title: Extraction and quantification of SO2 content in wines using a hollow fiber contactor.
abstract: Sulfites [Formula: see text] or sulfur dioxide (SO2) is a preservative widely used in fruits and fruit-derived products. This study aims to propose a membrane contactor process for the selective removal and recovery of SO2 from wines in order to obtain its reliable quantification. Currently, the aspiration and Ripper methods offer a difficult quantification of the sulfite content in red wines because they involve evaporation steps of diluted compounds and a colorimetric assay, respectively. Therefore, an inexpensive and accurate methodology is not currently available for continuous monitoring of SO2 in the liquids food industry. Red wine initially acidified at pH < 1 was treated by membrane extraction at 25 ℃. This operation is based on a hydrophobic Hollow Fiber Contactor, which separates the acidified red wine in the shell side and a diluted aqueous sodium hydroxide solution as receiving solution into the lumenside in countercurrent. Sulfite and bisulfite in the acidified red wine become molecular SO2, which is evaporated through the membrane pores filled with gas. Thus, SO2 is trapped in a colorless solution and the membrane contactor controls its transfer, decreasing experimental error induced in classical methods. Experimental results using model solutions with known concentration values of [Formula: see text] show an average extraction percentage of 98.91 after 4 min. On the other hand, two types of Chilean Cabernet Sauvignon wines were analyzed with the same system to quantify the content of free and total sulfites. Results show a good agreement between these methods and the proposed technique, which shows a lower experimental variability.
authors.affiliation: Laboratory of Membrane Separation Processes (LabProSeM), University of Santiago de Chile (USACH), Chile.
authors.forename: Andrea
authors.initials: A
authors.lastname: Plaza
authors.affiliation: Laboratory of Membrane Separation Processes (LabProSeM), University of Santiago de Chile (USACH), Chile julio.romero@usach.cl.
authors.forename: Julio
authors.initials: J
authors.lastname: Romero
authors.affiliation: Laboratory of Membrane Separation Processes (LabProSeM), University of Santiago de Chile (USACH), Chile.
authors.forename: Wladimir
authors.initials: W
authors.lastname: Silva
authors.affiliation: Laboratory of Membrane Separation Processes (LabProSeM), University of Santiago de Chile (USACH), Chile.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Morales
authors.affiliation: Laboratory of Membrane Separation Processes (LabProSeM), University of Santiago de Chile (USACH), Chile.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Torres
authors.affiliation: Laboratory of Conductive Polymers, University of Santiago de Chile (USACH), Chile.
authors.forename: María J
authors.initials: MJ
authors.lastname: Aguirre
mesh_terms: D002677:Chile; D005504:Food Analysis / Q000379:methods* / Q000592:standards; D005520:Food Preservatives / Q000032:analysis*; D005638:Fruit; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015203:Reproducibility of Results; D013045:Species Specificity; D013447:Sulfites / Q000032:analysis*; D013458:Sulfur Dioxide / Q000032:analysis*; D013696:Temperature; D027843:Vitis / Q000145:classification; D014920:Wine / Q000032:analysis*
chemical_list: D005520:Food Preservatives; D013447:Sulfites; D013458:Sulfur Dioxide
keywords: Ripper method; Wines; aspiration method; membrane contactor; sulfite; sulfur dioxide