ICP-AES and microwave assisted digestion were applied to determine P, Mg, Ca, Zn, Na, Cu, Ba, Ni, V, Cd, Sr, Co, and Li in the caps and stipes of
Edible wild-grown mushrooms are traditionally consumed as delicacy in lots of countries and many are also used in traditional Chinese medicine [
King Bolete (
Edible wild-grown mushrooms have a very effective mechanism to accumulate extremely high concentrations of macro- and microelements from soil [
Central Yunnan province is one of the most wild edible mushrooms resource-rich and largest production regions in China. The main species are
King Bolete (
Locations and numbers of
Code | Location | Number of samples |
---|---|---|
BE1 | Baofeng, Jinning, and Kunming | 11 |
BE2 | Yulu, Nanhua, and Chuxiong | 7 |
BE3 | Pubei, Yimen, and Yuxi | 12 |
BE4 | Longchuan, Nanhua, and Chuxiong | 10 |
BE5 | Qianchang, Yaoan, and Chuxiong | 8 |
BT6 | Shaqiao, Nanhua, and Chuxiong | 8 |
Localization of the sampling sites (dot) of
Deionized water and nitric acid solution were used to prepare all aqueous solutions and clean or soak the glassware. Nitric acid solution (HNO3 65%) and hydrogen peroxide (H2O2 30%) were used for digestion of samples in automatic microwave digestion system. The contents of the minerals in King Bolete were determined using inductively coupled plasma atomic emission spectrophotometer (ICP-9000, Shimadzu, Japan).
0.5 g of dried and powdered sample was mixed with 4 mL HNO3 (65%), 2 mL H2O2 (30%), and 3 mL deionized water in polytetrafluoroethylene (PTFE) pressure vessels and digested in microwave digestion system. Ultimate digest was transferred to 25 mL colorimetric cylinder using deionized water for constant volume and subjected to instrumental analysis. Concentration of all elements in caps and stipes was determined using inductively coupled plasma atomic emission spectrophotometer and for blank solutions and certified reference material (GBW07605) as well. Discrepancies between certified values and concentrations quantified were all below 10%.
Data on the parameters determined for caps and stipes of King Bolete are presented in Table
Elements content of
Elements | BE1 | BE2 | BE3 | BE4 | BE5 | BE6 |
---|---|---|---|---|---|---|
P | ||||||
Cap | 5523 ± 1070 | 9013 ± 2328 | 5528 ± 705 | 6021 ± 1044 | 4356 ± 1146 | 5420 ± 1410 |
