption factor decreased with higher concentratio n.Thus,it could be inferred that sensitive heavy metal could restrain the growth of mycelium;however,the reasons and principles for restraints were not yet discovered.C.Al(227.3mg/kg)in agaric was 3.4 times higher than the total content of Al(67.51 mg/kg)in lentinan,agrocybe cylindracea and ganodorma lucidum,which indicated that the accumulation ability of heavy metal for different edible fungi varied.Therefore,an overall consideration of both total and single content of heavy metal should be taken for hazardous risk assessment. |
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