| In this paper,50% ethanol was used as desorption solution, to optimize regeneration conditions for tea waste with ultrasonic and microwave assisted. And on this basis, use the optimal condition to regenerate tea waste with catechins, with two selective catechin adsorbent lignocellulose and PVPP. Then evaluate the regeneration performance of these three adsorbent through adsorption quantities, adsorption rate, desorption quantities, desorption rate, regeneration efficiency and surface properties. Moreover, this study also made an inquisition of applied the adsorption performance of tea waste to relace the inedible adsorbents like PVPP. Stored up the adsorption tea in 40?, and measured inclusion and chroma values, light transmittance change of tea infusion to evaluate preservation effect of adsorbed tea infusion; the dynamics model of tea color changes was also established in this study, to provide guidance for the color control of tea infusion. The results are as follows:Ultrasonic treatment had a significant effect (P< 0.01) on catechin and caffeine desorption of tea waste, while HPLC detection of microwave treatment was not significant, also the microwave process may not conducive to the collection of catechins. The optimal condition for ultrasonic treatment was 25?,40% ultrasonic frequency, and adsorbed for 30minutes. The desorption rate of ECGC and T-C was 87.54% and 87.32% respectively on this condition. Kinetic fitting of ultrasonic regeneration process, the results more in line with the pseudo-first-order kinetics equation, and the desorption efficiency of ester catechins was higher.2) Using 50% ethanol ultrasonic assisted regeneration showed that after six times regeneration, yield of PVPP was lower than tea waste and lignocellulose, and the adsorption rate of EGCG and total catechin were 89.21% and 81.73%by tea waste,85.02% and 76.94% by lignocellulose,59.41% and 60.79% by PVPP respectively.3) Ageing treatment resulted that the stored for 15 days after the three treatment and control have a significant difference (P< 0.01) on EGC, C, EC, EGCG, T-C content. The sequence of catechins in content was CK (477.99mg/L)> lignocellulose (324.71mg/L)> tea waste (155.08mg/L)>PVPP(47.52mg/L). Improvement to the color of tea infusion was PVPP> tea waste> lignocellulose. Kinetic results showed that tea color change is more in line with the zero order kinetics model. After 15 days of storage, concentration of amino acid was higher than other treatments with tea waste adsorbed. Pearson correlation analysis results show that tea catechins have significant correlation with colorimetric parameters L, a,b and h°, especially ECGC and GCG, it showed that the selective adsorption of catechins by tea waste and lignocellulose has more advantages to improve the tea color and light transmission rate of tea infusion compared with PVPP.4) 60min was the best adsorption timefor tea waste. After 15 days of storage, total catechins concentration with 60min adsorption treatment was 341.05mg/L, is about 70% of the control group; also it could reduce the colorimetric parameters L, a,b and h°, significantly; the light transmittance was more than 60%, which was significantly higher than control (32.48%). In summary, adsorbed 60minutes is superior to other treatments. |
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