1429–13588 | 11620–13010 | 4451–6406 | 3970–7381 | 1285–5655 | 2339–7256 | |
Stipe | 3022 ± 535 | 3891 ± 965 | 2150 ± 406 | 3616 ± 1577 | 2668 ± 668 | 3348 ± 1229 |
1614–6086 | 2635–5008 | 1595–2794 | 1679–7179 | 1285–3435 | 3966–5730 | |
Qc/s | 1.83 | 2.32 | 2.57 | 1.67 | 1.63 | 1.62 |
Mg | ||||||
Cap | 1221 ± 64 | 1447 ± 137 | 935 ± 184 | 1138 ± 185 | 1028 ± 163 | 918 ± 173 |
332–3071 | 2116–2334 | 737–1404 | 782–1416 | 365–1397 | 580–1136 | |
Stipe | 705 ± 42 | 710 ± 143 | 442 ± 59 | 939 ± 261 | 620 ± 48 | 636 ± 156 |
406–1771 | 462–889 | 339–523 | 607–1393 | 653–645 | 761–942 | |
Qc/s | 1.73 | 2.04 | 2.12 | 1.21 | 1.66 | 1.44 |
Ca | ||||||
Cap | 212 ± 15 | 249 ± 64 | 656 ± 126 | 635 ± 114 | 339 ± 104 | 367 ± 149 |
34–260 | 303–476 | 199–2435 | 353–1118 | 189–487 | 204–924 | |
Stipe | 209 ± 11 | 236 ± 72 | 239 ± 68 | 952 ± 202 | 144 ± 59 | 373 ± 121 |
26–279 | 115–338 | 125–349 | 151–1632 | 67–259 | 170–750 | |
Qc/s | 1.01 | 1.06 | 2.74 | 0.67 | 2.35 | 0.98 |
Zn | ||||||
Cap | 128 ± 69 | 534 ± 122 | 204 ± 72 | 113 ± 26 | 54 ± 16.6 | 86 ± 21 |
29–299 | 426–1370 | 102–652 | 79–167 | 16–71 | 38–103 | |
Stipe | 65 ± 13 | 332 ± 82 | 60 ± 24 | 66 ± 12 | 35 ± 9.3 | 47 ± 23 |
38–134 | 61–512 | 39–120 | 27–176 | 16–45 | 26–84 | |
Qc/s | 1.97 | 1.61 | 3.4 | 1.71 | 1.54 | 1.83 |
Na | ||||||
Cap | 19.3 ± 5.8 | 35.2 ± 16.7 | 15.3 ± 9.9 | 100 ± 21 | 63 ± 6.7 | 2.9 ± 0.4 |
5.8–57.2 | 5.2–134 | 3.8–89 | 38–156 | 55–74 | 1.3–5.8 | |
Stipe | 19.6 ± 6.2 | 27.5 ± 5 | 23.5 ± 8.1 | 129 ± 34 | 95 ± 17 | 148 ± 47 |
3.9–73.0 | 2.1–41.1 | 5.8–102 | 69–202 | 62–143 | 16–242 | |
Qc/s | 0.98 | 1.28 | 0.65 | 0.77 | 0.66 | 0.02 |
Cu | ||||||
Cap | 33.6 ± 1.8 | 884 ± 63 | 40.3 ± 17 | 53.4 ± 44 | 17 ± 5.7 | 26.8 ± 8 |
11.5–81.3 | 57–3025 | 22–79 | 19–202 | 5.4–23.5 | 17.3–41 | |
Stipe | 19.2 ± 2.3 | 703 ± 49 | 20.4 ± 11 | 32 ± 21 | 8.6 ± 2.7 | 13.9 ± 3.8 |
10.6–52.3 | 24–1496 | 9–54 | 14–87 | 5.4–13 | 9–20 | |
Qc/s | 1.75 | 1.26 | 1.98 | 1.67 | 1.98 | 1.93 |
Ni | ||||||
Cap | 2.7 ± 0.8 | 5.2 ± 1.1 | 2.1 ± 0.35 | 5.2 ± 1.8 | 2.4 ± 0.7 | 63.7 ± 14 |
1.27–4.33 | 3–9.9 | 1.5–2.6 | 2.1–7.9 | 1.2–3.2 | 49–83 | |
Stipe | 1.7 ± 0.6 | 2.3 ± 0.42 | 1.1 ± 0.22 | 5.1 ± 3.1 | 16.7 ± 8 | 42.9 ± 16 |
1.05–2.66 | 1.86–2.96 | 0.77–1.54 | 2.3–15.2 | 1.2–25.7 | 25–62 | |
