Mushrooms are edible fungus those have been eaten since the time of the ancient Egyptians, and were regarded as plants of immortality 1. Human have used mushroom collected in the wild as food and it is estimated that the first intentional cultivation of mushroom took place almost 1400 years ago 2. Mushrooms are fleshly fungi, spore bearing fruiting bodies which are produced above ground on soil. They often refer to fruiting body of the gill fungi, which do not contain chlorophyll like green plants and as a result cannot manufacture food by their own. They are very nutritious products that can be generated from lignocellulosic waste materials. The bioconversion of agricultural wastes into a value added products is a good mean of their use 3. Edible mushrooms are important sources of food. They form very nourishing meals especially for invalids, for they are easily digestible. They are consumed not only for their innate flavor and taste, but also for their important nutritional value 45. In Egypt, only a minute proportion of fruit bodies sold in the markets and they are always either Pleurotus or Agaricus mushroom 6. Mushrooms constitute an integral part of the normal human diet and in recent times, the amounts of consumption have been raised greatly, which includes variety of species 7. Compared with vegetables, mushrooms proved to be also a good source of many minerals 8. The minerals of highest content are potassium, followed by phosphorous, calcium and magnesium 910. Potassium is particularly abundant and accounts for nearly 45% of the total ash content 11. Mushrooms provide small, but nutritionally important, amounts of iron with high bioavailability (up to 90% can be absorbed)12. The water content of mushrooms is high, usually approximately 90%. However, amount of water is greatly influenced by relative humidity and temperature during growth and storage 13. The aim of the present study was to analyze the micronutrient contents of fresh and canned Agaricusbisporusand Pleurotusostreatusmushroom sold in Alexandria markets, Egypt.

A total of 95 samples, 30 of each fresh Agaricusand Pleurotusmushrooms were purchased from various markets in Alexandria in addition to 35 of canned samples (30 samples from Agaricus obtained from different commercial brands of different countries of origin in addition to five samples from Pleurotus obtained from the only available commercial brand). Only five samples were collected from the canned Pleurotus since only one commercial brand was available in the market.

The present study revealed that fresh Agaricus mushroom was insignificantly higher in its calcium and iron contents than Pleurotus mushroom although the later was significantly higher in its potassium content (3890.4 and 3102.9 mg/100g in case of Pleurotus and Agaricus; respectively). Canned Agaricus were higher in their micronutrient contents than the canned cut Pleurotus. Moreover, the variations were significant in case of calcium contents. Also, the variations in iron contents between whole Agaricus and cut Pleurotus were significant. The whole canned Agaricus was higher in its micronutrient contents than the cut canned Agaricus and both forms were higher in their contents than the fresh type. Although, there were significant variations in the calcium contents between fresh Agaricus and canned Agaricus as well as between both forms of canned Agaricus and whole fresh Agaricus, the variations were insignificant in case potassium. Also, there were significant variations in the iron content between fresh and canned Agaricus as well as between whole fresh Agaricus and whole canned Agaricus. Whole fresh Pleurotus had insignificantly lower calcium content than canned cut Pleurotus (33.8 and 47.1 mg/100g; respectively), it had significantly higher potassium content (3890.4 and 3174.5mg/100g; respectively). Fresh whole and canned cut Pleurotus had more or less similar iron contents (29.8 and 29.3 mg/100g; respectively) as shown in Table 1.

Table 2 illustrates that the French whole and cut canned Agaricus are higher in their microelements contents than the corresponding Chinese forms and the differences were statistically significant in case of iron and potassium contents in case of the cut forms. Unfortunately, the Egyptian cut Pleurotus was with the lowest calcium and iron contents when compared with both forms of the Chinese and French Agaricus. Also, there were statistically significant differences in its calcium contents when compared with the both forms, in its iron contents with cut and whole Agaricus and finally in its potassium contents when compared with the French whole Agaricus.

There are many minerals that are essential for a normal healthy body. Mushrooms like all living organisms have a good mix of minerals, and their fruiting bodies are characterized by high levels of assimilable mineral constituents17. The fructifications of mushrooms are characterized by a high level of well mineral constituents, whose level depends, among other things, on the species, age of the mushrooms, the diameter of the pilei and the substratum18. Mushroom fruiting bodies provide considerable amounts of absorbable mineral ingredients19.

From the mineral analysis reported in this study, it seems that the two mushrooms can provide a useful source of potassium, iron and calcium. Potassium was the most predominate mineral in the two studied species ranging from 3890.4% mg/100g in fresh Pleurotusostreatusto 3102.9% in fresh Agaricusbisporus with significant difference between them (Table 1). These contents are equivalent to 413.1 and 407.2 mg/100g on the wet weight basis respectively. They provide about hence recommendation daily intake for potassium at 4700 mg per day for men and women, recommendation daily intake for iron 8 mg per day for men ages 19-50 years and postmenopausal women, for females ages 19-50 years is significantly higher at 18 mg per day and recommendation daily intake for calcium for both men and women, ages 19-50 years 1000 mg per day, the recommendations are higher for men and women 9-18 years old 1300 mg per day 20. A Previous study reported that potassium alone constituted 45 percent of the total ash content of mushroom 21.

Regarding the minerals content of mushrooms, revealed that the calcium content of the two mushroom species were more similar about 33.8 and 36.0 mg/100g dry weight for fresh Pleurotusostreatusand Agaricusbisporus respectively with insignificant difference between them. Potassium was the dominate minerals in all tested mushrooms, 3102.9 and 3890.4 mg/100g dry weight for fresh Agaricusbisporus and Pleurotusostreatuswith significant difference between them. Also the present study showed the iron content of the two present studies were 29.8 and 37.5 mg/100g dry weight for fresh Pleurotusostreatusand Agaricusbisporus, in succession with significant difference between them.

Another study reported that, potassium, calcium, iron contents were 224.7, 25.8, 31.0 mg/100g and 203.9 30.7, 39.4 mg/100g in fresh Pleurotusostreatusand Agaricusbisporusrespectively 22. Previous study declared that, fresh Pleurotusostreatuscontained 3793.0, 33.0, 15.2 mg/100g for potassium, calcium and iron respectively and 28-30,000 mg/kg, 71.0 and 8.8 mg/100g for fresh Agaricusbisporus23.

The present study revealed that, the calcium contents of canned Agaricusbisporuswere about ten time higher than the fresh types (335.3 and 36 mg/100g, respectively) with significant difference between them, this high contents in canned mushroom may be attributed to the dipping mushrooms in CaCl₂ solution to produce firmer texture and caps opened slower 24.

Also, iron content of canned Agaricusbisporuswas about two times higher than the fresh type with significant difference between them, also their potassium content was approximately similar but without significant difference between them.

Other study reported that, the calcium, potassium and iron canned Agaricusbisporuswere 87.0, 2855.0 and 7.2 mg/100g dry weight contents respectively 24. There was a higher content of most minerals in the cap than in the stem of the mushroom except iron and calcium, which were more abundant in the stem 21.

Micronutrients analysis of canned and fresh Agaricus and Pleurotus revealed that these species of mushrooms are good sources of calcium, potassium, and iron, so they can be used as supplementary healthy foods for human nutrition.

All authors have made full contribution to data acquisition, interpretation of results, drafting and revising the final manuscript. All authors read and approved the final manuscript.

Limited number of cannedPleurotusostreatus samples were collected and analyzed because this variety is sold in Egypt only in fresh form.