Protein content and amino acid composition of grain amaranth depending on growing season, sowing date and nitrogen supply

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1 Ratarstvo ORIGINAL SCIENTIFIC PAPER Protein ontent and amino aid omposition of grain amaranth depending on growing season, sowing date and nitrogen supply Silva Grobelnik Mlakar 1, Manfred Jakop 1, Matjaţ Turinek 1, Martina Robaţer 1, Martina Bave 1, Fran Bave 1 1 Faulty of Agriulture and Life Sienes, University of Maribor, Pivola 1, Hoče, Slovenia (frani.bave@uni-mb.si) Abstrat The aim of a field experiment onduted in 1 and 2 was to evaluate the effets of sowing date and nitrogen fertilisation on protein ontent and amino aids omposition of amaranth seeds. Amaranthus ruentus L. G6 was sown at two sowing dates (May and June) and was fertilised aording to N-min and two target levels (N-min, N1=14, N2=). Grain protein ontent and sum of essential amino aids (EAA) were affeted by growing season and date of sowing. Higher protein ontent (.4%) with less EAA in protein ( g kg -1 ) was ahieved in grain sown in June. Nitrogen appliation of N2 resulted in the highest grain protein ontent. Among EAA only valine onentration responded to nitrogen supply. Leuine and methionine demonstrated to be the limiting amino aids. Key words: grain amaranth, sowing date, nitrogen fertilization, protein onentration, amino aid omposition Introdution Grain amaranth (Amaranthus spp.) was one of the staple foods in the pre-olonized South Amerian ivilizations' diet that has reeived inreased attention beause of its high nutritional value. Compared to most onsumed ereals, amaranth grains have been reported to ontain a higher protein ontent (ranging from 13. to.6 %), with a better balane of amino aids and a partiularly high lysine onentration from g kg 1 protein (Bave and Bave, 6; Grobelnik Mlakar et al., 9a). This high lysine onentration is omplemented with elevated levels of sulphur amino aid ontent (2 to 5 %), whih is higher than that measured in the most important legumes (1.4 % on average), suh as peas, beans and soybeans (Gorinstein and Moshe, 1991). Thus, aording to the protein referene pattern defined by FAO/WHO/UNU (1985), the amaranth's protein omposition is lose to the optimum human requirenments in most amino aids. As limiting amino aid mostly reported in the literature are leuine isoleuine, valine and also threonine. However, mentioned amino aids are not onsidered a serious problem sine they are found in exess in most ommon grains, and therefore amaranth is well suited for blending with ereals to produe fortified food (Grobelnik Mlakar et al., 9b). Sine nitrogen is one of the dominant yield reating fators and nitrogen supply determined the protein aumulation in the seed, it is important to know more about amaranth' protein quantity and quality response onneted to nitrogen fertilisation. Protein onentration strongly depends on amaranth speies, genotype and limati ondition, and is reported to range from 14. to.1 % in European prodution onditions (Jamriška, 1996; Aufhammer et al., 1999; Thanapornpoonpong, 4; Gimplinger et al., 7). Although some nitrogen fertilisation studies on grain amaranth have been undertaken, to date sare information is found in the literature about its protein onentration response (Bressani et al., 1989; Elbehri et al., 1993; Thanapornpoonpong, 4; Shulte auf'm Erley et al., 5; Pospišil et al., 6). 45. hrvatski i 5. međunarodni simpozij agronoma 727

