Characterization of Auricularia auricula polysaccharides and its antioxidant properties in fresh and pickled product

The study planned to determine proximate composition, antioxidant activity and chemical characterization in the fruit bodies of Auricularia auricula and pickled product. Two polysaccharide fractions (AAPF, AAPP) were purified from the fruiting body of A. auricula by ethanol precipitation, deproteination and macroporous resins and were subsequently lyophilized. The results showed that AAPF consisted of five monosaccharides, including glucose, rhamnose, arabinose, mannose and galactose with a molar ratio of 16.74:1.0:1.18:1.0:1.0; in contrast, AAPP was composed of four monosaccharides, namely arabinose, mannose, galactose and xylose with the molar ratio of 15.59:1.52:4.76:1.0. AAPF and AAPP were characterized by Fourier Transform Infrared spectroscopy (FTIR), which indicated peaks at approximately 3500 cm−1 and 522.28 cm−1 in the carbohydrate region and composed of β-glycoside linkages at the 1200–1000 cm−1 peaks. However, the antioxidant activity of AAPF demonstrated a significant result in scavenging free radicals except for DDPH. The in vitro test indicated that AAPF and AAPP have good antioxidant activity, demonstrating that A. auricula polysaccharide has immense potential as a functional food.