doi: 10.5053/ekoloji.2011.802
T h e M ineral C on ten ts o f Som e Wild E dible
M ushroom s
Y u su f U Z U N * 1, H üseyin G E N C C E L E P 2, A bdullah KAYA3, M ustafa Em re AKCAY1 1Yüzüncü Yıl University, Science Faculty, Department o f Biology, 65080 Van-TURKEY 2Ondokuz Mayıs University, Engineering Faculty, Department o f Food Engineering, 55200 Samsun-TURKEY
3Karamanoğlu Mehmetbey University, Kamil Özdağ Science Faculty, Department of Biology, 70200 Karaman-TURKEY
*Corresponding author: yusufuzun2004@yahoo.com.
A bstract
The aim o f this study was to determine and evaluate the amounts o f major elements (Ca, Mg, K) and trace elements (Fe, Zn, Cu, Mn, Pb, N i and Cd) found in forty five species o f wild-grown common edible mushrooms growing in the Bingöl and Selim (Kars) provinces o f Turkey. The minimum and maximum values o f the mineral elements concentrations varied for Ca (40-5700), M g (180-1900), K (5900-29000), Fe (5-1930), Zn (15-450), Cu (5-83), Mn (0.20-80), Pb (<0.010-2.3), N i (0.15-4.4), and Cd (<0.032-19.1) mg/kg dry weight. The potassium concentrations were found to be greater than those o f the other mineral constituents in all the species. The K, Zn, Cu, and N i concentrations were the greatest in Leucoagaricus leucothites.
Keyw ords: Bingöl, Edible mushrooms, heavy metals, minerals, Selim (Kars), Turkey. B a z ı Yenen M akrofunguslarin M ineral M adde İçeriklerinin B elirlenm esi Ö z et
Bingöl ve Selim (Kars) yöresinden toplanan 45 yenen makrofungus taksonuna ait; kalsiyum (Ca), magnezyum (Mg), potasyum (K), demir (Fe), çinko (Zn), bakır (Cu), mangan (Mn), kurşun (Pb), nikel (Ni) ve kadmiyum (Cd) analizleri yapılmıştır. Mantar örneklerinde belirlenen minimum ve maksimum değerler mg/kg kuru ağırlık olarak Ca (40-5720), M g (181-1927), K (5947-29228), Fe (5-1925), Zn (15 447), Cu (5-83), Mn (0,20-80), Pb (<0.010-2,3), N i (0,5-4,4) ve Cd (<0.032-19,1) belirlenmiştir. Tüm makrofungus örneklerinde potasyum miktarının diğer mineral maddelere oranla daha yüksek olduğu gözlenmiştir. K, Zn, Cu ve Ni'in en yüksek değerleri Leucoagaricus leucothites'de belirlenmiştir.
A nahtar K elim eler: Ağır metal, Bingöl, mineral madde, Selim (Kars), Türkiye, yenen makrofunguslar.
Uzun Y, Genccelep H, Kaya A, Akcay M E (2011) The Mineral Contents o f Some Wild Edible Mushrooms. Ekoloji 20 (80): 6-12.
IN T R O D U C T IO N
Wild-growing mushrooms have been a popular delicacy in many countries, particularly in central and east Europe (Kalac 2009). Wild mushrooms are also a popular food source in Turkey. Dry matter contents of mushrooms are low, usually in the range of 60-140 g/kg. Carbohydrates and crude proteins are the two main components. The content o f total lipids (crude fat) ranges mostly from 2 to 6% o f dry matter. Low dry matter and lipid contents result in the low energy value o f mushrooms. A relatively high proportion o f insoluble fibre, comprised o f chitin and other structural polysaccharides, seems to be nutritionally profitable. The contents o f potassium and phosphorus are higher than in most vegetables. Though the consumption o f wild edible mushrooms is increasing, even in the developed
Received: 08.07.2010 / Accepted: 05.12.2010 world their sensorial properties are preferred to nutritional value. In the developed countries, low energetic value has been appreciated (Latiff et al. 1996, Demirbaş 2001, Kalac 2009).
