Fig. 1. HPLC spectra of standard product（5 mg/mL）: (a) xylose; (b) xylobiose; (c) xylotriose; (d) xylotetrose

Fig. 2. Preparation of xylo-oligosaccharides from Camellia oleifera shell by irradiation-hydrothermal treatment: (a) xylo-oligosaccharides, xylose conversion and concentration ratio under different absorbed doses; (b) the concentration of xylo-oligosaccharides after irradiation-hydrothermal treatment; (c) the concentration of xylo-oligosaccharides solution after enzymatic hydrolysis; (d) inhibitors concentration in xylo-oligosaccharides solution after enzymatic hydrolysis

Fig. 3. Effect of different types of activated carbon on xylo-oligosaccharide solution: (a) the decolorization rate; (b) xylo-oligosaccharide concentration and retention; note: ^{a, b, c}, there are significant differences in the same series with different letters (p<0.05); 1 ~ 5: hydrothermal solution, enzymatic solution, HC-303 decolorizing solution, 110006619 decolorizing solution, Darco G60 decolorizing solution

Fig. 4. Effect of decolorization temperature on xylo-oligosaccharide solution: (a) the decolorization rate; (b) xylo-oligosaccharide concentration and retention; ^a,b,c,d, there are significant differences in the same series with different letters (p<0.05); 1-6: Darco G60 decolorizing solution at 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, and 80 ℃

Fig. 5. Effect of decolorization time on xylo-oligosaccharide solution: (a) the decolorization rate; (b) xylo-oligosaccharide concentration and retention; ^a,b,c,d, there are significant differences in the same series with different letters (p<0.05); 1 - 6: Darco G60 decolorizing solution at 20 min, 30 min, 40 min, 50 min, 60 min, and 70 min

Fig. 6. Effect of different amounts of activated carbon on xylo-oligosaccharide solution: (a) the decolorization rate;(b) xylo-oligosaccharide concentration and retention; ^{a, b, c, d, e}, there are significant differences in the same series with different letters (p<0.05); 1 - 5: Darco G60 decolorizing solution with activated carbon dosage of 10 mg/mL, 25 mg/mL, 50 mg/mL, 100 mg/mL, and 200 mg/mL

Fig. 7. Effect of different pH on xylo-oligosaccharide solution: (a) the decolorization rate; (b) xylo-oligosaccharide concentration and retention; ^{a, b, c, d, e}, there are significant differences in the same series with different letters (p<0.05); 1 - 5: Darco G60 decolorizing solution at pH of 2, 3, 4, 5, and 6

Fig. 8. Structure analysis of xylo-oligosaccharide in Camellia oleifera shell: (a) morphological characteristics of xylo-oligosaccharide under scanning electron microscope (a₁: 500×; a₂: 1 000×); (b) ultraviolet-visible spectrogram; (c) FTIR spectrogram

Fig. 9. Antioxidant analysis of xylo-oligosaccharide in Camellia oleifera shell: (a) scavenging effect on DPPH free radical;(b) scavenging effect on ABTS cationic free radical; (c) scavenging effect on superoxide anion;(d) scavenging effect on Hydroxyl radical