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Ultra and microfiltration of yacon juice (Polymnia sonchifolia) in obtainment of rich contents of fructans syrup.
Authors: Cristiane Fátima Gibertoni, Andressa Milene Parente Nogueira, Waldemar Gastoni Venturini Filho
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This work aimed the production of rich fructan syrup from yacon juice cleared in ceramic membranes of ultra and microfiltration. An initial assay with yacon juice whose roots haven’t undergone whitening process has shown that although there had been clarification of the permeate due to tangential filtration, there had been enzymatic dark of root resulting in darker products than the ones from whitened roots. The following assays evaluated the ultra and microfiltration processes using temperatures of 20, 40, 60 and 80°C where it was observed the increase of the permeate flow because of the temperature boost. The 40°C temperature was chosen to continue the work. Transmembrane pressures of 2 and 4 bar were combined with tangential speeds of 2 and 4 m/s showing that the combination of 2 bar pressure and 4 m/s tangential speed resulted in higher permeate flow. The best combinations of temperature, transmembrane pressure and tangential speed were used in tests of retentate concentration (up to 6) with decrease of 31% and 33% in the permeate flow, respectively, in micro and ultrafiltration. Physical-chemical analysis showed total solid accumulation and higher values of total acidity in the retentates of ultra and microfiltration as well as the tendency of lower values of soluble solids, ashes and gross protein of permeate compared with the retentates. On the other hand, ultra and microfiltration did not alter the carbohydrate composition. Permeates from tests of retentate concentration were concentrated up to 74.5-81.0°Brix to obtain syrup with no carbohydrate hydrolysis in this process. Ultra and microfiltration processes were efficient for clarifying the yacon juice and the root whitening process assured the production of rich fructan syrups.