Metals, such as iron, copper, zinc and manganese are essential metals, since they play an important role in biological systems. Lead and cadmium are toxic, even in traces. The essential metals can also produce toxic effects when the metal intake is excessively elevated (Tüzen et al. 2007, Baslar et al. 2009). Accurate and adequate food composition data are necessary for estimating the adequacy o f intakes o f essential nutrients and assessing exposure risks from intake o f toxic non-essential heavy metals. Trace elements, whether essential or non-essential, above threshold concentration levels, can cause morphological abnormalities, reduce growth and
increase mortality and mutagenic effects in humans (Olumuyiwa et al. 2007). The uptake o f metal ions in mushrooms differs from plants in many ways. The accumulation o f metals in macrofungi has been found to be affected by environmental and fungal factors (Garcia et al. 1998). Amount o f organic matter, pH, metal concentrations in soil are among the environmental factors (Demirbas, 2001, Tuzen et al. 2003, Mendil et al. 2005).
It is known that wild-growing mushrooms may accumulate great concentrations o f toxic metallic elements such as mercury, cadmium, lead and copper, metalloids, namely arsenic, and radionuclides (Svoboda et al. 2000, Falandysz et al. 2003). Many reports were presented from several countries, e.g. France (Michelot et al. 1998), Poland (Falandysz et al. 2003), Slovakia (Svoboda et al. 2000), Spain (Garcia et al. 1998), Turkey (Mendil et al. 2005, Gençcelep et al. 2009) and U SA (Aruguete et al. 1998).
Turkey has a large edible mushroom potential and is becoming an important exporter o f wild mushrooms. Mushrooms are also collected to make a substantial contribution to food intake. Therefore, it is necessary to know the levels o f essential elements in edible mushrooms (Işıloğlu et al. 2001). Trace metal levels in wild mushroom samples in Bingöl and Selim (Kars) provinces have not yet been determined. The purpose o f this study is to determine the essential and toxic elements (Ca, Mg, K, Fe, Zn, Cu, Mn, Pb, N i and Cd) found in several edible mushroom species from Bingöl and Selim (Kars), Turkey.
M A T E R IA L A N D M E T H O D S Sam p les
Samples o f 45 mushroom taxa were collected during field trips in the Bingöl and Selim (Kars) provinces o f Turkey between 2007 and 2009. Colour slides o f the macrofungal specimens were taken in their natural habitats and relevant notes were taken about their morphological and ecological features. Then, they were placed in specially prepared boxes and taken to the fungarium. Their spore prints were taken and spore dimensions were measured using an ocular micrometer. Then, dried specimens were placed in locked polyethylene bags and kept in a deep freezer at -20°C to protect against parasites. After obtaining the macroscopic and microscopic taxonomic data by mycological techniques, they were identified with the help o f the mycological
reference manuals o f Breitenbach and Kranzlin (1984-1995), Buczacki (1989), Dahncke (2004), Jordan (1995), Phillips (1981), and Watling and Gregory (1993). Specimens are kept in the Fungarium o f Yüzüncü Yıl University, Faculty o f Science.
M eth ods
All elements were determined using an atomic absorption spectrophotometer (Varian Techtron Model AAS 1000, Varian Associates, Palo Alto, CA. The species, which were digested in an acid solution o f H N O 3, were passed through the AAS system using different lamps, and calibrated with related minerals in different concentrations for different micronutrients (Anonymous 1990). To check for possible contamination by reagents or glassware, blanks containing 4mL o f ultrapure concentrated H N O 3 and 4ml o f H 2O 2 were run together with analytical samples and every batch o f the analytical samples were run together with the standard matrix. The values o f all the elements were calculated as mg/kg dry weight (dw). The detection limit is defined as the concentration corresponding to three times the standard deviation o f ten blanks. Detection limit values o f elements as mg per kg dw in AAS were found to be 0.015 for Ca, 0.003 for Mg, 0.012 for K, 0.060 for Fe, 0.013 for Zn, 0.041 for Cu, 0.029 for Mn, 0.010 for Pb, 0.063 for N i, and 0.032 for Cd. The results were within or above limits o f quantification for the determined minerals (calculated as 10-fold o f standard deviation from ten replicates o f the instrumental blank solution) 0, 0.5, 2, 4, and 8 mg/kg, respectively. The National Institute o f Standards and Technology (N IST ) reference materials [C a (N O 3)2, C d (N O 3)2, C u(N O 3)2, Fe(NO3)3, Pb(N O 3)2, M g(N O 3)2, M n (N O 3)2, N i(N O 3)2, and K N O 3 in H N O 3 0.5 mol/l] were used.
