Laboratory oven

For manual extraction, a Vortex-Genie 2 (Scientific Industries, New York, USA) was employed. The extraction tubes were put into an EBA 200 centrifuge (Hettich, Tuttlingen, Germany) for phase separation. After withdrawal of the organic phase, it was evaporated in a heating block (Barkey, Leopoldshöhe, Germany) with ten nitrogen-streamed vial positions (Linde, Pullach, Germany). Derivatization was carried out in a laboratory oven (Memmert, Schwabach, Germany).
The extracts were analyzed with an 6890 GC/5973N MSD (Agilent Technologies, Waldbronn, Germany). A 7683 autosampler was applied for injection into a hot split/splitless inlet (Agilent Technologies). Analytes were separated on an Optima 5 HT (30 m × 0.25 mm, 0.25 μm film thickness, Macherey-Nagel) column.

Pomegranate fruits (Punica granatum, L., Mollar cultivar) were directly harvested from pomegranate trees during the autumn season. Fruits were washed in cold tap water and drained, manually cut, and peeled to separate the seeds and peel. The obtained peel was cut into small pieces and dried at 70 °C for 24 h in a laboratory oven (Memmert GmbH + Co., KG, Schwabach, Germany). After drying, the peel pieces were cooled, powdered using a Grindomix GM 200 knifemill (Retsch GmbH, Haan, Germany), and stored at room temperature until extraction. The PPE was prepared by mixing 100 g of dried peel powder with 900 mL of acetone/water (70/30 v/v) at 20 °C for 2 h using a rock and roller mixer (Cole-Parmer, Staffordshire, UK). The extract was then filtered through filter paper (Whatman^® qualitative filter paper, Grade 1). Subsequently, the acetone solvent was removed using a rotary evaporator (Heidolph, Schwabach, Germany) at 30 °C, and the remaining extract was freeze-dried (SP Scientific, Gardiner, NY, USA) at −20 °C, 0.6 Pa for 72 h. The resulting freeze-dried extract was stored in a light-protected container at −20 °C until use.

The water solubility index (WSI) and water absorption capacity (WAC) of the PSPP were evaluated following the method described by Chang et al. [32 (link)] with minor modifications. One gram of the PSPP was mixed with 10 mL distilled water in a centrifuge tube in a water bath at 37 °C for 30 min before centrifugation at 3000 g for 10 min. The resulting supernatant was dried in a laboratory oven (Memmert, Büchenbach, Germany) at 105 °C for 24 h to obtain a constant dry solid weight and the weight of the precipitate at the bottom of the centrifuge tube was recorded. The WSI and WAC were calculated using the following equations: $\mathrm{WSI}=\frac{ \mathrm{residual} \mathrm{supernatant}’\mathrm{s} \mathrm{dry} \mathrm{weight} }{\mathrm{dried} \mathrm{powder}’\mathrm{s} \mathrm{weight}} \times 100$
$\mathrm{WAC}=\frac{\mathrm{weight} \mathrm{of} \mathrm{precipitate} }{\mathrm{dried} \mathrm{powder}’\mathrm{s} \mathrm{weight} – \mathrm{residual} \mathrm{supernatant}’\mathrm{s} \mathrm{dry} \mathrm{weight} } \times 100$