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Effect of substrate and harvest on the amino acid profile of Oyster mushroom (Pleurotus ostreatus)
ARTICLE IN PRESS
JOURNAL OF FOOD COMPOSITION AND ANALYSIS
Journal of Food Composition and Analysis 18 (2005) 447–450 www.elsevier.com/locate/jfca
Short Communication
Effect of substrate and harvest on the amino acid profile of Oyster mushroom (Pleurotus ostreatus) L. Ancona Mendeza, C.A. Sandoval Castrob,*, R. Belmar Cassob, C.M. Capetillo Lealb ! ! ! Departamento de Botanica, Facultad de Medicina Veterinaria y Zootecnia - Universidad Autonoma de Yucatan, ! Yucatan, ! M!erida 97100 Mexico Apartado Postal 4-116 Itzimna, b ! Facultad de Medicina Veterinaria y Zootecnia - Universidad Autonoma ! ! Departamento de Nutricion, de Yucatan, ! Yucatan, ! M!erida 97100 Mexico Apartado Postal 4-116 Itzimna, a
Received 26 June 2003; received in revised form 4 January 2004; accepted 23 February 2004
Abstract Oyster mushrooms (Pleurotus ostreatus (Jacq.: Fr.) Kumm.) were grown in either maize or pumpkin straw. Samples were taken for each one of the three harvests and analyzed for total nitrogen (N) content and amino acids profile. The substrate had no effect (P>0.05) on N content and amino acid profile of the fruits. However, N (g/100 g dm) increased (Po0.05) from 4.13 g in the first harvest to 5.74 g in the third harvest. In general, the amino acids tended to be higher on the first harvest samples, but no changes were found (P>0.05) in the amino acid profile due to substrate or harvest, except for valine decreasing (Po0.05) from 3.96 to 3.15 g/16 g N. Changes in the N content of the fruit could be explained by changes in the stipe and pileus proportions as they had different N content (3.15 and 5.4870.031 g N/100 g dm, respectively). The amino acid profile of the mushroom was adequate according to the FAO/WHO/UNU adult human amino acid requirements. r 2004 Published by Elsevier Inc. Keywords: P. ostreatus; Amino acids; Oyster mushroom
1. Introduction The high protein content of the edible mushroom Pleurotus ostreatus (Jacq.: Fr.) Kumm. is frequently reported (Crisan and Sands, 1978; Manzi et al., 1999), together with its capacity to
*Corresponding author. Tel.: +52-999-9-42-32-00; fax: +52-999-9-42-32-05. E-mail address: [email protected] (C.A.S. Castro). 0889-1575/$ - see front matter r 2004 Published by Elsevier Inc. doi:10.1016/j.jfca.2004.02.002
ARTICLE IN PRESS 448
L.A. Mendez et al. / Journal of Food Composition and Analysis 18 (2005) 447–450
adapt to commercial cultivation in a wide variety of substrates and environmental conditions ! worldwide (Guzman et al., 1993). The mixtures employed on the growth substrate (e.g. straws, hays, cereal grains) can influence the yield and nutritive value of cultivated mushrooms (Noble and Gaze, 1994; Tshinyangu, 1996). The protein content of P. ostreatus is frequently reported (Calvo, 1994) but there are only limited reports on its amino acid profile (Ocan˜a et al., 1996; Manzi et al., 1999) and it is not known to which extent the amino acid content or profile could change in relation with substrate quality in a similar fashion as protein (Noble and Gaze, 1994; Tshinyangu, 1996). The effect of harvest stage on amino acid profile has also not been reported. This is of particular relevance as the biological value of food protein depends on its amino acid profile (Williams, 2001). Protein and especially the amino acid content and profile of foods should be balanced to meet the requirement of the consumer. In order to achieve this, data on protein and amino acid content of the mushroom and factors which might modify these values are needed if proper dietary recommendations are to be made. To our knowledge, there are no reports of amino acid profile of P. ostreatus grown on maize or pumpkin straw nor its possible changes associated with harvest stage.
