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Yield and quality of leaf protein concentrates from Monochoria hastata (L.) Solms
Aquatic Botany, 40 ( 1991 ) 2 9 5 - 2 9 9
295
Elsevier Science Publishers B.V., Amsterdam
Short Communication Yield and quality of leaf protein concentrates from Monochoria hastata (L.) Solms V.N. Pandey and A.K. Srivastava Experimental Botany Laboratory, Department of Botany, University of Gorakhpur, Gorakhpur-273009, India (Accepted for publication 7 January 1991 )
ABSTRACT
Pandey, V.N. and Srivastava, A.K., 1991. Yield and quality of leaf protein concentrates from Monochoria hastata (L.) Solms. Aquat. Bot., 40: 295-299. The yield and composition of leaf biomass and leaf protein concentrate (LPC) were determined for Monochoria hastata (L.) Solms, a semi-aquatic weed. The fresh biomass yield was 38-39 tons ha- l which yielded a total of 1700 kg ha- ~ crude protein in three cuts. The various fractions of LPC showed a protein content ranging from 47.4 to 89.4% of dry matter and digestibility ranging from 40.2 to 85.4% of protein. The amino acid content of LPC was found to be nutritionally adequate, except for the sulphur-containing amino acids. The results suggest this plant has promising potential for LPC production.
INTRODUCTION
Monochoria hastata (L.) Solms (Pontederiaceae) is a semi-aquatic weed which grows profusely during the whole year in North Eastern India. It is a robust, fast-growing perennial herb commonly found in ponds, lakes and moist reservoirs (Srivastava, 1976). Its removal, like that of other water weeds, involves time and costs. It has been suggested that the utilization of water weeds is more advantageous than their destruction (Mitchell, 1974). Aquatic plants have a good potential for use as additional sources of food/feed (Bates and Hantages, 1976; Little, 1978). The promising potential of aquatic vegetation as a raw material for leaf protein concentrate (LPC) extraction, has been reported by many earlier workers (Boyd, 1968; Matai, 1976; Banerjee et al., 1985; Pandey and Srivastava, 1989). LPC obtained from aquatic vegetation are reported to have high nutritive value and potential for use as food/ feed supplements (Pirie, 1978, 1985 ). Therefore, the yield and in vitro nutritive value of LPC from M. hastata has been investigated and is reported here. 0304-3770/91/$03.50
© 1991 - - Elsevier Science Publishers B.V.
296
V.N. PANDEY AND A.K. SRIVASTAVA
MATERIALS AND METHODS
Fresh shoots of M. hastata were collected randomly from 10 plots ( 1 m 2 each) from dense stands growing naturally in waterlogged sites near Gorakhpur (latitude 26 ° 5' -27 ° 29' N and longitude 83 ° 4' -84 ° 26' E ). The first harvest was made in September 1986. The plants were allowed to continue to grow and the regrowth was harvested after 45 days. The fresh and dry biomass yields were recorded for each cut after washing the samples. Dry weights were determined by heating the samples to 80°C for less than 48 h, to constant weight. For extracting the LPC, 200 g fresh leaf sample were homogenized with 600 ml water in a Waring blender. The homogenate was filtered through muslin cloth to obtain the leaf extract. The unfractionated whole LPC was coagulated by heating the leaf extract to 80°C for 20 min. The chloroplastic and cytoplasmic fractions of LPC were obtained by differential heating. The leaf extract was first heated to 60 °C for 10 min to coagulate the chloroplastic fraction. After separation, the fluid was heated to 80°C to coagulate the cytoplasmic protein. The coagulated proteins were separated by centrifugation at 6000 r.p.m., followed by heating to 100 °C to make the protein more compact (Henry and Ford, 1965; Bickoff and Kohler, 1974 ). The nitrogen (N) contents of dried leaf samples/LPC were determined by the micro-method of Doneen (1932). The protein content was calculated by multiplying the N content by 6.25. The crude fibre content of LPC was estimated according to the methods of the Association of Official Analytical Chemists (1975). The ash content was estimated by heating the samples to 540°C for 4 h in a muffle furnace. Percent extractabilities of LPC, total N and protein N were calculated as follows % extractability of LPC dry weight of LPC = dry matter in the leaf samples used for the extraction of LPC × 100 % extractability of total N % total N in LPC - % total N in leaf dry matter x % LPC extracted % extractability of protein N % protein N in LPC - % total N in leaf dry matter × % LPC extracted The in vitro digestibility of protein in LPC was assayed with pepsin followed by trypsin, according to Saunders et al. (1973), and the results are expressed as the percent protein in LPC digested on a dry weight basis.
