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Nutritive value of some Nigerian edible mushrooms
FoodChemistryg (1982)263-268
NUTRITIVE VALUE OF SOME NIGERIAN EDIBLE MUSHROOMS S. K. OGUblDAblA,~ O. E. FAGADE
Department of Microbiology, University of Ife, lle-lfe, Nigeria (Received: 26 January, 1981)
ABSTRACT
Samples ofTermitomyces robustus, T. clypeatus and Pleurotus tuber-regium were analysed for their nutrient and toxic substances. The Termitomyces spp. contained as much as 31% proteins and about 32% carbohydrates, of which at least 26% were reducing sugars. Pleurotus tuber-regium contained 14"6% protein and 18.6% carbohydrates, of which only about 2"9% were reducing sugars. There was little difference in their crude fibre and ash content, while the fat content of T. robustus was a little higher than those of the other samples. The ascorbic acidcontent of each of the Termitomyces spp. (lOmg % and 14.3mg %) was much higher than that of Pleurotus sp. (3.3mg %). All the mushroom samples were low in hydrocyanic acid (HCN) and oxalate contents.
INTRODUCTION
Termitomyces robustus has been described as the most delicious edible mushroom by the Yoruba people of Nigeria (Oso, 1975). It makes its appearance after heavy rains (Alasoadura, 1967), growing in large numbers in contact with termite nests in forest soils from August to October. T. clypeatus also grows in contact with termite nests but makes its appearance at the beginning of the rainy season around April, while Pleurotus tuber-regium is often found around breadfruit trees (Zoberi, 1973). In Nigeria, wild mushrooms are collected for food and, when plentiful, are frequently sold along the roadside to passers-by. Although Termitomyces and Pleurotus spp. are widely distributed in Nigeria (Alasoadura, 1967), very little work has been done on any edible mushrooms. Mycologists in Nigeria (Alasoadura, 1966; Zoberi, 1972, 1973) have only used taxonomic characters to determine edible ones. A pioneer work (Oke, 1966a) has been carried out to determine the nutritive value of mixed edible mushroom samples. The present investigations were, 263 Food Chemistry 0308-8146/82/0008-0263/$02.75 !~) Applied Science Publishers Ltd, England, 1982 Printed in Great Britain
264
s.K.
OGUNDANA, O. E. FAGADE
therefore, carried out to determine the nutritive value of the widely accepted T. robustus, T. clypeatus and P. tuber-regium.
MATERIALS AND METHODS
Raw materials T. robustus was bought from sellers along Ife-Ibadan road and T. clypeatus was collected from the University of Ife maize plantation, while P. tuber-regium was harvested from a decaying log at the University of Ife staff quarters. All specimens were oven dried and ground into fine particles before use. Determination of nutrient and toxic substances Crude fibre and ash contents were determined according to the AOAC methods of analysis (AOAC, 1970); and the crude protein, ether extract and hydrocyanic acid were also determined by the methods of the AOAC (1975). The total oxalate content was estimated using Oke's method (1966a) whereby 2 g of sample were digested with 190 ml of distilled water and filtered into a conical flask, and diluted to 250 ml. To a 50 ml portion of the extract were added 10 ml 6N HCI; the solution was then filtered and the precipitate washed with hot water. The filtrate and the wash were combined and titrated against 6N NH4OH, using methyl red indicator. The solution was heated to about 90 °C and 10 ml of 5 ~ w/v CaCI 2 solution added to precipitate the oxalate. The precipitate formed overnight was washed free of calcium with distilled water; and then put with about 10-15 ml hot 25 ~ H2SO 4 into a 50 ml graduated conical flask, and diluted to 20 ml with distilled water. The resultant solution was finally warmed to about 80 °C and titrated against 0.05 N KMnO 