Abstract:

Objective: To optimize the microwave-ultrasonic assisted extraction of polysaccharides from bamboo shoot shell
and assess the antioxidant capacity in vitro of the extracted polysaccharides. Methods: The effects of extraction time, solid
to liquid ratio, microwave power, ultrasonic power and extraction time on the extraction yield of polysaccharides were
investigated. Based on the results of single-factor experiments, orthogonal array experiments were carried out to determine
the optimum process parameters. The antioxidant capacity of bamboo shoot shell polysaccharides was evaluated by the
scavenging activities against hydroxyl (OH·), superoxide anion (O2-·) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free
radicals, and compared with hot water-extractable polysaccharides from bamboo shoot shell. Results: The best conditions
for microwave-ultrasonic assisted extraction were determined as follows: extraction time, 30 min; solid to liquid ratio,
1:30 (g/mL); microwave power, 200 W; and ultrasonic power, 750 W, leading to an extraction yield of 2.76% and a
polysaccharide content of 37.63% in the crude extract. The half-inhibitory concentration (IC50) values for OH·, DPPH and
O2-· free radicals were 0.17, 0.43 mg/mL and greater than 16 mg/mL, respectively. Microwave-ultrasonic assisted extraction
was better than hot water extraction in terms of antioxidant activity. Conclusion: Compared with hot water extraction,
microwave-ultrasound assisted extraction is time saving and reveals higher extraction yield. In addition, water-extractable
polysaccharides from bamboo shoot shell have significant antioxidant activity in vitro.

Key words: bamboo shoot shell, polysaccharides, extraction, microwave, ultrasonic extraction, antioxidant activity