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Tratamento físico-químico em efluente de vinícola de pequeno porteLechinhoski, Maryelen 15 July 2015 (has links)
Os efluentes vinícolas apresentam concentração de matéria orgânica que varia entre 1.200 mg.L-1 a 92.000 mg.L-1 de DQO. O pH é ácido, variando entre 3,5 a 5,0. A concentração de compostos fenólicos varia entre 41 a 1450 mg.L-1 C6H5OH. Para nitrogênio amoniacal a concentração varia entre 12 a 208 mg.L-1 já para sulfetos entre 50 e 500 mg.L-1S. Com base nestas informações, foi proposto um sistema de tratamento de efluentes físico-químico em batelada, composto por oxidação avançada do tipo Fenton e duas colunas de adsorção preenchidas com adsorventes alternativos: uma com resíduos de olarias (restos de cerâmicas) e outra com resíduos sólidos da construção civil (britados em recicladora). O efluente vinícola foi caracterizado através dos seguintes parâmetros: pH, turbidez, DQO, sólidos, nitrogênio, fósforo e fenol total. Os materiais adsorventes citados foram comparados ao adsorvente convencional, carvão ativado, e caracterizados no que diz respeito a: pH, densidade aparente e relativa, teor de umidade, teor de material volátil e teor de cinzas. No ensaio final para a oxidação do efluente bruto, foi aplicada a concentração de peróxido de hidrogênio de 16 g.L-1 na relação com a H2O2/DQO denominada de “z” igual a 3,36, o catalisador da reação foi o sulfato ferroso na proporção de 1:15 (FeSO4.7H2O:H2O2). O tempo de reação foi de quatro horas a 30°C em mesa agitadora a 150 rpm. Após a oxidação por Fenton, o efluente foi submetido à adsorção em coluna de cerâmica na taxa de 5m3.m2.dia-1, sequencialmente o efluente foi inserido na coluna de resíduos sólidos da construção civil na taxa de aplicação de 4 m3.m2.dia-1. O desempenho do sistema foi avaliado em função de DQO, turbidez, nitrogênio, sólidos, fenol total e cor. Ao final do tratamento a eficiência na remoção de DQO foi de 92,25%, atingindo valores de DQO de 369 mg.L-1. Além disso, o sistema de tratamento aplicado se apresentou eficaz na remoção da cor (100%), fenol total (100%), turbidez (100%), sulfatos (98%) atingindo uma concentração de 40,5 mg.L-1, nitrogênio (10%) com 17,25 mg.L-1 e na remoção de sólidos: ST (95% com 2,29 mg.L-1), STF (71% com 0,92 mg.L-1), STV (97% com 1,37 mg.L-1), SST (95% com 0,08 mg.L-1), SSF (96% com 0,01 mg.L-1), SSV (91% com 0,09 mg.L-1), SDT (95% com 2,21 mg.L-1), SDF (67% com 0,9 mg.L-1) e SDV (97% com 1,27 mg.L-1). A vantagem da aplicação de Fenton no efluente bruto consistiu em aproveitar as características ácidas do efluente, condição necessária para que o sulfato de ferro não precipitasse, exercendo assim a função de catalisador da reação. Posteriormente a oxidação, foi necessário neutralizar o pH para precipitação do ferro, condição que ocorreu nas colunas de adsorção com os resíduos sólidos da construção civil, possibilitando a precipitação, filtração e remoção do ferro. A combinação deste sistema facilitou e minimizou o uso de reagentes químicos, possibilitando a aplicação prática em vinícolas de produção sazonal e que não possui grandes áreas para a instalação de sistemas maiores e mais complexos. Conclui-se que, o sistema físico-químico proposto apresenta relevante eficiência quanto à remoção de matéria orgânica, cor, sólidos, nitrogênio, sulfatos e fenol total, possibilitando a disposição em corpos hídricos ou rede pública de esgoto. / The organic matter present on those winery effluents varies from 1.200 mg.L-1 to 92.000 mg.L-1 of COD. The pH is acidic, varying from 3,5 to 5,0. The concentration of phenolic compounds ranges between 41 to 1450 mg.L-1 C6H5OH . For ammonia the concentration varies from 12 to 208 mg.L-1. Sulfates have to between 50 and 500 mg.L-1 S. Based on these information, a physical-chemical treatment system was proposed, analyzed into batches, which consisted of the advanced Fenton ́s Oxidation and two adsorption columns filled with alternated adsorbents: one with pottery residues and the other with residues from building (concrete) sites ( crushed on crushing machines). The winery effluent characterization was establish according to the following parameters: pH, turbidity, COD, solids, nitrogen, phosphate and phenols. The absorbents resources were characterize pH, bulk and relative densities, moisture content, volatile material, ash content. The assays begun with the oxidation of the raw effluent, followed by the addition of 16 g.L-1 of hydrogen peroxide related to a COD of z=3,36 (H2O2/DQO). Ferrous sulfate catalyzed the reaction at 1:15 portion (FeSO4.7H2O:H2O2), on an agitated platform at 150 rpm for four hours at 30oC. Once Fenton’s oxidation was concluded, the effluent was applied to the pottery absorption column, at 5m3/m2.day-1, and subsequently applied to the building sites residues column at 4m3/m2.day-1. The system’s performance was evaluate according to the COD, turbidity, nitrogen, solids, phenols and color. The COD efficiency removal obtained was 92,25%, reaching COD values of 369 mg.L-1. In addition, the chosen applied treatment revealed to be efficient on the elimination of color (100%), phenols (100%), turbidity (100%), sulfates (98%) reaching a concentration of 40.5 mg.L-1, nitrogen (10%) with 17.25 mg.L-1, and on solids removals: ST (95% with values of 2,29 mg.L-1), STF (71% and 0,92 mg.L-1), STV (97% and 1,37 mg.L-1), SST (95% and 0,08 mg.L-1), SSF (96% and 0,01 mg.L-1), SSV (91% and 0,09 mg.L-1), SDT (95% and 2,21 mg.L-1), SDF (67% and 0,9 mg.L-1) e SDV (97% and 1,27 mg.L-1). The advantage of the Fenton application on the raw effluent consisted on taking benefit of the acidic environment of the effluent, environment that gave the right condition to avoid the precipitation of the iron sulfate, becoming the reaction catalyst. Once the oxidation was completed, it was necessary to neutralize de pH to allow the iron precipitation, which took place into the building residues adsorption columns, allowing iron the precipitation, filtration and removal. These methods combined enabled and minimized the use of chemical reagents, allowing it to be easily mounted in wineries with seasonality production and wineries without a large area to install bigger and more complex systems. In conclusion, the physical – chemical system proposed revealed to be efficient on the removal of the organic mass, colors, solids, nitrogen, sulfates and phenols, allowing the discharge of effluent disposal.
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Vinhos brasileiros : teores totais e bioacessibilidade de As, Cd, Cu e Pb, teores de polifenóis totais e avaliação da rotulagem / Brazilian wine : total contents and bioaccessibility of As, Cd, Cu and Pb, total polyphenols contents and labeling assessementMazon, Elaine Marra de Azevedo 21 August 2018 (has links)
Orientador: Marcelo Alexandre Prado / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-21T19:36:01Z (GMT). No. of bitstreams: 1
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Previous issue date: 2013 / Resumo: O consumo de vinhos no Brasil aumentou cerca de 20% na última década, e sua comercialização vem se difundindo, principalmente, pelo aumento da oferta, aumento do poder aquisitivo da população brasileira, aumento da produção e pelos benefícios à saúde que lhe são atribuídos. A análise de elementos traço nos vinhos é de grande importância para o controle da qualidade, autenticidade, biodisponibilidade de metais e estudo da toxicidade, visando garantir a segurança alimentar para os consumidores. Este trabalho descreve o desenvolvimento de um método empregando a espectrometria de absorção atômica com forno de grafite para a determinação de arsênio (As), cádmio (Cd), cobre (Cu) e chumbo (Pb) em amostras de vinhos brasileiros. A digestão ácida preliminar não foi necessária no preparo de amostra. O programa de aquecimento, empregado no forno de grafite foi otimizado para os diferentes tipos de vinhos e as amostras foram diluídas na proporção de 1:3 com ácido nítrico (65% v/v) e peróxido de hidrogênio (30% m/m). A curva analítica foi preparada em meio aquoso e alguns