4. The calculation was made as recorded by Vogel (1961). Total nitrogen determinations were based on the Kjeldahl method (Kirk, 1950) and the ascorbic acid content was determined by the methods of Everest (1960). The methods used for the total sugars were those of Dubois et al. (1951) and the reducing sugars estimated by Somogyi-Nelson procedures (Hestrin et al., 1955). The qualitative analysis of the sugars was then carried out using the methods of Dubois et al. (1956) as modified by Faparusi (1970) whereby 0.01 ml of the sugar extract of each mushroom was spotted in triplicate on Whatman No. 1 chromatography paper and the chromatogram developed for 72 h in 1-butanol-acetic acidwater (4:1 : 1, by volume). After drying, one of the triplicate columns was cut off and the sugars on it located. The sugar spots were used to mark the regions of these spots on the duplicates, and corresponding areas removed and eluted for 3 h with 5 ml distilled water. To 2 ml of the eluate was added 0.05 ml of 80 ~ (w/v) aqueous phenol reagent followed by a rapid addition of 5 ml of concentrated H2SO 4. After the sample had stood at room temperature (25 °C) for 30 min, the optical density was determined at 480 nm, and the concentration of each sugar was calculated from the
N U T R I T I V E V A L U E OF SOME N I G E R I A N EDIBLE M U S H R O O M S
265
standard curve. All blanks were read against a blank containing distilled water in place of the sugar solution. RESULTS
Table 1 shows a typical proximate analysis of the mushroom samples. The results show that P. tuber-regium contains the highest amount of dry matter while T. clypeatus contains the least. There are few differences in the ash and crude fibre TABLE 1 PROXIMATE ANALYSIS OF SOME NIGERIAN EDIBLE MUSHROOMSa
Sample Termitomyces robustus Termitomyces clypeatus Pleurotus tuber.regium b
Dry matter
Ash
Crude fibre
Nitrogen
Crude protein
Ether extract
Total sugar
12.7
12-1
8-7
5.83
36.4
7.83
32.3
28.2
11-0
7.9
5.02
31.4
4.96
32.4
26.9
9.1
7-4
2.34
14-6
4.48
18-6
7.30 16-5
Reducing sugar
2.88
* All values e x p r e s s e d as p e r c e n t o f d r y m a t t e r . b V a l u e s r e c o r d e d w e r e t h o s e o f the pileus o n l y . TABLE 2 QUALITATIVE ANALYSIS OF SUGAR CONTENT OF SOME NIGERIAN EDIBLE MUSHROOMS
Sample Termitomyces robustus Termitomyces clypeatus Pleurotus tuber-regium*
Fructose
Galactose
Glucose
Lactose
Maltose
Sucrose
+ + -
++ ++ ++
++ ++ +
+ + -
++ ++ +
+ + -
Key: + + = high concentration; + = low concentration; - = absent. a Values r e c o r d e d w e r e t h o s e o f the pileus o n l y .
contents. The nitrogen and, consequently, the crude protein content of the two Termitomyces spp. are quite high in contrast to the low values obtained for Pleurotus. The amounts of fats and oil contained in T. clypeatus and P. tuberregium are virtually the same (4.96 % and 4.48 %, respectively) while the amount in T. robustus alone is almost equal to the total amount possessed by the other two mushroom samples. Termitomyces spp. contain high amounts of total and reducing sugars. Pleurotus sp. contains about half the sugar content of any of the Termitomyces spp., and also has a considerably lower reducing sugar content, 2.88 %. The qualitative analysis of the sugar content of mushroom samples is given in Table 2, while Table 3 shows the oxalic, hydrocyanic and ascorbic acid contents. All determinations are based on percentage of dry matter.
266
S. K. OGUNDANA, O. E. FAGADE
TABLE 3 OXALATE, HYDROCYANICAND ASCORBIC ACID CONTENTS OF SOME NIGERIAN EDIBLE MUSHROOMSa
Sample
Termitomyces robustus Termitomyces clypeatus Pleurotus tuber-regium~
Total oxalate
Hydrocyanic acid
Ascorbic acid
(%)
(mg %)
~mg %)
3.75 2.25 5.62
2-80 3.38 1-99
10.0 14.3 3.3
* All values expressed as percent of dry matter. b Values recorded were those of the pileus only.