LEAFPROTEINCONCENTRATESFROM MONOCHORIA HASTATA
297
For the determination of amino acid composition, 25 mg of defatted LPC were hydrolysed with 6 N HC1 in a sealed tube for 24 h at 110 ° C. After hydrolysis, HC1 was removed in vacuo and the residue was processed and analysed in an amino acid analyser (LKB-4101 ). All the analyses were replicated three times and the averages of the results are recorded in Tables 1, 2 and 3. RESULTS A N D D I S C U S S I O N
The leaves ofM. hastata are thick and soft, yet contain little mucilage, and thus are suitable for LPC extraction (Pirie, 1978 ). The data in Table 1 show that the above-ground green shoots of M. hastata have a high content and good extractability of protein, coupled with a low fibre content, compared with forage plants which are usually employed for LPC extraction (Morrison, 1961 ). Bailey (1965) also reported low fibre and high protein content in aquatic plants. The LPC yield in the three harvests is comparable with that of other plants used for this purpose (Boyd, 1968; Banerjee et al., 1985 ). Among different fractions ofM. hastata LPC, the cytoplasmic protein fraction had the highest content and digestibility of protein, followed by those in the unfractionated LPC and in the chloroplastic fraction, respectively (Table 2). These values are comparable with other LPC prepared from different plants (Pirie, 1978 ). The digestibility values of LPC samples indicate their promising potential for food or feed use (Pirie, 1978, 1985 ). The ash content in the plants and in LPC samples was, however, higher than the values recommended for human consumption (Humphries, 1978). TABLEI Composition and yield ofM. hastata
Fresh biomass yield (kgha -j ) Dry biomass yield (kgha - l ) Dry LPC yield (kgha -~ ) LPC extractability ( % of initial dry matter) Protein N extractability (% of initial protein N) Crude protein in plants (% dry weight ) Ash content in plants (% dry weight)
First cut
First regrowth cut
Second regrowth cut
39850.0
38950.0
39350.0
3805.4
3817.1
3856.2
936.1
908.5
871.5
24.5
23.8
22.6
62.6
57.6
60.5
39.5
39.3
39.6
7.3
6.7
6.9
298
V.N. PANDEY AND A.K. SR1VASTAVA
TABLE 2
Composition and digestibility o f L P C (% dry weight) Protein
Lipids
Crude
Ash
In vitro
digestibility o f protein
fibre
in L P C U nfractionated LPC
71.93
4.34
1.50
8.34
61.70
Chloroplastic
47.37
3.23
1.32
8.44
40.21
89.39
2.89
1.12
3.73
85.43
LPC
Cytoplasmic LPC
TABLE 3 A m i n o acid c o m p o s i t i o n o f u n f r a c t i o n a t e d L P C o f M . hastata A m i n o acid
g per 16 g N
F.A.O.'s adult a m i n o acid requirement
pattern Aspartic acid Threonine* Serine G l u t a m i c acid Proline Glycine Valine* M e t h i o n i n e * + cystine Isoleucine* Leucine*
Phenylalanine* + tyrosine Histidine** Lysine* Arginine**
6.73 3.17 3.71 7.90 3.39 4.12 4.78 2.20 3.21 5.92 7.99 3.60 4.19 4.41
4.0 5.0 3.5 4.0 7.0 6.0 5.5
F.A.O. = Food a n d Agricultural O r g a n i z a t i o n ( 1973 ). *Essential a m i n o acids. **Not essential for m a n .
