NUTRITIONAL ASSESSMENT OF SOME MUSHROOM SPECIES

M.M. Ndamitso, F.O. Abulude
Department of Chemistry, Federal University of Technology, Minna, Niger State, Nigeria

ABSTRACT

The aim of this paper was to determine the proximate, minerals and phytate compositions of selected mushroom samples (Lentinus subnudus (M₁), Chlorophyllum molybdities (M₂), Volvariella esculenta (M₃), Coprinus atramentarius (M₄), Pleurotus ostreatus (M₅), Termitomyces microcarpus (M₆) and Pleurotus pulmonarius (M₇) using standard methods of analyses. The mean of some of the results are: Crude protein:  9.1±0.15 – 13.80±0.15%, Crude fibre: 4.15±0.02 – 7.08±0.59%, Na: 177±2.56 – 910±2.56 mg/100 g, P: 480±2.31 – 884±2.43 mg/100 g and I: 12.60±0.20 – 18.00±0.20 mg/100 g. Phytate phosphorus: 0.64±0.20 – 1.39±0.20 (mg/100 g). From the results obtained, it is deduced that the mushroom species under this study are good sources of protein, fibre and average in minerals. It is gratifying to note that the heavy metals are below the recommended levels.

Key words: Mushroom species, food, protein, minerals, phytate, Akure, Nigeria.

INTRODUCTION

Mushrooms have for a long time been recognized not only as a delicacy, but also for their use as food in man’s diets. They have been found to be rich sources of protein, lipids, amino acids, glycogen, vitamins and mineral salts [18, 13, 17]. According to Adeyeye et al. [3], the mineral salts contents of mushrooms are superior to those of meat and fish and nearly twice those of most common vegetables. These fungi have also been mentioned for their medicinal values [19].

Although the nutritional and medicinal values of mushrooms have long been recognized [15, 12], in the past, their consumption has mainly been confined to rural Nigeria. However, in recent times, their consumption has assumed greater importance in the diets of both rural and urban dwellers. For example, they are being marketed along major highways and urban centres where the trade now booms. It is conceivable that the increased demand for mushrooms is predicated upon the phenomenal rise in the costs of the conventional sources of animal protein sources like the beef, pork, chicken, fish and eggs.

The aims of the study are to determine the proximate, mineral and phytate composition of the seven different species of mushrooms selected for this study.

MATERIALS AND METHODS

Source of materials and sample pretreatment
The mushrooms; Lentinus subnudus Berk (M₁), Chlorophyllum molybdities (Meyer: Fr.) Masse (M₂), Volvariella esculenta (Mass) Singer (M₃), Coprinus atramentarius (Bull.:Fr) Fr (M₄), Pleurotus ostreatus Jacq (M₅), Termitomyces microcarpus (Berk et Broome) Heim (M₆) and Pleurotus pulmonarius (Fr.) Quél. (M₇)  were collected from Federal College of Agriculture campus, Akure, Ondo State, southwest part of Nigeria. The bad or rotten samples were sorted out. The samples were oven dried at 65°C for 72 hours and were then pounded into powdered form using porcelain pestle and mortar. The milled samples were then sieved with a 2 mm mesh sized sieve and stored in waterproof polyethylene bags at room temperature for further analysis.

The proximate and mineral compositions were determined as described by AOAC, [5], while phytate content was determined using the methods described by Abulude and Ojediran [1]. The calorific values in kilojoules were calculated by multiplying the crude fat, protein and carbohydrate by Atwater factor of 37, 17 and 17 respectively and calculated fatty acid (0.8 x crude fat) [3].

Data obtained were generated in triplicates and analyzed using Mean, Standard deviation and one-way (one factor) analysis of variance with Duncan Multiple Range test at 95% confidence or p < 0.05.

RESULTS AND DISCUSSION

The results obtained for the proximate composition of the mushroom varieties are as presented in Table 1. This table shows the average proximate compositions of the mushroom species (p < 0.05) Pleurotus pulmonarius had the highest moisture while, Volvariella esculenta had the lowest. Termitomyces microcarpus had the highest dry matter (DM) while Pleurotus pulmonarius had the lowest. Pleurotus pulmonarius had the highest ash while Termitomyces microcarpus had the lowest.  Crude fibre of samples differed significantly (p < 0.05) with Coprinus atramentarius having the highest value while Lentinus subnudus had the lowest. Nitrogen free extract (NFE) of samples significantly differed (p < 0.05) and Chlorophyllum molybdities had the highest while Volvariella esculenta had the lowest. The crude protein of Pleurotus pulmonarius was the highest while Chlorophyllum molybdities was the lowest (p < 0.05). At p < 0.05 Volvariella esculenta had the highest crude fat while Chlorophyllum molybdities had the lowest. The results agreed with the results obtained for legumes [6] and Amaranthus hybridus and Telfairia occidentalis [4].  All the samples were low in fatty acid. The low results were not in agreement with high values obtained by Adeyeye and Omolayo [4] for  Amaranthus hybridus  (7.7 g/100 g)and Telfairia occidentalis (8.5 g/100 g). The calculated gross energy reported for P. notabilis (shell) by Adeyeye et al. [3] was 1032.1 KJ/100 g and it was 1119.5 KJ/100 g in Phylidonyris notabilis (flesh) while 453.19 KJ/100 g was recorded DuruMajesty et al. [7] for “Nduduagworagwo”. Our respective results were between 850.9 KJ/100 g and 1379.1 KJ/100 g. These results showed that foods have different energy values. It is gratifying to note that the moisture content is an advantage to the storage potential of the samples. The bulk density values were found to be between 0.39±0.05 to 0.43±0.05 g/cm³. The bulk density is generally affected by the particle size and the density of the flour and it is very important in determining the packaging requirement, material handling and application in wet processing in the food industry [2]. High moisture contents in food or feed samples aid microorganism attack which eventually leads to early spoilage.

