Effects of Extruded and Conventional Sorghum Flour on Postprandial Plasma Amino Acid and Glucose Patterns in Adult Men

Sorghum is a nutrient-rich grain shown to improve growth and alleviate malnutrition in clinical studies; however, starch-protein interactions can limit its protein digestibility. Extrusion can help to improve protein availability from some foods. Three probe feeding studies were conducted to assess amino acid availability from extruded sorghum flour using postprandial plasma amino acid concentrations. For each study, a randomized crossover design with a one-week washout period was used to determine responses in healthy men aged 21-34 yr following intake of either extruded (EX) or conventional (CON) sorghum flour. In probe 1 (P1) and probe 2 (P2), men consumed 34 g (n=2) or 68 g (n=3) of flour, with plasma amino acid concentrations determined every 30 min for 180 min. A third probe (P3) provided 68 g (n=4) of flour, and samples for both plasma amino acids and glucose were collected every 15 min for 90 min. Responses were calculated as both the area-under-the-curve (AUC) and the incremental AUC (iAUC). In all three probes, amino acid responses were similar between the flours. The plasma glucose AUC was significantly greater from EX compared to CON, but the iAUCs between them were not significantly different. In these initial probe trials, a small sample size, along with individual variability in responses may explain the lack of differences in patterns of postprandial amino acids. Additional research on extrusion techniques and response measures is warranted.