Estudo comparativo da composição e dos efeitos do tratamento termico em quatro variedades de quinua (Chenopodium quinoa, Willd)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1976

RESUMO

The purpose of this work was to study the temperature dependence of the (1) saponins extraction, (2) the composition and (3) The biological value of four Bolivian varieties of quinua (Chenopodium quinoa, Willd.). Extraction or washing of the saponins was routinely accomplished at temperatures of 50, 70 and 879C. The concentration of protein in the washed samples was affected by the temperature. The increase in concentration was maximum for three samples washed at 70°C, while a fourth one showed maximum concentration at 87°C. Saponins, as measured by their foaming activity ranged from 2.8% (dry basis) in the untreated Colorada Flour to 1.7% for the untreated Sajama flour. Although complete removal was accomplished at 70 and 87°C a small residual activity remained in the samples treated at 50°C. An increase in amino acid content was observed in three of the samples washed at 87°C, which could be explained by the simultaneous extraction of nitrogenous components lacking in amino acids. In general the sulfur amino acids were limiting (Protein Score, FAO pattern 1965) in both washed and unwashed samples. By comparing with amino acid patter~ of casein, limiting amino acids were isoleucine, tryptophan and valine. Highest PER values were obtained for the varieties Blanca(2.99) and Sajama (2.72) both treated at 879C, as compared with casein (3.21). Solubility curves a function of pH, were determined and suggested the presence of two or more proteins fractions which differ substancially in their isoelectric properties. Differential extraction showed that the globulins (the main fraction in all varieties studied) varied from 26 to 45% of the crude protein. These were followed by alburnins (4.5 to 20%) and prolarnins (0.5 to 8%). Glutelins and insoluble proteins calculated by difference accounted for 12 to 51% of total proteins.

ASSUNTO(S)

quinoa chenopodium

Documentos Relacionados