Pectic oligosaccharide production from passion fruit peel pectin using polygalacturonase from Aureobasidium melanogenum PBUAP44

Valorization of agricultural by-products offers a sustainable opportunity to reduce waste while generating high-value functional ingredients. In this study, pectic oligosaccharides (POS) were produced from pectin extracted from passion fruit peel (PFPEP) using polygalacturonase obtained from an Aureobasidium strain. Among the strains screened, A. melanogenum PBUAP44 exhibited the highest polygalacturonase activity (5.09 U/mL) and was selected for the enzyme production and subsequent application in PFPEP hydrolysis. Optimization using Box-Behnken response surface methodology shortened the required incubation period from 120 h to 95 h while maintaining enzyme activity at 5.64 U/mL, thereby increasing volumetric productivity by 40% under optimal condition (1% w/v dried passion fruit peel powder, pH 5.0). The crude enzyme showed optimal activity at pH 4.0 and 50 °C and retained over 80% of its activity after 6 h under these conditions. Enzymatic hydrolysis of PFPEP using the crude enzyme under optimized conditions (26.76 U/g PFPEP for 791.8 min) yielded POS predominantly composed of 15.56% di-galacturonic acid, with no detectable tri-galacturonic acid. This suggests the effectiveness of the crude enzymes in producing dimeric oligosaccharides. Furthermore, the produced POS significantly stimulated the growth of probiotic bacteria, Levilactobacillus brevis, demonstrating their potential as a functional food ingredient with in vitro prebiotic properties.