Qc/s | 1.59 | 2.26 | 1.91 | 1.02 | 0.14 | 1.48 |
Co | ||||||
Cap | 1.0 ± 0.34 | 0.8 ± 0.36 | 1.1 ± 0.39 | 0.9 ± 0.21 | 0.4 ± 0.1 | 8.4 ± 2.7 |
0.53–1.61 | 0.29–1.64 | 0.55–1.79 | 0.54–1.36 | 0.19–0.49 | 4–13.6 | |
Stipe | 0.9 ± 0.25 | 0.5 ± 0.15 | 1.0 ± 0.61 | 0.8 ± 0.18 | 4.6 ± 1.7 | 6.3 ± 2.4 |
0.34–2.13 | 0.27–0.67 | 0.38–2.04 | 0.31–2.56 | 0.39–5.9 | 2.5–8.7 | |
Qc/s | 1.11 | 1.6 | 1.1 | 1.13 | 0.09 | 1.33 |
Ba | ||||||
Cap | 8.1 ± 1.1 | 9.7 ± 3.4 | 6.6 ± 1.9 | 9.9 ± 4 | 4.8 ± 1.5 | 66.7 ± 32 |
2.59–12.0 | 3.96–20.3 | 3.44–9.13 | 4.5–18.2 | 2.7–6.9 | 26–136 | |
Stipe | 5.3 ± 0.58 | 4.4 ± 1.37 | 2.7 ± 0.7 | 9.6 ± 3.4 | 65.5 ± 20 | 41.1 ± 13 |
3.27–7.81 | 2.62–6.85 | 1.78–3.84 | 5.4–25.1 | 3.4–73 | 25–63 | |
Qc/s | 1.53 | 2.2 | 2.44 | 1.03 | 0.07 | 1.62 |
V | ||||||
Cap | 1.7 ± 0.56 | 3.9 ± 0.86 | 1.2 ± 0.34 | 3.7 ± 0.8 | 1.6 ± 0.7 | 27.3 ± 10.5 |
0.6–2.85 | 1.24–8.75 | 0.65–1.64 | 0.98–7.29 | 0.7–2.82 | 12.5–46.6 | |
Stipe | 1.1 ± 0.34 | 1.4 ± 0.41 | 0.5 ± 0.02 | 3.4 ± 1.1 | 15.3 ± 4.8 | 15.8 ± 7.5 |
0.45–1.93 | 1.02–2.11 | 0.33–0.92 | 1.5–11.1 | 0.9–23.9 | 8–30 | |
Qc/s | 1.55 | 2.79 | 2.4 | 1.09 | 0.1 | 1.73 |
Cd | ||||||
Cap | 2.1 ± 0.3 | 5.3 ± 1.9 | 1.2 ± 0.35 | 1.4 ± 0.67 | 1.6 ± 0.6 | 24.8 ± 5.6 |
0.48–5.37 | 1.2–13 | 0.74–2.05 | 0.76–2.99 | 0.41–2.6 | 11.8–36.5 | |
Stipe | 0.9 ± 0.25 | 1.5 ± 0.03 | 0.5 ± 0.1 | 0.9 ± 0.72 | 5.1 ± 1.9 | 10.1 ± 2.3 |
0.35–1.95 | 0.96–2.23 | 0.31–0.82 | 0.19–4.45 | 0.5–9.1 | 4–16.5 | |
Qc/s | 2.33 | 3.53 | 2.4 | 1.56 | 0.31 | 2.46 |
Sr | ||||||
Cap | 4.4 ± 0.32 | 1.5 ± 0.1 | 1.5 ± 0.4 | 2.1 ± 0.57 | 0.9 ± 0.3 | 11.5 ± 5.9 |
0.5–23.5 | 0.45–3.34 | 0.92–2.5 | 1.13–2.89 | 0.56–1.54 | 6.7–24.8 | |
Stipe | 1.4 ± 0.5 | 0.9 ± 0.2 | 1.0 ± 0.37 | 1.9 ± 1 | 9.7 ± 3.1 | 9.9 ± 2.6 |
0.78–2.14 | 0.59–1.09 | 0.64–1.82 | 0.53–4.26 | 0.59–15.4 | 6.8–12.9 | |
Qc/s | 3.14 | 1.67 | 1.5 | 1.11 | 0.09 | 1.16 |
Li | ||||||
Cap | 0.6 ± 0.03 | 1.6 ± 0.2 | 0.3 ± 0.05 | 1.6 ± 0.85 | 1.2 ± 0.45 | 5.9 ± 1.3 |
0.37–1.02 | 0.57–3.68 | 0.18–0.36 | 0.29–3.27 | 0.7–2.1 | 1.2–8.7 | |
Stipe | 0.4 ± 0.02 | 0.6 ± 0.17 | 0.2 ± 0.08 | 1.4 ± 1.1 | 3.1 ± 1.13 | 4.3 ± 1.26 |
0.06–0.91 | 0.42–0.88 | 0.07–0.33 | 0.57–3.96 | 0.87–4.1 | 0.3–3.89 | |
Qc/s | 1.5 | 2.67 | 1.5 | 1.14 | 0.39 | 1.37 |
Qc/s is the ratio of the element concentration in cap to stipe.