DISCUSSION
The values recorded for P. tuber-regium were those of the pileus only. This is because P. tuber-regium has a subterranean globose sclerotium which, although also edible, is disproportionately fatter than the pileus. For instance, a whole fruiting body may weigh up to 20 g, of which the pileus may weigh just about I g. Since all attempts to work with the whole fungus by combining various proportions of the pileus and sclerotium did not yield reliable results, attention was therefore focused on the pileus (the part harvested and eaten most). In the present study, the Nigerian edible mushrooms investigated contain large amounts of water and are consequently low in dry matter content. This agrees with the results obtained by Oke (1966a) in his study of mixed mushroom samples; but the ash and cellulose contents obtained in this study are higher than those obtained for maize, sorghum and rice (Oke, 1965). The crude fibre of Pleurotus sp. expected to be highest, because of its tough texture, was lowest; and the proximate analysis of this mushroom only adds up to approximately 50 ~o of the dry matter. This is probably due to the waxy substance it contains (Zoberi, 1973). Although the protein content of Pleurotus, 14.6 %, was much lower than those of Termitomyces spp. (36'4~o and 31-4%), it is still higher than the value (13%) obtained for Hydnum imbricatum (Mlodecki et al., 1974), which was, on its own, considered to be sufficiently nutritious. In general, the protein values obtained for the mushrooms lend further support to the assertion of some workers (Fink & Hoppenhaus, 1958; Rafalski et al., 1968) that the protein contents of some mushrooms are as good as animal proteins and even surpass most vegetable proteins. The oxalic acid content has been used as an index of toxicity in vegetables since large amounts would lower the nutritive value (Oke, 1966a). It is interesting to note that the oxalate contents of the mushroom samples investigated were low. The mushroom also showed low values of hydrocyanic acid compared with those recorded for poisonous varieties, and well below the toxic dose of 60 mg for man (Nicholls, 1951).
NUTRITIVE VALUE OF SOME NIGERIAN EDIBLE MUSHROOMS
267
The various sugars present in the m u s h r o o m s (Table 2) are similar to those obtained in Agaricus campestris (Hughes et al., 1958). The high reducing sugar content in Termitomyces spp., which could provide easily absorbed nutritious food materials, p r o b a b l y accounts for the easy attack by flies leading to the development o f maggots within 2 4 h o f emergence o f the Termitomyces spp. f r o m soil. Conversely, the relatively lower total sugar and very small a m o u n t o f reducing sugar in Pleurotus sp. could therefore a c c o u n t for its not being infested by maggots. Finally, the ascorbic acid content obtained for Termitomyces spp. in the present study c o m p a r e s favourably with those o f some animal organs. For instance, Oke (1966b) found that c o o k e d beef kidney contained 15 mg 9/o; pig spleen, l I m g 9/o; while the u n c o o k e d goat lung and heart contained 9 and 10 mg 9/o,respectively. This means, therefore, that the Termitomyces spp. can serve both as a delicious food for man and as a livestock feed (Gawecki & Frelich, 1967). F r o m the results obtained in this study, the Termitomyces spp. have been shown to be nutritionally better than Pleurotus sp., and to meet b o d y requirements, possessing higher protein, c a r b o h y d r a t e , fat and vitamin C contents. This provides scientific support for the preference o f Termitomyces to Pleurotus spp. and other edible mushrooms.
ACKNOWLEDGEMENTS The authors are grateful to Professor O. L. Oke for providing laboratory facilities and to Mr John D u n k w u for his technical assistance.
REFERENCES ALASOADURA,S. O. (1966). Studies in the higher fungi of Nigeria. lI--Macrofungi associated with
termite nests, Nova Hediwigia Z. Kryptogamenkd., ll, 387-93. ALASOADURA,S. O. (1967). Studies in the higher fungi of Nigeria. I-The Genus Term itomyces Heim, J.
