Optimization of ultrasound assisted extraction of functional ingredients from Stevia rebaudiana Bertoni leaves
نویسندگان
چکیده
*Corresponding author e-mail: [email protected] A b s t r a c t. The aim of the present study was to reveal an effective extraction procedure for maximization of the yield of steviol glycosides and total phenolic compounds as well as antioxidant activity in stevia extracts. Ultrasound assisted extraction was compared with conventional solvent extraction. The examined solvents were water (100oC/24 h) and 70% ethanol (at 70°C for 30 min). Qualitative and quantitative analyses of steviol glycosides in the extracts obtained were performed using high performance liquid chromatography. Total phenolic compounds, flavonoids, and radical scavenging capacity by 2, 2-azino-di-3-ethylbenzothialozine-sulphonic acid) assay were also determined. The highest content of steviol glycosides, total phenolic compounds, and flavonoids in stevia extracts were obtained when ultrasound assisted extraction was used. The antioxidant activity of the extracts was correlated with the total amount of phenolic compounds. The results indicated that the examined sonication parameters represented as the probe diameter (7 and 22 mm) and treatment time (2, 4, 6, 8, and 10 min) significantly contributed to the yield of steviol glycosides, total phenolic compounds, and flavonoids. The optimum conditions for the maximum yield of steviol glycosides, total phenolic compounds, and flavonoids were as follows: extraction time 10 min, probe diameter 22 mm, and temperature 81.2oC. K e y w o r d s: sonication, stevia, steviol glucosides, phenolic compounds, extruction efficiency
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Evaluation and comparison of different extraction methods from Stevia rebaudiana
Background and objectives: Stevia rebaudiana Bertoni is a herbaceous and a small shrub of the Compositae family. It is native to certain regions of South America. Since 1970s, Stevia extracts have been extensively used in many countries as a sugar substitute. Stevia is cultivated in many countries: Paraguay, USA, Mexico, Central America, Japan, China,...
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