2.3. Non-starch polysaccharide extractionAbout 100 mg of CM of chayote fruit pulp or tuber wassoaked in 1.5 mL of sodium phosphate buffer (0.05 M; pH 6.0) andsequentially hydrolyzed with amylases and proteases. Heat-stable-amylase from B. licheniformis (10 L; Megazyme InternationalIreland; EC 3.2.1.1; 3000 U mL−1) was added to the mixture, andthe mixture was incubated at 90◦C for 1 h. The pH was adjustedto 4.5 with 0.4 M HCl, and 20 L of amyloglucosidase (from A.niger; Megazyme International Ireland Limited; Ireland; EC 3.2.1.3;3300 U mL−1on soluble starch) was added. The mixture was thenincubated at 60◦C for 1 h. At the end, the pH was adjusted to 7.5 with0.4 M NaOH, and 10 L of B. licheniformis proteases (MegazymeInternational Ireland Limited; Ireland; EC 3.4.21.14; 350 tyrosineU mL−1) was added. The mixture was then incubated at 60◦C foran additional 30 min. The hydrolyzate was centrifuged at 9000 × gfor 15 min, and the supernatant was pooled into a new flask andbrought to 80% ethanol in water (v/v), heated to 70◦C for 15 minand ice-cooled to precipitate the water-soluble polysaccharides.The water-insoluble residue was washed five times with deionizedwater, frozen in liquid N2, freeze-dried and weighed. This frac-tion was named the water-insoluble polysaccharide fraction. Theethanolic mixture was pelleted by centrifugation at 9000 × g. Theethanolic supernatant was dried, resuspended in water and ana-lyzed by HPAEC-PAD to determine the glucose released from starch.The residue was washed extensively with ice-cold 80% ethanol inwater (v/v), resuspended in water, frozen in liquid N2, freeze-driedand weighed. This fraction was named the water-soluble polysac-charide fraction.