West Afr. Sci. Assoc., 12(2), 139-46. AOAC (1970). Official Methods of Analysis, l lth Edn, Association of Official Analytical Chemists, Washington, DC, USA. AOAC (1975). Official Methods of Analysis, 12th Edn, Association of Official Analytical Chemists, Washington, DC, USA. DUBOIS,M., GILLIES,K., HAMILTON,J. K., REBERS,P. A. & SMITH,F. (1951). Quantitative analysis of sugars by paper chromatography, Nature (London), 168, 167. DUBOlS,M., GILLIES,K., HAMILTON,J. K., REBERS,P. A. & SMITH,F. (1956). Colorimetric method for the determination of sugars and related substances, Anal. Chem., 28, 350-56. EVEREST, D. F. (1960). Determination of ascorbic acid in highly coloured solutions with Nbromosuccinimide, Analyst, 85, 515-16. FAPARUSl,S. I., (1970). Sugar changes during the preparation of Burukutu beer, J. Sci. Food Agric., 21, 79-81. F INK,H. & HOPPENHAUS,K. W. (1958). Peculiar observations in the estimation of biological quality of the proteins of edible boletus (Boletus edulis) and mushroom (Psalliota biospora) with reference to dietetics and therapeutics, Nutr. Abstr. Rev., 28, Abs. 4886. GAWECKI,K. & FRELICH,A. (1967). Mushroom meal for sheep, Nutr. Abstr. Rev., 37.
268
S. K. OGUNDANA, O. E. FAGADE
H~rmN, S., FEINGOLD,D. S. & SCHRAMN,D. (1955). Somogyi-Nelson method for reducing sugars, in Methods in Enzymology, Academic Press, New York, USA. HUGHES,D. W., LYNCH, D. L. & SOMNERS,G. F. (1958). Chromatographic identification of the amino acids and carbohydrates in the cultivated mushroom (Agaricus campestris L. ex. Fries), J. Agric. Food Chem., 6, 850-3. KIRK, P. L. (1950). Kjeldahl method for total Nitrogen, Anal. Chem., 22, 254-8. MLODECKI,H., L~SOT^,W. & M^TYS,J. (1974). Hygienic evaluation of Hydnum imbricatum. 1--Values for amino acids, minerals and fats, Nutr. Abstr. Rev., 44, Abs. 2184. NICHOLLS, L. (1951). Tropical Nutrition and Dietetics, 4th Edn, London. OKE, O. L. (1965). Chemical studies on some Nigerian cereals, Cereal Chem., 42(3), 299-302. OK£, O. L. (19660). Nutritive value of mushrooms, West Aft. Pharm., 8(3), 51-4. OKE, O. L. (1966b). Ascorbic content of some animal organs, Nutrition (London), 20(3), 110-12. Oso, B. A. (1975). Mushrooms and the Yoruba people of Nigeria, Mycologia, 67(2), 311-19. RAF^LSKI, H., MLODECKI,H., SALM,J., LASOTA,W. & SWITONIAK,T. (1968). Nutritive value of field agaric, Nutr. Abstr. Rev., 38, Abs. 4755. VOGEL,A. I. (1961). A Textbook of Quantitative Analysis including Elementary Instrumental Analysis, 3rd Edn, Longmans, London. ZonEpa, M. H. (1972). Tropical Macrofungi, Macmillian, London. ZOBI~RI, M. H. (1973). Some edible mushrooms from Nigeria, Niger. Field, 38(2), 81-90.
NUTRITIVE VALUE OF SOME NIGERIAN EDIBLE MUSHROOMS S. K. OGUblDAblA,~ O. E. FAGADE
Department of Microbiology, University of Ife, lle-lfe, Nigeria (Received: 26 January, 1981)
ABSTRACT
Samples ofTermitomyces robustus, T. clypeatus and Pleurotus tuber-regium were analysed for their nutrient and toxic substances. The Termitomyces spp. contained as much as 31% proteins and about 32% carbohydrates, of which at least 26% were reducing sugars. Pleurotus tuber-regium contained 14"6% protein and 18.6% carbohydrates, of which only about 2"9% were reducing sugars. There was little difference in their crude fibre and ash content, while the fat content of T. robustus was a little higher than those of the other samples. The ascorbic acidcontent of each of the Termitomyces spp. (lOmg % and 14.3mg %) was much higher than that of Pleurotus sp. (3.3mg %). All the mushroom samples were low in hydrocyanic acid (HCN) and oxalate contents.
