Studies on extraction of stevioside from stevia (Stevia rebaudiana Bertoni) leaves
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Date
2014
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Punjab Agricultural University, Ludhiana
Abstract
A study was conducted on Stevia rebaudiana Bertoni leaves in order to study the impact of varying process conditions on stevioside extraction. Four experiments were conducted by varying three factors viz. time, temperature/power and leaf-solvent ratio to three levels. In first experiment, levels of time were 20, 70 and 120 min, temperature were 30, 60 and 90°C and leaf-water ratio were 1:5, 1:15 and 1:25. In second experiment, methanol was used as a solvent with levels of time as 10, 25 and 40 min, levels of temperature as 30, 45 and 60°C and leaf-methanol ratio as 1:5, 1:7.5 and 1:10. In third and fourth experiment, microwave was used as source of power. In both experiments, time and power were varied as 0.5, 1.25 and 2.0 min and 180, 540 and 900 watt. In experiment where water was used as solvent, leaf-solvent ratio was varied as 1:5, 1:15 and 1:25 and with methanol it was varied as 1:5, 1:7.5 and 1:10. The extraction conditions were optimized keeping in consideration five responses, namely Stevioside content (%), Color (A420), Sugar content (%), TSS (°Brix) and pH using Response Surface Methodology. Stevioside content increased with extraction time up to 70 min, temperature up to 77°C and leaf-water ratio up to 1:16 with water and increased with time, temperature and leaf-methanol ratio up to 21 min, 53.5°C and 1:7.6 when methanol was used. When microwave assisted extraction was performed using water as a solvent, stevioside increased with time, power and leaf-water ratio up to 1.12 min, 635 watt and 1:18 respectively. With methanol it increased with time, power and leaf-water ratio up to 1.09 min, 696 watt and 1:7.7 respectively, and decreased afterwards. Microwave assisted extraction using water was found to be most suited method for stevioside extraction from Stevia rebaudiana Bertoni leaves yielding highest stevioside content.
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Keywords
Processing and Food Engineering, stevia leaves, Food Science and Technology, Stevioside, Stevia rebaudiana Bertoni, Sweeteners