FIBER ENRICHED PRODUCTS OBTAINED THROUGH ENZYMATIC TREATMENT OF Cucumis moschata, Duch. WASTAGE

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

Helsinki, Finlandia

Congreso; Dietary Fiber 2006 Multifunctional Complex of Components. http://viikki.helsinki.fi/df2006/index.htm; 2006

AACC, ICC, Academy of Finland, University of Helsinki.

In Argentina, the consumption of calabacita criolla (Cucumis moschata, Duch.) is very popular since it can be used for preparing either sweet or salty foods. The aim of this work was to enzymatically isolate and characterize fiber-enriched products obtained from left over of this pumpkin industrialization. Water was removed from mesocarp through a juice extractor. Residue was washed twice, dried (85ºC, 2 h), milled and sieved. This powder was digested (20 h, 30ºC) under stirring into a 0.5 M-sodium citrate buffer (pH 5.2) without (B) or with a cell wall (CW) enzyme (hemicellulase H, or cellulase, C). Insolubles were separated and CW polysaccharides (CWP) precipitated from supernatant after ethanol addition: B, H and C-products. They were filtered, freeze-dried and dialysed. Total carbohydrates (TCC), galacturonic acid (GAC), methanol and protein contents were determined and degree of methylation (DM) was calculated. Neutral sugars (NS) were determined by GLC of alditol acetates. H-product presented a TCC and GAC (from homogalacturonans, HG) of 91 and 10%, respectively, the latter with 64%-DM. Hence, the high proportion of NS (97%) mostly consisted of glucose (Glc) with only 1% of Arbinose (Ara) and traces of Rhamnose (Rha), Xylose ( Xyl), Mannose (Man) and Galactose (Gal). C was mainly constituted by Rha (23%), Gal (25%), Ara (16%) and Glc (17%), with Xyl (6%) and Man (9%). Residual Glc may come in part from cellulose after cleavage by cellulase. Enzyme produced total hydrolysis of cellulose framework, leading free pectins and a little part of hemicelluloses to be solubilized into buffer (pH 5.2), which in addition produced rupture of ionic bonds and calcium bridges due to its chelating effect. C obtained after ethanol addition presented 80% of TCC and 75% of GAC (60%-DM). C was then mainly constituted by RG I and RG II, the latter detected by presence of 2-Me-Fucose and 2-Me-Xylose. B-product obtained under the effect of buffer extraction permitted us to extract pectins bound to CWP by ionic bonds and Ca-bridges. Probably, a certain degree of glycosidic bonds might also be broken through elimination reaction, especially the backbone of methyl-esterified pectins. B was also mainly constituted by RG I and II, but showing a higher proportion of GAC to Rha (17:1) than the one observed for C (11:1). B rendering was the lowest one observed. B, H and C were water soluble after swelling and showed different thickening properties.