Table 2 shows the results of the mineral compositions of the selected mushrooms (mg/100 g). The table showed the mineral contents of the mushrooms with Termitomyces microcarpus having the highest sodium (910±2.56) while Chlorophyllum molybdities (177±2.56) had the lowest (at p < 0.05). The potassium contents differed significantly (p < 0.05) where Termitomyces microcarpus (3680±2.33) had the highest value while Chlorophyllum molybdities had the lowest (926±2.11). Termitomyces microcarpus had the highest calcium while Volvariella esculenta had the lowest (at p < 0.05). The results obtained in this study are far above the results obtained in mushrooms harvested in India [14] and Romania [9]. The differences observed could be due to the soil contents and methods of analyses. Calcium plays important roles in human and animal nutrition as it contributes to the normal development and maintenance of bones and teeth, clothing of blood, nerve irritability, normal heart action, muscle activity, activates enzymes [8]. Pleurotus pulmonarius had the highest magnesium while Pleurotus ostreatus had the lowest (at p < 0.05).The phosphorus contents of the samples also differed significantly with Termitomyces microcarpus having the highest average while Chlorophyllum molybdities had the lowest.Phosphorus is used for normal development and maintenance of bones and teeth, cell activity, normal acid-base balance of blood, muscle activity, metabolism of carbohydrates and fats while potassium helps in fluid balance, regular heart rhythm, regulation of nerve impulse conduction and cell metabolism [10]. The average zinc contents also differed significantly (p < 0.05) with Pleurotus pulmonarius having the highest while Chlorophyllum molybdities had the lowest. The average copper contents also differed significantly (p < 0.05) where Termitomyces microcarpus had the highest while Chlorophyllum molybdities had the lowest. The mean manganese contents of the samples differed significantly (p < 0.05) where Termitomyces microcarpus had the highest while Lentinus subnudus had the lowest. Cadmium was not detectable in all the samples. The average lead contents of the samples also differed significantly (p < 0.05) where Termitomyces microcarpus had the highest while Volvariella esculenta had the lowest (0.60±0.02). In researches carried out in Ghana and Spain, Pb was found to be 0.04–0.023 [22] and 2.3–3.6 mg/kg [11] respectively, our results were in agreement theirs. The maximum permissible limits released by SON [20] for Cd and Pb are 0.003 and 0.01 mg/L respectively. It gratifying to note, that consumers are not likely to be exposed to Cd, but care should be taken not to ingest Pb poison. The Pb contact could be due to the traffic flow of the area of harvest. The chloride contents of the species also showed significant differences where Termitomyces microcarpus had the highest average and Chlorophyllum molybdities the lowest. The highest value of iodine was obtained for Coprinus atramentarius and the least for Pleurotus pulmonarius. According to Mar and Terra [16], fresh water foods are not known to high iodine content. Generally, the iodine content of foods of both animal and plant origin is related to the soil in which they are grown.

Table 3 depicted the results of the phytate phosphorus and phytate compositions of mushroom samples. The phytate phosphorus and phytate contents of the species showed significant differences with Lentinus subnudus having the highest average while Coprinus atramentarius had the lowest. The results showed that all the samples contained low levels of phytate phosphorus and phytate. These values compared well with the values reported for Dioscorea rotundata (2.8±0.03 mg/100 g) D. cayenensis (2.60 mg/100 g) and D. esculenta (0.22±0.03 mg/100 g) [21], but much more lower than the values reported for mungbean and acha flours (452.16±0.16 – 576.23±0.35 mg/100 g) and 114.22±0.18 mg/100 g respectively. According to Udensi et al. [21], it means that the mushroom samples will have available minerals for absorption in the body. Adequate food processing would reduce phytate contents, thereby providing available minerals in the body.