modificadores foram investigados para cada elemento. As determinações foram realizadas nas seguintes faixas lineares 10-100 µg L-1 Cu; 5,0 - 60 µg L-1 Pb; 0,5 - 2,0 µg L-1 Cd; 10 - 60 µg L-1 As. Os limites de quantificação obtidos foram 11,5; 2,5; 0,22 e 5,0 µg L-1, respectivamente. As recuperações obtidas variaram de 92-103% (vinho tinto) e 99-106% (vinho branco) para o Cu, 97-107% (vinho tinto) e 95-101% (vinho branco) para o Pb, 89-102% (vinho tinto) e 98-106% (vinho branco) para o Cd, e 103-106% (vinho tinto) e 99-107% (vinho branco) para o As. Foram analisadas 45 amostras de vinhos nacionais adquiridos no comércio de Campinas/SP de diversas regiões do Brasil. Foram determinados os teores de As, Cd, Cu e Pb nas amostras de vinho e os valores encontrados estavam abaixo dos teores estabelecidos pela legislação brasileira. Foram calculadas as contribuições dos vinhos estudados na dieta de um adulto, com relação a ingesta destes elementos e os valores demonstraram que os vinhos estudados apresentaram baixa contribuição. Também foram determinados os valores de pH e os teores de polifenóis totais nos vinhos, as amostras apresentaram valores compatíveis com os relatados na literatura com valores médios para polifenóis em vinhos de mesa de 2046,0 mg L-1, vinhos tinto 1443,0 mg L-1 e espumantes 1606,0 mg L-1. Os valores de pH variaram de 2,8 a 3,8 entre os vinhos. Foi feito o estudo da acessibilidade e da fração dialisável pelo método in vitro dos elementos As, Cd, Cu e Pb nos vinhos e os resultados demonstraram para todos os elementos que a fração solúvel foi maior que 37% e a dialisável, maior que 43%, indicando alta capacidade de acessibilidade. Quanto aos dizeres de rotulagem foi observada uma necessidade de complementação da atual legislação específica para vinhos, com a finalidade de melhorar a qualidade das informações oferecidas ao consumidor através dos rótulos dos vinhos / Abstract: Wine consumption in Brazil has been increasing in 20% in the last decade, and its sales have been disseminating mainly due to offer and production increase, and to health benefits attributed to it. The analysis of trace elements in wine is of great importance for quality control, authenticity, metal bioavailability and toxicity study, aiming at granting safety to consumers. This paper describes the development of a method which employs atomic absorption spectrometry with graphite oven in order to determine arsenic, cadmium, copper and lead in Brazilian wines samples. A preliminary acid digestion has not been necessary in the sample preparation. The heating program employed to the graphite oven has been optimized for the different types of wine and the samples have been diluted in proportion of 1:3 with nitric acid (65% v/v) and hydrogen peroxide (30% m/m). The analytical curve has been prepared in aqueous medium and some modifiers have been investigated for each element. The determinations have been performed in the following linear ranges 10-100 µg L-1 Cu; 5,0 - 60 µg L-1 Pb; 0,5 - 2,0 µg L-1 Cd; 10 - 60 µg L-1 As. The qualification limits obtained were 11,5; 2,5; 0,22 e 5,0 µg L-1, respectively. The recoveries obtained ranged from 92-103% (red wine) and 99-106% (white wine) for Cu, 97-107% (red wine) and 95-101% (white wine) for Pb, 89-102% (red wine) and 98-106% (white wine) for Cd, and 103-106% (red wine) and 99-107% (white wine) for As. Brazilian wines, about 45 samples from Campinas/SP local market have been analyzed at several Brazilian regions. The contents of As, Cd, Cu and Pb have been determined in the samples and the amounts found out were below the contents established by the Brazilian legislation. The contribution of those elements on the diet of an adult have been calculated, and the amounts have shown that the studied wines presented low contribution. The pH levels and the total polyphenols contents have also been determined, the samples presented compatible rates according to the literature, with average rates for polyphenol in table wines at 2046,0 mg L-1, red wines 1443,0 mg L-1 and sparking 1606,0 mg L-1. The pH rates varied from 2,8 to 3,8 among the wines. The accessibility and the dialysis fraction through the in vitro method have also been studied for the elements As, Cd, Cu and Pb in the wines. The results show that for all elements soluble fractions greater than 37% and higher than 43% dialyzable indicating high capacity accessibility. As for labeling was observed a need complement the current legislation for wine in order to improve the quality of information offered to consumers through wine labels / Doutorado / Ciência de Alimentos / Doutora em Ciência de Alimentos
