Characterisation of Fiber Obtained from Pumpkin (Cucumis moschata duch.) Mesocarp Through Enzymatic Treatment

E.N.FISSORE; N.M.PONCE; C.A.STORTZ; A.M.ROJAS; L.N.GERSCHENSON

FOOD SCIENCE AND TECHNOLOGY INTERNATIONAL

SAGE Publications

Lugar: Londres; Año: 2007 vol. 13 p. 141 - 151

1082-0132

Cell wall-enriched pumpkin (Cucumis moschata, Duch) powder was submitted to enzymatic hydrolysis by cellulase or hemicellulase in order to evaluate the performance of these cell wall-degrading enzymes on that substrate. Different enzyme-substrate ratios were evaluated and the effect exerted by the buffer on cell wall polysaccharides. Cellulase produced the release of pectin macromolecules which include homogalacturonans side chains, the rhamnogalacturonan I core, and the rhamnogalacturonan II, in conjunction with xylogalacturonans. The content of galacturonic acid in product ranged from 545 to 781 g/kg of fiber. Hemicellulases produced intense pectin hydrolysis leading to fiber-fractions with galacturonic acid contents ranging from 390 to 444 g/kg of fiber and enriched in glucose polymers as the enzyme proportion increased. Few rhamnogalacturonan I was present. The acidic citrate buffer (pH 5.2) used for allowing enzyme activity could per se remove noncovalent cross-links like ionic bonds. As a consequence, pectin-in-extensin entanglements, pectins joined by Ca-bridges through the homogalacturonan side chains, and some pectins that are originally soluble in cold water due to little or no binding to the cell wall, could be removed by this citrate buffer. Enzymatic hydrolysis as well as buffer extraction produced fiber products with an important thickening effect of aqueous systems. This effect was smaller as the ratio enzyme-substrate was increased and, in general, the fiber fractions isolated produced an in vitro glucose diffusion retardation.