The amino acid composition of unfractionated LPC (Table 3 ) shows that the LPC contained all the essential amino acids in varying concentrations. The lysine content of the samples was adequate from a nutritional viewpoint. Methionine and cystine contents were, however, appreciably lower, probably because some of the sulphur-containing amino acids were partially or wholly destroyed during hydrolysis prior to amino acid analysis (Byers, 1983 ). M. hastata appears to be a promising plant for LPC extraction owing to its large stands, high biomass productivity, good regrowth capacity, low fibre
LEAFPROTEINCONCENTRATESFROMMONOCHORIAHASTATA
299
content of plants and LPC, high protein content, high digestibility and favourable amino acid composition of LPC. The non-toxic nature ofM. hastata is indicated by its regular grazing by cattle. However, in vivo evaluation of the nutritive value and toxicity, if any, is essential before it can be recommended for food and feed use.
REFERENCES Association of Official Analytical Chemists, 1975. Official Methods of Analysis. A.O.A.C., Washington, DC, 1018 pp. Bailey, T.A., 1965. Commercial possibilities of dehydrated aquatic plants. Proc. Southern Weed Conf., 18: 543-551. Banerjee, A., Bagchi, D.K. and Matai, S., 1985. Allmania nodiflora R. Br. (Amaranthaceae), a promising source of leaf protein. Aquat. Bot., 22: 393-396. Bates, R.P. and Hentages, J.F., 1976. Aquatic weeds - - eradicate or cultivate. Econ. Bot., 30: 39-50. Bickoff, E.M. and Kohler, G.O., 1974. Preparation of edible protein of leafy green crops such as alfalfa. U.S. Patent 3,823,128, July 9. Boyd, C.E., 1968. Freshwater plants: a potential source of protein. Econ. Bot., 22: 259-368. Byers, M., 1983. Extracted leaf proteins: their amino acid composition and nutritional quality. In: L. Telek and H.D. Graham (Editors), Leaf Protein Concentrates. AVI, Westport, CT, p. 135. Doneen, L.D., 1932. A micro method for nitrogen estimation in plant material. Plant Physiol., 7: 717-719. Food and Agricultural Organization, 1973. Energy and Protein Requirements. Tech. Rep. Ser., 522, FAO, Rome. Henry, K.M. and Ford, J.E., 1965. The nutritive value of leaf protein concentrates determined in biological tests with rats and by microbiological methods. J. Sci. Food Agric., 16: 425. Humphries, C., 1978. The use of leaf protein in human foods. Plant Foods Manuf., 2:167-180. Little, E.C.S. (Editor), 1968. Handbook of Utilization of Aquatic Plants. F.A.O., Rome, p. 121. Matai, S., 1976. Protein from water weeds. In: C.K. Varshney and Y. Rzoska (Editors), Aquatic Weeds in South East Asia. Proceedings of a Regional Seminar on Noxious Aquatic Vegetation, The Hague, 1973, pp. 369-373. Mitchell, D.S. (Editor), 1974. Aquatic Vegetation and its Use and Control. UNESCO, Paris. Morrison, J.P., 1961. Feeds and Feeding Abridged. Morrison Clinton, IA, pp. 1-696. Pandey, V.N. and Srivastava, A.K., 1989. Veronica anagallis-aquatica L. a potential source of leaf protein. Aquat. Bot., 34: 385-388. Pirie, N.W., 1978. Leaf Protein and other Aspects of Fodder Fractionation, Cambridge University Press, London, pp. 1-183. Pirie, N.W., 1985. Leaf protein in human diets. In: I. Tasaki (Editor), Recent Advances in Leaf Protein Research. Faculty of Agriculture, Nagoya University Farm, Nagoya, Japan, pp. 6366. Saunders, R.M., Connor, M.A., Booth, A.N., Bickoff, E.M. and Kohler, G.O., 1973. Measurement of digestibility of alfalfa protein concentrates by in vivo and in vitro methods. J. Nutr., 103: 530-535. Srivastava, T.N., 1976. Flora Gorakhpurensis. Today and Tomorrow's, New Delhi, 320 pp.
