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Análise isotópica do gás carbônico de espumantes comercializados no Brasil /Jubileu, Bruno da Silva, 1980. January 2015 (has links)
Orientador: Waldemar Gastoni Venturini Filho / Banca: Carlos Ducatti / Banca: Maria Marcia Pereira Sartori / Banca: Muris Sleiman / Banca: Vladimir Eliodoro Costa / Resumo: O objetivo deste trabalho foi analisar isotopicamente o gás carbônico de espumantes para detectar adulteração, utilizando o método de análise isotópica para determinar a origem deste gás; se proveniente de plantas dos ciclos fotossintéticos C3 (uva), C4 (açúcar de cana) ou de outra fonte. Para isso, foram analisadas amostras comerciais de espumante e espumante moscatel, espumantes elaborados em laboratório, sumo de uva, açúcar e gás carbônico comercial. Também foram analisadas outras bebidas carbonatadas (água mineral, refrigerantes, vinhos, etc.). Os resultados foram submetidos à análise de variância e teste de Tukey para a detecção de possíveis diferenças entre as médias das razões isotópicas de 13C/12C, ao nível de significância de p <0,05. Seguindo a legislação brasileira para vinhos espumantes determinou-se o intervalo de valores possíveis de δ13C para que as bebidas estivessem em acordo com as normas. Em relação aos espumantes, quatro estavam fora do intervalo de valores estabelecido; para os espumantes moscatéis, nenhum estava em desacordo com a legislação brasileira. / Abstract: The objective of this study was to analyze isotopically carbonic gas sparkling to detect tampering using the isotopic analysis method to determine the source of carbon dioxide (whether from plants the photosynthetic cycles C3 (grape and beet), C4 (sugar cane) or from another source. For this purpose, samples were analyzed Muscat commercial sparkling wine and sparkling wine, sparkling prepared in the laboratory, grape juice, sugar and commercial CO2. They also analyzed other carbonated beverages (mineral water, soft drinks, wines, etc.). The results were submitted to ANOVA and Tukey test for the detection of possible differences between the means of the isotopic ratios 13C / 12C, at a significance level of p <0.05. Following the Brazilian legislation for sparkling wines determined the possible range of values of δ13C for the drinks were in accordance with the rules. Regarding sparkling, four were outside the range established; for muscat sparkling, none was at odds with Brazilian law. / Doutor
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Caracterização química, energética, aromática e sensorial de vinhos de mesa de uvas americanas /Uliana, Maíra Rodrigues, 1983- January 2013 (has links)
Orientador: Waldemar Gastoni Venturini Filho / Banca: Giuseppina Pace Pereira Lima / Banca: Léa Silvia Sant'Ana / Banca: Regina Marta Evangelista / Banca: Ricardo Figueira / Resumo: Os objetivos deste trabalho foram caracterizar físico-química, energética, aromática e sensorialmente vinhos provenientes de uvas americanas e/ou híbridos produzidos em vinícolas brasileiras. Foram utilizados vinhos provenientes de uvas tintas das variedades Bordô, Isabel e Máximo, e de uvas brancas das variedades Niagara e BRS Lorena. Para a caracterização físico-química e energética os vinhos foram analisados pelas seguintes determinações químicas: teor alcoólico; densidade; extrato seco total e reduzido; relação álcool em peso/extrato seco reduzido, açúcares redutores; acidez total, volátil e fixa; pH; dióxido de enxofre total e livre; e valor energético. As amostras foram avaliadas por cromatografia gás-líquido, em um cromatógrafo gasoso equipado com um injetor split/splitless e um detector de ionização de chama (DIC), para a quantificação de seus compostos volátéis majoritários. Já para a porção dos compostos voláteis minoritários, as frações livre e glicosilada desses vinhos foram extraídas e analisadas utilizando um sistema GC-MS constituído por cromatógrafo gasoso e detector de espectro de massas. Todos os compostos foram quantificados como equivalentes ao 4-nonanol. Na análise sensorial foi utilizado o teste de aceitação por escala hedônica, para avaliação da aceitabilidade desses vinhos. Para os resultados da caracterização físico-química, enegética, compostos voláteis majoritários e teste escala hedônica foi realizada análise de variância e as médias foram comparadas pelo teste de Tukey. A análise de componentes principais (APC) foi utilizada para avaliar a porção dos compostos voláteis minoritários. Todos os vinhos analisados apresentaram parâmetros físico-químicos dentro dos estipulados pela legislação brasileira. Os vinhos varietais Bordô e Isabel possuem mais... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objectives of this study were to characterize physical-chemical, energy, aromatic and sensory the wines from American grapes and/or hybrids produced in Brazilian wineries. It has been used wines from red grapes varieties Bordô, Isabel and Máximo, and white grape varieties Niagara and BRS Lorena. The wines physical-chemical and energy characterization were analyzed through the following chemical determinations: alcohol content, density, total and reduced dry extract, alcohol in weight/reduced dry extract ratio, reducing sugars, total, volatile and fixed acidity, pH, free and total sulfur dioxide, and energy value. The samples were analyzed by gas chromatography in a gas chromatograph equipped with a split/splitless injector and a flame ionizing detector (FID), for the major volatile compounds quantification. As for the minority portion of volatile compounds, the free and glycosylated fractions of those wines were extracted and analyzed using a GC-MS system consisting of a gas chromatograph and a mass spectral detector. All compounds were quantified as 4-nonanol equivalent. The sensory analysis used the acceptance test by hedonic scale, for the acceptability evaluation of these wines. For the results of physical-chemical characterization, energetic, major volatile compounds and hedonic scale test it has been performed variance analysis and the means were compared by Tukey test. The principal component analysis (PCA) was used to assess the volatile minority compounds portion. All wines analyzed showed physic-chemical parameters within the stipulated by the Brazilian law. The varietal wines Bordô and Isabella have more and in a higher concentration, responsible compounds for the foxy aroma of wines from American varieties, as compared with the varietal Máximo. The varietal... (Complete abstract click electronic access below) / Doutor
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Evaluation of single-bounce attenuated total reflectanceFourier transform infrared and two-dimensional correlation spectroscopy in quantitative analysisCocciardi, Robert Arthur January 2003 (has links)
No description available.