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Deletion analysis of the Ure2p in Saccharomyces cerevisiae and effect of NCR on the production of ethyl carbamate during wine fermentationsErasmus, Daniel J. 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The wine yeast Saccharomyces cerevisiae has the ability to utilize several different
nitrogenous compounds to fulfill its metabolic requirements. Based upon different
growth rates of the yeast in a particular nitrogen source, nitrogen compounds have
been classified as either good or poor nitrogen sources. In an environment which
contains different quality nitrogen sources, such as grape must, the yeast first utilizes
good and then the poor nitrogen sources. This discrimination between good and
poor nitrogen sources is referred to as nitrogen catabolite repression (NCR).
Examples of good nitrogen sources are ammonia, glutamine and asparagine.
Nitrogen sources such as allantoin, y-aminobutyrate (GABA), arginine and proline
are poor quality nitrogen sources.
Several regulatory proteins, Ure2p, Gln3p, Da180p,Gat1pand Deh1p, mediate NCR
in S. cerevisiae. These trans-acting factors regulate transcription of NCR sensitive
genes. All these proteins, except Ure2p, bind cis-acting elements in the promoters
of genes that are responsible for degradation of poor nitrogen sources. Gln3p is an
activator of NCR sensitive genes in the absence of good nitrogen sources. The
predominant mechanism by which NCR functions is by using Ure2p to inactivate the
activator Gln3p in the presence of a good nitrogen source.
Several research groups have studied the Ure2p, mainly due to its prion-like
characteristics. The Ure2p has two domains: a prion inducing domain located in the
N-terminal region and a NCR regulatory domain located in the C-terminal domain.
The aims of this study were (i) to determine the part of the C-terminal domain which
is responsible for NCR, (ii) to establish if ure2 deletion mutants produce less ethyl
carbamate during wine fermentations and (iii) if NCR functions in industrial yeast
strains. Nested deletions of the URE2 gene revealed that the NCR regulatory
domain resides in the last ten amino acids of the Ure2p. This was established by
Northern blot analysis on the NCR sensitive genes DAL5, CAN1, and GAP1 genes.
Ethyl carbamate in wine is produced by spontaneous chemical reaction between
urea and ethanol in wine. Urea is produced by S. cerevisiae during the metabolism of arginine. Arginine is degraded to ornithine and urea by arginase, the product of
the CAR1 gene. Degradation of urea by S. cerevisiae is accomplished by urea
amidolyase, a bi-functional enzyme and product of the DUR1,2 gene which is subject
to NCR. This study investigated if a ure2 mutant strain produced less ethyl
carbamate during wine fermentations.
Wine fermentations were conducted with diploid laboratory strains: a ure2 mutant
strain and its isogenic wild type strain. GC/MS analysis of the wine revealed that the
ure2 mutant produced less ethyl carbamate but more ethanol than the wild type
strain when arginine, di-ammoniumphosphate, asparagine or glutamine were added
as nitrogen sources, in combinations and separately. There was no significant
difference between the wild type fermentation and the ure2 mutant fermentation
when no nitrogen was added. It was found that a combination between the deletion
of URE2 and the addition of a good nitrogen source resulted in lower levels of ethyl
carbamate.
