Pectic oligosaccharides hydrolyzed from orange peel by fungal multi-enzyme complexes and their prebiotic and antibacterial potentials

• Hydrolysis of orange peel wastes and prebiotic and antibacterial potentials were investigated.
• Membrane separation was used for fractionation of the hydrolyzate.
• Pectic oligosaccharides with MW of 1–3 kDa showed prebiotic property.
• Pectic oligosaccharides with MW of <3 kDa showed higher antimicrobial activities.

Orange peel wastes were enzymatically depolymerized into pectic oligosaccharides (POS) by multi-enzyme complexes from Aspergillus japonicus PJ01. The hydrolyzate was fractionated via membrane separation into three fractions: POS1 <1 kDa; 1 kDa < POS2 < 3 kDa; POS3 > 3 kDa. Compositional analysis showed that these fractions were rich in glucose, arabinose, and galacturonic acid. The prebiotic potentials of these fractions were evaluated via single culture with Bifidobacterium infantis, Lactobacillus acidophilus, Clostridium perfringens, and Bacteroides fragilis. Results showed that POS2 had higher prebiotic property than POS1 and 3, and it was comparable to fructooligosaccharide. In mixed culture, POS2 showed positive effect on B. infantis, while negative effect on B. fragilis according to the results of real-time quantitative PCR analysis. The antimicrobial activities of the POS were examined by typical bacteria Staphylococcus aureus, Bacillus subtilis, and Escherichia coli. Results showed that POS1 and 2 had higher antimicrobial activities than POS3.

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