INTRODUCTION
Termitomyces robustus has been described as the most delicious edible mushroom by the Yoruba people of Nigeria (Oso, 1975). It makes its appearance after heavy rains (Alasoadura, 1967), growing in large numbers in contact with termite nests in forest soils from August to October. T. clypeatus also grows in contact with termite nests but makes its appearance at the beginning of the rainy season around April, while Pleurotus tuber-regium is often found around breadfruit trees (Zoberi, 1973). In Nigeria, wild mushrooms are collected for food and, when plentiful, are frequently sold along the roadside to passers-by. Although Termitomyces and Pleurotus spp. are widely distributed in Nigeria (Alasoadura, 1967), very little work has been done on any edible mushrooms. Mycologists in Nigeria (Alasoadura, 1966; Zoberi, 1972, 1973) have only used taxonomic characters to determine edible ones. A pioneer work (Oke, 1966a) has been carried out to determine the nutritive value of mixed edible mushroom samples. The present investigations were, 263 Food Chemistry 0308-8146/82/0008-0263/$02.75 !~) Applied Science Publishers Ltd, England, 1982 Printed in Great Britain
264
s.K.
OGUNDANA, O. E. FAGADE
therefore, carried out to determine the nutritive value of the widely accepted T. robustus, T. clypeatus and P. tuber-regium.
MATERIALS AND METHODS
Raw materials T. robustus was bought from sellers along Ife-Ibadan road and T. clypeatus was collected from the University of Ife maize plantation, while P. tuber-regium was harvested from a decaying log at the University of Ife staff quarters. All specimens were oven dried and ground into fine particles before use. Determination of nutrient and toxic substances Crude fibre and ash contents were determined according to the AOAC methods of analysis (AOAC, 1970); and the crude protein, ether extract and hydrocyanic acid were also determined by the methods of the AOAC (1975). The total oxalate content was estimated using Oke's method (1966a) whereby 2 g of sample were digested with 190 ml of distilled water and filtered into a conical flask, and diluted to 250 ml. To a 50 ml portion of the extract were added 10 ml 6N HCI; the solution was then filtered and the precipitate washed with hot water. The filtrate and the wash were combined and titrated against 6N NH4OH, using methyl red indicator. The solution was heated to about 90 °C and 10 ml of 5 ~ w/v CaCI 2 solution added to precipitate the oxalate. The precipitate formed overnight was washed free of calcium with distilled water; and then put with about 10-15 ml hot 25 ~ H2SO 4 into a 50 ml graduated conical flask, and diluted to 20 ml with distilled water. The resultant solution was finally warmed to about 80 °C and titrated against 0.05 N KMnO 4. The calculation was made as recorded by Vogel (1961). Total nitrogen determinations were based on the Kjeldahl method (Kirk, 1950) and the ascorbic acid content was determined by the methods of Everest (1960). The methods used for the total sugars were those of Dubois et al. (1951) and the reducing sugars estimated by Somogyi-Nelson procedures (Hestrin et al., 1955). The qualitative analysis of the sugars was then carried out using the methods of Dubois et al. (1956) as modified by Faparusi (1970) whereby 0.01 ml of the sugar extract of each mushroom was spotted in triplicate on Whatman No. 1 chromatography paper and the chromatogram developed for 72 h in 1-butanol-acetic acidwater (4:1 : 1, by volume). After drying, one of the triplicate columns was cut off and the sugars on it located. The sugar spots were used to mark the regions of these spots on the duplicates, and corresponding areas removed and eluted for 3 h with 5 ml distilled water. To 2 ml of the eluate was added 0.05 ml of 80 ~ (w/v) aqueous phenol reagent followed by a rapid addition of 5 ml of concentrated H2SO 4. After the sample had stood at room temperature (25 °C) for 30 min, the optical density was determined at 480 nm, and the concentration of each sugar was calculated from the
N U T R I T I V E V A L U E OF SOME N I G E R I A N EDIBLE M U S H R O O M S
265
standard curve. All blanks were read against a blank containing distilled water in place of the sugar solution. RESULTS