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Chemical and sensory profiling of dry and semi-dry South African Chenin blanc winesVan Antwerpen, Lindi 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Chenin blanc wine is of economic importance to South Africa and a range of diverse dry and semi-dry wines are locally produced in this genre. Currently, the use of three distinctly different style names, each aimed at providing consumers with information about the flavour of the wines, is encouraged by the South African (SA) wine industry. The styles are fresh and fruity (FF), rich and ripe unwooded (RRUW) and rich and ripe wooded (RRW). Feedback from retail sectors over the past few years, however, repeatedly suggested that the style names are perceived as confusing by SA consumers. This master study was undertaken to re-evaluate the FF, RRUW and RRW style classification, based on both the volatile fermentation-derived aroma composition and the sensory attributes of a set of wines containing all the styles under investigation.
For the purposes of chemical profiling, a set of 105 commercial Chenin blanc wines, selected to be representative of these three styles and originating from the major SA wine producing areas, were analysed by Gas Chromatography (GC) to quantify fermentation-derived volatile aroma compounds in the wines. ANOVA performed on the chemical data showed that 29 compounds represent significant differences between at least two of the 3 styles (FF, RRUW and RRW). Principal component analysis (PCA) of the volatile compounds showed a large degree differentiation between FF and RRW wine styles, however, RRUW wine styles overlapped with the other two styles. Considering vintage effects, ANOVA indicated no significant differences within FF (vintages 2009 and 2010) and RRW (vintages 2008 and 2009) styles, whereas only 2 esters and 4 terpenes showed significant differences between the three wine producing regions investigated for this purpose, Paarl/Wellington, Breede River and Stellenbosch. Volatile aroma compounds generated for Chenin blanc were included in the Winetech database consisting of the most important cultivars of South Africa. Combining the data for the volatiles for Chardonnay and Sauvignon blanc from this database and the data for Chenin blanc obtained in this study, a PCA indicated a clear separation between Chenin blanc and the other two white cultivars.
Sensory evaluation of the style classification was done by two separate sensory tests. Firstly, a sorting task was performed by wine industry experts to categorise 21 Chenin blanc wines (FF, RRUW and RRW) based on their similarity. The results showed a differentiation between FF and RRW styles, however, RRUW was mostly classified together with FF wines. This indicated a possible continuum between the three styles, as opposed to three distinct different categories, currently suggested by the style names.
The second sensory analysis test, Descriptive Sensory Analysis (DSA), was performed by a trained panel to generate sensory profiles for 42 wines. ANOVA of the flavour attribute intensities between different styles once again showed significant differences between FF and RRW, with RRUW wines forming a continuum between the FF and RRW styles. These results provide valuable information that could be used by the wine industry for labelling purposes. / AFRIKAANSE OPSOMMING: Chenin blanc is van ekonomiese belang vir Suid Afrika en ‘n wye reeks droë en semi-droë wyne word plaaslik geproduseer in hierdie kategorie. Tans word die gebruik van drie duidelike verskillende stylbenamings, elkeen daarop gemik om aan die verbruiker inligting te verskaf oor die geur van die wyn, deur die Suid Afrikaanse (SA) wynindustrie aangemoedig. Die style is vars en vrugtig, ryk en ryp ongehout en ryk en ryp gehout. Terugvoer van die handelssektor oor die afgelope aantal jare, het daarop gedui dat die stylbenamings tot verwarring onder SA verbruikers lei. Hierdie meestersstudie is onderneem om die stylklassifikasie, vars en vrugtig, ryk en ryp ongehout en ryk en ryp gehout, te her-evalueer op grond van die vlugtige aroma komponente wat tydens die fermentasie proses gevorm word, asook die sensoriese eienskappe van ‘n verteenwoordigende stel wyne van elk van die style wat ondersoek is.
Vir die doel van die chemiese profilering, is ‘n stel van 105 kommersiële wyne, wat geselekteer is om verteenwoordigend te wees van die drie style ondersoek en ook afkomstig is van die vernaamste SA wynproduserende streke, gebruik. Die wyne is met behulp van gas chromatografie ontleed om die vlugtige komponente wat van die fermentasie proses afkomstig is, te kwantifiseer. Die analise van variansie, het getoon dat 29 komponente statisties beduidend verskil het tussen die drie style. Hoofkomponent analise van die vlugtige komponente, het getoon dat die vars en vrugtige wyne en ryk en ryp gehoute wyne, duidelik onderskeibaar was van mekaar op grond van die vlugtige data, maar die ryk en ryp ongehoute wyne het met die ander twee style oorvleuel. In terme van oesjaar effekte, was daar geen beduidende verskille in die aroma profiele van die vars en vrugtige styl (oesjare 2009 en 2010) en ryk en ryp ongehoute styl (oesjare 2008 en 2009) nie, terwyl die konsentrasie van slegs twee esters en 4 terpene statisties beduidend verskil het tussen die wynproduserende streke Paarl/Wellington, Breederivier en Stellenbosch. Resultate van die gekwantifiseerde vlugtige komponente is in die databasis van Winetech gevoeg, waar die konsentrasies van soortgelyke komponente van die vernaamste SA wynkultivars reeds vervat is. Hoofkomponent analises van die gekombineerde resultate vir Chenin blanc, Chardonnay en Sauvignon blanc wyne, het getoon dat daar ‘n duidelike verkil tussen Chenin blanc en die ander twee wit wynkultivars was.