High density micro array analysis done on an industrial strain wine yeast in
Chardonnay grape must revealed that the GAP1, CAN1, CAR1 and DUR1,2 genes,
responsible for transport and metabolism of arginine and degradation of urea, are
NCR sensitive. These data strongly suggest that NCR functions in industrial yeast
strains. / AFRIKAANSE OPSOMMING: Die wyngis Saccharomyces cerevisiae kan verskillende stikstofbronne gebruik om in
sy stikstofbehoeftes te voldoen. Stikstofbronne word as goeie of swak stikstofbronne
geklassifiseer op grond van die groeitempo van die gis op die betrokke stikstofbron.
'n Goeie stikstofbron laat die gis vinniger groei as wat dit op 'n swak stikstofbron sou
groei. In omgewings soos druiwemos waar daar 'n verskeidenheid van
stikstofbronne teenwoordig is, sal die gis eers die goeie bronne en daarna die swak
bronne benut. Stikstofbronne soos ammonium, asparagien en glutamien word
geklassifiseer as goeie bronne. Allantoïen, y-amino-butaraat (GABA), prolien en
arginien word as swak stikstofbronne geklassifiseer. Die meganisme waarmee S.
cerevisiae tussen die stikstofbronne onderskei, staan as stikstof kataboliet
onderdrukking (NCR) bekend.
Die proteïene wat vir verantwoordelik is NCR naamlik Ure2p, Gln3p, Gat1 p, Dal80p
en Deh1 p, bind met die uitsondering van Ure2p, almal aan cis-werkende elemente in
die promoters van NCR-sensitiewe gene. Die trans-werkende faktore reguleer die
transkripsie van NCR-sensitiewe gene. NCR werk hoofsaaklik deur die inhibering
van Gln3p deur Ure2p in die teenwoordigheid van 'n goeie stikstofbron. Die oorgrote
meerderheid NCR-sensitiewe gene word deur Gln3p in die afwesigheid van 'n goeie
stikstofbron geaktiveer.
Heelwat navorsing is op die prionvormings vermoë van Ure2p gedoen. Ure2p het
twee domeine: 'n N-terminale domein wat vir prionvorming verantwoordelik is en die
C-terminale domein waar die NCR funksie van Ure2p gesetel is. Die doel van die
studie was (i) om te bepaal waar in die C-terminale domein van Ure2p die NCR
regulering geleë is, (ii) of ure2 delesie mutante minder etielkarbamaat tydens
wynfermentasies produseer en (iii) of NCR in industriële gisrasse funksioneel is.
Delesie analises van URE2 het getoon dat die NCR regulerings domein in die laaste
tien aminosure gesetel is. Dit is vas gestel m.b.v. noordlike klad tegniek analises op
die OALS, CAN1 en GAP1 gene.Etielkarbamaat in wyn word deur die spontane chemiese reaksie tussen ureum en
alkohol geproduseer. Ureum word gedurende die metabolisme van arginien in S.
cerevisiae geproduseer. Arginien word deur arginase, produk van die CAR1 geen,
na ornitien en ureum afgebreek. Die bi-funksionele ureum amidoliase, gekodeer
deur die DUR1,2 geen, breek ureum na CO2 en NH/ af. As gevolg van die NCRsensitiwiteit
van dié gene is ondersoek ingestel na In ure2 mutant se vermoë om
minder etielkarbamaat tydens wynfermentasies te produseer. Chardonnay
druiwemos is met In diploiede laboratorium ras en die isogeniese ure2 mutant
gefermenteer. GC/MS analise op die wyn het getoon dat die ure2 mutant minder
etielkarbamaat, maar meer alkohol in vergelyking met die wilde tipe gis produseer,
as arginien, di-ammoniumfosfaat, asparagien en glutamien, afsonderlik of
gesamentlik byvoeg is. Daar was egter nie In merkwaardige verskil tussen die
fermentasies waar geen stikstof bygevoeg is nie. Dit dui daarop dat In kombinasie
van In URE2 delesie en die byvoeging van stikstof etielkarbamaat vlakke verlaag.
Mikro-skyfie analise van In industriële gis in Chardonnay mos het getoon dat die
GAP1, CAN1, CAR1 en DUR1,2 gene wat verantwoordelik is vir die transport en
metabolisme van arginien en degradasie van ureum, wel NCR-sensitief is. Dit dui
daarop dat NCRwel in industriële gisrasse funksioneel is.
