Study On The Mechanism Andextracting Method Of Tea Residue Protein By CTAB-tween80 Reverse Microe Mulsion

Tea residue is a kind of by-product from the tea polyphenols processing industry,whichincludes about 21–28%proteins on dry basis.Recently,it was reported that tea protein has bioactive activity characteristics,such as antioxidant for DPPH and O₂^-and preventing biological cells mutagenesis from irradiation,and the amino acid composition and contents of tea protein is reaso nable.In this work,the extraction of tea protein by C TAB-Tween80 reverse micelles with ultrasound assisted extraction?UAE?was investigated.CTAB-Tween80 reverse micelles were composed of Hexadecyl trimethyl ammonium Bromide?C TAB?and Tween80,isooctane,octanol and KC l.Ultrasonic power,extraction time,KC l concentration,p H and temperature have effects on the extraction efficiency of tea protein,which has been researched.Based on the single-factor experiments,the optimum extraction was obtained by the method of response surface analysis?RSA?.The results showed that the highest extraction yield of tea protein was achieved at the ultrasonic power 340 W,time 60 min,KCl concentration 0.15 M,pH 7.5 and temperature 45?.In this case,the tea protein extraction rate reached 46.29%.This study evaluated the mass transfer process of tea-residue protein extracted by CTAB-Tween80 reverse micelles and investigated the effects of stirring speed,concentration of KCL,pH,tea-residue particle size,extraction temperature.The control procedures in the extraction process of tea-residue protein was analysed and determined,then a macroscopic mass transfer model of tea-residue protein extracted by the reverse micelles was established.The results showed that the stirring speed 150 r/min,concentration of KCL 0.15 mol/L,tea-residue particle size is 80 mesh,pH 7 and when extraction temperature at 45?,the extraction effect is best.Based on the Arrhenius equation,the apparent activation e nergy for the extraction of tea-residue protein was calculated as 18.30 kJ/mol.The macroscopic mass transfer model of tea-residue protein extracted by C TAB-Tween80 reverse micelles was established,which is2.68exp?-2200.8/T?/t=1+2?1-x?-3?1-x?^^?2/3?,after model validation,agreed well with the actual extraction process.The model of tea-residue protein extraction process is understanded,which can effectively control and enhance extraction process,increase the extraction rate and provide reliable data and theoretical reference for further research.Scanning electron microscope?SEM?,secondary structures,amino acid compositions,and functional properties of tea protein extracted by CTAB-Tween80 reverse micelles were researched and contrasted with those using alkaline extraction.SEM results indicated that tea protein separated by CTAB-Tween80 reverse micelle trended a reduction the size of droplets.Tea protein with reverse micelles contained a higher content of?-helix,?-sheet and turn structures,whic h indicated that tea protein using alkaline extraction has lost its ordered structures.Amino acids analysis indicated that tea protein by reverse micelles contained high levels of histidine,threonine,lysine,serine,glycine,arginine,alanine,proline,and cysteine compared to alkaline methods.Moreover,the results showed that tea residue protein had the lowest solubility at p H4.0,then solubility had a rising trend with increasing pH value.The oil absorption capacity and the water absorption capacity were 2.54g/g and 1.78g/g,respectively,while the foam stability valued 59.30%.Besides,the emulsibility valued 60.27%with reverse micelle system CTAB-Tween80 preparation,the number was 84.56%in terms of emulsion stability.And the foam capacity valued 68.69%.Tea residue protein with reverse micelle system CTAB-Tween80 preparation can form gel.In summary,tea residue protein with reverse micelle system CTAB-Tween80 preparation shows e xcellentemulsibility,emulsion stability and foam capacity despite its slightly poorer performance in the oil absorption capacity,water holding capacity and foam stability test,in comparison with tea residue protein with either alkali-solution and acid-isolation or enzymatic method,so reverse micelle system can keep the tea residue protein functional properties better.To investigate the influence of different alcohols on the isotropic microemulsion zone of a 1-butyl-3-methylimidazolium hexafluorophosphate?BmimPF₆?/Tween80 system,pseudo ternary phase diagrams of BmimPF₆/Tween80/alcohol systems under different conditions were constructed.Phase diagrams showed that the microemulsion domain became largeras the Tween80/alcohol weight ratio increased for i-C₅H₁₁OH.Different chain lengths of alcohols affected themagnitude of microemulsion regions and this was also dependent on the alcohol solubility in BmimPF₆.The single-phase microemulsion area decreased as the alcohol chain length increased.The single-phase region of the ethanol-containing system was the largest among the systems studied.Then,the extraction of tea protein by BmimPF₆/Tween80/alcohol systems with ultrasound assisted extraction?UAE?was investigated.BmimPF₆ concentration,the concentration of tea crude protein,ultrasonic power,extraction time and temperature have effects on the extraction efficiency of tea protein,which has been researched.Based on the single-factor experiments,the optimum extraction was obtained by the method of response surface analysis?RSA?.The results showed that the highest extraction yield of tea protein was achieved at the concentration of bmimPF₆ 0.2 mg/mL,the concentration of tea crude protein 0.1 g/mL,ultrasonic power 322W,time 67 min and temperature 50?.In this case,the tea protein extraction rate reached 59.33%.