Radical scavenging activity of an inulin-gallic acid graft and its prebiotic effect on Lactobacillus acidophilus in vitro growth

Abstract

In order to generate a new antioxidant and prebiotic dietary fibre, gallic acid (GA) was grafted onto native inulin. Inulin-gallic acid (IGA) graft was confirmed by UV and infrared spectroscopy (FT-IR). The antioxidant activity was evaluated by spectroscopic methods and the prebiotic activity of IGA was determined by In-Vitro growth of Lactobacillus acidophilus. UV spectra show absorbance peaks at 214 and 266–268 nm showing aromatic ring presence in the IGA graft and FT-IR spectra showed a band at 1743 cm−1, confirming the covalent bond between the polymer and GA. GA provides a significant antioxidant capacity to IGA graft. Inulin shows a significant capacity to stimulate the growth of L. acidophilus and GA grafted onto inulin (16.3 mg/g polymer) does not interfere with its prebiotic capacity. It is possible to provide radical-scavenging capacity to inulin-type fructo-oligosaccharides avoiding the decrease of its prebiotic properties, which could extend their potential use as functional foods.

Keywords

• Inulin
• Molecular grafting
• Prebiotics
• Radical scavenging activity