R E S U L T A N D D IS C U S S IO N
In general, most o f the mushrooms studied contained considerably high amounts o f minerals. The levels o f essential elements in the mushroom species were higher than those o f the toxic elements. Element concentrations o f the mushroom species are presented in Table 1. Mushrooms contained a wide range o f minerals from 40-5720 for Ca, 180
1930 for Mg, 5950-29230 for K, 5-1925 for Fe, 15 450 for Zn, 5-83 for Cu, 0.2-80 for Mn, <0.010-2.3 for Pb, 0.15-4.4 for Ni, and <0.032-19.1 mg/kg dw for Cd (Table 1). The most abundant elements were
Table 1. Content o f Ca, Mg, K, Fe, Zn, Cu, Mn, Pb, N i and Cd in a whole fruiting bodies o f a single specimens o f wild
grown edible mushrooms (mg/kg dw).
S p e c i e s C a F e K M g Z n C d C u M n N î P b
H e lv ella lacu nosa 1 7 8 0 8 9 1 2 1 0 0 5 6 0 2 2 0 0 .8 9 5 9 1 6 .8 2 .1 8 < 0 . 0 1
H e lv ella íeucopus 1 2 6 2 9 8 3 0 0 3 9 0 8 7 0 .2 9 10 2 .3 0 .8 7 < 0 . 0 1
M orchetía sp . 5 8 8 1 5 0 1 2 6 3 0 1 4 2 0 3 1 0 1 .5 1 4 5 3 0 .2 3 .1 2 < 0 . 0 1
M orch ella crassipes 1 4 1 5 1 0 0 9 2 9 0 1 0 4 5 81 1.01 5 2 1 2 .8 0 .8 1 1 .5
M orch ella rígida 1 1 8 0 4 8 1 0 2 8 0 7 6 0 6 0 0 .4 8 4 9 7 .4 0 .6 0 0 .9
M orch ella vulgaris 2 5 0 1 1 0 1 3 8 3 0 7 9 0 2 4 0 1 .0 8 4 3 1 7 .7 2 .4 2 < 0 . 0 1
A g aricu s aw en sis 4 6 0 3 2 2 8 6 0 0 1 0 5 0 4 1 0 0 .3 2 7 1 3 4 .2 4 .1 4 < 0 . 0 1
A g aricu s benesii 121 3 3 1 1 9 6 0 8 5 5 2 1 0 0 .3 3 4 7 5 .8 2 .1 3 < 0 . 0 1
A g aricu s bisporus 8 0 0 5 0 2 7 4 9 0 1 4 5 0 1 1 0 0 .5 0 7 8 4 .3 1 .1 0 1 .6
A g aricu s bitorquis 1 8 6 0 1 0 0 1 0 6 5 0 1 1 1 0 2 6 0 1 .0 0 4 4 1 5 .1 2 .5 6 1 .4
A g aricu s cam pestris v a r . campestris 7 1 8 3 4 1 3 1 0 0 1 1 7 0 3 0 5 0 .3 4 4 6 7 .1 3 .0 5 < 0 . 0 1
A g aricu s langei 4 9 0 5 1 5 3 5 0 9 4 0 3 6 0 < 0 . 0 3 2 7 0 1 6 .5 3 .6 2 < 0 . 0 1
A g aricu s litoralis 3 9 0 1 6 4 8 9 3 0 6 3 4 5 4 0 .1 8 3 1 8 .5 3 .2 8 1.1
A g aricu s silvícola v a r . silvícola 2 0 0 1 9 3 0 2 1 5 0 0 9 7 0 3 0 5 1 9 .1 6 3 1 6 .8 3 .0 5 0 .7
B o v ista plú m bea 1 0 5 5 0 2 0 5 8 0 7 8 5 2 4 5 0 .3 5 5 9 1 1 .2 2 .4 5 < 0 . 0 1
C h lo ro ph yllu m agaricoídes 5 6 0 2 4 1 6 6 6 0 8 7 5 2 0 0 0 .2 4 5 8 1 0 .7 2 .0 3 < 0 . 0 1
Leu co agaricu s leucothites 6 9 0 3 0 2 9 2 3 0 1 2 7 0 4 5 0 0 .3 0 8 3 5 9 .3 4 .4 7 0 .4