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Fermentation optimization of pediocin PD-1 production and a comparative study of the effect of pediocin PD-1, plantaricin 423 and nisin on biofilms of Oenococcus oeniNel, Hannes Augustinus 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Lactic acid bacteria are present in many foods and beverages and are used as starter cultures in
the production of a variety of fermented products. Many of these bacteria produce ribosomally
synthesized antimicrobial peptides (bacteriocins), which inhibit the growth of bacteria genetically
closely related to the producer cell. Since many of these target bacteria include foodbome
pathogens such as Bacillus spp., Clostridium spp., Listeria spp., and Staphylococcus spp., the
practical importance of these peptides as food preservatives has been well documented and, in the
case of nisin and pediocin PA-I, commercially explored.
The increased demand from health conscious consumers for foods with no chemical
preservatives is putting renewed pressure on the producer to supply a "clean and green" product,
but with the same or even an extended shelf life. Various research groups are screening lactic
acid bacteria for production of novel broad-spectrum antimicrobial peptides or are exploring the
possibilities of altering known bacteriocins to inhibit Gram-negative bacteria, yeasts and molds.
Pediocin PD-I, produced by Pediococcus damnosus NCFB 1832, belongs to the class Ila
bacteriocins, i.e. heat-stable Listeria-active peptides, containing the YGNGV -consensus sequence
in the N-terminal region. Little is known about the production and mode of activity of pediocin
PD-I.
In this study, production of pediocin PD-I was significantly increased by optimizing the
growth medium, De Man Rogosa and Sharpe (MRS) broth. Addition of bacteriological peptone
(1.7%, w/v), manganous sulphate (0.014%, w/v) and Tween 80 (3%, v/v), and lowering of the pH
during fermentation stimulated pediocin PD-I production and the level of organic acids
produced. Maximum levels of bacteriocin activity were recorded at an initial pH of 6.7 in the
latter medium. Under these conditions the specific bacteriocin activity increased by a factor of
approximately six after 55 h of fermentation.
The effect of pediocin PD-I, plantaricin 423, produced by Lactobacillus plantarum 423, and
commercial grade nisin (Aplin and Barrett Ltd., Trowbrige, Wilts, England) was tested against
planktonic cells of Oenococcus oeni and a biofilm of the cells established on stainless steel
surfaces identical to those used in wineries. After 5 h of treatment with 3000 AU (arbitrary
units )/ml of each bacteriocin, all planktonic cells of 0. oeni in a modified Chardonnay must
medium were killed. All viable cells in the biofilm were killed after only 1 h in the presence of 3000 AU/ml of anyone of the bacteriocins. In addition, pediocin PD-I, plantaricin 423 and nisin
removed the biofilms from the surfaces and reduced the biomass either completely, as in the case
of pediocin PD-I, or by 58% and 50% as in the case of plantaricin 423 and nisin, respectively.
These same results were recorded after 5 h of treatment with 3000 AU/ml in a modified
Chardonnay must medium.
To our knowledge this is the first report of controlling biofilm formation of malolactic bacteria
on stainless steel surfaces with natural antimicrobial peptides. This implies that, apart from being
very effective in controlling the cell numbers of free-living cells of 0. oeni, the three
bacteriocins, especially pediocin PD-I, could also be used as natural sanitizers. The fact that the
production and activity levels ofpediocin PD-I could be increased without genetically modifying
the producer strain is an added advantage. / AFRIKAANSE OPSOMMING: Melksuurbakterieë is teenwoordig in verskeie soorte voedsel- en drankprodukte en word as
suurselkulture in die produksie van 'n verskeidenheid gefermenteerde produkte gebruik. Baie van
hierdie bakterieë produseer ribosomaal-vervaardigde antimikrobiese peptiede (bakteriosiene) wat
die groei van ander bakterieë, geneties naverwant aan die produserende organisme, inhibeer.