2 Temperature ( o C) Preipitation (mm) Temperature ( o C) Preipitation (mm) Field Crop Prodution However, the responses of grain protein to amaranth sowing date (Aufhammer et al., 1995) and response of amino aid omposition to nitrogen appliation (Thanapornpoonpong, 4) are even more rarely analysed. The objetives of this study, whih was a part of a broader national researh projet on grain amaranth (L ) and trials established to optimise amaranth prodution pratie in NE part of Slovenia, was to determine the impat of sowing date and nitrogen appliation on Amaranthus ruentus 'G6' rude protein quantity and quality. Material and methods Whole mature grain samples of Amaranthus ruenthus 'G6' were obtained from four-year field fatorial experiment arried out at the University Agriulture Centre Pohorski Dvor, Maribor in the frame of whih sowing date and nitrogen fertilisation where studied in 1, 2. Used amaranth, among tested genotypes the most appropriate for our prodution onditions (Grobelnik Mlakar, ), was hand sown on two sowing dates; at the beginning of seond deade of May and June. Stands were hand thinned to a population of 5 plants per m 2 at the 4 to 6 leaf-stage. Nitrogen was applied aording to mineral nitrogen amount defined at the time of sowing to the depth of 9 m and stated target value in three levels: ontrol (C) = no mineral nitrogen fertilisation; N1 = target value 14 kg N ha -1 and level N2 = target value kg N ha -1. Nitrogen (in form of alium ammonium nitrate) was applied in growth stage of 4 to 6 leaves developed to target value N1, and N2 treatments were fertilised with additional nitrogen in the stage of visible infloresene. The average limati ondition ( ) of loation and deade wheather onditions in the ourse of the investigated growing seasons are presented in Figure 1. It should be pointed out that the weather onditions in the period after the beginning of amaranth flowering (end of July, August) until grain harvesting (end of September, beginning of Otober) differed. The September temperatures reorded in 1 were lower than in 2, and preipitation in August and September was above all differently distributed among deades of both growing seasons Figure. 1. Average deade temperature ( o C) and deade preipitation (mm) in growing seasons ompared to long-term average ( ) th Croatian & 5 th International Symposium on Agriulture

3 Ratarstvo Crude protein onentration in perentage alulated on dry mass (original moisture ontent in grain was 9-12%) was determined aording to Kjehldahl proedure, and nitrogen to protein onversion fator of 5.85 was used in the alulation (Beker et al., 1981). Amino aids were determined by ion-exhange hromatography with an amino aid analyzer INGOS AAA 4 at the Department of Chemistry and Biohemistry, Faulty of Animal Siene, University of Kaposvar. Analyses were performed for eah treatment in two repliations. Data was evaluated by analysis of variane using the Statgraphis Centurion XV statistial program (Statgraphis, 5). If a signifiant F value (p <.5) was deteted, Dunan s multiple-range test was used to determine the signifiane of differenes among means. Results and disussion The protein ontent in grain dry matter was affeted by year, sowing date and nitrogen fertilisation (Table 1). Climati harateristis during 2 were more favourable than in 1, not only for grain protein ontent, but also for rop yield performane. Thus, the grain yield in 2 was for 1,47 kg ha -1 (expressed at the 12 % moisture level) and aboveground biomass for 18,98 kg ha -1 higher than in 1 (Grobelnik Mlakar, 6). The sum of essential amino aids was impaired by the weather ondition, but the onentration of NEAA was not affeted. Higher protein ontent with less essential amino aids in protein was ahieved in grain of amaranth sown in June. Nitrogen appliation to the target value kg N ha -1 resulted in the highest grain protein ontent. Among amino aids presented, only onentration of valine in protein was affeted by nitrogen supply. Appliation of nitrogen to the target value 14 kg N ha -1 resulted in signifiant inrease of valine onentration for 1.9 % in omparison to ontrol, and for 1.6 % in omparison to N2 treatment (Table 1). Table 1. Statistial analysis summary of the impat of year (Y), sowing date (SD) and nitrogen fertilisation (N) on grain protein ontent (GP) and individual essential amino aids ANOVA Mean values by fators' levels (% on DW, g kg -1 of protein) Y SD N 1 2 May June C N1 N2 GP * ** * 14.7b.1a 14.4b.4a 14.6b 14.8b.3a EAA a * ** ns a b a b NEAA b ns ns ns HIS ns * ns b 27.9a ILE ns * ns LEU * ** ns 58.23a 57.35b 58.4a 57.18b LYS ns ns ns MET C ns ** ns a 22.35b PHE ** * ns 42.8b 44.61a THR ** ns ns 38.62a 37.13b TRP ns ns ns VAL ** ** * 42.69b 45.25a 44.73a 43.22b 43.65b 44.49a 43.78b a Sum of histidine (HIS), isoleuine (ILE), leuine (LEU), lysine (LYS), methionine (MET), phenylalanine (PHE), threonine (THR), tryptophan (TRP) and valine (VAL) b Sum of alanine, asparti aid, ystine, glutami aid, serine, proline, glyine, tyrosine and arginine Methionine + ystine 45. hrvatski i 5. međunarodni simpozij agronoma 729