295
Elsevier Science Publishers B.V., Amsterdam
Short Communication Yield and quality of leaf protein concentrates from Monochoria hastata (L.) Solms V.N. Pandey and A.K. Srivastava Experimental Botany Laboratory, Department of Botany, University of Gorakhpur, Gorakhpur-273009, India (Accepted for publication 7 January 1991 )
ABSTRACT
Pandey, V.N. and Srivastava, A.K., 1991. Yield and quality of leaf protein concentrates from Monochoria hastata (L.) Solms. Aquat. Bot., 40: 295-299. The yield and composition of leaf biomass and leaf protein concentrate (LPC) were determined for Monochoria hastata (L.) Solms, a semi-aquatic weed. The fresh biomass yield was 38-39 tons ha- l which yielded a total of 1700 kg ha- ~ crude protein in three cuts. The various fractions of LPC showed a protein content ranging from 47.4 to 89.4% of dry matter and digestibility ranging from 40.2 to 85.4% of protein. The amino acid content of LPC was found to be nutritionally adequate, except for the sulphur-containing amino acids. The results suggest this plant has promising potential for LPC production.
INTRODUCTION
Monochoria hastata (L.) Solms (Pontederiaceae) is a semi-aquatic weed which grows profusely during the whole year in North Eastern India. It is a robust, fast-growing perennial herb commonly found in ponds, lakes and moist reservoirs (Srivastava, 1976). Its removal, like that of other water weeds, involves time and costs. It has been suggested that the utilization of water weeds is more advantageous than their destruction (Mitchell, 1974). Aquatic plants have a good potential for use as additional sources of food/feed (Bates and Hantages, 1976; Little, 1978). The promising potential of aquatic vegetation as a raw material for leaf protein concentrate (LPC) extraction, has been reported by many earlier workers (Boyd, 1968; Matai, 1976; Banerjee et al., 1985; Pandey and Srivastava, 1989). LPC obtained from aquatic vegetation are reported to have high nutritive value and potential for use as food/ feed supplements (Pirie, 1978, 1985 ). Therefore, the yield and in vitro nutritive value of LPC from M. hastata has been investigated and is reported here. 0304-3770/91/$03.50
© 1991 - - Elsevier Science Publishers B.V.
296
V.N. PANDEY AND A.K. SRIVASTAVA
MATERIALS AND METHODS
Fresh shoots of M. hastata were collected randomly from 10 plots ( 1 m 2 each) from dense stands growing naturally in waterlogged sites near Gorakhpur (latitude 26 ° 5' -27 ° 29' N and longitude 83 ° 4' -84 ° 26' E ). The first harvest was made in September 1986. The plants were allowed to continue to grow and the regrowth was harvested after 45 days. The fresh and dry biomass yields were recorded for each cut after washing the samples. Dry weights were determined by heating the samples to 80°C for less than 48 h, to constant weight. For extracting the LPC, 200 g fresh leaf sample were homogenized with 600 ml water in a Waring blender. The homogenate was filtered through muslin cloth to obtain the leaf extract. The unfractionated whole LPC was coagulated by heating the leaf extract to 80°C for 20 min. The chloroplastic and cytoplasmic fractions of LPC were obtained by differential heating. The leaf extract was first heated to 60 °C for 10 min to coagulate the chloroplastic fraction. After separation, the fluid was heated to 80°C to coagulate the cytoplasmic protein. The coagulated proteins were separated by centrifugation at 6000 r.p.m., followed by heating to 100 °C to make the protein more compact (Henry and Ford, 1965; Bickoff and Kohler, 1974 ). The nitrogen (N) contents of dried leaf samples/LPC were determined by the micro-method of Doneen (1932). The protein content was calculated by multiplying the N content by 6.25. The crude fibre content of LPC was estimated according to the methods of the Association of Official Analytical Chemists (1975). The ash content was estimated by heating the samples to 540°C for 4 h in a muffle furnace. Percent extractabilities of LPC, total N and protein N were calculated as follows % extractability of LPC dry weight of LPC = dry matter in the leaf samples used for the extraction of LPC × 100 % extractability of total N % total N in LPC - % total N in leaf dry matter x % LPC extracted % extractability of protein N % protein N in LPC - % total N in leaf dry matter × % LPC extracted The in vitro digestibility of protein in LPC was assayed with pepsin followed by trypsin, according to Saunders et al. (1973), and the results are expressed as the percent protein in LPC digested on a dry weight basis.
