ABSTRACT Thermal and rheological characterization of flaxseed mucilage (FM) was conducted and complemented by an evaluation of its glass‐forming fragility ( m ) during spray‐dried microencapsulation. FM (3 g/100 mL) was gelled and analyzed using DSC, TGA, and rheology. Thermal decomposition grouping based on TGA peak deconvolution revealed three water‐soluble degradation events, with P‐II (29.7% ± 2.5%) as the dominant fraction, followed by P‐III (10.2% ± 1.9%) and P‐I (5.8% ± 0.6%). Spray drying increased the relative contributions of P‐I and P‐II by approximately 2% and 6%, respectively ( p ≤ 0.05). In spray‐dried FM without insulin (FM‐WI), modest changes in polymer distribution were observed, whereas in insulin‐loaded FM (FM‐I), the P‐I fraction increased by an additional ~4.7% ( p ≤ 0.05), whereas P‐II and P‐III remained unchanged. These trends suggest selective rearrangements in polymer associations, potentially related to protein–polysaccharide interactions. Thermal parameters T g , Δ T g , δ , Δ T , and fragility ( m ) exhibited a clear dependence on heating rate, with rates ≤ 2°C/min yielding lower T g and m values and greater apparent thermal stability compared to rates ≥ 5°C/min. Fragility analysis indicated minimal effects of dehydration alone, as m changed only from 27.0 (FM) to 27.2 (FM‐WI), whereas insulin incorporation increased m to 28.6 in FM‐I, consistent with enhanced dynamic heterogeneity. Thermal transitions were comparable for FM and FM‐WI, showing no significant difference in T g (41.8°C ± 6.1°C and 39.8°C ± 1.4°C, respectively), whereas a pronounced decrease was observed for FM‐I (24.6°C ± 2.1°C). Enthalpic recovery at T g (Δ H rec ) increased from 11.4 ± 2.1 J/g in FM to 45.2 ± 2.3 J/g in FM‐WI and 38.9 ± 1.4 J/g in FM‐I, highlighting differences in thermal relaxation behavior among the systems. VFT modeling yielded D = 53.6 at 1°C/min for FM, decreasing slightly to 52.8 in FM‐WI and more markedly to 47.0 in FM‐I. Overall, spray drying produced only modest effects on relaxation strength, whereas insulin incorporation led to significant modifications in polymer distribution, thermal behavior, and fragility. FM therefore remains a functional microencapsulation matrix, with performance governed by thermal history and protein–polysaccharide interactions.
Reyes‐Hernández et al. (Wed,) studied this question.