REFERENCES

1. Abulude F.O., Ojediran V.A., 2006. Development and quality evaluation of fortified ‘Ämala’. Acta Scientiarum  Polonorum Technologia Alimentaria. 5 (2), 127–134.
2. Adebowale A.A., Sanni S.A., Oladapo F.O., 2008. Chemical, functional and sensory properties of instant yam breadfruit flour. Nig. Food J., 26 (1), 2–12.
3. Adeyeye E.I, Adubiaro H.A., Awodola O.J., 2008. Comparability of chemical composition and functional properties of shell and flesh of Penaecus notabilis. Pak. J. Nutr., 7 (6), 741–747.
4. Adeyeye E.I., Omolayo F.O., 2011. Chemical composition and functional properties of leaf protein concentrates of Amarantus hybridus and Telfairia occidentalis. Agric. Bio. J. North America. Doi: 10.5251/abjna.2011.2.3499.511.
5. AOAC, 2005. Official methods of analysis. Association of Official Analytical Chemists, Washington, DC., USA.
6. Arawande J.O., Borokini F.B., 2010. Comparative study on chemical composition and functional properties of three Nigerian legumes (Jack Beans, Pigeon Pea and Cowpea). J. Emerging Trends in Eng. Appl. Sci.,1 (1), 89.
7. DuruMajesty K.C., Agomuo Emmanuel A., Amadi Benjamin A., 2012. Nutrient composition of “Nduduagworagwo”, A traditional food of Akokwa people in Ideato North L.G.A of Imo State, Nigeria. Continental J. Food Science and Technology, 6 (3), 27–32.
8. Ebenso I.E., 2003. Dietary calcium supplement for edible tropical land snails Archachatina marginata in Niger Delta, Nigeria. Livestock Research for Rural Development, Centre for Investigation in sustainable Systems of Agricultural Productions, 15: no. 5 article 6.
9. Elekes C.C., Busuioc G., 2010. The biomineral concentrations and accumulation in some wild growing edible species of mushrooms. Annals. Food Science and Technology, 11 (1), 74–78.  
10. Eneji C.A., Ogogo A.U., Emmanuel-Ikpeme C.A., Okon O.E., 2008. Nutritional assessment of some Nigerian land and water snail species. Ethiopian J. Env. Studies and Magt., 1 (2), 56–60.
11. García M.A., Alonso J., Melgar M.J., 2009. Lead in edible mushrooms: levels and bioaccumulation factors. J. Hazard Mater., 167(1–3), 777–783, doi: 10.1016/j.jhazmat.2009.01.058. Epub 2009.
12. Kattawan A., Chanlekha K., Kongkachuichai R., Chaaroensiri R., 2011. Effects of cooking on antioxidant activities and polyphenol content of edible mushrooms commonly consumed in Thailand. Pak. J. Nutr., 10 (11), 1094–1103.
13. Koyyalamudi S.R., Jeong S.C., Song C.H., Cho K.Y., Pang G., 2009. "Vitamin D2 formation and bioavailability from Agaricus bisporus button mushrooms treated with ultraviolet irradiation" (PDF). Journal of Agricultural and Food Chemistry, 57 (8), 3351–3355. doi:10.1021/jf803908q. PMID 19281276.
14. Mallikarjuna S.E., Ranjini A., Haware Devendra J., Vijayalakshmi M.R., Shashirekha M.N., Rajarathnam S., 2013. Mineral Composition of Four Edible Mushrooms. Journal of Chemistry, http://dx.doi.org/10.1155/2013/805284
15. Manzi P., Aguzzi A., Pizzoferrato L., 2001. Nutritive value of mushrooms widely consumed in Italy. Food Chem., 73, 321–325.
16. Mar and Terra, 2010. Freshwater fish do not contain iodine in their composition. www.mareterra.com. Accessed 7/10/2010.
17. Nabubuya A., Muyonga J.H., Kabasa J.D., 2010. Nutritional and hypocholesterolemic properties of  Termitomyces microcarpus mushrooms. AJFAND, 10 (3), 2235–2257.
18. Okwulehie I.C., Odunze E.T., 2004: Evaluation of the myco-chemical and mineral composition of some tropical edible mushroom. J. Sustainable Agric. Environ., 6 (1), 63–70.
19. Selvi S., Uma Devi P., Suja S., Murugan S., Chinnarswamy P., 2007. Comparison of non-enzymic antioxidant status of fresh and dried form of Pleurotus florida and Calocybe indica, Pak. J.  Nutr., 6 (5), 468–471.
20. Standard Organisation of Nigeria (SON), 2007. Nigerian standard for drinking water. Nigerian Industrial Standard NIS 554: 2007.
21. Udensi E.A., Oselebe H.O., Onuoha A.U., 2010. Antinutritional assessment of D. alata varieties. Pak. J.  Nutr., 9 (2), 179–181.
22. Quarcoo A., Adotey G., 2013. Determination of heavy metals in Pleurotus ostreatus (Oyster mushroom) and Termitomyces clypeatus (Termite mushroom) sold on selected markets in Accra, Ghana. Mycosphere, 4(5), 960–967, Doi: 10.5943/mycosphere/4/5/9.

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