Physicochemical Properties of Soluble Dietary Fiber from Passion Fruit Peel Based on Various Extraction Methods

In response to the significant waste of bioresources from passion fruit peels in the current market, aiming to enhance the economic benefits of soluble dietary fiber (SDF) derived from passion fruit peels in the food industry, this study extracted the SDF from passion fruit peels using six different methods and assessed how these methods affected its physicochemical properties. The results indicated that the acid-assisted extraction method (AAE-1) was the most effective at protein removal among the six methods, and the SDF derived from this method had the highest extraction yield (17.05%), cation exchange capacity (1.17 mL/g), total monosaccharide content (92.6620 µg/mg), xylose (3.2187 µg/mg), and mannose (3.7334 µg/mg). The SDF extracted by enzyme-assisted extraction method (EAE) showed the highest DPPH free radical scavenging capacity (66.67%), reducing sugar content (5.71%), oil-holding capacity (5.86 g/g), and glucose content (55.9662 µg/mg). The SDF extracted by alkali-assisted extraction method (AAE-2) provided the highest water-holding capacity (7.82 g/g), solubility (4.24 mL/g), and rhamnose content (3.0854 µg/mg). The SDF extracted by microwave-assisted extraction method (MAE) possessed the highest total sugar content (20.15%), ABTS radical scavenging capacity (65.46%), ferric ion-reducing capacity (58.83%), and galactose content (7.8912 µg/mg). The SDF extracted by hot water-assisted extraction method (HWE) of soluble fiber from passion fruit peels had the highest arabinose content (5.3775 µg/mg) and galacturonic acid content (35.6795 µg/mg), as well as the highest weight-average molecular weight (Mw) and number-average molecular weight (Mn). These findings provide a theoretical foundation for the development and utilization of passion fruit peels.