Die sensoriese evaluerings is uitgevoer deur van twee verskillende metodes gebruik te maak. Eerstens is 21 wyne (met al drie style verteenwoordig) deur wynindustrie eksperts gesorteer op grond van die waargenome eendersheid van die onderskeie wyne en die resultate is grafies geprojekteer. Die resultate het getoon dat daar ‘n duidelike verskil waargeneem is deur die assessors tussen die vars en vrugtige styl en ryk en ryp gehoute styl. Die ryk en ryp ongehoute wyne het in die analises meer met die vars en vrugtige style geassosieer, as die ryk en ryp gehoute wyne.
Die tweede sensoriese metode is uitgevoer deur sensoriese paneel wat vir die doel van hierdie studie opgelei is om die geur eienskappe van 42 wyne (al drie style verteenwoordig) te profileer. Analise van statistiese beduidende verskille tussen die voorkoms van die geurkomponente en hul intensiteite vir elke styl, het weereens aangedui dat daar ‘n kontinuum bestaan tussen die style. Hierdie resultate kan van waarde vir die wynindustrie wees in besluite rakende etikettering.
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The antioxidant activity of South African wines in different test systems as affected by cultivar and ageingDe Beer, Dalene 03 1900 (has links)
Thesis (M. Sc.Voedselwet.)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Phenolic compounds in wine, due to their antioxidant activity, are reportedly
responsible for the health-promoting properties of wines. The effect of cultivar
and in-bottle ageing on the antioxidant activity of South African wines in
different types of antioxidant assays was, therefore, investigated.
The antioxidant activity of commercial South African red (Cabernet
Sauvignon, Ruby Cabernet, Pinotage, Shiraz, Merlot) and white (Sauvignon
blanc, Chenin blanc, Chardonnay, Colombard) cultivar wines was compared
using the 2,2’-azino-di-(3-ethylbenzothialozine-sulphonic acid) radical cation
(ABTS·+) scavenging, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·)
scavenging and microsomal lipid peroxidation (MLP) assays. The red wines
was more effective than the white wines on an “as-is” and an equal total
phenol content. The total antioxidant activity (TAAABTS and TAADPPH) of Ruby
Cabernet was the lowest of the red wines, but the antioxidant potency (APABTS
and APDPPH) of red wine phenolic fractions did not differ (P ³ 0.05). Ruby
Cabernet and Pinotage were the least effective inhibitors of MLP, while Merlot
was the most effective of the red wines. Pinotage phenolic fractions had
lower (P < 0.05) APMLP than that of other red wines. Of the white wines,
Chardonnay and Chenin blanc had the highest and lowest effectivity
respectively according to all antioxidant parameters. Ascorbic acid present in
some wines increased and decreased their TAA and % MLP inhibition
respectively. TAA and % MLP inhibition correlated well (r ³ 0.7, P < 0.001)
with total phenol content of red and white wines, as well as with flavanol
content of red wines and tartaric acid ester content of white wines. The
% MLP inhibition also correlated well with flavanol content of white wines. No
correlation (P > 0.01) was obtained between TAA or % MLP inhibition and
monomeric anthocyanin content of red wines. In the deoxyribose assay, red
wines were more pro-oxidant and exhibited lower hydroxyl radical scavenging
and metal chelating abilities than white wines.
The effect of in-bottle ageing on antioxidant activity of wines was
determined using the ABTS·+ and DPPH· scavenging assays. The TAA and
total phenol content of experimental red (Pinotage and Cabernet Sauvignon)and white (Chardonnay and Chenin blanc) cultivar wines, decreased
(P < 0.05) during 12 months of storage at 0, 15 and 30 ºC. The TAAABTS of
Cabernet Sauvignon and Chardonnay, stored at 30 ºC were lower (P < 0.05)
than at 0 ºC. The APABTS and APDPPH of most wines also decreased during
storage. The monomeric anthocyanin content of red wines decreased
(P < 0.05) rapidly at 15 and 30 ºC. The flavanol content of wines (except
Chenin blanc) increased during the first 9 months, decreasing again after 12
months, while minor changes in the flavonol and tartaric acid ester content of
both red and white wines were observed. The TAAABTS exhibited a good
correlation (r ³ 0.7, P < 0.001) with total phenol content of red and white
wines, as well as with flavonol and tartaric acid ester content of red and white
wines and flavanol content of white wines. The monomeric anthocyanin
content of red wines correlated (r = 0.50, P < 0.001) weakly with TAAABTS.
The decrease in the TAAABTS of wines could thus be mainly attributed to a
decrease in their total phenol content. / AFRIKAANSE OPSOMMING: Die antioksidant aktiwiteit van fenoliese komponente in wyn is waarskynlik
verantwoordelik vir die gesondheidsvoordele daarvan. Die studie het dus
gepoog om effek van kultivar en veroudering na bottelering op die
antioksidant aktiwiteit van Suid-Afrikaanse wyne te ondersoek.
