Physicochemical and functional properties of octenyl succinic anhydride-modified polysaccharides from fermented lotus...

This study aimed to develop an efficient extraction method of polysaccharide from lotus leaves, and improve the functional properties of the polysaccharide. To this end, the lotus leaves were fermented before polysaccharide extraction, and the yielding polysaccharide was chemically modified. Lactiplantibacillus plantarum Z-1 was screened as the optimal fermentation strain. Under the optimized fermentation conditions (fermentation time 3 days, temperature 37 °C, and 2% inoculum), the polysaccharide extraction yield was 5.25 ± 0.13%, significantly higher than that from unfermented lotus leaves (2.17 ± 0.12%). Modification of the fermented lotus leaf polysaccharide (FLLP) with octenyl succinic anhydride (OSA) provided OSAF1, OSAF2 and OSAF3 with degree of substitution (DS) of 0.018, 0.033 and 0.049, respectively. The NMR and FT-IR analyses confirmed the successful grafting of octenyl succinyl moieties onto FLLP. Modification of FLLP significantly enhanced its functional properties in a DS-dependent manner. The three OSAFs possessed decreased surface tension, increased zeta potential magnitude, increased viscosity, improved emulsifying and foaming properties. At a concentration of 2%, the emulsifying activity and emulsion stability of OSAF3 increased by 74.3% and 98.9%, respectively; and at 0.5%, the foaming capacity and stability also increased by 53.75% and 40.0%. The present study developed a more effective method for the extraction of polysaccharide from lotus leaf compared with the reported methods, and a protocol to improve the functional property of FLLP. This work provides scientific basis for better utilization of lotus leaf resources.