| In recent years, more and more researches focused on the adsorption of yeast at home and abroad. But most of these researches focused on the adsorption phenomenon, especially for China,there were few studies on adsorption mechanism. In this research, the adsorption properties of preteated yeast cells on tea polyphenols (TP) were studied. The objectives of this study are to find the adsorption mechanism and influencing factors, as well as the changes in the stability and antioxidant activity of TP absorbed. And providing a scientific basis for yeast used in foods as an adsorbent.First of all, yeast cells were pre-treated by alcohol,3 % sodium chloride,alkaline protease and sodium hydroxide respectively to prepare ACY, AEY, AY and AWGP, which were used to adsorb TP in aqueous solution. The results showed as follows: 30mL,40mg/mL,pH 4.00 of TP solution, 2.00 g (md) pretreated yeast cells, adsorption time 4h and adsorption temperature 40℃, then the rate of TP adsopted (W/W) reached: ACY 98.1%,AEY 94.3%,AY 92.2%,AWGP 73.2% and the unit adsorption quantity was: ACY 319.8 mg/g, AEY 307.5 mg/g, AY 303.8 mg/g and AWGP 238.5 mg/g.The adsorption kinetics analysis showed that the processes of adsorption was in accordance with the Langmuir isotherm formula and Freundlich isotherm formula at the concentration of TP solution lower than 10 mg/mL. While the concentration of TP solution was higher than 10 mg/mL, the accordance between the theoretical curves and the test curves was unaccordant. The results illustrated that the adsorption of yeast on TP was not just monomolecular physical or chemical adsorption, and at the same time TP was adsorbed into cell interior through the cell wall and cell membrane.Secondly, the effect of pretreatment methods on cellular components and physical-chemical properties of cell surface were studied to discuss the adsorption mechanism. The results showed that yeast protein was conducive to the adsorption of yeast on TP. The results of desorption by pepsin showed that the association between TP and protein certainly affected the chemical adsorption ability of yeast cells on TP. And cells would have stronger adsorption ability with the stronger hydrophobicity, more positively charged and stronger van der Waals force of cells surface. The adsorption behavior was the result of these factors. The results further showed both physical adsorption and chemical adsorption were included in the process of adsorption of yeast cells on TP. Because of the protein and some properties of cells surface, a part of TP adsorbed on the cell surface, and more extracellular TP move into the cells by chemical adsorption of protein. The adsorption process was mainly led by surface adsorption.Thirdly, the desorption conditions were studied by static experiments as follows: 90% ethanol with 0.50 mol/L NaCl as the desorption agent, liquid ratio 1:10, desorption time 30 min, after three processes of desorption, the final desorption rates of TP were respectively up to ACY 56.25%,AEY 69.91%,AY 55.81%,AWGP 25.22%.Finally, the results of antioxidant test showed the antioxidant activity of TP was affected due to the obstacles of release and transfer. And the protein of yeast associated with some hydroxyl of TP, which also affected the antioxidant activity of TP. To a certain extent, yeast cells can play the role as microencapsules to release TP slowly in the medium. So yeast can be used as a protective carrier of TP.
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