Ao se fazer a recomendação de proteína para diferentes grupos populacionais [13], além da composição aminoacídica (SARWAR et al., 1997) [28], devem ser consideradas a quantidade total de nitrogênio e a digestibilidade da mistura protéica. Uma mistura protéica de
QUALIDADE NUTRICIONAL E ESCORE QUÍMICO DE AMINOÁCIDOS DE DIFERENTES FONTES PROTÉICAS
SUMMARYNUTRITIONAL QUALITY AND CHEMICAL SCORE OF AMINO ACIDS FROM DIFFERENT PROTEIN SOURCES. Proteins are essential for animals, therefore, they must be present in diet, in appropriate amounts. Besides the quantitative aspect, the qualitative aspect should be taken into account, i.e. its nutritional value, which will depend on its composition, digestibility, bioavailability of essential amino acids, absence of toxicity, and of antinutritional factors. The purpose of this work was to evaluate the digestibility in vivo, the chemical score of amino acids (EQ), and the protein digestibility corrected amino acid score (PDCAAS) of the following protein resources: frog meat without bone, frog meat with bone, mechanically separated frog meat (CMS), beef meat, egg powder, casein, wheat, corn, conventional soybean, Kunitz trypsin inhibitor and lipoxygenase free soybean (KTI-LOX-soybean), textured soybean protein (PTS) and beans. Animal proteins presented higher digestibility values than those from vegetables. Frog meat without bone was the protein with the highest protein digestibility of all proteins studied, not differing from casein, CMS, beef and frog meat with bone. Comparing animal proteins, the one of egg powder was the one which presented the lowest digestibility. No animal protein presented essential limiting amino acids when compared to those of FAO/WHO. Beans, conventional soybean, KTI-LOX-soybean and PTS presented sulfurized amino acids (methione+cysteine) as limiting ones. Whereas for wheat and corn, the most limiting amino acid was lysine. KTI-LOX-soybean presented higher PDCAAS values than those of conventional soybean, presenting a possible increase in genetically improved soybean and processed soybean protein quality. Keywords: protein quality, digestibility, PDCAAS, essential amino acids. A digestibilidade é a medida da porcentagem das proteínas que são hidrolisadas pelas enzimas digestivas e absorvidas pelo organismo na forma de aminoácidos ou de qualquer outro composto nitrogenado. Trata-se de um determinante da qualidade protéica da dieta. Quando certas ligações peptídicas não são hidrolisadas no processo digestivo, parte da proteína é excretada nas fezes ou transformada em produtos do metabolismo pelos microorganismos do intestino grosso [30].
