Drying of Stevia leaves using laboratory and pilot scale dryers

A. Samsudin and I. Ab. Aziz

Abstract

Drying at temperatures of 50 – 60 °C was an effective method in removing moisture content of Stevia plants. At this temperature, the quality of dried leaves produced in terms of colour, sweetness and nutrient content was better compared with drying at 70 °C. The drying process took 5 to 6 h using a laboratory dryer and more than 7 h using a pilot scale dryer to reduce the moisture content from 80% to 3 – 5%. A total of 72 – 74% dried leaves were obtained after threshing the final dried samples. The dried leaves had a brighter (L*), greener (a*) and slightly yellow (b*) colour with values of 54, – 3.0 and 9 respectively, when dried at 50 °C compared to samples dried at 60 – 70 °C. Dried Stevia leaves contained stevioside and various types of nutrients and minerals. In every 100 g of dried leaves, there were 16 g protein, 65 g carbohydrate, 2,805 mg potassium, 620 mg calcium, 268 mg phosphorous and 16 mg vitamin C. Dried Stevia leaves also contained soluble sugars at 5 – 7% brix with pH around 6.

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