Comparison of Textural and Rheological Properties in Emulsion Gels Based on Lentil Flour and Lentil Protein...

Lentil flour or lentil protein concentrate, alginate and sunflower oil at 30% or 50% were used to produce emulsion gels (EG) by cold-set gelation using glucono-δ-lactone and calcium citrate. Control gels were prepared without the addition of oil to compare the rheological and textural characteristics. Rheological properties were evaluated through amplitude, frequency and temperature sweeps and creep-recovery tests. Texture profile analysis and confocal laser scanning microscopy provided complementary characterization. Lentil protein concentrate EG exhibited higher storage modulus, lower creep compliance, and higher hardness than lentil flour systems, consistent with the formation of a denser and more cohesive protein network, as confirmed by microscopy. Increasing oil content from 30% to 50% enhanced the elastic character of both systems. Oil-free control gels displayed markedly higher stiffness than their emulsified counterparts in rheological assays, as showed in k coefficient of power law adjustment (LF0 = 2.1 × 10⁴ ± 3 × 10³; LF30 = 50 ± 10; LF5 = 170 ± 30; LP0 = 8.4 × 10³ ± 9 × 10²; LP30 = 190 ± 60; LP50 = 600 ± 100). This suggest that oil droplets behave as inactive fillers. Springiness increased upon oil incorporation relative to controls across all formulations. Confocal laser scanning microscopy showed that increasing oil content promotes coalescence in lentil flour EG, whereas lentil protein concentrate forms denser matrices that restrict droplet growth (D50 = 4.9 μm and 6.6 μm for LF30 and LF50 respectively; 3.9 and 3.3 μm for LP30 and LP50, respectively). These results suggest that lentil protein concentrate-based EG, particularly at higher oil fractions, are promising candidates as structured ingredients for plant-based food applications.