4 Amino aid onentration (g kg -1 ) Protein onentration (% on DW) Field Crop Prodution Among all interations tested as a soure of variane, only interation Y x SD was signifiant in grain protein ontent, and threonine and phenylalanine onentration in protein (Figure 2). In the first experimental year the sowing date in June resulted in signifiantly lower protein level (. %) than in 2 (.8 %), while sowings in May were very similar (14.3 % and 14.4%). The threonine onentration in 1 was lower in June (37.75 g kg -1 ) than in May (39.48 g kg -1 ), and statistially the same as onentration of both sowing dates in 2. The opposite was demonstrated for phenylalanine levels; the highest value was analysed in grain protein of amaranth sown in June 2 (45.38 g kg -1 ), followed by g kg -1 in May 2, and both sowings in 1 (Figure 2) a THR PHE GP a b b b b a 16, b 25 14, May June May June ,5 Figure. 2. Conentration of amino aid and protein in 1 and 2 Aording to mean values of partiular essential amino aids obtained in trial and omparisons to FAO/WHO/UNU (1985) standards for preshool hildren, the first limiting amino aid was leuine (hemial sore 88), followed by methionine (hemial sore 92). The average value of summed EAA evaluated in treatments (375 g kg -1 ) is higher than standard requirements for preshool hildren (339 g kg -1 ). High values of hemial sores were found in HIS, ILE, PHE, THR, TRP, VAL, whereas the LYS onentration, aording to its flutuation, seems to be also limiting. When onsidering the standards for adults and shool hildren, the biologial value of protein in A. ruenthus G6 is well balaned (Table 2) th Croatian & 5 th International Symposium on Agriulture