2. Materials and methods A total of 12 samples were taken during each of the three first harvests of P. ostreatus (UADY13) grown in maize or pumpkin straw. Samples were dried at 60 C during 72 h, ground and kept on air tight plastic containers for further analysis. After total nitrogen (N) was determined (AOAC, 1980), sub-samples equivalent to 0.0128 g of N were taken and the amino acid profiles were determined by HPLC. The hydrolysis was carried out with HCl 6N. The resulting hydrolyzate was employed for amino acid analysis using pre-column derivatization with DABS-Cl (Knecht and Chang, 1986). In addition, 3 samples were divided into the stipe and pileus portions to assess their total N contents. All analyses were carried out in duplicate. Minitab statistical software (Minitab, 1997) was used to perform a two-way analysis of variance to assess the effects of substrate and harvest on total N and amino acid profile. Differences between means were assessed with the Tukey test.
3. Results and discussion The substrate had no effect (P>0.05) on N content, however, N increased (Po0.05) from 4.13 to 5.74 g/100 dry matter (dm) from the 1st to the 3rd harvest (Table 1). Although it was not measured, it was observed that as the harvest progressed, the mushrooms were bigger, resulting in changes in the structure of the fruiting body (less stipe and more pileus). Thus, the observed increase on N probably reflects changes in the fruit structure (stipe and pileus) as these fractions had different (Po0.05) N content (3.15 and 5.4770.032 g N /100 g dm, respectively). The change observed in N content might be reflecting chemical changes in the structure of the substrates which in turn might have facilitated nutrient uptake by the mushroom. Thus, change in the fruiting body structure might also be a result of the availability and/or easiness of nutrient uptake by the mushroom at the different harvest stages. Further research is needed in this area.
ARTICLE IN PRESS L.A. Mendez et al. / Journal of Food Composition and Analysis 18 (2005) 447–450
449
Table 1 Effect of substrate (maize straw (MS) and pumpkin straw (PS)) and harvest on total nitrogen (N) and amino acid profiles of P. ostreatus Substratea
N (g/100 g dm b) Amino acid (g/16 g N) Valine Isoleucine Leucine Phenylalanine Lysine Proline Aspartate Glutamate Serine Histidine Glycine Alanine
SEM
Harvest 1st n=12
SEM
MS n=18
PS n=18
2nd n=12
3rd n=12
5.02
4.85
0.117
4.13a
4.94b
5.74c
0.144
3.49 3.68 4.78 2.58 6.11 2.86 6.80 17.09 3.60 4.25 3.83 3.33
3.58 3.14 4.99 2.98 6.09 3.57 6.98 16.91 4.68 6.28 5.43 3.99
0.083 0.273 0.197 0.218 0.898 0.647 0.927 1.710 0.547 0.836 0.653 0.372
3.96a 3.45a 5.32a 3.15a 6.08a 4.48a 5.98a 16.22a 5.08a 7.65a 6.05a 4.65a
3.50b 3.83a 4.82a 2.40a 6.28a 2.16a 7.41a 13.25a 3.47a 3.68a 3.40a 3.11a
3.15b 2.94a 4.51a 2.79a 5.95a 3.00a 7.27a 21.52a 3.88a 4.46a 4.45a 3.22a
0.102 0.333 0.241 0.266 1.099 0.793 1.136 2.094 0.670 1.023 0.800 0.455
Values in the same line with different literal differ at Po0.05. a No effect of substrate was found then literals are not provided. b dm: Dry matter.
