Study On Characteristic Analysis Of Mineral Elements Of Common Wild Boletus In Yunnan Province

The terrain,forest types and soil species of Yunnan Province is complicated and diversed,which provide favorable conditions for the growth of edible fungi.Therefore,this region has become an important producing area of edible mushrooms.More than 390 bolete species were reported in China,among which 200 species were edible.There are 140 species of boletes in Yunnan Province,accounting for more than 70% of the known mushrooms in China.Except some toxic or bitter varieties,most of them are edible.As a kind of rare fungus,porcini are rich in nutrients and many mineral elements.Due to their delicious taste and abundant nutritional value,they are very popular in the world.In this study,14 mineral elements such as P,K,Fe,Ca,Na,Mg,Zn,Cu,Mn,Ba,Co,As,Cd and Pb were determined by ICP-AES.The objectives of this study are below: analyzing the variation of mineral elements among different regions and species of bolete mushrooms;comparing the difference of mineral elements among different parts of bolete mushrooms;exploring the accumulation abilities of mineral elements in different parts of bolete mushrooms;assuring the safety of these mushrooms by comparing the toxic heavy metals,such as As,Cd and Pb,with the national standard and WHO.The results are as follows:(1)The cap and stipe of samples are rich in mineral elements.K and P are the most abundant elements in the fruiting body.Their contents are 5619-20500 and 2772-11672 mg/kg,respectively.The contents of Fe,Ca,Na,Mg and Zn are a little lower.The average contents of Cu,Mn and Ba are between 9 and 310 mg/kg.The average content of Co is less than 30 mg/kg.Studies have shown that fruiting bodies of these mushrooms are rich in mineral elements and can be used as the dietary source of human mineral elements.(2)According to the ratio of the cap and the stalk(QC/S),it was found that the enrichments of the elements in different parts(cap and stipe)were different.The accumulations of P,K,Zn and Cu in caps are higher than that in stipes.The contents of Ca,Fe,Co and other elements in the stipes are higher.In this experiment,66.25% QC/S of samples is greater than 1,showing the cap has a good enrichment for the elements.(3)For the BCF,the enrichment abilities of P and K are the strongest(BCF> 1),followed by Cu,Zn,and the enrichment ability was higher in the cap than that in the strip.The enrichment abilities of Fe,Ca,Na,Mg,Ba and Co are the weakest(BCF <1),indicating that they re difficult to migrate into mushroom species.(4)The results of principal component analysis showed that the cumulative contribution rates of the first three principal components were 75.644% and 76.630%,respectively.Because 64.477% contribution rate of the cap is extracted from the first two principal components,the characteristic elements in this part are Fe,Ba,P,Mg and Cu.Because 57.37% contribution rate of the strip is extracted from the first two principal components,the characteristic elements in this part are Mg,Mn,K,Fe,Zn and Cu.Therefore,the characteristic elements of these mushrooms are Fe,Mg and Cu.(5)The content of 11 elements in the cap and strip of 23 species of Boletus mushrooms are determined by this experiment.There is a certain correlation between these elements.In the cap and strip,there are 15 mineral elements with significant correlation(p <0.05)and 23 mineral elements with extremely significant(p <0.01).The correlation of these elements is strong,indicating that there is an intrinsic correlation between them during the growth of mushrooms.The cluster analysis shows that there are significant correlations of enrichment among different parts of different species of these mushrooms.(6)The contents of toxic heavy metal elements such as As,Cd,and Pb are higher than GB 2762-2012 "limited levels of pollutants in food".This results indicate that there is a potential risk to human health.The content of As element in the 64% samples are excessive.The content of Cd element in 80% samples are excessive.The content of Pb element in 73% samples are excessive.Health risk assessment shows that adults who eat these mushrooms everyday may cause a health risk.(7)The analysis of bolete mushrooms from different regions showed that the accumulations of elements are obvious different according to different environments.The bolete mushrooms from Kunming,Chuxiong and Yuxi Cities have stronger accumulation abilities for mineral elements than that from Honghe and Xianggelila Cities.