L y cop erâo n molle 5 8 0 1 0 2 0 1 2 0 5 0 6 6 6 2 5 0 1 0 .2 81 3 4 .8 2 .5 3 < 0 . 0 1
Lycoperdon pratense 7 3 0 2 7 1 7 1 0 0 1 2 1 5 4 2 0 0 .2 7 6 6 5 3 .8 4 .1 9 < 0 . 0 1
L y cop erâo n pyriforme 3 2 7 2 9 1 4 1 2 0 1 9 3 0 4 5 0 .3 0 7 9 1 6 .5 0 .4 5 2 .3
M acrolepiota procera v a r . procera 2 0 0 6 7 1 4 4 1 5 6 1 4 1 7 0 0 .6 7 4 0 1 9 .3 1 .7 1 < 0 . 0 1
A rm ílla ria ostoyae 8 7 2 3 6 1 8 5 1 0 5 9 0 2 1 0 2 .3 6 4 8 1 4 .1 2 .1 0 < 0 . 0 1
M a ra sm iu s oreades 5 6 0 1 7 2 0 7 8 5 6 3 0 2 6 0 0 .1 7 5 4 1 8 .4 2 .6 0 < 0 . 0 1
H o h en bu eh elia petaloides 7 8 0 2 7 1 0 4 5 0 9 8 2 7 9 0 .2 7 3 5 1 7 .8 0 .7 9 1.1
P leu ro tu s eryngii 3 4 0 1 4 0 8 4 2 0 1 1 3 0 3 5 0 .2 1 5 3 2 .7 3 .2 0 1.1
P leu ro tu s fu scas v a r . ferulae 2 2 4 4 2 8 4 3 0 1 8 0 2 8 0 0 .4 2 2 9 1 6 .2 2 .8 4 < 0 . 0 1
P leu ro tu s o stre atu f 2 9 5 1 2 5 1 8 2 7 0 1 5 4 0 2 5 0 1 .2 5 5 4 9 .3 2 .5 1 < 0 . 0 1
P leu ro tu s ostreatush 3 4 0 6 5 1 7 7 7 5 1 1 3 0 2 6 5 0 .5 1 6 2 0 .2 0 2 .6 4 < 0 . 0 1
P lu te u s ro m é lii 8 9 0 3 5 0 1 7 1 8 0 1 4 6 0 18 3 .5 2 7 8 1 4 .9 0 .1 8 1 .9
A grocybe cylindracea 8 6 1 9 0 1 2 9 5 0 8 3 0 1 7 0 1 .8 8 3 4 4 .6 1 .6 9 < 0 . 0 1
A grocybe praecox 3 7 0 8 6 1 2 3 1 0 5 6 0 1 5 0 0 .8 6 2 7 1 6 .9 1 .4 9 < 0 . 0 1
P h o lio ta au riveü a 4 0 3 2 1 6 4 6 0 6 9 0 1 6 5 0 .2 1 2 8 5 .2 1 .6 6 < 0 . 0 1
S tro p h a ria coronilla 4 3 0 1 0 1 2 3 3 5 4 0 0 1 7 0 0 .1 0 2 1 1 3 .5 1 .6 6 < 0 . 0 1
L e p ista n u da* 4 0 3 9 1 5 5 5 5 5 0 0 1 6 0 0 .1 0 3 7 6 .8 1 .6 1 < 0 . 0 1
L e p ista n u d ab 1 7 0 1 7 1 1 5 2 0 8 5 0 1 8 5 0 .1 0 3 7 2 4 .2 1 .8 5 < 0 . 0 1
M elan oleu ca m elak u ca 3 8 0 1 7 0 7 2 5 0 1 0 6 0 5 2 1 .0 1 3 6 8 .1 3 .2 0 1 .2
Tricholom a sp . 4 1 0 3 6 1 1 6 8 0 3 4 5 3 9 0 0 .3 6 2 0 4 3 3 .8 7 < 0 . 0 1
Tricholom a p o p u lin u m a 1 4 0 1 9 1 1 2 5 0 2 0 5 8 9 0 .1 9 1 2 6 .5 0 .8 9 < 0 . 0 1
Trich o lo m a p o p u lin u m b 3 4 0 2 4 7 7 5 0 4 1 0 2 4 0 .2 4 15 5 .1 0 .2 4 0 .6
S u iü u s brevipes 7 0 2 2 6 9 6 0 5 5 0 15 0 .2 2 3 1 5 .0 0 .1 5 0 .6
S u iü u s luteus 1 13 3 0 1 2 7 0 0 5 0 0 1 4 6 0 .2 2 3 8 1 0 .8 1 .4 6 < 0 . 0 1
P h a llu s im pudicus v a r . im pudicus 7 4 0 8 5 5 9 5 0 6 0 0 5 2 0 .8 5 2 0 8 0 0 .5 2 0 .7
L ae tip o ru s su lph ureus 5 7 0 0 1 1 9 0 1 9 9 6 0 1 0 1 0 3 1 4 1 .3 9 7 7 2 8 .5 3 .1 4 < 0 . 0 1
