Effect of Temperature on Antioxidant Activity in Mulberry Leaf Tea and Mulberry Leaf Tea Powder Production

Abstract

     The objectives of this research were 1) to study the effect of drying temperature at 3 levels which are 60, 70 and 80 °C on antioxidant activity of mulberry leaf tea for 1 hour 2) to assess sensory quality and overall acceptance 3) to study mulberry leaf tea powder production 4) to evaluate the shelf life of mulberry tea and mulberry leaf tea powder. The results showed that mulberry tea was dried at 60 °C when analyzed for antioxidant activity by DPPH assay, had the highest activity of scavenging DPPH with EC₅₀ was 162.95±4.95 mg/ml, while 70 °C and 80 °C were 193.42±10.07 and 256.17±7.68 mg/ml, respectively. Moreover, overall acceptance quality of mulberry tea was dried at 60, 70 and 80 °C were like slightly. When storing mulberry leaf tea products which was drying at 60 °C for 3 months, it was found that the moisture content after storing for 0, 1, 2 and 3 months were 3.71%±0.06, 4.17%±0.04, 4.45%±0.07 and 4.55%±0.36, respectively. The total microbial were 3.8×10³, 6.8×10³, 7.8×10³ and 8.5×10³ CFU/g, respectively. Salmonella sp. and Staphylococcus aureus were not found. The results showed that when mulberry leaf tea product was stored at room temperature for 3 months, it was still safe for consumption according to Thai community product standard on dried mulberry for infusion. Production of mulberry tea powder products by freeze-drying, this study concluded that it is possible to improve the formula of mulberry leaf tea powder for future studies because mulberry tea powder was stored for 3 months, it was found that water activity was not different (p>0.05), which was in the range of 0.22-0.30. The total microbial when stored for 0, 1, 2 and 3 months were <10, <100, 3.2×10² and 3.8×10² CFU/g, respectively which according to Thai community product standard on instant mixed herbs drink.