Die antioksidant aktiwiteit van kommersiële Suid-Afrikaanse rooi
(Cabernet Sauvignon, Ruby Cabernet, Pinotage, Shiraz, Merlot) en wit
(Sauvignon blanc, Chenin blanc, Chardonnay, Colombard) kultivarwyne is
vergelyk deur middel van die 2,2’-azino-di-(3-etielbensotialosien-sulfoon
suur)-radikaal katioon (ABTS·+) vernietigingstoets, 2,2-difeniel-1-pikrielhidrasielradikaal
(DPPH·) vernietigingstoets en mikrosomale lipiedperoksidasietoets
(MLP). Die antioksidant aktiwiteit en die antioksidant
kragtigheid (AK) van die rooiwyne was beter as dié van witwyne in al drie
antioksidant toetse. Die totale antioksidant aktiwiteit (TAAABTS en TAADPPH)
van Ruby Cabernet was die laagste van die rooiwyne, terwyl die AKABTS en
AKDPPH van rooiwyn fenoliese fraksies nie van mekaar verskil (P ³ 0.05) het
nie. Van die rooiwyne, het Ruby Cabernet en Pinotage die laagste en Merlot
die hoogste effektiwiteit in die MLP toets getoon. Die AKMLP van Pinotage se
fenoliese fraksies was die laagste van die rooiwyne. Die witwyne,
Chardonnay en Chenin blanc, het onderskeidelik die beste en swakste
antioksidant aktiwiteit en AK van die witwyne getoon in al drie antioksidant
toetse. Askorbiensuur wat in sommige witwyne voorgekom het, het die TAA
van hierdie wyne verhoog, maar hul % MLP inhibisie verlaag. Die TAA en %
MLP inhibisie het goed gekorreleer (r ³ 0.7, P < 0.001) met die totale
fenolinhoud van rooi- en witwyne, asook die flavanolinhoud van rooiwyne en
die wynsteensuur-esterinhoud van witwyne. Die % MLP inhibisie het ook
goed gekorreleer met die flavanolinhoud van witwyne. Geen korrelasie
(P > 0.1) is waargeneem tussen antioksidant aktiwiteit van rooiwyne en hul
monomeriese antosianien-inhoud. Rooiwyn was meer pro-oksidatief in die
deoksieribose toets as witwyne, maar was die swakste hidroksieradikaalvernietigers
en metaalcheleerders.Die effek van veroudering na bottelering op die antioksidant aktiwiteit
van wyne soos bepaal met die ABTS·+ en DPPH· vernietigingstoetse, is
ondersoek. Die TAA en die totale fenolinhoud van eksperimentele rooi-
(Pinotage en Cabernet Sauvignon) en witwyne (Chardonnay en Chenin blanc)
het afgeneem (P < 0.05) tydens opberging na bottelering by 0, 15 en 30 ºC
oor 12 maande. Opberging by 30 ºC het ‘n groter vermindering (P < 0.05) in
die TAAABTS waarde vir Cabernet Sauvignon en Chardonnay veroorsaak as by
0 ºC. Die meeste wyne se APABTS en APDPPH waardes het ook verminder
(P < 0.05) na 12 maande. Drastiese vermindering (P < 0.05) in die
monomeriese antosianieninhoud van rooiwyne is opgemerk tydens opberging
by 15 en 30 ºC. Tydens die eerste 9 maande se opberging het die
flavanolinhoud van wyne toegeneem (P < 0.05) en daarna afgeneem
(P < 0.05) tot by 12 maande, terwyl flavonol- en wynsteensuuresterinhoud van
beide rooi- en witwyne min verandering ondergaan het. Die totale fenolinhoud
van rooi- en witwyne, asook die flavonol en wynsteensuur-esterinhoud van
rooi-en witwyne en die flavanolinhoud van witwyne, het goed gekorreleer
(r ³ 0.7, P < 0.001) met die TAAABTS. In teenstelling met die resultate vir
kommersiële kultivarwyne, was die TAAABTS van rooiwyne swak gekorreleer
(r = 0.5, P < 0.001) met hul monomeriese antosianieninhoud. Die afname in
TAAABTS van wyne tydens veroudering kon dus meestal toegeskryf word aan
die afname in hul totale fenolinhoud.
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Application of modern chromatographic technologies for the analysis of volatile compounds in South African winesWeldegergis, Berhane Tekle 12 1900 (has links)
Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT:
The present study was initiated by the wine industry of South Africa to overcome the
lack of available information on the flavor and aroma of South African wines. The
aim was to develop new analytical methods and improve existing ones for the analysis
of volatile compounds in the South African wines. Initially a new analytical method
based on stir bar sorptive extraction (SBSE) in the headspace mode for the analysis of
37 pre-selected volatile compounds was developed and validated. Consequently, the
method was improved by making important modifications and increasing the number
of compounds analyzed to 39. This method was successfully applied to a large
number of Pinotage wines of vintages 2005 and 2006. The quantitative data of these
wines were subjected to chemometric analysis in order to investigate possible co-
/variances. A clear distinction was observed between the two vintages, where the
2005 wines were more characterized by wood-related compounds and the 2006 wines
by the fermentation compounds. The developed method was further applied to other
cultivars of vintage 2005, including two white (Sauvignon Blanc and Chardonnay)
and three red (Shiraz, Cabernet Sauvignon and Merlot) cultivars. In a similar fashion,
the quantitative data of the six cultivars of vintage of 2005 were analysed by
chemometric methods. Significant differences were observed between the two white
cultivars and among the four red cultivars. It was shown that among these cultivars,
the major role-players were the wood and fermentation related volatiles. A striking
observation was the confirmation of the unique character of the Pinotage wines
compared to the other red cultivars, mainly influenced by the high level of isoamyl
acetate and low level of isoamyl alcohol, the former being categorized as a varietal
compound for Pinotage expressed by a fruity (banana) odor.
In addition, advanced chromatographic technology in the form of comprehensive twodimensional
gas chromatography (GC × GC) coupled to time-of-flight mass
spectrometry (TOFMS) was investigated for the detailed analysis of volatile
compounds in young South African wines. This work focused primarily on Pinotage
wines. In the first instance, solid phase micro extraction (SPME) in the headspace
mode in combination with GC × GC-TOFMS was used. Due to the high resolution
and large peak capacity of GC × GC, more than 200 compounds previously reported
as wine components were identified. These compounds were dominated by the highly volatile and less polar compounds, mainly due to the characteristics of SPME. In an
attempt to further extend these results, another selective extraction method, solid
phase extraction (SPE) was used in combination with GC × GC-TOFMS analysis.
