Optimization of green tea extracts spray drying as affected by temperature and maltodextrin content
2016
Susantikarn, P. | Donlao, N.
The optimum spray drying condition of green tea extract was investigated in this study. Dried green tea leaves samples were ground using a hammer mill and passed through a 5 mm mesh. One kilogram of product was extracted with 20 L of 90°C water for 60 minutes. Solids were filtered off, extract was concentrated to obtain solution containing 10% total solid using a vacuum evaporator. The concentrated extract was then mixed with maltodextrin at a ratio of 3, 5 and 7% (w/v), respectively. The solutions were subjected to spray drying at 170, 190 and 210°C, with 80°C outlet temperature. The tea powder were collected and kept in aluminum foil bags for analysis. The results revealed that moisture content and total phenolic content of samples were varied in the range of 4.40-4.87% and 14.78-20.37%, respectively. Water activity, solubility, hygroscopicity and bulk density of the samples were varied in the range of 0.21-0.29, 94.76-98.53%, 8.61-13.72% and 0.36-0.48 g/ml, respectively. Color value of tea powder ( L *, a and b) are 30.31-32.84, 1.89-2.59 and 8.61-9.62, respectively. Based on the results it was suggested that spray drying at 210°C with 3% maltodextrin content was produced good properties of green tea powder.
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