Effect of blanching, drying and preservation of dried wax apple (Syzygium samarangense) leaf tea

Wax apple (Syzygium samarangense) is now widely cultivated in Vietnam. Its leaf has a source of antioxidant, cytotoxic activities by acylphloroglucinol derivatives. Leaf of S. samarangense has antibacterial, antidiabetic, anti-diarrheal, analgesic, antiinflammation and immunostimulant activities. Objective of this study focused on the effect of blanching temperature and time; heat pump drying temperature and storage condition to total phenolic content and sensory score of the dried wax apple (S. samarangense) herb tea. Results showed that S. samarangense should be blanched in hot water 95°C at 15 sec in ascorbic acid 1.5% and then being dried by heat pump dryer at 50°C until 18% moisture. The final herbal tea could be preserved under vacuum in PET/AL/PE bag at 4°C to maintain total phenolic content for 12 months.