Qc/s value is a quotient between the minerals concentrations in caps and stipes, which is used to express the elements distribution within the fruiting body of the mushrooms. Significant differences have been suggested in loads of accumulated elements between caps and stipes, and some were caused by the site or year of mushroom collection [
P is the essential element that nearly participates in all physiological chemical reactions such as forming the bones, teeth, and nucleic acid, maintaining balance of ATP metabolism, and regulating acid-base balance. Rich concentrations are found in King Bolete and with the range of 4356–9013 mg kg−1 and 2150–3891 mg kg−1 dm for cap and stipe, respectively. So contents in caps are higher than in stipes, and Qc/s values vary between 1.62 and 2.57 (Table
Caps of King Bolete contain Mg at 918–1447 mg kg−1 dm, which are higher than for stipes (442–939 mg kg−1 dm). Lower values of 590–960 mg kg−1 dm were obtained for caps of King Bolete collected from Poland [
Ca is the activator of more than 200 kinds of enzymes in the human body, which can make each organ function well. Na concentration values distribution in King Bolete varies depending on the sites (Table
Zinc contents were reported at between 28 and 140 mg kg−1 dm for edible wild-grown mushrooms collected from China [
Na content for caps is between 2.9 and 100 mg kg−1 dm and for stipes between 19.6 and 148 mg kg−1 dm. Higher values were determined in cultivated and some preserved mushrooms and content was 860, 1000, and 16000–25000 mg kg−1 dm for
Cu is an essential element, and a large variation of values is noted; they ranged, respectively, between 17–884 and 8.6–703 mg kg−1 dm for caps and stipes (Table
Published data on Ni and Co in caps and stipes of King Bolete is few and relatively insufficient. Ni content of King Bolete at six sites varied between 2.1 and 63.7 mg kg−1 dm in caps and between 1.1 and 42.9 mg kg−1 dm in stipes. The mean Co concentrations were 0.4–8.4 and 0.5–6.4 mg kg−1 for caps and stipes, respectively. Published data on Co contents were usually below or around 0.5 mg/kg DM, which were lower than the results in this study [
As shown in Table
Ba content is in the range of 4.8–66.7 and 2.7–65.5 for caps and stipes, respectively, and these values are particularly higher than the reference data previously reported, which were 0.2–1.5 mg kg−1 dm for caps and 0.36–1.4 mg kg−1 dm for stipes [
Reports on V contents on King Bolete were very few, and literature data were 0.02–0.09 mg kg−1 dm in caps, 0.03 mg kg−1 dm in stipes, and 1.27 mg kg−1 dm in whole fruiting body [
Cd is toxic metallic element is found in edible mushrooms and can leach out of fruiting bodies during boiling. Tolerance limit is 2
King Bolete contains Sr at 0.9–11.5 mg kg−1 dm in caps and at 0.9–9.9 mg kg−1 dm in stipes, which is higher value than for samples from Poland. Most of the sites surveyed caps, when compared to stipes containing higher content of Sr, and opposite feature was found in earlier reports [
The lithium salt, Li2CO3, is considered as a therapeutic for neurodisorders. Li is a trace element in fungi, and content is relatively low [
King Bolete collected from central Yunnan province contained high content of elements such as P, Mg, Ca, Zn, Na, and Cu, next for Ba, Ni, V, Cd, and Sr, and the least for Co and Li. Distribution of elements in different parts of King Bolete was unevenly, mainly depending on the hymenophore in the caps. In addition, spatial variations of Qc/s value were noted for King Bolete from different sites, which seem to be due to variations in local soil substrate geochemistry. Our results indicated that there is a close relationship between element concentrations and hymenophore in cap and bedrock soil geochemistry.
The authors declare that there is no conflict of interests regarding the publication of this paper.
This study has been supported by the National Natural Science Foundation of China (31460538, 31260496, and 31160409), the Special Project on the Countryside Comprehensive Reform (2014NG007-18), and the Science Foundation of the Yunnan Province Department of Education (2013Z074).