Omdat baie van hierdie bakterieë voedselpatogene soos Bacillus spp., Clostridium spp., Listeria
spp. en Staphylococcus spp. insluit, is die praktiese belang van hierdie peptiede reeds deeglik
ondersoek en word, soos in die geval van nisien en pediosien PA-I, kommersieel gebruik.
Die toenemende behoefte van die verbruiker na voedselprodukte met geen chemiese
preserveermiddels plaas nuwe druk op die vervaardiger om veilige voedselprodukte te produseer,
maar met dieselfde of selfs langer rakleeftyd. Verskeie navorsingsgroepe bestudeer
melksuurbakterieë vir die produksie van unieke antimikrobiese peptiede met 'n wye spektrum van
inhibisie en ondersoek ook die moontlikhede om hierdie bakteriosiene geneties te manipuleer ten
einde Gram-negatiewe bakterieë, giste en swamme te inhibeer.
Pediosien PD-l, geproduseer deur Pediococcus damnosus NCFB 1832, word as 'n klass na
bakteriosien geklassifiseer. Hierdie groep sluit in die hitte-stabiele Listeria-aktiewe peptiede, met
'n YGNGV-konsensus volgorde in die N-terminale deel van die peptied. Min is egter bekend oor
die meganisme van werking van hierdie bakteriosiene.
In hierdie studie is die produksie van pediosien PD-l betekenisvol verhoog met die
optimalisering van die vloeibare groeimedium De Man Rogosa en Sharpe (MRS). Die
toevoeging van bakteriologiese peptone (1.7%, miv), mangaan sulfaat (0.014%, miv) en Tween
80 (3.0%, v/v) en 'n afname in die pH gedurende groei het pediosien PD-l-poduksie gestimuleer
en sodoende ook die vlak van organiese sure wat geproduseer is. Maksimum vlakke van
bakteriosien-aktiwiteit is in hierdie medium met 'n aanvangs-pH van 6.7 waargeneem. Onder
hierdie omstandighede, en na 55 uur van fermentasie, het die spesifieke aktiwiteit van die
bakteriosien met 'n faktor van ongeveer ses verhoog.
Die effek van pediosien PD-l, plantarisien 423, geproduseer deur Lactobacillus plantarum
423, en 'n kommersiële graad nisien (Aplin and Barrett Ltd., Trowbride, Wilts, Engeland) is teen
die planktoniese selle van Oenococcus oeni en 'n biofilm van hierdie selle, gevestig op 'n vlekvrye
staaloppervlak identies aan wat in wynkelders gebruik word, getoets. Na 5 ure van behandeling met 3000 AB (arbitrêre eenhede)/ml van elke bakteriosien, is al die planktoniese selle van O. oeni
in 'n gemodifiseerde Chardonnay mos-medium vernietig. Alle lewensvatbare selle in die biofilm
is ook na slegs 1 uur in die teenwoordigheid van 3000 AE/ml van enige een van hierdie
bakteriosiene vernietig. Verdermeer het pediosien PD-I, plantarisien 423 en nisien ook die
biofilm op die vlekvrye staal-oppervlak verwyder. In die geval van pediosien PD-I is 'n totale
afname van die biomassa-oppervlak waargeneem, terwyl plantarisien 423 en nisien 58% en 50%
van die totale biomassa verwyder het. Hierdie resultate is na 5 ure van behandeling (3000
AE/ml) in 'n gemodifiseerde Chardonnay mos-medium waargeneem.
Sover ons kennis strek is hierdie die eerste verslag rakende die gebruik van natuurlike
antimikrobiese peptiede om biofilm-vorming deur appel-melksuurbakterieë op vlekvrye staal
oppervlaktes te beheer. Dit impliseer dat bakteriosiene, spesifiek pediosien PD-I, benewens die
beheer van planktoniese selle van appel-melksuurbakterieë, ook as natuurlike oppervlak-reinigers
gebruik kan word. Die feit dat die produksie en aktiwiteitsvlakke van pediosien PD-I verhoog
kon word sonder om die organisme geneties te modifiseer is 'n verdere voordeel.