Table 1 shows a typical proximate analysis of the mushroom samples. The results show that P. tuber-regium contains the highest amount of dry matter while T. clypeatus contains the least. There are few differences in the ash and crude fibre TABLE 1 PROXIMATE ANALYSIS OF SOME NIGERIAN EDIBLE MUSHROOMSa
Sample Termitomyces robustus Termitomyces clypeatus Pleurotus tuber.regium b
Dry matter
Ash
Crude fibre
Nitrogen
Crude protein
Ether extract
Total sugar
12.7
12-1
8-7
5.83
36.4
7.83
32.3
28.2
11-0
7.9
5.02
31.4
4.96
32.4
26.9
9.1
7-4
2.34
14-6
4.48
18-6
7.30 16-5
Reducing sugar
2.88
* All values e x p r e s s e d as p e r c e n t o f d r y m a t t e r . b V a l u e s r e c o r d e d w e r e t h o s e o f the pileus o n l y . TABLE 2 QUALITATIVE ANALYSIS OF SUGAR CONTENT OF SOME NIGERIAN EDIBLE MUSHROOMS
Sample Termitomyces robustus Termitomyces clypeatus Pleurotus tuber-regium*
Fructose
Galactose
Glucose
Lactose
Maltose
Sucrose
+ + -
++ ++ ++
++ ++ +
+ + -
++ ++ +
+ + -
Key: + + = high concentration; + = low concentration; - = absent. a Values r e c o r d e d w e r e t h o s e o f the pileus o n l y .
contents. The nitrogen and, consequently, the crude protein content of the two Termitomyces spp. are quite high in contrast to the low values obtained for Pleurotus. The amounts of fats and oil contained in T. clypeatus and P. tuberregium are virtually the same (4.96 % and 4.48 %, respectively) while the amount in T. robustus alone is almost equal to the total amount possessed by the other two mushroom samples. Termitomyces spp. contain high amounts of total and reducing sugars. Pleurotus sp. contains about half the sugar content of any of the Termitomyces spp., and also has a considerably lower reducing sugar content, 2.88 %. The qualitative analysis of the sugar content of mushroom samples is given in Table 2, while Table 3 shows the oxalic, hydrocyanic and ascorbic acid contents. All determinations are based on percentage of dry matter.
266
S. K. OGUNDANA, O. E. FAGADE
TABLE 3 OXALATE, HYDROCYANICAND ASCORBIC ACID CONTENTS OF SOME NIGERIAN EDIBLE MUSHROOMSa
Sample
Termitomyces robustus Termitomyces clypeatus Pleurotus tuber-regium~
Total oxalate
Hydrocyanic acid
Ascorbic acid
(%)
(mg %)
~mg %)
3.75 2.25 5.62
2-80 3.38 1-99
10.0 14.3 3.3
* All values expressed as percent of dry matter. b Values recorded were those of the pileus only.
DISCUSSION
The values recorded for P. tuber-regium were those of the pileus only. This is because P. tuber-regium has a subterranean globose sclerotium which, although also edible, is disproportionately fatter than the pileus. For instance, a whole fruiting body may weigh up to 20 g, of which the pileus may weigh just about I g. Since all attempts to work with the whole fungus by combining various proportions of the pileus and sclerotium did not yield reliable results, attention was therefore focused on the pileus (the part harvested and eaten most). In the present study, the Nigerian edible mushrooms investigated contain large amounts of water and are consequently low in dry matter content. This agrees with the results obtained by Oke (1966a) in his study of mixed mushroom samples; but the ash and cellulose contents obtained in this study are higher than those obtained for maize, sorghum and rice (Oke, 1965). The crude fibre of Pleurotus sp. expected to be highest, because of its tough texture, was lowest; and the proximate analysis of this mushroom only adds up to approximately 50 ~o of the dry matter. This is probably due to the waxy substance it contains (Zoberi, 1973). Although the protein content of Pleurotus, 14.6 %, was much lower than those of Termitomyces spp. (36'4~o and 31-4%), it is still higher than the value (13%) obtained for Hydnum imbricatum (Mlodecki et al., 1974), which was, on its own, considered to be sufficiently nutritious. In general, the protein values obtained for the mushrooms lend further support to the assertion of some workers (Fink & Hoppenhaus, 1958; Rafalski et al., 1968) that the protein contents of some mushrooms are as good as animal proteins and even surpass most vegetable proteins. The oxalic acid content has been used as an index of toxicity in vegetables since large amounts would lower the nutritive value (Oke, 1966a). It is interesting to note that the oxalate contents of the mushroom samples investigated were low. The mushroom also showed low values of hydrocyanic acid compared with those recorded for poisonous varieties, and well below the toxic dose of 60 mg for man (Nicholls, 1951).
