Release of antioxidant compounds of Zingiber officinale by ultrasound-assisted aqueous extraction and evaluation of their in vitro bioaccessibility

Ginger rhizome is widely used in culinary preparations and in traditional medicine. Its benefits are associated with its antioxidant properties related to phenolics and terpenoids compounds, which use to be thermolabile. Ultrasound-assisted extraction has been useful for enhancing the release of thermosensitive compounds present in vegetable tissues. Therefore, the aim of this study was to evaluate the influence of ultrasound-assisted extraction on the release of antioxidants from ginger in aqueous media as well as their in vitro bioaccessibility. Central composite rotatable design was applied to obtain the optimal conditions for the extraction; the variables studied were amplitude (80-90%) and temperature (30-50 C). Total phenolic content, antioxidant capacity (DPPH, ABTS+ and FRAP), and in vitro bioaccessibility were determined. Amplitude was the main parameter influencing the extraction of antioxidants. The ginger aqueous extracts showed a bioaccessibility of around 30%. The release of antioxidant compounds from ginger by ultrasound-assisted extraction avoids the use of high temperatures and solvents commonly used in conventional extraction methods.