LEAFPROTEINCONCENTRATESFROM MONOCHORIA HASTATA
297
For the determination of amino acid composition, 25 mg of defatted LPC were hydrolysed with 6 N HC1 in a sealed tube for 24 h at 110 ° C. After hydrolysis, HC1 was removed in vacuo and the residue was processed and analysed in an amino acid analyser (LKB-4101 ). All the analyses were replicated three times and the averages of the results are recorded in Tables 1, 2 and 3. RESULTS A N D D I S C U S S I O N
The leaves ofM. hastata are thick and soft, yet contain little mucilage, and thus are suitable for LPC extraction (Pirie, 1978 ). The data in Table 1 show that the above-ground green shoots of M. hastata have a high content and good extractability of protein, coupled with a low fibre content, compared with forage plants which are usually employed for LPC extraction (Morrison, 1961 ). Bailey (1965) also reported low fibre and high protein content in aquatic plants. The LPC yield in the three harvests is comparable with that of other plants used for this purpose (Boyd, 1968; Banerjee et al., 1985 ). Among different fractions ofM. hastata LPC, the cytoplasmic protein fraction had the highest content and digestibility of protein, followed by those in the unfractionated LPC and in the chloroplastic fraction, respectively (Table 2). These values are comparable with other LPC prepared from different plants (Pirie, 1978 ). The digestibility values of LPC samples indicate their promising potential for food or feed use (Pirie, 1978, 1985 ). The ash content in the plants and in LPC samples was, however, higher than the values recommended for human consumption (Humphries, 1978). TABLEI Composition and yield ofM. hastata
Fresh biomass yield (kgha -j ) Dry biomass yield (kgha - l ) Dry LPC yield (kgha -~ ) LPC extractability ( % of initial dry matter) Protein N extractability (% of initial protein N) Crude protein in plants (% dry weight ) Ash content in plants (% dry weight)
First cut
First regrowth cut
Second regrowth cut
39850.0
38950.0
39350.0
3805.4
3817.1
3856.2
936.1
908.5
871.5
24.5
23.8
22.6
62.6
57.6
60.5
39.5
39.3
39.6
7.3
6.7
6.9
298
V.N. PANDEY AND A.K. SR1VASTAVA
TABLE 2
Composition and digestibility o f L P C (% dry weight) Protein
Lipids
Crude
Ash
In vitro
digestibility o f protein
fibre
in L P C U nfractionated LPC
71.93
4.34
1.50
8.34
61.70
Chloroplastic
47.37
3.23
1.32
8.44
40.21
89.39
2.89
1.12
3.73
85.43
LPC
Cytoplasmic LPC
TABLE 3 A m i n o acid c o m p o s i t i o n o f u n f r a c t i o n a t e d L P C o f M . hastata A m i n o acid
g per 16 g N
F.A.O.'s adult a m i n o acid requirement
pattern Aspartic acid Threonine* Serine G l u t a m i c acid Proline Glycine Valine* M e t h i o n i n e * + cystine Isoleucine* Leucine*
Phenylalanine* + tyrosine Histidine** Lysine* Arginine**
6.73 3.17 3.71 7.90 3.39 4.12 4.78 2.20 3.21 5.92 7.99 3.60 4.19 4.41
4.0 5.0 3.5 4.0 7.0 6.0 5.5
F.A.O. = Food a n d Agricultural O r g a n i z a t i o n ( 1973 ). *Essential a m i n o acids. **Not essential for m a n .