The amino acid profile of the fruits was not affected by the substrate (Table 1). However, although the amino acids contents tended to be higher in first harvest samples, no changes were found (P>0.05) in the amino acid profile due to substrate or harvest, except for valine decreasing (Po0.05) from 3.96 to 3.15 g/16 g N. The quality of the substrate employed in the present study had no effect on amino acid profile (P>0.05). The amino acid profiles found are similar to previous literature reports although higher values where found for aspartate, glutamate and lysine (Crisan and Sands, 1978; Manzi et al., 1999). The differences found could be attributed to the genetic variability associated with the selection process applied in commercial mushrooms species as P. ostreatus (Manzi et al., 1999; Tshinyangu, 1996). Nevertheless, the similarity in all the amino acid profiles reported in the literature suggests that although N (protein) content might be affected by substrate, the quality itself of this protein, the amino acid profile, is not affected. Protein synthesis is encoded in the DNA and this fraction might remain largely similar within the specie despite the selection process in commercial varieties. To our knowledge, currently there is no commercial pleurotus selection focused on protein quality. However, further studies must be performed before final conclusions are drawn. The amino acid profile of the mushroom was adequate according to the FAO/WHO/UNU (1985) adult human amino acid requirements. When the revised requirements proposed by Young and El-Khoury (1996) (higher than those previously stated by FAO/WHO/UNU) are use as standard, lysine, leucine and phenylalanine are slightly lower than the requirements, thus, these amino acids can be considered as potentially limiting in agreement with the report of Manzi et al. (1999). However, it should be pointed out that mushroom protein will only be a limiting
ARTICLE IN PRESS 450
L.A. Mendez et al. / Journal of Food Composition and Analysis 18 (2005) 447–450
nutritional factor when used as the sole dietary protein source. Thus, under normal dietary conditions, the amino acid profile found confirms the high biological value of P. ostreatus protein. 4. Conclusion There are no changes in the amino acid profile of P. ostreatus grown in maize or pumpkin straw during the first three harvests. The N content of the mushroom is affected by the stipe and pileus proportions. References AOAC, 1980. Official Methods of Analysis of the Association of Official Analytical Chemists, 13th Edition. AOAC, Washington, USA. ! ! de hongos Calvo, L., 1994. Valor nutritivo y toxicologico de los hongos. In: S!anchez V!azquez (Ed.), Produccion ! comestibles. Centro de Investigaciones Ecologicas del Sureste, Mexico, pp. 31–36. Crisan, E., Sands, A., 1978. Nutritional value. In: Chang, S.T., Hayes, W.A. (Eds.), The Biology and Cultivation of Edible Mushrooms. Academic Press, London, pp. 137–168. FAO/WHO/UNU, 1985. Energy and protein requirements. Report of a Joint FAO/WHO/UNU expert consultation. Technical Report Series No. 724. World Health Organization, Geneva. ! Guzman, G., Mata, G., Salmones, D., Soto-Velazco, C., Guzm!an-D!avalos, L., 1993. El cultivo de los hongos ! a especies tropicales y subtropicales en esquilmos y residuos agroindustriales. comestibles, con especial atencion Instituto Polit!ecnico Nacional, M!exico. Knecht, R., Chang, J., 1986. Liquid chromatographic determination of amino acids after gas-phase hydrolysis and derivatization with (dimethylamino)azobenensulfonyl chloride. Analytical Chemistry 58, 2375–2379. Manzi, P., Gambelli, L., Marconi, S., Vivanti, V., Pizzoferrato, L., 1999. Nutrients in edible mushrooms: an interspecies comparative study. Food Chemistry 65, 477–482. Minitab Release 12, 1997. Minitab Reference Manual. Minitab, State college, Philadelphia. Noble, R., Gaze, R.H., 1994. Controlled environment composting for mushroom cultivation: substrates based on wheat and barley straw and deep litter poultry manure. Journal of Agricultural Science 123, 71–79. ! y Ocan˜a, R., Mart!ınez, G., Duarte, M., Serwatowski, R., Paredes, O., 1996. Tecnolog!ıa para la produccion ! de setas (pleurotus ostreatus). Acta Universitaria. Universidad de Guanajuato 6 (1), 52–63. conservacion Tshinyangu, K.K., 1996. Effect of grass hay substrate on nutritional value of pleurotus ostreatus var. colombinus. Die Nahrung 40, 79–83. Williams, S.R., 2001. Basic Nutrition and Diet Therapy, 11th Edition. Mosby, St. Louis. Young, V.R., El-Khoury, A.E., 1996. Human amino acid requirements: a re-evaluation. Retrieved June 06, 2003 from the World Wide Web: Food and Nutrition Bulletin 17(3), http://www.unu.edu/unupress/food/8f173e/ 8F173E03.htm.