Using this technique, more than 275 compounds, most of them unidentified using the
previous method, were detected. These groups of compounds include volatile phenols,
lactones as well as mostly aromatic esters and norisoprenoids, which can potentially
influence the aroma and flavor of wine. The techniques developed as part of this study
have extended our knowledge of the volatile composition of South African wines. / AFRIKAANSE OPSOMMING:
Hierdie studie is geïnisieer deur die wyn industrie van Suid-Afrika om die tekort aan
beskikbare inligting aangaande wyn aroma van Suid-Afrikaanse wyne te oorkom. Die
doel was om nuwe analitiese metodes te ontwikkel en die huidige metodes te verbeter
vir die analise van vlugtige verbindings in Suid-Afrikaanse wyne. Oorspronklik is ʼn
nuwe analitiese metode ontwikkel en gevalideer gebaseer is op ‘stir bar sorptive
extraction’ (SBSE) in die gas fase vir die analise van 37 vooraf geselekteerde vlugtige
verbindings. Die metode is verbeter deur belangrike modifikasies aan te bring en die
hoeveelheid verbindings wat analiseer word te vermeerder na 39. Hierdie metode is
suksesvol aangewend op ʼn groot hoeveelheid Pinotage wyne van oesjare 2005 en
2006. Die kwantitatiewe data van hierdie wyne is onderwerp aan verskillende
chemometriese analises om moontlike ko-/variasies te ondersoek. ʼn Duidelike
onderskeid is opgemerk tussen die twee oesjare, waar die 2005 wyne gekarakteriseer
is deur hout-verwante verbindings en die 2006 wyne weer meer deur fermentasie
verbindings. Die verbeterde metode is verder aangewend vir analiese van ander
kultivars van oesjare 2005, wat twee wit (Sauvignon Blanc en Chardonnay) en drie
rooies (Shiraz, Cabernet Sauvignon en Merlot) ingesluit het. Die kwantitatiewe data
van die ses kultivars van oesjaar 2005 is op ʼn soortgelyke wyse geanaliseer deur
verskillende chemometriese metodes te gebruik. Beduidende verskille is opgemerk
tussen die twee wit kultivars en tussen die vier rooi kultivars. Die hoof rolspelers
tussen die ses kultivars was weereens die verbindings wat ʼn hout en fermentasie aard
het. Die unieke karakter van die Pinotage wyne in vergelyking met die ander rooi
kultivars was opvallend. Hierdie wyn word gekarakteriseer deur hoë vlakke van
isoamiel asetaat en lae vlakke van isoamiel alkohol, waar eersgenoemde gekatogiseer
word as ʼn verbinding wat ʼn vrugte (piesang) geur in Pinotage uitdruk.
Verder is gevorderde chromatografiese tegnologie in die vorm van ‘comprehensive
two-dimentional gas chromatography’ (GC x GC) gekoppel met ‘time-of-flight mass
spectroscopy’ (TOFMS) ondersoek vir die analiese van vlugtige verbindings in jong
Suid-Afrikaanse wyne. Hierdie werk het hoofsaaklik op Pinotage wyne gefokus.
Eerstens is ‘solid phase micro extraction’ (SPME) in die gas fase gekombineer met
GC x GC-TOFMS. As gevolg van die hoë resolusie en groot piek kapasiteit van GC x
GC is meer as 200 verbindings wat voorheen gerapporteer is as wyn komponente geïdentifiseer. Hierdie verbindings is gedomineer deur hoë vlugtige polêre
verbindings, hoofsaaklik as gevolg van die karaktersitieke van SPME..In ʼn poging om
die metode verder te verbeter is ʼn selektiewe ekstraksie metode naamlik ‘solid phase
extraction’ (SPE) in kombinasie met GC x GC-TOFMS gebruik. Met hierdie tegniek
is meer as 275 verbindings geïdentifiseer, waarvan die meeste nie met die vorige
metode waargeneem is nie. Hierdie verbindings sluit vlugtige fenole, laktone en
meestal aromatiese esters en norisoprenoïdes in, wat moontlik die reuk en smaak van
wyn kan beïnvloed. Die metodes ontwikkel gedurende die studie het nuwe informasie
verskaf aangaande die vlugtige komponente teenwoordig in Suid Afrikaanse wyne.
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Stir bar sorptive extraction for the analysis of beverages and foodstuffsTredoux, A. G. J. 03 1900 (has links)
Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2008. / The main goal of this study was the development of new technologies based on modern
analytical techniques for analysis of volatiles in wines. Due to the exponential growth of
the wine industry and consumer demands for an enjoyable, safe-to-consume, and high
quality product, the need for arose for methodologies aiding the understanding of wine
better arose. Chemical analysis is a valuable way of studying the composition of wine in
depth. Very sophisticated instrumentation is available nowadays but almost always the
sample needs to be cleaned up or concentrated before such analysis. This study
investigates the use of stir bar sorptive extraction (SBSE) as such a technique. It is shown
that SBSE combined with gas chromatography-mass spectrometry (GC-MS) is extremely
suited for a wide number of analyses and during the course of the study the technique was
applied for troublesome analytical challenges in various beverages and foodstuffs. The
study focuses on the development of a screening technique for volatiles in wine using
SBSE and the application of the data to various chemometrical techniques for
classification purposes. A second part of the study shows the applicability of SBSE for
extraction of pesticides, contaminants and preservatives from wine, water, lemon
flavoured beverages and yoghurt. The method is also elaborated upon by development of
faster analysis methods for wine and beer and the investigation of using SBSE for
headspace sampling of wine. In all the applications, SBSE technology was shown to be
sensitive, repeatable, robust and very simple to use.
