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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Treatment of algae-induced tastes and odors by chlorine, chlorine dioxide and permanganate

Buffin, Lisa Webster 11 May 2010 (has links)
Chlorine (Cl₂(sq»' chlorine dioxide (ClO₂ ) and potassium permanganate (KMnO₄) were evaluated as oxidants for the removal of grassy and cucumber odors associated with the pure compounds, cis-3-hexenol and trans-2, cis-6-nonadienal, respectively, and for the removal of fishy odors associated with a culture of an alga, Synura petersenii. The effects of the oxidants on the pure compounds were assessed both by Flavor Profile Analysis (FPA) and gas chromatography/mass spectrometry (GC/MS). The effects of the oxidants on the algae culture were evaluated by FPA only. In addition, an unoxidized sample of Synura petersenii was analyzed by gas chromatography coupled with mass spectrometry (GC/MS) for possible identification of fishy-smelling compounds. Chlorine (1-6 mg/L) and KMn04 (0.25-4 mg/L) markedly reduced grassy and cucumber odors associated with the two compounds. Gas chromatography/mass spectrometry confirmed that these compounds were reduced to below method detection limits. Levels of Cl₂(&q) required (up to 6 mg/L) to reduce the grassy odors associated with cis-3-hexenol were higher than those of KMnO₄ â ¢ The high Cl₂(&q) doses may have contributed to the formation of chemical odors observed by panelists. Two isomers of chlorohexenol were confidently identified as byproducts of cis-3-hexenol chlorination and may have contributed to the chemical odors that developed after CI2(aq) treatment. Chlorine and KMnO₄ (both at 10 mg/L) either reduced or destroyed the fishy odor associated with the culture of Synura petersenii; however, oxidation caused either the development or unmasking of fruity, cucumber, melon and grassy odors. Chlorine dioxide (3 mg/L) did not reduce the grassy and cucumber odors associated with cis-3-hexenol and trans-2, cis-6-nonadienal , respectively. Gas chromatography and mass spectrometry confirmed that concentrations of these compounds were not reduced to below method detection limits. Furthermore, at a concentration of 10 mg/L, Cl₂ did not effectively reduce either the fishy or other objectionable odors associated with Synura petersenii culture. Hexanal, with an odor described as "green" or "like lettuce heart," and trans-2, cis-6-nonadienal (cucumber odor) were confirmed as algal products in a two-week-old culture of Synura petersenii. In addition, decatrienal was confidently identified as a product of Synura and may have contributed to the fishy odor associated with this alga. / Master of Science

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