The amino acid composition of unfractionated LPC (Table 3 ) shows that the LPC contained all the essential amino acids in varying concentrations. The lysine content of the samples was adequate from a nutritional viewpoint. Methionine and cystine contents were, however, appreciably lower, probably because some of the sulphur-containing amino acids were partially or wholly destroyed during hydrolysis prior to amino acid analysis (Byers, 1983 ). M. hastata appears to be a promising plant for LPC extraction owing to its large stands, high biomass productivity, good regrowth capacity, low fibre
LEAFPROTEINCONCENTRATESFROMMONOCHORIAHASTATA
299
content of plants and LPC, high protein content, high digestibility and favourable amino acid composition of LPC. The non-toxic nature ofM. hastata is indicated by its regular grazing by cattle. However, in vivo evaluation of the nutritive value and toxicity, if any, is essential before it can be recommended for food and feed use.
REFERENCES Association of Official Analytical Chemists, 1975. Official Methods of Analysis. A.O.A.C., Washington, DC, 1018 pp. Bailey, T.A., 1965. Commercial possibilities of dehydrated aquatic plants. Proc. Southern Weed Conf., 18: 543-551. Banerjee, A., Bagchi, D.K. and Matai, S., 1985. Allmania nodiflora R. Br. (Amaranthaceae), a promising source of leaf protein. Aquat. Bot., 22: 393-396. Bates, R.P. and Hentages, J.F., 1976. Aquatic weeds - - eradicate or cultivate. Econ. Bot., 30: 39-50. Bickoff, E.M. and Kohler, G.O., 1974. Preparation of edible protein of leafy green crops such as alfalfa. U.S. Patent 3,823,128, July 9. Boyd, C.E., 1968. Freshwater plants: a potential source of protein. Econ. Bot., 22: 259-368. Byers, M., 1983. Extracted leaf proteins: their amino acid composition and nutritional quality. In: L. Telek and H.D. Graham (Editors), Leaf Protein Concentrates. AVI, Westport, CT, p. 135. Doneen, L.D., 1932. A micro method for nitrogen estimation in plant material. Plant Physiol., 7: 717-719. Food and Agricultural Organization, 1973. Energy and Protein Requirements. Tech. Rep. Ser., 522, FAO, Rome. Henry, K.M. and Ford, J.E., 1965. The nutritive value of leaf protein concentrates determined in biological tests with rats and by microbiological methods. J. Sci. Food Agric., 16: 425. Humphries, C., 1978. The use of leaf protein in human foods. Plant Foods Manuf., 2:167-180. Little, E.C.S. (Editor), 1968. Handbook of Utilization of Aquatic Plants. F.A.O., Rome, p. 121. Matai, S., 1976. Protein from water weeds. In: C.K. Varshney and Y. Rzoska (Editors), Aquatic Weeds in South East Asia. Proceedings of a Regional Seminar on Noxious Aquatic Vegetation, The Hague, 1973, pp. 369-373. Mitchell, D.S. (Editor), 1974. Aquatic Vegetation and its Use and Control. UNESCO, Paris. Morrison, J.P., 1961. Feeds and Feeding Abridged. Morrison Clinton, IA, pp. 1-696. Pandey, V.N. and Srivastava, A.K., 1989. Veronica anagallis-aquatica L. a potential source of leaf protein. Aquat. Bot., 34: 385-388. Pirie, N.W., 1978. Leaf Protein and other Aspects of Fodder Fractionation, Cambridge University Press, London, pp. 1-183. Pirie, N.W., 1985. Leaf protein in human diets. In: I. Tasaki (Editor), Recent Advances in Leaf Protein Research. Faculty of Agriculture, Nagoya University Farm, Nagoya, Japan, pp. 6366. Saunders, R.M., Connor, M.A., Booth, A.N., Bickoff, E.M. and Kohler, G.O., 1973. Measurement of digestibility of alfalfa protein concentrates by in vivo and in vitro methods. J. Nutr., 103: 530-535. Srivastava, T.N., 1976. Flora Gorakhpurensis. Today and Tomorrow's, New Delhi, 320 pp.