Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / 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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/5358 |
| Date | 03 1900 |
| Creators | Bauer, Rolene |
| Contributors | Crouch, A., Burger, B., University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Rights | University of Stellenbosch |
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