Extrusion modification and hydration properties of three tea residues

The modificaditon was conducted by an extrusion method using tea residues of green tea,black tea,respecticely. And the water solubility,water holding capacity and swelling power of the modified tea residues were determined. The experimental results showed that the optimum conditions of extruding the green tea and black tea residues were as follows:screw speed 630 r/min,moisture content 28%,residue particle size 20 mesh. The optimum conditions for extruding the puer tea residue were as follows:screw speed 540 r/min,moisture content 40%,residue particle size 20 mesh. Under the optimum extrusion conditions,the content of water-soluble polysaccharides in green tea,black tea and puer tea modified by double extrusions were 5.33%,4.63% and 5.12%,respectively. After double-extrusion,the water solubility,water holding capacity and swelling power of black tea leave increased by 64.71%,16.67% and 52.38%,respectively. The water solubility and water holding capacity of green tea residues increased by 7.41%,17.86%,respectively. The water solubility of puer tea residues was increased by 86.21%.