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Pressurized hot water extraction of phenolic compounds from leaves of Stevia rebaudiana: An UPLC-ESI-MSMS study

Bioactive polyphenolic compounds are present in Stevia rebaudiana leaves and pressurized hot water was applied for their extraction. The extraction was carried out at a constant pressure of 10.34 MPa and the effects of extraction parameters, temperature (10–160°C), time (5 and 10 min) and cycles (1, 2, 3), on the polyphenolic composition and content were determined. A total of 33 polyphenolic compounds of effects of temperature and cycle number did not cause significant difference in extraction yield four major categories namely phenolic acids, flavonols, flavones and flavanols were determined in the stevia extracts using UPLC-ESI-MS2 but the main polyphenolics were mono- and diacyl caffeoylquinic acids and quercetin glycosides. The observed PHWE parameters had a statistically significant effect on extraction yield of all analysed stevia polyphenol subclasses. Cumulative of flavan-3-ols. There was no difference in phenolic acids and flavonols with prolonged static extraction time at the highest temperature. Increasing the cycle number minimizes the effect of static time prolongation. The most suitable extraction conditions of stevia phenolic acids and flavanols was found to be at the 130 °C and for flavonols and flavones at 160 °C at same extraction time of 10 min and 3 cycles.

polyphenolics ; Stevia rebaudiana leaves ; pressurized hot water extraction ; UPLC-ESI-MSMS

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