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Investigation into the mechanism of action and biological role of Saccharomyces cerevisiae mannoproteins which reduce visible haziness in white wineBrown, Shauna L January 2003 (has links)
Heat induced protein haze is a common problem in white wine. Grape derived pathogenesis related proteins slowly denature and aggregate during wine storage and this gives rise to light dispersing haze. Protein haze formation is currently prevented by removing proteins using bentonite, an aluminium silicate clay, but this method has drawbacks. A potential alternative or complementary method is the use of haze protective factors ( HPF ), specific mannoproteins from Saccharomyces cerevisiae that visually reduce protein haze. Hpf1p was originally isolated from Muscat Gordo Blanco wine and Hpf2p from a synthetic grape juice ferment. Based on partial amino acid sequences, putative structural genes, HPF1 and HPF2, for these proteins were identified. HPF1 has a homologue, HPF1 ', ( 71 % similarity ) in S. cerevisiae. Sequence analysis suggests that Hpf1p, Hpf1 ' p and Hpf2p are localised to the cell wall or plasma membrane. This study aimed to determine the biological function of the HPF genes in S. cerevisiae. HPF overexpression and deletion strains were constructed and analysed for cell wall related phenotypes. Under a number of conditions, including cold temperature and ethanol stress, the hpf1 Δ hpf1 ' Δ strain was more tolerant than the wild type strain. However, mating efficiency of the hpf1 Δ hpf1 ' Δ strain was significantly less than the wild type strain and this was found to be correlated with the persistence of a septum between the mating partners. The decreased mating efficiency was also mating type specific, only occurring in MAT α cells. This study also aimed to establish conclusively that the HPF genes do indeed encode proteins with haze protective properties. Haze protective activity of the material from ferment supernatants was assessed. Material from the HPF deletion strains exhibited significantly less haze protective activity than the wild type. Moreover, material derived from HPF1 and HPF1 ' overexpressors was more active than material from the wild type. A 6xHis - tagged Hpf2p was expressed and purified using immobilised metal affinity chromatography. This Hpf2p had significant haze protective activity. Modification of N - glycans of 6xHis - Hpf2p by Endoglycosidase H decreased its haze protective activity.visually reduce protein haze. Hpf1p was originally isolated from Muscat Gordo Blanco wine and Hpf2p from a synthetic grape juice ferment. Based on partial amino acid sequences, putative structural genes, HPF1 and HPF2, for these proteins were identified. HPF1 has a homologue, HPF1 ', ( 71 % similarity ) in S. cerevisiae. Sequence analysis suggests that Hpf1p, Hpf1 ' p and Hpf2p are localised to the cell wall or plasma membrane. This study aimed to determine the biological function of the HPF genes in S. cerevisiae. HPF overexpression and deletion strains were constructed and analysed for cell wall related phenotypes. Under a number of conditions, including cold temperature and ethanol stress, the hpf1 Δ hpf1 ' Δ strain was more tolerant than the wild type strain. However, mating efficiency of the hpf1 Δ hpf1 ' Δ strain was significantly less than the wild type strain and this was found to be correlated with the persistence of a septum between the mating partners. The decreased mating efficiency was also mating type specific, only occurring in MAT α cells. This study also aimed to establish conclusively that the HPF genes do indeed encode proteins with haze protective properties. Haze protective activity of the material from ferment supernatants was assessed. Material from the HPF deletion strains exhibited significantly less haze protective activity than the wild type. Moreover, material derived from HPF1 and HPF1 ' overexpressors was more active than material from the wild type. A 6xHis - tagged Hpf2p was expressed and purified using immobilised metal affinity chromatography. This Hpf2p had significant haze protective activity. Modification of N - glycans of 6xHis - Hpf2p by Endoglycosidase H decreased its haze protective activity. / Thesis (Ph.D.)--School of Agriculture and Wine, 2003.
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Sensory, chemical and consumer analysis of Brettanomyces spoilage in South African winesBotha, Janita J 03 1900 (has links)
Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This study focussed on the sensory effects of the main volatile compounds produced by
Brettanomyces yeast causing spoilage in wine. This research firstly aimed to determine the
detection thresholds of eight Brett-related spoilage compounds in wine. The second aim was to
determine the sensory effect of the four most important Brett-related compounds when present
individually in wine. The third aim was to determine the sensory effects of these four compounds
when present in wine in a range of combinations, and to further investigate their effect on
consumer liking. Finally, this project aimed to investigate the incidence of these compounds in a
small range of South African wines.
The sensory detection thresholds of 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol, 4-
vinylphenol, 4-vinylguaiacol, isovaleric acid, isobutyric acid and acetic acid were determined.
Apart from 4-ethylcatechol, these values generally agreed well with recent literature where
values determined in wine are available. However, the discrepancies highlighted the importance
of the effect of the medium (wine) when determining sensory detection thresholds. The use of
the median as alternative calculation method was also investigated, and it was found that this
method gives more insightful results than the standard American Society of Testing Materials
(ASTM E679-04) method.
Four compounds, namely 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol and isovaleric acid
were profiled individually in wine using a trained sensory panel. It was found that all four
compounds caused a suppression of the natural berry-like character in the wine, which induced
a sick-sweet character. 4-ethylphenol contributed Elastoplast™ and leather aromas in the wine,
both of which are commonly associated with Brettanomyces taint. 4-ethylguaiacol added a
medicinal aroma to the wine, and 4-ethylcatechol and isovaleric acid were responsible for
savoury and pungent aromas, respectively.
4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol and isovaleric acid were also profiled in
combination according to the central composite design. Several univariate and multivariate
methods were applied to the dataset obtained. PARAFAC, a multiway method not widely
utilized regarding sensory data, was applied to the data, the results of which were
complementary to those obtained during univariate and multivariate analyses. It was found that
there is a great deal of interaction between the four compounds profiled in terms of sensory
effects. The most notable was the Elastoplast™ attribute, the intensity of which was affected by
all four compounds. The pungent attribute was also affected by the 4-ethylphenol concentration. Consumer analysis revealed that some of the samples spiked with Brettanomyces-spoilage
compounds were preferred to the unspiked (control sample). However, no further relationship
could be found between consumer liking and either chemical composition or sensory profile. It is
therefore speculated that consumer liking of Brettanomyces infected wine is driven by more
complex sensory or socio-demographic factors.
