Millet bran dietary fibres treated by heating, dual enzymolysis united with acrylic-grafting or hydroxypropylation: effects on the properties of heat-induced egg white protein gel

Introduction Millet bran is an abundant dietary fibre resource, but it is rarely used in Foods. Methods To enhance the functional properties and applications of foxtail millet bran dietary fibre (MBDF), MBDF modified by heating, cellulase and xylanase hydrolysis combined with acrylic-grafting (MBDF-HDEAG) or hydroxypropylation (MBDF-HDEH) were prepared, and the effects of these modified MBDFs on heat-induced egg white protein gel (H-EWPG) were studies. Results and discussion The results showed that heating and enzymolysis united with acrylic-grafting or hydroxypropylation both enhanced the surface area, soluble fibre content, water-retention and expansion abilities of MBDF. The addition of unmodified MBDF, MBDF-HDEAG and MBDF-HDEH increased the β-sheet content of H-EWPG and made its microstructure denser and granular. Compared with MBDF, MBDF-HDEAG and MBDF-HDEH more effectively improved the gel and texture properties of H-EWPG including water-holding ability (from 20.45 to 34.63 g/100 g), pH (from 4.53 to 7.66), hardness (from 63.92 to 104.53 g), chewiness (from 57.97 to 122.84 g), and gumminess (from 63.92 to 118.18), and a reduction in transparency and springiness ( p < 0.05). MBDF showed the highest reducing effect on the freeze-thaw dehydration of H-EWPG (from 39.02 to 21.62%). Therefore, addition of MBDFs modified by heating, enzymolysis united with acrylic-grafting or hydroxypropylation can improve gel properties of H-EWPG.