Extraction methods and characterization of pectin from passion fruit (Passiflora edulis f. edulis) peels grown under Mediterranean climate conditions

In recent years, recognition of the purple passion fruit (Passiflora edulis f. edulis) has gained significant traction. Given its widespread application in the food industry, extracting pectin from the resultant waste fractions is of significant importance for sustainability and the global economy. In this study, pectin from passion fruit cultivated under Turkish (Gazipaşa) climatic conditions —for the first time in the literature— was extracted using four different methods to determine the optimum extraction technique. Conventional acid extraction (95 °C, 60 min), microwave-assisted extraction (600 Watt, 9 min), ultrasound-assisted extraction (85 °C, 30 min, 37 kHz), and ultrasound-assisted conventional acid extraction (95 °C, 30 min followed by 30 min, 37 kHz) were selected for pectin production. Citric acid (pH 2.0) and a solid-liquid ratio of 1:30 were maintained constant across all methodologies. The physicochemical properties of the pectins were characterized through analyses of yield, moisture content, degree of esterification (DE), galacturonic acid content (GA), color values, water and oil holding capacities (WHC/OHC), and total antioxidant capacity. The results indicated that all pectin samples possessed a high degree of esterification. No statistically significant differences were observed among the extraction methods regarding yield (10.98%–15.97%) and moisture (3.80%–5.85%) contents (p>0.05). While pectin produced via ultrasound-assisted extraction yielded the highest DE, GA content, and OHC (p<0.05), pectin obtained through microwave-assisted extraction exhibited the highest WHC and total antioxidant capacity (p<0.05). The pectins demonstrated superior characteristics compared to commercial pectin. The identity of the products as pectin was verified by the presence of specific bands in their FTIR spectra. Considering reduced processing time and resultant physicochemical properties of the pectins, the microwave-assisted method shows significant promise.