JOURNAL OF FOOD COMPOSITION AND ANALYSIS
Journal of Food Composition and Analysis 18 (2005) 447–450 www.elsevier.com/locate/jfca
Short Communication
Effect of substrate and harvest on the amino acid profile of Oyster mushroom (Pleurotus ostreatus) L. Ancona Mendeza, C.A. Sandoval Castrob,*, R. Belmar Cassob, C.M. Capetillo Lealb ! ! ! Departamento de Botanica, Facultad de Medicina Veterinaria y Zootecnia - Universidad Autonoma de Yucatan, ! Yucatan, ! M!erida 97100 Mexico Apartado Postal 4-116 Itzimna, b ! Facultad de Medicina Veterinaria y Zootecnia - Universidad Autonoma ! ! Departamento de Nutricion, de Yucatan, ! Yucatan, ! M!erida 97100 Mexico Apartado Postal 4-116 Itzimna, a
Received 26 June 2003; received in revised form 4 January 2004; accepted 23 February 2004
Abstract Oyster mushrooms (Pleurotus ostreatus (Jacq.: Fr.) Kumm.) were grown in either maize or pumpkin straw. Samples were taken for each one of the three harvests and analyzed for total nitrogen (N) content and amino acids profile. The substrate had no effect (P>0.05) on N content and amino acid profile of the fruits. However, N (g/100 g dm) increased (Po0.05) from 4.13 g in the first harvest to 5.74 g in the third harvest. In general, the amino acids tended to be higher on the first harvest samples, but no changes were found (P>0.05) in the amino acid profile due to substrate or harvest, except for valine decreasing (Po0.05) from 3.96 to 3.15 g/16 g N. Changes in the N content of the fruit could be explained by changes in the stipe and pileus proportions as they had different N content (3.15 and 5.4870.031 g N/100 g dm, respectively). The amino acid profile of the mushroom was adequate according to the FAO/WHO/UNU adult human amino acid requirements. r 2004 Published by Elsevier Inc. Keywords: P. ostreatus; Amino acids; Oyster mushroom
1. Introduction The high protein content of the edible mushroom Pleurotus ostreatus (Jacq.: Fr.) Kumm. is frequently reported (Crisan and Sands, 1978; Manzi et al., 1999), together with its capacity to
*Corresponding author. Tel.: +52-999-9-42-32-00; fax: +52-999-9-42-32-05. E-mail address: [email protected] (C.A.S. Castro). 0889-1575/$ - see front matter r 2004 Published by Elsevier Inc. doi:10.1016/j.jfca.2004.02.002
ARTICLE IN PRESS 448
L.A. Mendez et al. / Journal of Food Composition and Analysis 18 (2005) 447–450
adapt to commercial cultivation in a wide variety of substrates and environmental conditions ! worldwide (Guzman et al., 1993). The mixtures employed on the growth substrate (e.g. straws, hays, cereal grains) can influence the yield and nutritive value of cultivated mushrooms (Noble and Gaze, 1994; Tshinyangu, 1996). The protein content of P. ostreatus is frequently reported (Calvo, 1994) but there are only limited reports on its amino acid profile (Ocan˜a et al., 1996; Manzi et al., 1999) and it is not known to which extent the amino acid content or profile could change in relation with substrate quality in a similar fashion as protein (Noble and Gaze, 1994; Tshinyangu, 1996). The effect of harvest stage on amino acid profile has also not been reported. This is of particular relevance as the biological value of food protein depends on its amino acid profile (Williams, 2001). Protein and especially the amino acid content and profile of foods should be balanced to meet the requirement of the consumer. In order to achieve this, data on protein and amino acid content of the mushroom and factors which might modify these values are needed if proper dietary recommendations are to be made. To our knowledge, there are no reports of amino acid profile of P. ostreatus grown on maize or pumpkin straw nor its possible changes associated with harvest stage.
