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Proanthocyanidin content in Stevia rebaudiana Bertoni leaves obtained by accelerated solvent extraction (ASE)

Proanthocyanidins (PA) or condensed tannins are polyphenolic compounds, oligomers or polymers of flavan-3-ol units, widely distributed in plant foods. In recent years, considerable attention has been drawn to PAs because of their potential health benefits such as antioxidant and radical scavenging functions, anti-inflammatory activities, cardio-protective properties, etc. Therefore, it is essential to evaluate the PA content of foods/extracts in order to estimate their significance for human health. Besides having a high level of sweetening compounds (steviol glycosides), Stevia Rebaudiana Bertoni leaf extracts are multifunctional source of natural antioxidants such as: flavonoids, phenolic acids, proanthocyanidins, fatty acids, proteins, and vitamins. Due to the high content of various phytochemicals, stevia extracts possess antioxidant, antimicrobial, antifungal and other health-beneficial activities. Consequently, the content of a broad range of biologically active compounds marks stevia leaves as a valuable ingredient for functional food products. Considering all of the above, the aim of this study was to evaluate the content of PA in the water extracts of Stevia rebaudiana Bertoni leaves. Extracts were obtained by accelerated solvent extraction (ASE) under different extraction temperatures (100-160 ºC), extraction times (5 and 10 min), and cycle numbers (1, 2 and 3). When looking at the influence of extraction temperature, obtained results indicated that temperature of 160°C provided the highest content of PA, as well as the longer extraction times. Furthermore, increased number of cycles provided more of the PA for all temperatures, but only for 2 cycles after which content of PA remained the same. Number of cycles per length of static time showed no influence on the amount of PA.

Stevia rebaudiana Bertoni leaves; water extract; proanthocyanidins; accelerated solvent extraction (ASE)

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