Academia Journal of Scientific Research 5(9): 349-364, September 2017 DOI: 10.15413/ajsr.2017.0627 ISSN 2315-7712 ©2017 Academia Publishing Research Paper Proximate composition and mineral profiles of selected edible mushroom consumed in northern part of Nigeria Accepted 17th July, 2017 ABSTRACT Mushrooms are highly consumed by different ethnic groups in different states across the region (northern Nigeria). They have broad cultural acceptance and constitute a traditionally very important nutritious food. However, their assessment as food, which is based on chemical analysis, has not been adequately studied and documented. Standard procedures were used to determine the proximate chemical composition of edible mushrooms. Atomic absorption and flame spectrophotometer were used to determine the mineral and heavy element composition. The results were compared using an analysis of variance test. There were significant differences in the proximate nutritive values of the various edible mushrooms (p>0.05) studied. Despite differences in the chemical composition of the edible mushroom species, the overall nutritional potential of the whole mushroom species was quite good. The results of the analysis showed high significant amounts of protein and minerals, ranging from 1.24 -48.44 mg/g and 0.09 -57.54 mg/g for macro and micro elements, Odoh Raphael*, Ugwuja Daniel respectively. Furthermore, crude fibre ranged from 3.32 – 19.76% and Izuchukwu and Udegbunam Ifeoma carbohydrate from 20.54 – 64.78%, both of which were found to be relatively Sandra high. All species were moderate in fat content, with a range of 1.11 to 8.43%. Department of Chemical Sciences, Faculty Although Pb and Cd were detected in some of the species of mushrooms, these of pure and applied Sciences Federal results indicated that the studied mushrooms have good nutritive value for University Wukari, PMB 1020, Wukari, human consumption. Taraba State, Nigeria. *Corresponding author. E-mail: Key words: Analysis, consumed, edible mushrooms, macro and micro elements, [email protected]. proximate composition. INTRODUCTION Several ethnic groups consume mushrooms worldwide common in most part of environments. They are rich in (Chang and Mshigeni, 2001; Vetter, 1994; Nakalembe et al., vitamins and mineral elements (Fasidi et al., 1990; 2009). Edible mushrooms have the potential to contribute Sivrikaya et al., 2002) and the bioavailability of some enormously to food value and diet, especially in the supply elements depend on the level of interactions with various of both macro- and micro-nutrients. The nutritive value of nutrients. Apart from their use as food, demands have mushrooms is attributed to their high content of essential been accelerated with the exponential human population amino acids, vitamins, minerals and low lipid content. growth and some scientific evidences suggest that many People consume mushroom are generally found to have species contain substances that may prevent or reduce greater intake levels of most vitamins and minerals. Some cancer, heart diseases, diabetes and viral infections mushrooms are sources of food, diets, and are consumed (Genders, 1974; Oei, 1991). Mushrooms have been a food all over the world. Food is one of the prime basic needs of supplement in various cultures and are cultivated and humans; for good health, labour productivity, and mental eaten for their edibility and delicacy. Mushrooms are development. They have a high nutritional value and are considered as source of proteins, vitamins, fats, Academia Journal of Scientific Research; Odoh et al. 350 carbohydrates, amino acids and minerals (Colak et al., Carbohydrate was determined by difference. 2009). They fall between the best vegetables and animal protein source. The protein content of mushrooms has been reported to be twice that of vegetables and four times Digestion procedure that of oranges and significantly higher than that of wheat (FAO, 2006). Mushrooms contains also an appreciable A procedure recommended by Environmental Protection quantities of crude fibres, although, little information exist Agency (EPA, Method 3050B) was used as the on its Total Dietary Fibre (TDF) content. The crude fibre conventional acid extraction method. 1.00 g of sample was content values reported in several studies suggest that placed in 250 ml flask for digestion. In the first step, the mushrooms are potential sources of dietary fibre sample was heated to 95C with 10 ml of 50% HNO3 (Adadayo, 2011). Mushrooms generally contain low fat without boiling. After cooling the sample, it was refluxed and oil content (Poppe, 2000). As a result, they are with repeated additions of 65% HNO3 until no brown recommended as good source of food supplement for fumes were given off by the sample. Then the solution was patients with cardiac problems or at risk of lipid induced allowed to evaporate until the volume was reduced to 5 3 disorders. Despite the numerous studies on nutrients and cm . After cooling, 10 ml