2. Materials and methods A total of 12 samples were taken during each of the three first harvests of P. ostreatus (UADY13) grown in maize or pumpkin straw. Samples were dried at 60 C during 72 h, ground and kept on air tight plastic containers for further analysis. After total nitrogen (N) was determined (AOAC, 1980), sub-samples equivalent to 0.0128 g of N were taken and the amino acid profiles were determined by HPLC. The hydrolysis was carried out with HCl 6N. The resulting hydrolyzate was employed for amino acid analysis using pre-column derivatization with DABS-Cl (Knecht and Chang, 1986). In addition, 3 samples were divided into the stipe and pileus portions to assess their total N contents. All analyses were carried out in duplicate. Minitab statistical software (Minitab, 1997) was used to perform a two-way analysis of variance to assess the effects of substrate and harvest on total N and amino acid profile. Differences between means were assessed with the Tukey test.
3. Results and discussion The substrate had no effect (P>0.05) on N content, however, N increased (Po0.05) from 4.13 to 5.74 g/100 dry matter (dm) from the 1st to the 3rd harvest (Table 1). Although it was not measured, it was observed that as the harvest progressed, the mushrooms were bigger, resulting in changes in the structure of the fruiting body (less stipe and more pileus). Thus, the observed increase on N probably reflects changes in the fruit structure (stipe and pileus) as these fractions had different (Po0.05) N content (3.15 and 5.4770.032 g N /100 g dm, respectively). The change observed in N content might be reflecting chemical changes in the structure of the substrates which in turn might have facilitated nutrient uptake by the mushroom. Thus, change in the fruiting body structure might also be a result of the availability and/or easiness of nutrient uptake by the mushroom at the different harvest stages. Further research is needed in this area.
ARTICLE IN PRESS L.A. Mendez et al. / Journal of Food Composition and Analysis 18 (2005) 447–450
449
Table 1 Effect of substrate (maize straw (MS) and pumpkin straw (PS)) and harvest on total nitrogen (N) and amino acid profiles of P. ostreatus Substratea
N (g/100 g dm b) Amino acid (g/16 g N) Valine Isoleucine Leucine Phenylalanine Lysine Proline Aspartate Glutamate Serine Histidine Glycine Alanine
SEM
Harvest 1st n=12
SEM
MS n=18
PS n=18
2nd n=12
3rd n=12
5.02
4.85
0.117
4.13a
4.94b
5.74c
0.144
3.49 3.68 4.78 2.58 6.11 2.86 6.80 17.09 3.60 4.25 3.83 3.33
3.58 3.14 4.99 2.98 6.09 3.57 6.98 16.91 4.68 6.28 5.43 3.99
0.083 0.273 0.197 0.218 0.898 0.647 0.927 1.710 0.547 0.836 0.653 0.372
3.96a 3.45a 5.32a 3.15a 6.08a 4.48a 5.98a 16.22a 5.08a 7.65a 6.05a 4.65a
3.50b 3.83a 4.82a 2.40a 6.28a 2.16a 7.41a 13.25a 3.47a 3.68a 3.40a 3.11a
3.15b 2.94a 4.51a 2.79a 5.95a 3.00a 7.27a 21.52a 3.88a 4.46a 4.45a 3.22a
0.102 0.333 0.241 0.266 1.099 0.793 1.136 2.094 0.670 1.023 0.800 0.455
Values in the same line with different literal differ at Po0.05. a No effect of substrate was found then literals are not provided. b dm: Dry matter.