5 Ratarstvo Table 2. Average amino aid omposition in grain of Amaranthus ruentus 'G6' obtained in trial (g kg -1 of protein) in omparison to amino aid requirements Amino aid HIS ILE LEU LYS MET PHE THR TRP VAL Average onentr. ± SD a Min. onentr. a Max. onentr. a Standard b Preshool hild Shool hild Adult d Chemial sore * (11) a Average (± standard deviation), minimal and maximal amino aid onentration obtained in trial b FAO/WHO/UNU standard (1985) taken from table 38; requirements for preshool hildren (2-5 years), shool hildren (1-12 years) and adults Methionine + ystine d Phenylalanine + tyrosine * Grain protein supplies 1% or more of the requirement. Limiting amino aid is in itali. Chemial sore was based on FAO/WHO/UNU (1985) pattern for preshool hildren Conlusions Protein ontent in grain of amaranth as well as amino aid omposition are both impaired by growing season and date of sowing. The less favourable year (1) and sowing date (May) for protein aumulation in grain resulted in higher essential amino aids onentration. Sine nitrogen appliation inreased protein ontent and maintained the amino aids levels, this measure an be used for the nutritional improvement of amaranth grain yields. Referenes Aufhammer W., Kübler E., and Lee J.H. (1999). Grain quality of the pseudoereals bukwheat (Fagopyrum esulentum Moenh), quinoa (Chenopodium quinoa Willd.) and amaranth (Amaranthus hypohondriaus L. A. hybridus L. ) in relation to growing onditions. Die Bodenkultur. 5(1): Aufhammer W., Kaul H.P., Herz P., Nalborezyk E., Dalbiak A., and Gontarzyk M. (1995). Grain yield formation and nitrogen uptake of amaranth. European Journal of Agronomy. 4(3): Bave F., and Bave M. (6). Grain amaranths. In Organi Prodution and Use of Alternative Crops, Boa Raton, USA:CRC Press/Taylor and Franis. Beker R., Wheeler E.L., Lorenz K., Stafford A.E., Grosjean O.K., Betshart A.A., and Saunders R.M. (1981). A Compositional Study of Amaranth Grain. Journal of Food Siene. 46(4): Bressani R. (1989). The Proteins of Grain Amaranth. Food Review International.5(1): Elbehri A., Putnam D.H., and Shmitt M. (1993). Nitrogen-fertilizer and ultivar effets on yield and nitrogen-use effi ieny of grain amaranth. Agronomy Journal. 85: Gorinstein S., and Moshe R. (1991). Evaluation of Four Amaranthus Speies through Protein eletrophoreti Patterns and Their Amino Aid Composition. Journal of Agriultural and Food Chemistry. 39(5): Grobelnik Mlakar S., and Bave F. (). Zrnati šţiri. In Novi izzivi v poljedelstvu. Moravske Toplie Tajnšek A., and Šantave I. (eds.), Ljubljana, Slovenia: Slovensko agronomsko društvo. 45. hrvatski i 5. međunarodni simpozij agronoma 731

6 Field Crop Prodution Grobelnik Mlakar S. (4). Vpliv roka setve, gostote posevka in gnojenja z mineralnim dušikom na pridelek in kakovost zrnja košatega šţira (Amaranthus ruentus L.) v. 'G6''. M.S. thesis. Grobelnik Mlakar S., Turinek M., Jakop M., Bave M., and Bave F. (9a). Nutrition value and use of grain amaranth: potential future appliation in bread making. Agriultura 6(2):5-. Grobelnik Mlakar S., Bave M., Turinek M., and Bave F. (9b). Rheologial Properties of Dough Made from Grain Amaranth-Cereal Composite Flours Based on Wheat and Spelt. Czeh Journal of Food Sienes. 27(5): (Approved manusript). FAO/WHO/UNU. (1985). Energy and protein requirements. Report of a joint FAO/WHO/UNU expert onsultation. Tehnial report series 724. Geneva, Switzerland:WHO. Gimplinger D.M., Dobos G., Shönlehner R., and, Kaul H.P. (7). Yield and quality of grain amaranth (Amaranthus sp.) in Eastern Austria. Plant, Soil and Environment. 53(3):-112. Available from: Jamriška P. (199). The effet of the stand organisation on the yield of amaranth (Amaranthus hypohondriaus). Rostlinna Vyroba, 36: Pospišil A., Pospišil M., Varga B., and Sveţnjak Z. (6). Grain yield and protein onentration of two amaranth speies (Amaranthus spp.) as influened by the nitrogen fertilization. European Journal of Agronomy. 25(3): Available from: Shulte auf'm Erley, G., H.-P. Kaul, M. Kruse, W. Aufhammer (5): Yield and nitrogen utilization effiieny of the pseudoereals amaranth, quinoa, and bukwheat under differing nitrogen fertilization. European Journal of Agronomy. 22(1):95-1. Statgraphis Centurion XV. (5): User Manual. StatPoint. Thanapornpoonpong S. (4). Effet of nitrogen fertilizer on nitrogen assimilation and seed quality of amaranth (Amaranthus spp.) and quinoa (Chenopodium quinoa Willd), PhD thesis th Croatian & 5 th International Symposium on Agriulture

EFFECT OF DIFFERENT METHODS OF PRESERVATION ON THE QUALITY OF CATTLE AND GOAT MEAT. Abstract

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