Optimized spouted bed production of antioxidant dried powder from green tea

Abstract

This study evaluated the feasibility and optimization of the spouted bed drying to produce standardized dried Camellia sinensis extract. We explored processing variables such as inert particle type (Teflon^® or glass beads), drying aid concentration (colloidal SiO₂—Aerosil 200^®), and drying inlet temperatures (80, 110, or 140 °C). Regression analysis of the results allowed for constructing response surface graphs, highlighting variable impacts on product properties and spouted bed performance. The optimal conditions involved Teflon^® beads and a drying temperature of 110 °C, resulting in a product with excellent moisture content, water activity, and active constituent retention. The product demonstrated significant antioxidant activity in DPPH assays, with an IC₅₀ between 4.4 to 6.7 µg/mL, surpassing the synthetic antioxidant butylated hydroxytoluene (BHT), which had an IC₅₀ of 12.5 µg/mL. Rancimat assays showed that the dried extract effectively protected crude sunflower oil from oxidation, increasing its shelf life from 8.2 to 13.1 months.

Keywords:

• Antioxidant activity
• Camellia sinensis
• drying
• experimental design
• extraction
• spouted bed

Acknowledgement

The authors would like to thank the São Paulo Research Foundation (FAPESP)—Grants 2018/26069-0 and 2021/08152-0, and the National Council of Research and Development (CNPq) for the fellowship to the first author.

Disclosure statement

The authors report no conflict of interest.