The amino acid profile of the fruits was not affected by the substrate (Table 1). However, although the amino acids contents tended to be higher in first harvest samples, no changes were found (P>0.05) in the amino acid profile due to substrate or harvest, except for valine decreasing (Po0.05) from 3.96 to 3.15 g/16 g N. The quality of the substrate employed in the present study had no effect on amino acid profile (P>0.05). The amino acid profiles found are similar to previous literature reports although higher values where found for aspartate, glutamate and lysine (Crisan and Sands, 1978; Manzi et al., 1999). The differences found could be attributed to the genetic variability associated with the selection process applied in commercial mushrooms species as P. ostreatus (Manzi et al., 1999; Tshinyangu, 1996). Nevertheless, the similarity in all the amino acid profiles reported in the literature suggests that although N (protein) content might be affected by substrate, the quality itself of this protein, the amino acid profile, is not affected. Protein synthesis is encoded in the DNA and this fraction might remain largely similar within the specie despite the selection process in commercial varieties. To our knowledge, currently there is no commercial pleurotus selection focused on protein quality. However, further studies must be performed before final conclusions are drawn. The amino acid profile of the mushroom was adequate according to the FAO/WHO/UNU (1985) adult human amino acid requirements. When the revised requirements proposed by Young and El-Khoury (1996) (higher than those previously stated by FAO/WHO/UNU) are use as standard, lysine, leucine and phenylalanine are slightly lower than the requirements, thus, these amino acids can be considered as potentially limiting in agreement with the report of Manzi et al. (1999). However, it should be pointed out that mushroom protein will only be a limiting
ARTICLE IN PRESS 450
L.A. Mendez et al. / Journal of Food Composition and Analysis 18 (2005) 447–450
nutritional factor when used as the sole dietary protein source. Thus, under normal dietary conditions, the amino acid profile found confirms the high biological value of P. ostreatus protein. 4. Conclusion There are no changes in the amino acid profile of P. ostreatus grown in maize or pumpkin straw during the first three harvests. The N content of the mushroom is affected by the stipe and pileus proportions. References AOAC, 1980. Official Methods of Analysis of the Association of Official Analytical Chemists, 13th Edition. AOAC, Washington, USA. ! ! de hongos Calvo, L., 1994. Valor nutritivo y toxicologico de los hongos. In: S!anchez V!azquez (Ed.), Produccion ! comestibles. Centro de Investigaciones Ecologicas del Sureste, Mexico, pp. 31–36. Crisan, E., Sands, A., 1978. Nutritional value. In: Chang, S.T., Hayes, W.A. (Eds.), The Biology and Cultivation of Edible Mushrooms. Academic Press, London, pp. 137–168. FAO/WHO/UNU, 1985. Energy and protein requirements. Report of a Joint FAO/WHO/UNU expert consultation. Technical Report Series No. 724. World Health Organization, Geneva. ! Guzman, G., Mata, G., Salmones, D., Soto-Velazco, C., Guzm!an-D!avalos, L., 1993. El cultivo de los hongos ! a especies tropicales y subtropicales en esquilmos y residuos agroindustriales. comestibles, con especial atencion Instituto Polit!ecnico Nacional, M!exico. Knecht, R., Chang, J., 1986. Liquid chromatographic determination of amino acids after gas-phase hydrolysis and derivatization with (dimethylamino)azobenensulfonyl chloride. Analytical Chemistry 58, 2375–2379. Manzi, P., Gambelli, L., Marconi, S., Vivanti, V., Pizzoferrato, L., 1999. Nutrients in edible mushrooms: an interspecies comparative study. Food Chemistry 65, 477–482. Minitab Release 12, 1997. Minitab Reference Manual. Minitab, State college, Philadelphia. Noble, R., Gaze, R.H., 1994. Controlled environment composting for mushroom cultivation: substrates based on wheat and barley straw and deep litter poultry manure. Journal of Agricultural Science 123, 71–79. ! y Ocan˜a, R., Mart!ınez, G., Duarte, M., Serwatowski, R., Paredes, O., 1996. Tecnolog!ıa para la produccion ! de setas (pleurotus ostreatus). Acta Universitaria. Universidad de Guanajuato 6 (1), 52–63. conservacion Tshinyangu, K.K., 1996. Effect of grass hay substrate on nutritional value of pleurotus ostreatus var. colombinus. Die Nahrung 40, 79–83. Williams, S.R., 2001. Basic Nutrition and Diet Therapy, 11th Edition. Mosby, St. Louis. Young, V.R., El-Khoury, A.E., 1996. Human amino acid requirements: a re-evaluation. Retrieved June 06, 2003 from the World Wide Web: Food and Nutrition Bulletin 17(3), http://www.unu.edu/unupress/food/8f173e/ 8F173E03.htm.