Commercial cell wall hydrolytic enzymes for producing pectin-enriched products from butternut (Cucurbita moschata, Duchesne ex Poiret) Original Research Article

A cell wall-enriched butternut (Cucurbita moschata Duch ex Poiret) powder was obtained by drying mesocarp wastes; this powder was used as the substrate for commercial cellulase (A-product) or hemicellulase (B-product) action. Yields were 4.70% and 6.12%, respectively. Both pectin-enriched products were water soluble fibers and only the latter showed important thickening effect at 20 g dm−3-concentration in water. This product was a highly methylated (methylation degree, DM, 72.6) pectin with 45.2 g/100 g of galacturonic acid and 11 g/100 g of neutral sugars. Cellulase produced intense hydrolysis leading to a less methylated (DM: 54.2) A-fraction. It was observed that not only average molecular weight, but also the molecular structure derived from chemical composition affected flow behavior and viscosity enhancing capacity. As A-fraction was enriched in rhamnogalacturonan I, probably, rhamnose kinks were responsible for the poor thickening effect at 20 g dm−3-concentration in water, in spite of its homogeneous molecular weight profile, which showed only one peak at 793,000. This fraction presented the lowest density of macromolecular interactions in water, behaving as a diluted hydrocolloid solution as confirmed by its fitting to the Cox–Merz rule. Both isolated soluble fractions produced a delay in the glucose dialysis assay.