Modification of tea residue dietary fiber by high-temperature cooking assisted enzymatic method: Structural, physicochemical and functional properties

The research aimed to assess the effects of high-temperature cooking assisted enzymatic method on the structural, physicochemical and functional properties of soluble dietary fiber (SDF) from tea residue (GM-SDF). Under the optimal extraction conditions obtained by response surface methodology, the GM-SDF yield was significantly higher than that of untreated tea residue (U-SDF). It could be found results showed that GM-SDF possessed more hydrophilic groups, higher crystallinity, as well as a looser and more complicated structure by FTIR, XRD and SEM analysis. Besides, the differences in monosaccharide composition and molecular weight between U-SDF and GM-SDF were observed. Additionally, physicochemical properties analysis showed that water holding capacity, oil holding capacity and water swelling capacity of GM-SDF increased by 73.1%, 57.2% and 81.8% than that of U-SDF, respectively. Moreover, compared with U-SDF, GM-SDF exhibited higher adsorption capacity of glucose, sodium cholate, cholesterol and capacity of delaying glucose diffusion and dialysis. Furthermore, the inhibitory effect of GM-SDF on α-amylase was similar to that of acarbose. To sum up, the study showed that high-temperature cooking assisted enzymatic method can effectively extract dietary fiber from tea residue and improve the physicochemical and functional properties, which possesses great potential for application in functional food.