Gelling capacity of pectin isolated with citric acid and/or ultrasound

ZUKOWSKI, ENZO; CASTELLARIN, IVANA; GERSCHENSON LÍA N; FISSORE ELIANA N

Conferencia; e-Conference on Food Texture and Rheology; 2019

Orange (Citrus sinensis) juice industry generates peel residues which are sold for the extraction of pectin or used for animal consumption. Pectin is a family of polysaccharides found in the cell walls of plants used by many food and cosmetic industries as a gelling and thickener agent. This work evaluates the effect on the rheological behavior of the use of ultrasound as a pre-treatment for the extraction of pectin from orange residue, comparing the rheological behavior of pectin fractions isolated from orange albedo and pulp by extraction with citric acid. The oranges were processed discarding the flavedo and the juice. The albedo was separated from the pulp and both tissues were dried in an oven. Albedo (A) and pulp (P) powders (5g) were added to citric acid solutions (150ml, pH 2.3) at 85°C for 60min with or without an ultrasound (US) pre-treatment (10min, 80% amplitude, 20kHz, 750W, Sonics VCX-750, USA). The insoluble residues were separated by centrifugation. The supernatants were precipitated with 96% ethanol, filtered and lyophilized. Fractions obtained were: A1 (albedo, no US), P1 (pulp, no US), A2 (Albedo, US), P2 (pulp, US).The gelling capacity of the isolated fractions was evaluated through dynamic rheology.Pectin degree of methylation (DM) defines its mechanism of gel formation. High DM pectins (DM>50%) form gels in aqueous systems with high contents of soluble solids (>65%) and low pH values (2.0-3.8).Low DM pectins (DM