Abstract:

In the present study, food-grade tertiary calcium phosphate (TCP) and 731 type anion exchange resin were selected out of 11 kinds of adsorbents as better ones towards fluoride in the infusion of traditional Tibetan Bian tea. To prepare lowfluoride Bian tea cream, equilibrium and kinetic studies of fluoride from Bian tea infusion with a fluoride of 7.18 mg/L were made, and the technological conditions of TCP adsorption for reducing fluoride were optimized by orthogonal array design method. Meanwhile, the Bian tea cream prepared based on optimized fluoride reduction process was evaluated for its sensory quality. TCP was found to have stronger ability to adsorb fluoride at high temperature, with a saturated adsorption quantity of over 10.63 mg/g. The best process parameters for TCP adsorption towards fluoride were as follows: tea infusion temperature 100 ℃; TCP loading 0.7 g/100 mL; and adsorption time 20 min, and the resulting removal rate of fluoride from Bian tea infusion was up to 95.80%. After the reduction of fluoride, concentration was done to obtain a low-fluoride tea cream. The product exhibited a fluoride content of 66.52 mg/kg, 94.80% lower than that of the control (directly concentrated without fluoride reduction), and its redilution had the characteristics of brilliant red color, strong stale flavor, and pure and mild taste.

Key words: low-fluoride Bian tea cream, tertiary calcium phosphate, adsorption for reducing fluoride