Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The total sale of brandy for 2007 in South Africa was R 7 300 000 000 and local statistics
indicate that brandy is by far the most purchased spirit beverage. Sales of brandy even outweigh
the total sales for whisky and the forecast for the estimated sales of brandy in the next
five years is said to increase by 25%. It is therefore crucial to investigate those factors that
influence the production of brandy as better understanding and control of these processes leads
to the production of a brandy that is consistent and of premium quality.
Many factors influence the final outcome of distillates. Of these factors, the distillation technique,
the apparatus used for the purpose of distillation together with the low wine is of utmost
importance as they influence the sensory profile and the chemical composition of the distillate.
The effect of different variations of pot still designs on the chemical composition and the
sensory profile of the resultant distillate was investigated. Five different Pot still variations were
used and varied with regards to the design of their pot still head and swans neck apparatus.
Two low wines were used for the purpose of distillations and were both from 2007 vintage. GCFID
was used to identify the volatile compounds found in the distillates and together with
Quantitative Descriptive Analysis (QDA) a profile of the distillates was produced which was used
to differentiate between the different pot still variations and their effect on the final product. The
data generated from the QDA sessions was subjected to Principal Component Analysis (PCA)
and together with the chemical analysis a correlation between certain compounds and sensory
attributes were found in the distillates. Distillate samples were also subjected to a sensory style
classification system and were classified accordingly.
The chemical composition of the two low wines prior to distillations differed significantly from
each other with low wine one containing a larger amount of total esters and carbonyl
compounds whilst low wine two contained a larger amount of total higher alcohols and acids.
The distillates of low wine one also contained over all larger amounts of total esters and in the
case of the distillates of low wine two, they contained larger amounts of higher alcohols and
acids than low wine one.
Variation one was based on the Alambic Charentais method of pot still design and it was found
that only variation one influenced the chemical composition and the sensory profile of the
distillates. This variation produced a distillate with a lower amount of total esters and more
specifically ethyl acetate as well containing a lower intensity of the fruit and sweet associated
caramel aromas and flavours. The esters, ethyl acetate and the ethyl esters of the long chained
fatty acids were found to correlate with the sensory attributes known as fruit associated aroma,
soapy aroma, and spicy aroma and therefore indicated that these compounds are responsible
for these attributes. There were no correlations found between the chemical compounds,
sensory attributes and sensory style classifications in the distillates of both low wine one and
two. It was shown that the addition of certain esters, carbonyl compounds, higher alcohols and
acids in specific ratios could alter the sensory classification of the distillates. Therefore the
chemical composition and the sensory characteristics of distillates are largely dependent on the
chemical composition of the low wine prior to distillation rather than the pot still design.
Therefore, with further research it could be possible to predict the outcome of the chemical
composition of the distillates by analyzing the chemical compounds found in the low wine prior
to distillation. / AFRIKAANSE OPSOMMING: Die totale verkope aan brandewyn vir 2007 in Suid Afrika beloop R7 300 000 000 en statistiek
wys dat brandewyn by verre die mees gesogte spiritus drank is. Verkope van brandewyn is selfs
meer as die verkope van whisky en die voorspelling is dat die verkope van brandewyn met 25%
gaan vermeerder in die volgende vyf jaar. Dit is dus belangrik om die faktore te ondersoek wat
die produksie van brandewyn beïnvloed om sodoende die verstokingsproses te verstaan en te
kontroleer om ‘n konsekwente kwaliteitsproduk op die mark te plaas.
Baie faktore beïnvloed die finale produk. Faktore soos die distillasie tegnieke, die apperate wat
gebruik word vir distillasie tesame met die rabatspiritus is van die uiterste belang aangesien dit
die sensoriese profiel en die chemiese samestelling van die distillaat beïnvloed. Die effek van
die verskillende variasies van potketelhelms op die chemiese samestelling van die distillate
word ondersoek. Vyf verskillende helms met variasies in die swaannek ontwerp was gebruik.
Twee verskillende rabatspiritus, van die 2007 oesjaar, was gebruik vir distillasie. GC-FID was
gebruik om die vlugtige komponente van die distillate mee vas te stel. Kwantitatiewe
Beskrywende Analise (QDA) is gebruik om ‘n profiel van die distillate op te stel wat weer gebruik
is om te differensieer tussen die verskillende potketelhelm variasies en hulle effek op die finale
produk. Die data wat deur die QDA sessies gegenereer was, is in die Vernaamste Komponent
Analise (PCA) ingevoer en tesame met die chemiese analise is ‘n korrelasie tussen sekere
komponente en die sensoriese analise van die distillate gevind. Distillaat monsters was ook aan
sensoriese styl van klassifikasie onderwerp en is as volg daarvan geklassifiseer.
Die chemiese samestelling van die twee rabatspiritus voor finale distillasie het betekenisvol van
mekaar verskil ten opsigte daarvan dat die eerste rabatspiritus het hoë konsentrasies esters en
karboniel verbindings gehad terwyl die tweede rabatspiritus meer hoë konsentrasies van sure
en hoër alkohole gehad het. Die distillaat van die eerste rabatspiritus het ook hoë konsentrasies
esters en karboniel verbindings gehad terwyl die distillaat van die tweede rabatspiritus weer hoë
konsentrasies van sure en hoër alkohole gehad het.
Variasie een is gebaseer op die Alambic Charentais van potketel ontwerp en daar is ook gevind
dat hierdie variasie die enigste een was wat die chemiese samestelling en die sensoriese profiel
van die distillate beïnvloed het. Hierdie variasie het ‘n distillaat geproduseer wat lae
konsentrasies van totale esters, veral etielasetaat, sowel as laer intensiteit van vrugtige en soet
geassosieerde karamel aromas en geure. Die esters, etielasetaat en etiel esters van die lang
ketting vetsure, is gevind dat dit goed korreleer met die sensoriese eienskappe wat geassosieer
word met vrugtige aromas, spesery-agtige aromas en seperige aromas. Daar is geen korrelasie
gevind tussen die chemiese verbindings, sensoriese eienskappe en sensoriese styl van
klassifikasie van distillate een en twee nie. Dit was ook bewys dat byvoeging van esters,
karboniel verbindings, sure en hoër alkohole, in spesifieke verhoudings, die sensoriese
eienskappe kan verander. Dus is die chemiese samestelling en sensoriese eienskappe van die
distillate grootliks afhanklik van die chemiese samestelling van die rabatspiritus, voor die
tweede distillasie, as wat dit afhanklik is van die potketelhelm ontwerp. Gevolglik, met verdere
v
navorsing, is dit moontlik om die uitkoms van die chemiese samestelling van die distillaat te
voorspel deur die analise van die chemiese verbindings van die rabatspiritus te ontleed.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/4057 |
| Date | 03 1900 |
| Creators | Bougas, Nina Valleska |
| Contributors | Lambrechts, Marius, Van Rensburg, Pierre, University of Stellenbosch. Faculty of Agrisciences. Dept. of Viticulture and Oenology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 87 p. :ill. |
| Rights | University of Stellenbosch |
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