Ultrasound-assisted ethanolic extraction of punicalagin from pomegranate by-products influenced by cultivar, pre-drying treatment, particle size, and temperature

Abstract

The novelty of this research is to describe the effect of different ultrasound-assisted extraction operating conditions on the punicalagin (∑Pn) and total phenolic content (TPC) yield of pomegranate peel of two cultivars: Wonderful (W) and Mollar de Elche (ME). Besides cultivar, drying method (convective and freeze drying), particle size (<56 and 56–101 μm), extraction temperature (25 and 45 °C) and time (0–60 min) were categorical variables included in the experimental design to optimize the process using a polynomial regression model. Both ∑Pn and TPC extraction was higher in freeze-dried than in convectively dried samples. Although the interaction of the above-mentioned variables must be considered, the type of drying influenced the extraction of ∑Pn between cultivars, being higher in ME than W when the material was freeze-dried. For the smallest particle size and higher temperature (45 °C), the extracted ∑Pn and TPC was higher than samples with higher particle size and lower extraction temperature (25 °C).