EFFECT OF TREATMENTS ON PHYSICOCHEMICAL PROPERTIES OF DIETARY FIBER FROM QUINCE (Cydonia Oblonga Miller) BY-PRODUCTS.

DE ESCALADA PLA, MARINA; FISSORE ELIANA N; ROJAS ANA M; GERSCHENSON LÍA N

California, USA

Congreso; IFT 2009 Annual meeting + Food expo; 2009

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 study quince Cydonia oblonga Miller by-products physicochemical properties evaluating different ways to recover fiber rich product from quince wastes. Water washing (MA) or ethanol treatment prior a low temperature drying (ME), also a shorter but higher temperature drying (M) were alternative of processes studied. Drying was more efficient for M (80ºC, 4 h) than for MA and ME (30ºC, 24 h), as indicated by moisture contents. MA and ME showed lower free glucose contents and higher proportions of proteins than M. Fat was concentrated in MA and partially removed in ME. No significant differences were found between ash proportions neither on total phenolic compounds. Galacturonic acid (UA) was the main component of the non cellulosic carbohydrates (NC) in the cell wall material, representing more than 50% of the alcohol insoluble residue extracted from ME and MA, and more than 70% from M. MA presented the highest proportion of cellulose (12.2%). NC/UA rate, ranged between 1.36 and 1.77, and indicated that quince wastes have pectin constituted essentially by homogalacturonan, being very poor in hairy regions. M presented the lowest rate and also the lowest acetylation degree. Water or ethanol (MA or ME) pretreatment before drying affected significantly (p<0,001) the degree of methylation. An important proportion of lignin was present in the isolated quince products. ME presented the lowest true density and compressibility and no differences were observed on X-ray diffraction patterns of powder samples. Knowledge of fibre physicochemical properties and how they changed with treatments have significance for better understanding its functional behavior from nutritional view point and also technological purposes.