Formulation-dependent effects of hemp seed by-products on batter properties, structure, and check-all-that-apply -derived consumer response of gluten-free muffins

The valorisation of hemp seed oil by-products offers a promising strategy to enhance the nutritional and technological quality of gluten-free baked goods. This study evaluated the incorporation of hemp seed cake flour (HSCF) and hemp seed protein concentrate (HSPC) at 15%, 20%, and 30% substitution levels in gluten-free muffins, assessing effects on batter properties, muffin structure, composition, colour, texture, and sensory perception. Compared with the control, HSCF slightly increased batter texture parameters and, at 30%, reduced density (0.886 vs 0.927 g/mL) while increasing volume (90.6 vs 80.9 mL) and specific volume (2.3 vs 2.0 mL/g). HSPC produced stronger increases in batter texture parameters and density (0.962-1.028 g/mL), yielding the lowest volume (77.0 mL) and specific volume (1.9 mL/g) at 30% due to matrix strengthening. Fortification progressively improved nutritional quality: protein rose from 5.4 g/100 g (control) to 9.1 g/100 g in 30% HSPC muffins, and fibre increased from 0.2 to 5.2 g/100 g in 30% HSCF samples, enabling "source of fibre" labelling at 20-30% HSCF. Colour shifted towards darker, duller reddish brown hues, with Delta E up to 21.84 in 20% HSPC crust and 32.50 in 30% HSCF crumb. Muffin texture remained largely unaffected at <= 20% substitution. Sensory analysis revealed a gradual transition from cake-like to hemp-characteristic profiles, with bitterness, herbaceous notes, dark colour, dryness, grittiness, and crumbliness driving disliking. Overall, moderate fortification with hemp by-products provides an optimal balance of nutritional enhancement, structural performance, and sensory quality, supporting their potential for sustainable gluten-free product development.