CONICET | Buscador de Institutos y Recursos Humanos

By-products of vegetable-food processing represent a major disposal problem for the industry and its transformation into value-added products, as fibers are, may contribute to diminish pollution and to recover valuable biomass and nutrients. The aim of this work was to: i)evaluate different techniques for the isolation of fiber rich products isolated from quince (Cydonia oblonga Miller) by-products of industrialization and ii) study the chemical composition and physicochemical properties of that products. Water washing (MA) or ethanol treatment (ME) prior to a low temperature drying or a direct drying at high temperature (M) were the processes studied.. MA and ME powders showed lower free glucose contents and higher contents of moisture and proteins than M. Fat was more concentrated in MA and partially removed in ME. No significant differences between products were found in ash or total phenolic contents. Uronic acids (UA) were the main component of the non-cellulosic carbohydrates (NC) in the cell wall material, representing more than 50% of the alcohol insoluble residue (AIR) extracted from ME and MA, and more than 70% of the one of M. MA presented the highest proportion of cellulose (12.2%). NC/UA ratio, ranged from 1.36 to 1.77; M presented the lowest ratio fact that indicated that this fraction had pectin macromolecules essentially constituted by homogalacturonan. It also showed the lowest acetylation degree. Water (MA) or ethanol (ME) pretreatment before drying affected significantly (p<0,001) the degree of pectin methylation. An important proportion of lignin was present in the isolated products. ME powder presented the lowest true density and compressibility and no differences were observed on sample X-ray diffraction patterns. Knowledge acquired will help in determining the possibilities of product application for technological purposes as well as their nutritional potential.

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