A New Protocol for Measuring Gluten Index: Assessing Gluten Quality Independent of Protein Quantity

Background and Objectives When assessing wheat gluten quality, traditional dough rheological tests often confound protein quality with protein quantity, making it difficult to distinguish the contribution of each factor. This study presents a modified gluten index (GI) protocol designed to evaluate wheat gluten quality independent of protein content for hard red spring wheat. Findings Wet gluten (WG) mass significantly affected GI values, with a greater effect observed in weaker genotypes than in stronger ones. To address this limitation, the modified GI protocol standardized WG mass and applied additional force during centrifugation using customized inserts. The modified protocol effectively distinguished gluten quality among diverse Canadian hard red spring wheat genotypes, despite variation in flour protein content and dough rheological properties. Conclusions The influence of WG mass on GI must be carefully considered in GI measurement. The modified GI protocol successfully isolated protein quality from protein quantity, allowing for a more accurate assessment of intrinsic gluten functionality. Significance and Novelty This study introduced a modification to the conventional GI method that allows assessment of gluten quality independent of protein content. The enhanced protocol would benefit wheat breeding programs and allow accurate evaluation of gluten quality regardless of protein levels and growth environments.