Effect of High Moisture Extrusion on True Ileal Amino Acid Digestibility and DIAAS of Quinoa–Pea Protein-Based Meat Analogues

Abstract

The true ileal digestibility (TID) of amino acids (AA) and protein quality (DIAAS) of meat analogues (MA) were investigated by comparison with the ingredients before high moisture extrusion. Three experimental diets, a blend of QF and pea protein isolate (PPI) (QF:PPI=2:8) before (flour mix, FM) and after high moisture extrusion (meat analogues, MA), as well as air-classified quinoa flour (QF), were fed to 6 healthy ileal cannulated pigs using a 3 × 3 Latin square design with three 7-day experimental periods. Pigs also received a protein-free diet for 7 days to correct endogenous amino acid (AA) excretions on an individual animal basis. True ileal digestibility (TID) of AA, the amount of digestible AA, and digestible indispensable amino acid score (DIAAS) were calculated for each diet. Although high moisture extrusion had no effect on the TID of crude protein, with FM and MA showing TID values of 89.8% and 91.9%, respectively, it led to a significant improvement in the TID of indispensable amino acids, increasing from 91.6% in FM to 94.9% in MA (P<0.05). The TID of methionine, isoleucine, lysine, and tryptophan in particular was enhanced following high moisture extrusion (P<0.05). DIAAS values of MA were 76% (reference values: children aged 0.5–3 years), and 89% (older children, adolescents, and adults), which were greater than those of FM (68% and 80%, respectively, for the same age groups). In both age groups, sulphur-containing amino acids were identified as the first limiting AA in FM and MA. The improvement of the TID of AA and protein quality of plant proteins in MA may be attributed to the changes in food matrix, denaturation of proteins, and reduction of anti-nutritional factors during high moisture extrusion.