L e n tin u s tigrinus 3 2 5 0 3 1 8 4 6 0 1 4 5 0 1 3 0 0 .3 1 1 6 1 1 .6 1 .3 1 < 0 . 0 1
L a c ta r ia s controversus 2 7 8 2 5 1 0 7 7 0 2 3 0 1 1 8 0 .2 5 2 3 1 1 .7 0 .7 9 < 0 . 0 1
L a c ta r ia s deterrimus 4 4 5 0 3 7 1 1 1 0 0 7 5 5 2 3 0 0 .3 7 4 3 6 .7 2 .2 8 < 0 . 0 1
L a c ta r ia s sem isang u ijlu u s 2 3 8 4 2 1 0 5 4 0 9 7 0 4 4 0 .4 2 6 3 1.5 0 .4 4 0 .6
R u ssu la delica 6 4 3 2 1 2 0 8 0 3 8 0 1 9 0 0 .2 4 12 9 .7 1 .8 8 < 0 . 0 1 M e a n 7 1 7 1 5 0 1 3 8 6 0 8 4 0 1 9 0 1 .2 4 4 1 7 .2 2 .1 0 .3 M i n i m u m c o n t e n t 4 0 5 5 9 5 0 1 8 0 15 < 0 . 0 3 2 5 0 .2 0 .1 5 < 0 . 0 1 M a x i m u m c o n t e n t 5 7 0 0 1 9 3 0 2 9 2 3 0 1 9 3 0 4 5 0 1 9 .1 8 3 8 0 4 .4 2 .3 a, b, different location
potassium, calcium and magnesium. The iron, zinc, and copper content varied highly between the m ushroom species examined where Pb was determined to be at the lowest level (<0.010-2.36 mg/kg dw).
The results of the nutritionally valuable minerals show that the 45 mushroom species contained high amounts of potassium, calcium, magnesium and iron. This is in good agreement with the report of the analysis of cultivated mushrooms, such as Agaricus bisporus and Pleurotus ostreatus (Mattila et al.
2001).
The potassium content was higher than the level of other minerals in all the mushrooms in this study, varying between 5947 (Phallus impudicus var.
impudicus) and 29230 mg/kg dw (Leucoagaricus leucothites). Gençcelep et al. (2009) reported potassium contents of wild edible mushrooms being between 12600 and 29100 mg/kg dw. Sanmeea et al. (2003) reported that potassium accumulation in mushrooms could rise up to 45200 mg/kg. The overall data indicates that the mushrooms may contain elevated levels of potassium.
Calcium concentrations ranged from 40 (Pholiota aurivella) to 85720 (Laetiporus sulphureus) mg/kg dw. In our previous study, the concentration levels of C a in Morchella vulgaris 870 mg/kg, Helvella lacunosa 470 mg/kg, and Lepista nuda 8800 mg/kg were found (Gençcelep et al. 2009). In this study, different calcium concentrations of the same mushroom
species were found, since environmental factors are very important for metal concentrations in mush rooms. But, it seems to be higher when compared to the concentrations (100-2400 mg/kg dw) obtained by Sanmeea et al. (2003).
