Comparative study on the physicochemical and functional properties of the mucilage in the carpel of Nymphaea odorata using ultrasonic and classical heating extractions.

The cooked carpel of Nymphaea odorata has a large amount of transparent mucilage; however, the basic characteristics of this mucilage have not yet been reported. This study compared the physicochemical and functional properties of this mucilage obtained using conventional hot water extraction (HWM) and ultrasonic-assisted extraction (UAM). Neither HWM nor UAM affected the viability of mouse skin fibroblasts (NIH/3 T3) below 100 µg/mL. UAM had a higher yield production, phenol concentration, and in vitro antioxidant activity, but it had a lower viscosity and water-holding capacity than that of HWM. The Fourier transform infrared spectra revealed that the dialyzed HWM and UAM, named HWMD and UAMD, respectively, appeared to have major spectral differences at 1730 cm-1 and 1605 cm-1, implying that the degree of methylation was different between HWMD and UAMD. Compared to HWMD, UAMD in low-molecular weight polysaccharides increased. Indeed, the basic characteristics of native mucilage in the carpel of N. odorata were greatly changed by various extractions. Nevertheless, sugar analysis indicated that glucuronic acid was the main composition of HWMD and UAMD.