Finally, the concentration of 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol, 4-vinylphenol, 4-
vinylguaiacol, isovaleric acid, isobutyric acid and acetic acid was determined in a small set of
South African wines, selected to contain a high proportion of wines spoiled by Brettanomyces.
Significant correlations were found between 4-ethylphenol and 4-ethylguaiacol, as well as 4-
ethylphenol and isovaleric acid. However, no correlation could be found between 4-ethylphenol
and 4-ethylcatechol. It is speculated that this lack of relationship is due to the different precursor
profiles present in the analysed wines. This study paved the way for future investigations on the
sensory effects of Brettanomyces spoilage in Pinotage red wine. / AFRIKAANSE OPSOMMING: Hierdie studie het gefokus op die sensoriese invloed van die belangrikste vlugtige komponente
wat deur die Brettanomyces gis geproduseer word en bederf veroorsaak in wyn. Eerstens is
gefokus op die bepaling van die deteksiedrempelwaardes van agt Brett-verwante bederwende
komponente. Die tweede doelwit was om die sensoriese invloed van vier van die mees
belangrike Brett-komponente te bepaal wanneer hulle individueel in wyn voorkom. Die derde
doelwit was om die sensoriese invloed van hierdie vier komponente te bepaal wanneer hulle in
verskillende kombinasies in wyn voorkom, asook die effek daarvan op verbruikervoorkeur.
Laastens is gepoog om die voorkoms van hierdie komponente in ‘n klein seleksie van Suid-
Afrikaanse wyne te bepaal.
Die sensoriese deteksiedrempelwaardes vir 4-etielfenol, 4-etielguaiacol, 4-etielcatechol, 4-
vinielfenol, 4-vinielguaiacol, isovaleraatsuur, isobuteraatsuur en asynsuur is bepaal. Met die
uitsondering van 4-etielcatechol het die waardes oor die algemeen goed ooreengestem met
waardes wat onlangs in die wetenskaplike literatuur gepubliseer is. Die uitsonderings het egter
die belangrikheid van die medium (wyn) gedurende die bepaling van sensoriese
deteksiedrempelwaardes uitgelig. Die gebruik van die mediaan as ‘n alternatiewe
berekeningsmetode is ook ondersoek en daar is gevind dat hierdie metode meer insiggewende
resultate lewer as die standaard American Society of Testing Materials (ASTM E679-04)
metode.
Vier komponente naamlik 4-etielfenol, 4-etielguaiacol, 4-etielcatechol en isovaleraatsuur is
individueel in wyn geprofileer met behulp van ‘n opgeleide sensoriese paneel. Daar is gevind
dat al vier die komponente die natuurlike bessiekarakter in die wyn onderdruk terwyl dit
aanleiding gee tot ‘n onnatuurlike soet karakter. 4-etielfenol is gekenmerk aan Elastoplast™ en
leeragtige aromas in die wyn en beide van hulle word algemeen geassosieer met
Brettanomyces bederf. 4-etielguaiacol het ‘n medisinale aroma tot die wyn toegevoeg en 4-
etielcatechol en isovaleraatsuur het respektiewelik souterige (“savoury”) en sterk (“pungent”)
aromas tot gevolg gehad.
4-etielfenol, 4-etielguaiacol, 4-etielcatechol en isovaleraatsuur is ook in verskeie kombinasies
geprofileer volgens die sentrale saamgestelde ontwerp (“central composite design”). Verskeie
enkelveranderlike en meerveranderlike statistiese analisemetodes is ook op die datastel
uitgevoer. PARAFAC, ‘n meerrigtingsmetode wat nie normaalweg vir sensoriese analise data
gebruik word nie, is ook uitgevoer op die data en die resultate was komplimentêr tot die van die
enkelveranderlike en meerveranderlike analisemetodes. Daar is gevind dat, met betrekking tot sensoriese effekte, daar noemenswaardige interaksie tussen die vier komponente plaasvind.
Die mees opmerklike hiervan was die Elastoplast™ aroma, waarvan die intensiteit deur al vier
die ander komponente geaffekteer is. Verder is die sterk (“pungent”) aroma beïnvloed deur die
4-etielfenol konsentrasie.
Verbruikersvoorkeur-analise het aangedui dat sommige van die monsters waarby
Brettanomyces bederwende komponente gevoeg is, verkies word bó die kontrole-wyn. Daar
kon egter geen verdere verband gevind word tussen die verbruiker se voorkeur en, nog die
chemise komposisie of sensoriese profiele, van die wyn nie. Daar kan dus gespekuleer word
dat verbruiker voorkeur van Brettanomyces bederfde wyn gedryf word deur meer komplekse en
sosio-demografiese faktore.
Laastens is die konsentrasies van 4-etielfenol, 4-etielguaiacol, 4-etielcatechol, 4-vinielfenol, 4-
vinielguaiacol, isovaleraatsuur, isobuteraatsuur en asynsuur in ‘n seleksie van Suid-Afrikaanse
wyne bepaal. Dié wyne is spesifiek so gekies sodat ‘n aansienlike aantal van hulle met
Brettanomyces bederf was. Betekenisvolle korrelasies is gevind tussen 4-etielfenol and 4-
etielguaiacol, sowel as 4-etielfenol en isovaleraatsuur. Daar is egter geen korrelasie tussen 4-
etielfenol and 4-etielcatechol gevind nie. Daar word vermoed dat hierdie gebrek aan korrelasie
te wyte is aan die voorloperkomponent profiele teenwoordig in die wyne. Hierdie studie het die
weg gebaan vir verdere ondersoeke na die sensoriese effekte van Brettanomyces bederf in
Pinotage rooi wyn.