The magnesium content was 180 mg/kg dw in Pleurotus fuscus var. ferulae and 1930 mg/kg dw in Lycoperdon pyriforme. The level o f magnesium reported in this study was relatively low compared to earlier published reports (Demirbaş 2001) in which magnesium contents were 330 mg/kg dw in Tricholoma anatolicum and 6560 mg/kg dw in Morchella deliciosa. In our previous study, the magnesium concentrations in Morchella vulgaris 1920 mg/kg, Helvella lacunosa 1190 mg/kg, and Lepista nuda 3410 mg/kg were found (Gençcelep et al. 2009). However, in this study, lower magnesium concentrations o f the same mushroom species were found. Sanmeea et al. (2003) reported that mature Astraeus hygrometricus had the highest concentrations o f M g (1600 mg/kg).
The iron content o f the mushrooms ranged from 5 mg/kg dw in Agaricus langei to 1930 mg/kg dw in Agaricus silvicola var. silvicola. In literature, the iron values in the dry weight o f mushrooms was 31.3 1190 mg/kg (Sesli and Tüzen 1999), 56.1-7162 mg/kg (Işıloğlu et al. 2001) and 50.1-842 mg/kg (Gençcelep et al. 2009). It is known that adequate iron level in a diet is very important in order to decrease the incidence o f anemia.
Zinc was determined to be at the lowest level (15 mg/kg dw) in Suillus brevipes, with the highest level (450 mg/kg dw) was in Leucoagaricus leucothites. The reported literature zinc content ranged between 22.1 and 214.3 mg/kg dw (Kalac and Svoboda, 2000, Gençcelep et al., 2009, Kaya and Bağ, 2010, Kaya et al., 2011). M ushrooms are known as good zinc accumulators (Isıloğlu et al. 2001). In this study, some mushroom species had a zinc content above 400 mg/kg dw (Agaricus arvensis, Leucoagaricus leucothites, and Lycoperdon pratense). These mush rooms species collected from locations near the downtown area o f the city o f Bingöl may be affected by soil pollution.
Minimum and maximum values o f copper were 5 and 83 mg/kg dw in Pleurotus eryngii and Leucoagaricus leucothites, respectively. Tüzen et al. (1998) and Sesli and Tüzen (1999) reported copper contents o f wild edible mushroom s as being between 4.71-51 and 10.3-145 mg/kg dw,
respectively. Copper contents found in this study are comparable with those reported in literature. In this study and our previous study, copper contents were found in the mushrooms Pleurotus ostreatus 54.8-62.6 and 47.1 mg/kg dw, Lepista nuda 37.3-37.5, and 26.6 mg/kg dw, respectively (Gençcelep et al. 2009). Copper concentrations, accumulated in mushroom species, are usually 100-300 mg/kg dw, which is not considered a health risk. An acidic peptide was identifed in Grifola frondosa, which increases the proportion o f soluble copper absorption from the intestine (Kalac and Svoboda 2000). Copper contents in mushroom s higher than those in vegetables should be considered as a nutritional source o f the element. Nevertheless, for people, the bioavailability o f copper in mushroom s was reported to be low, due to the limited absorption from the small intestine (Schellman et al. 1980).
The manganese content o f the mushrooms ranged from 0.2 mg/kg dw in Pleurotus ostreatus to 80 mg/kg dw in Phallus impudicus var. impudicus The reported manganese values in literature for mushrooms was 21.7-74.3 mg/kg and 5.54- 135 mg/kg dw (Soylak et al. 2005, Gençcelep et al. 2009), respectively. The manganese values in this study are in agreement with the results found in literature.
Lead was found only in sixteen o f the 45 species. Pb concentrations o f mushroom samples were generally low, except Lycoperdon pyriforme with an amount o f 2.3 mg/kg dw. The Pb levels o f all other samples were not higher as compared to the reported Pb values for mushrooms by Tüzen et al. (1998) (2.35 mg/kg), Kalac and Svoboda (2000) (0.5 20 mg/kg), and Kaya and Bag (2010) (2.166 mg/kg). Lead has been reported to cause irreversible damage to the central nervous system and permanent mental retardation. The acceptable daily intake o f Pb for adults is 0.21-0.25 mg day-1 (Anonymous 1993). This shows that too high a consumption o f Lycoperdon pyriforme, collected from this habitat, could lead to Pb body burden.