of 30% H2O2 was added slowly minerals contents of different mushroom species globally, without allowing any losses. The mixture was refluxed little or no work has been carried out on the nutritional with 10 cm3 of 37% HCl at 95C for 15 min. The digestate component of edible mushroom species in northern parts obtained was filtered through a 0.45 µm membrane paper, of Nigeria and there are several edible species that are yet diluted to 100 cm3 with deionized water and stored at 4C to be exploited. Therefore, this study was carried out to for analyses. The total extraction procedure lasted for 3–4 investigate the proximate composition, mineral and some h. heavy metal content of ten selected edible mushrooms in The resultant solution was cooled and filtered into 100 northern Nigeria. cm3 standard flasks and made to mark with distilled water (Asaolu, 1995). Atomic absorption spectrophotometer (Buck scientific model 200A) was used for Ca, Mg, Cd, Cu, MATERIALS AND METHODS Fe, Pb, Mn and Zn, and flame photometer for Na and K. Collection of samples and sample preparation Statistical analysis Ten varieties of edible mushrooms species were studied. The mushrooms were morels (Morchella sp), maitake Microsoft Excel (2007) package was used for statistical (grifola frondosa), porcini (Boletus edultis), giant puftball analysis by employing the independent sample t-test. The (Calvatia gigantean), chanterelles (Cantharellus cibarius), summary statistics such as mean, standard deviation (SD) matsutake (Tricholoma matsutake), shaggy mane (Coprinus and correlation were computed. Significant tests were comatus), black trumpt (Craterellus cornucopioides), carried out at the 0.05 level. Significant difference was caesaris mushroom (Amanita caesarea) and Portobello observed when the probability associated with the t test (Pleurotous ostreatus). These mushrooms were obtained (p) was less than the level of significance (that is, p < 0.05). from various places: farms, highways, markets and various The data were also subjected to analyses of variance (one- spots such as garden, rotten woods, palm trees rots, plant way ANOVA). wastes, waste site etc in the study areas. The mushroom samples were uprooted, destalked, washed and cleaned to remove extraneous substances, and sun-dried for some RESULTS AND DISCUSSION days. The mushrooms were later milled to obtain mushroom meals using mortar and pestle and were stored The results of proximate composition of the edible in a container for the analysis. mushrooms consumed in the study areas are presented in Tables 1 – 10, and the summary of the proximate composition of the edible mushrooms is presented in Determination of the nutritional value Table 11. The moisture content in all varieties of edible mushroom studied ranged from 20.55 – 67.76%. The Proximate analysis moisture contents of the mushrooms were relatively high with average value of 44.73±9.67%. Maitake (G. frondosa) Moisture, ash, crude fat, crude fat and crude fibre were had the highest moisture content (67.76%), while the determined in accordance with the official methods of the lowest values were recorded in chanterelles (C. cibarius) association of official analytical chemists (AOAC, 1999). and shaggy mane (C. comatus). The high moisture content Nitrogen was determined using micro-kjeldahl method provides greater activity of water soluble enzymes and co- (Pearson, 1976) and the percentage of nitrogen was enzymes needed for metabolic activities of these converted to crude protein through multiplying by 6.25. mushrooms (Crisan and Sands, 1978; Adejumo and Academia Journal of Scientific Research; Odoh et al. 351 Table 1: Proximate composition of in Morels (Morchella sp). Moisture Sample Ash (%) Carbohydrate (%) Fat (%) Crude fibre (%) Crude protein (%) (%) 1 6.52 54.78 1.11 12.32 25.65 49.54 2 8.53 57.99 1.21 11.32 21.32 51.32 3 10.87 48.65 1.55 13.45 21.44 50.55 4 9.88 52.77 1.22 15.33 22.12 49.88 5 9.55 45.89 1.12 10.67 20.23 47.68 6 7.55 46.78 1.45 14.34 21.55 51.44 7 8.34 44.56 1.32 11.21 24.89 49.88 8 7.98 50.54 1.43 9.76 19.23 51.54 9 8.76 47.88 1.21 9.34 17.32 45.67 10 6.45 45.78 1.43 10.54 21.67 47.76 Mean 8.44 49.56 1.31 11.83 21.54 49.53 STD 1.41 4.39 0.15 1.99 2.44 1.93 MIN 6.45 44.56 1.11 9.34 17.32 45.67 MAX 10.87 57.99 1.55 15.33 25.65 51.54 Table 2: Proximate composition of Maitake (Grifola frondosa). Moisture Sample Ash (%) Carbohydrate (%) Fat (%) Crude fibre (%) Crude protein (%) (%) 1 16.34 24.78 2.11 10.32 15.65 59.54 2 18.53 27.99 2.21 10.32 21.32 51.32 3 10.87 28.65 2.55 10.45 21.44 60.55 4 19.88 22.77 2.22 12.33 22.12 49.88 5 19.55 25.89 2.12 10.67 18.23 47.68 6 17.55 26.78 2.45 11.34 19.55 61.44 7 8.34 24.56 2.32 11.21 14.89 39.88 8 17.98 20.54 2.43 10.76 19.23 41.54 9 18.76 27.88 2.21 11.34 17.32 55.67 10 16.45 25.78 2.43 10.54 18.67 67.76 Mean 16.43 25.56 2.31 10.93 18.84 53.53 STD 3.82 2.52 0.15 0.63 2.42 9.05 MIN 8.34 20.54 2.11 10.32 14.89 39.88 MAX 19.88 28.65 2.55 12.33 22.12 67.76 Awesanya, 2005; Sivrikaya et al., 2002).