Effect of drying temperature on antioxidant activity, phenolic compound profile and hygroscopic behavior of pomegranate peel and seed flours

Abstract

The aim of this study was to evaluate the effect of drying temperature on the quality of pomegranate peel (PPF) and seed (PSF) flours. The flours were obtained after drying the peel and seed at temperatures of 50, 60 and 70 °C until they reached hygroscopic equilibrium, were crushed and characterized in terms of phenolic compound profile, antioxidant activity and hygroscopic behaviour using water adsorption isotherms. Seventeen individual phenolic compounds were identified, quantified in PSF and 21 in PPF, with PPF having a higher phenolic content and antioxidant capacity compared to PSF; there was an influence of temperature on the profile of total phenolic compounds, with the highest concentrations being observed in samples obtained at 60 °C. All the models fitted to the water adsorption data of the PPF and PSF flours can be used to estimate the isotherms, especially the Peleg model. The PSF isotherms were classified as Type II and the PPF isotherms as Type III. The flours evaluated in this study represent an alternative for the technological and industrial use of pomegranate peel and seeds, favoring the production of new condiments with important bioactive properties.