As it is the case for most o f the minerals investigated in this study, Lycoperdon pyriforme contained high nickel content with an amount o f 4.4 mg/kg dw. The reported N i values for wild-growing mushrooms were 0.4-15.9, 0.4-2, 1.72-24.1 mg/kg dw (Işıloğlu et al. 2001, Kalac and Svoboda 2000, Soylak et al. 2005), respectively. The N i levels are generally in agreement with previous studies, and are not higher than the allowed amount 0.05-5
mg/kg o f Anonymous (1975) for plants and foods. Nickel has been linked to lung cancer and the tolerable upper intake level for this toxic element is reported as 1 mg/day (Anonymous 1993).
Mushroom, in particular, can be very rich in cadmium. Cadm ium content was below the detection limit in Agaricus langei, and it was the highest in Agaricus silvicola var. silvicola and Lycoperdon molle (19.1 and 10.2 mg/kg dw, respectively) which is relatively high compared to reported literature data (Kalac et al. 2004, Mendil et al. 2005). Cd levels were below 2.0 mg/kg dw in the other mushrooms species in this study. The consumption o f these mushrooms is likely to cause Cd body burden judging from the acceptable daily intake o f 0.06-0.07 mg/day/kg bodyweight (Anonymous 1993). Cadmium is known as a principal toxic element, since it inhibits many life processes. Cadmium has been associated with renal damage; cancer and childhood aggression (Anonymous 1993). Thus, cadmium seems to be the most deleterious element among heavy metals in mushrooms. Its acceptable daily or weekly intake may be easily reached by consumption o f an accumulating mushroom species (Kalac et al. 2004).
Akyuz and Kirbag (2010) found that Pleurotus eryngii var. eryngii as mean values for 11.0-18900 mg/kg K, 350-1030 mg/kg Ca, 160-880 mg/kg Na, 602.4-1524.5 mg/kg Fe, 44.7-102.7 mg/kg Zn, 17.7 37.5 mg/kg Mn, and 12.6-36.0 mg/kg Cu (dry weight). In this study, the mineral levels for Pleurotus eryngii are generally lower.
Gengcelep et al. (2009) found mean values as mg/kg dry weight for Ca (870), M g (1920), K (20400), Fe (203), Zn (133), Cu (73.4) and M n (16.9) in Morchella vulgaris in Erzurum, Turkey. In this study, values o f Ca (249.1), M g (558.3), K (12100), Fe (89.2), Zn (218.5), Cu (59.7) and M n (16.8) found in Morchella vulgaris are lower than that in the previous study.
M ushrooms in fresh, cooked or processed forms
seems to be a good source o f minerals including iron, potassium, calcium, magnesium, manganese and zinc. However, m inim um knowledge is available on the bioavailability o f their components due to high content o f indigestible chitin. The results obtained for trace elements in analyzed mushroom species seem acceptable for human consumption at nutritional levels.
Results from over 150 original papers, dealing with heavy metals in edible mushrooms show that cadmium, mercury, and lead are the toxic metals for man (Kalac and Svoboda 2000). According to Anoymous (1993) standards, acceptable intakes o f cadmium and lead for an adult are 0.42-0.49 and 1.5-1.75 m g per week, respectively. The trace element concentrations in mushrooms are generally species-dependent (Kalac and Svoboda 2000) and considerably affected by the pH or organic matter content o f the soil (Mendil et al. 2005).
According to the E U Scientific Committee for Food Adult Weight parameter, 60 kg o f body weight was used for intake calculations as the weight o f an average consumer. In addition, for intake calcula tions, usually a 300 g portion o f fresh mushrooms, which contains 30 g o f dry matter, per meal is assumed (Kalac and Svoboda 2000, Svoboda et al. 2000). The metal intakes by a normal (60 kg) consumer in mg/serving for Lycoperdon pyriforme (0.0708 for Pb), Agaricus silvicola var. silvicola (0.5733 for Cd) and Lycoperdon molle (0.3066 for Cd), were calculated from Table 1. Provisional tolerable weekly intake values for Pb and Cd for adults (of 60 kg) are 1.50 and 0.42 mg, respectively (Anonymous 2001). These values correspond to 0.21, and 0.06 m g o f Pb and Cd, respectively, on a daily basis.
A C K N O W L E D G E M E N T S
The authors would like to thank to Yüzüncü Yıl University Scientific and Research Projects Presidency (2006-FED-B09 and 2007-FBE-YL065) for its financial support.
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