Analytical MethodsNutritional value and metal content of wild edible mushrooms collected from West Macedonia and Epirus, Greece
Introduction
Wild-growing mushrooms are a popular and favourite delicacy in many European countries, mainly in middle and south Europe. For instance, many people collect wild edible mushrooms in Greece substantially contributing to food intake. Therefore, it is important to determine the basic composition and the levels of essential and toxic elements in wild edible mushrooms.
However, data on the diversity of the mycoflora in Greece are very scarce and fragmentary, covering mainly fungi of phytophalogical importance and macrofungi. Existing figures produce a total of about 2500 recorded mushroom species (Zervakis. G.I., 2001). Check list of Greek fungi reports 811 species, assigned in 214 genera and 58 families of Basidiomycotina and 77 species of macrofungi assigned in 17 families and 42 genera, belonging to Ascomycetes. If this amount is added to the number of Basidiomycetes, the total number of mushrooms species in Greece rises to over 900 (Venturella & Zervakis, 2000).
West Macedonia and Epirus regions located in Northwestern Greece have a mild and rainy climate, especially, in spring and autumn, providing nearly ideal conditions for fungal growth, with temperatures ranging between 8 and 25 °C.
Fruiting bodies of mushrooms are appreciated, not only for texture and flavour but also for their chemical and nutritional characteristics (Manzi, Aguzzi, & Pizzoferrato, 2001). Mushrooms are valuable healthy and nutritious foods, low in calories and high in vegetable proteins, vitamins, iron, zinc, selenium, sodium, chitin, fibres and minerals (Mendil et al., 2004, Ouzouni, 2004, Ouzouni and Riganakos K.A., 2007, Ouzouni et al., 2007, Racz et al., 1996).
In general, the fruiting bodies of mushrooms, on dry weight basis, contain about 56.8% carbohydrate, 25.0% protein, 5.7% fats and 12.5% ash (Demirbas, 2002, Latiff et al., 1996, Mendil et al., 2004). Compared to green plants, mushrooms can build up large concentrations of some heavy metals, such as lead, cadmium and mercury, and a great effort has been made to evaluate the possible danger to human health from the ingestion of mushrooms (Gast et al., 1988, Soylak et al., 2005). Lead, cadmium, iron, copper, manganese, zinc, cobalt, chromium, nickel, magnesium, aluminium, tin and arsenic were chosen as representative trace metals whose levels in the environment represent a reliable index of environmental pollution. Metals such as iron, copper, manganese, and zinc are essential metals since they play an important role in biological systems, whereas lead and cadmium are non-essential metals as they are toxic even in traces (Schroeder, 1973). The essential metals can also produce toxic effects when the metal intake is excessively elevated.
The aim of the present study was to determine the basic composition and the essential and toxic elements (Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, Cd, Al, As and Sn) using Atomic Absorption Spectroscopy (AAS) of ten wild edible mushrooms species from West Macedonia and Epirus, regions of Greece.
Section snippets
Sample preparation
Fruiting bodies of ten (10) wild edible species (Cantharellus cibarius, Rusula delica var chloroides, Ramaria largentii, Hygrophorus russula, Amanita caesaria, Fistulina hepatica, Boletus aureus, Armillaria tabesceus, A. mellea, Lepista nuda), belonging to nine (9) different families, were collected from forests in West Macedonia and Epirus, during autumn 2006 and spring 2007. The areas of the study included pasturelands and forests (unpolluted areas) distant from potential pollution sources,
Results and discussion
The families of mushroom species used in this study, their habitat and their common names are given in Table 2.
Basic chemical composition of mushrooms is depicted in Table 3, expressed in a dry weight (d.w.) basis as g/100 g. Additionally, all metal concentrations of mushroom samples were determined on a dry weight basis respectively and are given in Table 4 as μg/g. The conventionally adopted as toxic metals studied in these experiments are Cd, Pb, and As.
When the nutritional value of mushrooms
Conclusions
The mushrooms studied were found to be a good source of proteins (mean value 27.52% d.w.), carbohydrates (mean value 61.45% d.w.) and trace functional minerals. They have a low fat content making them ideal components in several diets. Also, their low content of toxic metals (Pb, Cd and As) shows that the collection areas are not polluted. Therefore all these collected edible mushroom species can be used in well-balanced diets and also can be consumed unreservedly without any health risk.
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