Produção e caracterização de hidrolisado pancreatico de isolado proteico de soja para nutrição clinica

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

This work dealt with the pancreatic hydrolysis of soy protein isolates (SPI) for the production of a low molecular weight hydrolysis, as well as the biochemical and nutritional characterization of the product. The selected process was a discontinuous one at 37° C in deionized water and without pH adjustment in order to minimize concentration of inorganic ions in the final product. Hydrolysis was terminated by heat treatment, 72° C for 5 minute, and separation of the soluble from insoluble material was by centrifugation at 7000g. Bath, the soluble, low molecular weight hydrolysate (HI) and the insoluble, high molecular weight hydrolysate (Ppt), were lyophilized. various substrates concentrations (S) and enzyme/substrate ratios (E/S) were tested in order to attain extensive hydrolysis of the SPI. Reaction conditions were: 5.5% substrate, E/S= 1/35 (w/w), deionized water, initial pH-7.1, final pH= b37° C, duration 8 hours. Under such conditions, the degree of hydrolysis (DH) was 14.4%, nitrogen solubility in 10% TCA was 40.3% and 73.2% with respect to total N and supernatant N, respectivaly. The HI hydrolysate exhibited 21% DH and mean peptide lenght of 5 residues (incorrected for free aminoacids), wich were considered satisfactory far the apllication intended. Compositional differences were established between the SPI and its hydrolysis products. There was a decrease of acidic amino acids in the Ppt and of the aromatic aminoacids, phenilalanina and tyrosine in the HI hydrolysates, with respect to the SPI. Trypsin inhibitor activities were 72.17, 1.18 and 12.14 TILf/ mg of protein for SPI, Ppt and HI, respectivaly. Phytate leve 1s were considerable higher in the HI, 30.74 than in Ppt, 4.95 mg/ g of proteins. Evaluation of molecular weight profile of the HI hydrolysate, obtained by gel permeation in Sephadex S-25, reaction with trinitrobenzenosulfonic acid (TNBS) and free (AAL) and total (AAT) aminoacid determinations, revealed a content of 23.77. of peptides with 18 residues, 25.67. with 12 residues, 30X with 5 residues, 37. with 3 and 0.03% with 2 residues of amino acids. Free aminoacids were mainly aromatic and branched-chain amino acids. A nutritional evaluation were carried out using three biolog!cals assays with Wistar rats. Biological assay I showed that for wealing rats, the HI hydrolysate exhibited lower quality indices (PER, NPU and BV) than SPI and casein, with exception of digestibility, which was the same for all diets. Biological assays 11 and 11 were carried out with groups of wealing rats previously submitted to a 15-days non-protein diet. The HI hydrolysate showed a performance similar to that of casein and SPI during the inicial phase of assay II. In assay III, it was shown that supplementation of the HI hidrolysate with 0-B7. leucine, 1.147. valine and 37. methionine improved its efficiency above that of casein when supplemented with 27. of methionine, during the initial five days of recovery. On the basis of the above considerations, i t was concluded that the low molecular weight hydrolysate HI, showed molecular weight characteristics and nutritional evaluation result which indicated the possibility of it being used in clinical situations requiring a modified source of protein.

ASSUNTO(S)

soja como alimento nutrição - necessidades

ACESSO AO ARTIGO

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