Determination of crude protein and amino acids in soybean mealby Near Infrared Spectroscopy / Determinação de proteina bruta e aminoacidos em farelo de soja por espectroscopia no infravermelho proximo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

In this work it was determined the amount of crude protein and amino acids in soybean meal by using near infrared spectroscopy and multivariate calibration base on partial least squares method (PLS). It was used 150 samples from different brazilian regions divided in several suppliers as Bunge, Caramuru, Cargill, Ceval and ADM that insure a good distribution and representivity of the samples. The spectra were collected in the range of 1300 to 2400 nm, obtaining 551 variables. The crude protein analysis were performed by a nitrogen analyser LECO FP-428 following the reference method AACC 946-30 (American Association of Cereal Chemists ,1995). The amino acids determination were performed by Hitachi L-8500 equipament by using post column derivatization with acid hidrolysis (HCl 6 mol/L) for all amino acids, except tryptophan analysed by alcalin hydrolisis (LiOH 4 mol/L) and the methionine and cystine by performic acid oxidation, following ia collaborative study of the journal of AOAC (Association of Official Analytical Chemists). The models valuation show that is possible to determine with confidence crude protein, glutamic acid, aspartic acid, arginine, threonine, valine, leucine, tyrosine, tryptophan, cystine and methionine. The amino acids lysine, alanine, isoleucine and phenylalanine that present concentration ranges least than three times the standard deviation of reference method are out of recomendation of ASTM E1655-00 norm, and these ranges must be increased and the models improved. By other hand, the models for the amino acids histidine, serine, glycine and proline must be descarted and rebuilt, since the increase of concentration range of samples in not enough due the standard deviation of reference method employed (post column) is high and it can not satisfy the ASTM recommendation, then another reference method, as pre column derivation, must be used. In the majory of the cases, it was obtained good results for crude protein and several amino acids for the models developed by using near infrared spectroscopy, with the advantage that this methodology is very fast, economic and not produce toxic residues.

ASSUNTO(S)

proteina aminoacidos infravermelho proximo farelo de soja

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