SOLUBLE FIBRE FROM BEETROOT (Beta vulgaris L. var. conditiva) WASTES

ELIANA N. FISSORE; ANA MARIA ROJAS; LIA NOEMI GERSCHENSON

Roma

Conferencia; 5th International Dietary Fibre Conference 2012; 2012

AACC -INRAN

The objective of this research was to explore the feasibility of isolation of pectin from residues of beetroot (Beta vulgaris L. var. conditiva) industrialization with the primary aim of waste upgrading. For the extraction procedure beetroots were peeled and juice was removed. The residue was washed, dried (85ºC, 2h), milled and sieved (420-710 m). The cell wall material obtained (10g) was treated with with 2 M-NaOH solution (500 mL) at 25ºC for 30 min and then filtered. The residue obtained was mixed with citrate buffer solution and the pH was adjusted to 5.2 with citric acid; the systems were then submitted to digestion with a cell wall degrading enzyme. Enzymes used were hemicellulase or cellulase (SIGMA, St. Louis, USA). The assay was performed at 30C for 20h (Fissore et al., 2011). Insolubles obtained after digestion were separated through filtration and cell wall polysaccharides were finally precipitated from each supernatant through ethanol addition (2 volumes), collected through filtration under vacuum and freeze-dried. Yields obtained were 9.6% for hemicellulase treatment and 20.7% for cellulase treatment. Both fractions were characterized by an almost total demethylation (Degree of methylation 2.5%) and deacetylation (Degree of acetylation < 2%). Hemicellulase fraction showed a total carbohydrate content of 94% with 47% galacturonic acid and 2% protein. Cellulase fraction presented 88 % total carbohydrate content with 54% galacturonic acid and 2% protein. The most important distribution of molecular weights for both fractions occurred around a broad (685-300 KDa) peak at 457 KDa. The extractive process developed permitted the extraction of products enriched in low methoxyl pectins with high yields, especially when celullase was used. These water-soluble fibre products with important molecular weights have promising chemical characteristics in relation to their use as potential thickeners in food and pharmaceutical ormulations. The results obtained contribute to the conversion of residues of beetroot into value added products and its adaptation for bioconversion of other agro- industrial residues can be performed tending to environmental protection, non-contaminating industrial procedures and optimum raw materials utilization.