<p>Parboiling is a desirable pretreatment to improve grain milling and stabilization, however, it also alters grain macromolecules and effect on grain composition. The aim of parboiling or hydrothermal treatment is to alter the grain characteristics to enhance the milling properties. This study observed the impact of these treatments on the extractability and other characteristics of protein concentrate. The effect of parboiling (<i>soak-boil (SB) and soak-steam</i>,<i> (SS))</i> treatments on the foxtail millet has been investigated based on protein quality, amino acid scoring, molecular variation and digestibility study of its protein concentrate (PC). The results indicated that the isoelectric point (IpH) of protein concentrates slightly shifted from 4.2 to 4.6 upon parboiling. The PC appeared fragmented, uneven, and loose, changes in the functional groups and side chain interactions having minor peaks at 576–522&#xa0;cm^− 1 and 1075&#xa0;cm^− 1. Optimal protein efficiency ratio (PER₃₎ values of untreated protein concentrate UPC (4.76), soak-boil protein concentrate SBPC (4.73) and soak-steam protein concentrate SSPC (4.12) however they have relatively lower biological values, BV (UPC-52.96, SBPC-35.48 and SSPC-46.55). Aspartate and glutamate were present in relatively higher amount compared to cysteine and glycine; lysine was limiting wherein amino acids bio-accessibility decreased from 44.66% to 36.78% due to significant alterations in the protein structure with the formation of disulfide linkages and changes in secondary structure. Since parboiling is desirable to stabilize the millet grain, its effect on protein quality was not adverse especially in soak steam method of parboiling. Hydrothermal treatments led to a decline in the purity and extractability of protein concentrates; however, protein concentrates obtained from soak-steam treated foxtail millets portray better amino acid profile.</p>