Acolein in wine : bacterial origin and analytical detection

Bauer, Rolene (2010-03)

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010.

Thesis

ENGLISH ABSTRACT: Wine quality is compromised by the presence of 3-hydroxypropionaldehyde (3-HPA) due to spontaneous conversion into acrolein under wine making conditions. Acrolein is highly toxic and is presence has been correlated with the development of bitterness in wine. Lactic acid bacterial strains isolated from South African red wine, Lactobacillus pentosus and Lactobacillus brevis, are implicated in accumulating 3- HPA during anaerobic glycerol fermentation. The environmental conditions leading to its accumulation are elucidated. In aqueous solution 3-HPA undergoes reversible dimerization and hydration, resulting in an equilibrium state between different derivatives. Interconversion between 3-HPA derivatives and acrolein is a complex and highly dynamic process driven by hydration and dehydration reactions. Acrolein is furthermore highly reactive and its steady-state concentration in complex systems very low. As a result analytical detection and quantification in solution is problematic. This study highlights the roles played by natural chemical derivatives and shows that the acrolein dimer can be used as a marker for indicating the presence of acrolein in wines. Solid-phase microextraction (SPME) coupled to gas chromatograph mass spectrometry (GC-MS) was validated as a technique for direct detection of the acrolein dimer in wine. The potential of a recently introduced sorptive extractive technique with a sample enrichment probe (SEP) was also investigated. The SPME technique simplifies the detection process and allows for rapid sampling of the acrolein marker, while SEP is more sensitive.

AFRIKAANSE OPSOMMING: Die teenwoodigheid van 3-hidroksiepropioonaldehied (3-HPA) in wyn het ‘n negatiewe invloed op kwaliteit as gevolg van die moontlike omskakeling na akroleien tydens die wynmaak prosses. Akroleien is hoog toksies en is moontlik betrokke by die ontwikkeling van ‘n bitter komponent in wyn. Hierdie studie wys dat stamme van die melksuurbakteriëe Lactobacillus pentosus en Lactobacillus brevis, geisoleer uit Suid-Afrikaanse wyn, 3-HPA tydens anaerobiese alkoholiese fermentasie kan opbou. Kondisies wat ontwikkeling beinvloed is bestudeer. 3-HPA ondergaan omkeerbare dimerisasie en hidrasie in oplossing en het ‘n ewewig tussen veskillende derivate tot gevolg. Omkakeling tussen 3-HPA derivate en akroleien is ‘n komplekse en hoogs dinamiese prosses wat gedryf word deur hidrasie en dehidrasie reaksies. Akroleien is verder hoogs reaktief en die ewewigskonsentrasie van hierdie aldehied in komplekse omgewings is laag. Analitiese waarneming en kwantifisering is gevolglik problematies. Hierdie studie lig die rol wat natuurlike chemise derivate speel duidelik uit en wys dat die akroleien dimeer as ‘n merker gebruik kan word om die teenwoodigeid van akoleien in wyn te staaf. Soliede-fase mikro-ekstraksie (SPME) gekoppel aan gas chromatografie massa spektroskopie (GC-MS) is gevalideer as ‘n tegniek vir die direkte waarneming van die akroleien dimeer in wyn. Die potensiaal van ‘n nuwe ekstraksie tegniek, gebasseer op ‘n peiler wat vir die monster verreik (SEP), was ook ondersoek. Die SPME tegniek is vinnig en vergemaklik analiese, terwyl SEP meer sensitief is.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/5358
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