Production of High-Aroma Instant Tea Powder Using Various Novel Technologies

Various nonthermal processing technologies were applied, including pulsed electric field (PEF) technology, freeze concentration and vacuum freeze-drying. The black tea was extracted with hot water extraction, cold extraction and PEF extraction. Results indicated that PEF-assisted extraction had the best extraction efficiency for the main chemical components from tea at lower temperatures. Optimal PEF extraction conditions were achieved (tea leaves/water ratio of 1:16, electric field strengths of 20 kV/cm and pulse frequency of 125 Hz). The effects of PEF-assisted extraction on the chemical component contents and sensory qualities of the tea infusion were investigated. Results showed that extraction yield (22.7%) of black tea powder could be enhanced over PEF-assisted extraction, whereas its original flavor could be retained by freeze concentration and vacuum freeze-drying. It also turned out that a total of 61 major aromatic compounds were identified in the tea powder. Floral and sweet flavor components were high and pure. Practical Applications Instant black tea is presently manufactured through hot water extraction or cold-water extraction from the tea infusion and by spray/freeze-drying of the concentrated brew of extracted tea leaves; the drawback of this method is inferior quality. The product obtained from the new method had an excellent quality and good aromatic characteristics to the other ordinary instant black tea powder manufacturing methods. The process developed in this study could be suitable for black tea manufacturers to produce high-aroma instant black tea powder.