Standardization of Vacuum Drying Conditions Based on Biochemical Composition of Pomegranate Peel for Polyphenol Extraction

Abstract:

Pomegranate (Punica granatum L.) peel is a nutrient-rich agro-industrial by-product, valued for its high concentration of polyphenols and antioxidant compounds. However, these bioactive constituents are sensitive to thermal degradation, necessitating the standardization of drying techniques. This study was conducted to optimize vacuum tray drying conditions for the Mridula variety of pomegranate peel to maximize the retention of total phenolic content (TPC). Pomegranate peels were subjected to vacuum drying at -600 mmHg pressure across three temperature levels (40 °C, 50 °C, and 60 °C). The influence of these temperatures on moisture reduction, TPC, and overall antioxidant activity was systematically evaluated using a Completely Randomized Design (CRD). Results indicated that drying temperature significantly influenced phenolic retention (p < 0.05), with TPC decreasing as the temperature increased from 40 °C to 60 °C. The highest TPC yield of 242.15 ± 3.56 mg GAE g⁻¹ was achieved at 40 °C, identifying this as the optimal processing condition. These findings provide a scalable, effective method for preserving the functional quality of pomegranate peel powder for nutraceutical and food industry applications.