NUTRITIVE VALUE OF SOME NIGERIAN EDIBLE MUSHROOMS
267
The various sugars present in the m u s h r o o m s (Table 2) are similar to those obtained in Agaricus campestris (Hughes et al., 1958). The high reducing sugar content in Termitomyces spp., which could provide easily absorbed nutritious food materials, p r o b a b l y accounts for the easy attack by flies leading to the development o f maggots within 2 4 h o f emergence o f the Termitomyces spp. f r o m soil. Conversely, the relatively lower total sugar and very small a m o u n t o f reducing sugar in Pleurotus sp. could therefore a c c o u n t for its not being infested by maggots. Finally, the ascorbic acid content obtained for Termitomyces spp. in the present study c o m p a r e s favourably with those o f some animal organs. For instance, Oke (1966b) found that c o o k e d beef kidney contained 15 mg 9/o; pig spleen, l I m g 9/o; while the u n c o o k e d goat lung and heart contained 9 and 10 mg 9/o,respectively. This means, therefore, that the Termitomyces spp. can serve both as a delicious food for man and as a livestock feed (Gawecki & Frelich, 1967). F r o m the results obtained in this study, the Termitomyces spp. have been shown to be nutritionally better than Pleurotus sp., and to meet b o d y requirements, possessing higher protein, c a r b o h y d r a t e , fat and vitamin C contents. This provides scientific support for the preference o f Termitomyces to Pleurotus spp. and other edible mushrooms.
ACKNOWLEDGEMENTS The authors are grateful to Professor O. L. Oke for providing laboratory facilities and to Mr John D u n k w u for his technical assistance.
REFERENCES ALASOADURA,S. O. (1966). Studies in the higher fungi of Nigeria. lI--Macrofungi associated with
termite nests, Nova Hediwigia Z. Kryptogamenkd., ll, 387-93. ALASOADURA,S. O. (1967). Studies in the higher fungi of Nigeria. I-The Genus Term itomyces Heim, J.
West Afr. Sci. Assoc., 12(2), 139-46. AOAC (1970). Official Methods of Analysis, l lth Edn, Association of Official Analytical Chemists, Washington, DC, USA. AOAC (1975). Official Methods of Analysis, 12th Edn, Association of Official Analytical Chemists, Washington, DC, USA. DUBOIS,M., GILLIES,K., HAMILTON,J. K., REBERS,P. A. & SMITH,F. (1951). Quantitative analysis of sugars by paper chromatography, Nature (London), 168, 167. DUBOlS,M., GILLIES,K., HAMILTON,J. K., REBERS,P. A. & SMITH,F. (1956). Colorimetric method for the determination of sugars and related substances, Anal. Chem., 28, 350-56. EVEREST, D. F. (1960). Determination of ascorbic acid in highly coloured solutions with Nbromosuccinimide, Analyst, 85, 515-16. FAPARUSl,S. I., (1970). Sugar changes during the preparation of Burukutu beer, J. Sci. Food Agric., 21, 79-81. F INK,H. & HOPPENHAUS,K. W. (1958). Peculiar observations in the estimation of biological quality of the proteins of edible boletus (Boletus edulis) and mushroom (Psalliota biospora) with reference to dietetics and therapeutics, Nutr. Abstr. Rev., 28, Abs. 4886. GAWECKI,K. & FRELICH,A. (1967). Mushroom meal for sheep, Nutr. Abstr. Rev., 37.
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S. K. OGUNDANA, O. E. FAGADE
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