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Caracterização físico-química do vinho paulista / Physicochemical characterization of the paulista wineRoberto Sobrinho, Merenice 21 August 2018 (has links)
Orientador: Helena Teixeira Godoy / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-21T19:42:12Z (GMT). No. of bitstreams: 1
RobertoSobrinho_Merenice_D.pdf: 1477674 bytes, checksum: 5fe6158bfbdcf36f980d7b9780573936 (MD5)
Previous issue date: 2013 / Resumo: A legislação brasileira define o vinho como um produto elaborado com uvas frescas, sãs e maduras, produzido por processo fermentativo adequado. Não é permitida a adição de água como constituinte do produto; a adição de sacarose na correção do mosto é restrita a 3ºGL (20ºC) e a presença de contaminantes deve controlada a fim de garantir a saúde pública. A vitivinicultura do estado de São Paulo está passando por um processo de revitalização cujo objetivo é a melhoria da qualidade do produto. As variedades de uvas mais utlizadas, Vitis labrusca e híbridas não são as mais indicadas para a vinificação. O uso de matéria prima inadequada ou a realização do processo fermentativo de forma equivocada pode levar à obtenção de um vinho com parâmetros de identidade e qualidade em desacordo com a legislação brasileira, comprometendo a ascenção de mercado. Dentre a literatura consultada, são escassos os dados quanto a composição dos vinhos produzidos no estado de São Paulo. O objetivo desse trabalho foi realizar a caracterização físico-quimica e investigar os padrões de identidade e qualidade dos vinhos paulistas. Neste estudo, foram realizadas diversas análises a fim de proporcionar dados que possam contribuir para a avaliação da qualidade do vinho paulista e, consequentemente, direcionar as correções necessárias nos processos de vinificação. Para tanto, foram realizadas análises de pH, acidez total, acidez volátil bruta, acidez volátil corrigida, açúcares totais, anidrido sulfuroso total, grau alcoólico, acetaldeído, metanol, razão isotópica de carbono e oxigênio. Foram analisadas 24 amostras de vinhos paulistas, elaborados por 12 produtores, a partir de uvas americanas, híbridas e viníferas na safra de 2011. A partir dos resultados obtidos foi possível observar que 87,5% das amostras estudadas atenderam aos requisitos legais do Padrão de Identidade e Qualidade. Apenas duas amostras, de produtores diferentes, excederam os limites legais para acidez, que pode ser explicado pelo excesso de chuvas verificado durante a safra de 2011 na região. Quanto ao teor de açúcares, apenas uma amostra apresentou divergência entre o valor referenciado na rotulagem e o encontrado nos ensaios. Todos os vinhos avaliados apresentaram graduação alcoólica adequada aos limites legais, porém houve divergência de até 16,4% entre os teores registrados nos rótulos e os verificados nos ensaios. Os níveis de metanol encontrados estiveram abaixo do limite máximo estabelecido. Para o acetaldeído as concentrações variaram entre 4,51± 0,52 mg.L-1 e 87,22 ± 2,21 mg.L-1, sendo que o recomendado na literatura é de até 50 mg.L-1. Os resultados para a razão isotópica de carbono demonstraram que 55% dos vinhos avaliados se apresentaram fora dos limites legais para a correção da graduação alcoólica. Para a razão isotópica de oxigênio todas as amostras analisadas se encontraram acima dos valores de referência para vinhos de São Paulo da safra de 2011, indicando que não há adição de água exógena. No entanto, amostras que se apresentaram em desacordo com a legislação, indicam que há necessidade de intensificar as orientações aos produtores para que possam realizar um controle mais efetivo no processo de produção para a melhoria da qualidade do produto / Abstract: The wine industry in the state of São Paulo is undergoing a revitalization process aimed at improving the quality of the product. Brazilian law defines wine as a product made from fresh, healthy and ripe grapes, produced by appropriate fermentation. It is not permitted to add water as a constituent of the product; adding sucrose to correct the wort is restricted to 3 GL (20 ° C) and the presence of contaminants must be controlled to ensure public health. The most utilized varieties are vitis labrusca and hybrid, but they are not quite suitable for winemaking. The use of inappropriate raw material or inadequate performance of the fermentation process can lead to obtaining a wine with parameters of quality and identity that differ from the Brazilian legislation, undermining the rising market. Among the literature, there are few data regarding the composition of the wines produced in the state of São Paulo. In this study, several analysis were conducted to provide data that can help to evaluate the quality of the Paulista wine and consequently direct the necessary corrections in the process of winemaking. The aim of this study was to characterize physico-chemically and investigate the patterns of identity and quality of the wines described by Brazilian law. Thus, we performed analyzes of pH, total acidity, volatile acidity crude, volatile acidity adjusted, total sugars, total sulfur dioxide, alcohol content, acetaldehyde, methanol, and carbon isotope ratio of oxygen. We analyzed 24 samples of Paulista wines, processed by 12 producers from American, wine grapes and hybrid grapes from the 2011harvest. From the results, it was observed that 87.5% of the samples met the legal requirements. Only two samples from different producers, exceeded the legal limits for acidity, which can be explained by excessive rainfall occurred during the harvest of 2011. As for the sugar content, only one sample showed divergence between the value found in the assays and the value referenced in labeling. All wines showed high alcohol content appropriate to the legal limits, but there was a difference of up to 15% percent from the levels recorded on labels and checked in for tests. The levels of methanol were found below the limit. For acetaldehyde concentrations ranged between 4.51 ± 0.52 mg.L-1 and 87.22 ± 2.21 mg.L-1, and the recommended is 50 mg.L-1. The results for the carbon isotope ratio demonstrated that 55% of the wines evaluated were out of the legal limits for correction of alcoholic content. For oxygen isotope ratio of all samples were found above the reference values for wines from São Paulo crop of 2011, indicating no addition of exogenous water. However, the samples that are at odds with the legislation indicate that there is a need to strengthen the guidelines for producers and perform a more effective control of the production process / Doutorado / Ciência de Alimentos / Doutora em Ciência de Alimentos
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