Enzymatic extraction of pectic oligosaccharides from finger citron ( Citrus medica L. var. sarcodactylis Swingle) pomace with antioxidant potential

Food Funct. 2021 Oct 19;12(20):9855-9865. doi: 10.1039/d1fo01576a.


Finger citron pomace is a cheap and renewable by-product of the citrus processing industry, representing up to 60% of the fruit biomass. In this study, a pectinase-based and ultrasonic-assisted method was firstly used to extract pectic oligosaccharides (POS) from finger citron pomace. Using the orthogonal experiment design (OED), the maximum conversion rate of up to 64.5% from pomace to POS was obtained under the extraction conditions of 0.25 mg mL-1 pectinase and 50 mg mL-1 pectin at 45 °C and pH 4.5 for 2 h. The extracted POS was then fractionated and purified to homogeneous oligosaccharides (FCPOS-1) with a molecular weight of 2.15 kDa, and the analyses of monosaccharide composition, FTIR, NMR and ESI-MS indicated that FCPOS-1 consisted of GalA and a small amount of mannose, galactose and arabinose. Multiple antioxidant activity assays in vitro revealed that FCPOS-1 possessed remarkable antioxidant properties, especially scavenging activity against DPPH radicals up to 94.07%. FCPOS-1 has the potential to be an effective natural antioxidant for applications in the food and pharmaceutical industries.

MeSH terms

  • Antioxidants / pharmacology*
  • Arabinose / analysis
  • Chemical Fractionation / methods
  • Citrus / chemistry*
  • Fruit / chemistry
  • Galactose / analysis
  • Humans
  • Magnetic Resonance Spectroscopy / methods
  • Mannose / analysis
  • Molecular Weight
  • Oligosaccharides / isolation & purification*
  • Oligosaccharides / pharmacology*
  • Pectins / isolation & purification*
  • Polygalacturonase / metabolism*
  • Spectroscopy, Fourier Transform Infrared / methods


  • Antioxidants
  • Oligosaccharides
  • Pectins
  • Arabinose
  • Polygalacturonase
  • Mannose
  • Galactose