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The use of enzymes for increased aroma formation in wineStidwell, Tanya Gwendryth 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Monoterpene alcohols (monoterpenols) play an important role in the flavour and aroma of
grapes and wine. This is especially applicable to wines of a muscat variety, but these
flavour compounds are also present in other non-muscat grape varieties, where they
supplement other varietal flavours and aromas. These monoterpenols can be found in grapes and wine as free, volatile and odorous molecules, as well as in flavourless, nonvolatile
glycosidic complexes. These complexes most often occur as
6-0-a-L-arabinofuranosyl-p-D-glucopyranosides (vicianosides), 6-0-P-D-xylopyranosyl-
P-D-gluco-pyranosides (primverosides), 6-0-P-D-glucopyranosyl-p-D-glucopyranosides
(gentio-biosides ), 6-0-a-L -rhamnopyra nosyl-p-D-g lucopyra nos ides (rutinos ides), or
6-0-p-D-apiofuranosyl-p-D-glucopyranosides of mainly linalool, geraniol, nerol, a-terpineol
and hotrienol. These precursors are, however, hydrolyzed only to a limited extent by
endogenous glycosidases during the fermentation process, as they exhibit very low activity
in wine conditions.
The monoterpenols can be released from their sugar moieties by one of two
methods: either an acid or an enzymatic hydrolysis. The enzymatic hydrolysis mechanism
is fully understood, and the process functions in two successive steps: firstly, depending on
the precursor, the glycosidic linkage is cleaved by an a-L-arabinofuranosidase, an
a-L-rhamnosidase, a p-D-xylosidase, or a p-D-apiosidase. The second step involves the
liberation of the monoterpene alcohol by a p-glucosidase. This enzymatic hydrolysis does
not influence the intrinsic aromatic characteristics of the wine, as opposed to acid
hydrolysis.
As the endogenous grape glycosides of Vitis vinifera and the yeast Saccharomyces
cerevisiae show very low activity towards these aromatic precursors during the handling of
the juice and winemaking processes, the focus has increasingly fallen on introducing
exogenous p-glucosidases to wines and juices. Genes encoding p-glucosidases and
a-L-arabinofuranosidases have been cloned from various organisms, including bacteria,
fungi and yeasts. However, the activities and properties of these enzymes are not always
suitable for exploitation under winemaking conditions, where a low pH, low temperatures,
and high ethanol and glucose concentrations prevail. A genetically engineered wine yeast
strain of S. cerevisiae that expresses glycosidases that are active in these conditions would
be useful in improving the flavour and aroma of wines, thereby adding to the complexity
and value of the wine.
Two p-glucosidase genes, BGL 1 and BGL2 from Saccharomycopsis fibufigera, were
subcloned into two Escherichia coli-yeast shuttle vectors. A dominant selectable marker
gene (SMR1) was also inserted onto these plasmids. These plasmids were designated pBGL 1 (containing the BGL 1 gene) and pBGL2 (containing the BGL2 gene) respectively.
Introduction of the two plasmids into two strains of S. cerevisiae then followed. A laboratory
strain, L1278, was transformed to confirm the effective secretion of the expressed protein.
An industrial yeast strain, VIN13, was subsequently transformed by making use of the
selectable marker (resistance against sulfometuron). Enzyme assays with the synthetic
substrate p-nitrophenol-j3-D-glucopyranoside (pNPG) were performed to determine the
activity of the j3-glucosidases over a period of days, as well as at certain temperatures and
pH values. The stability of the enzymes was also investigated.
These recombinant yeasts were able to degrade the pNPG efficiently. They showed
promising results concerning pH optima, with a substantial amount of activity found at the
pH levels as found in the wine environment. There was also a slight increase in specific
activity at lower temperatures. The recombinant yeast strains were also tested in smallscale
fermentations. Three wines were made, of which two were from white cultivars
(Chenin blanc and GewOrtztraminer) and one from red (Pinotage). Results obtained from
micro-extraction from the finished wines showed that the terpenol content did increase,
although this was not the only wine component influenced. Other flavour compounds also
showed increases, especially the esters. This also played a role in the flavour increase in
the wine.
Future work would include optimizing the available results. This would entail the
addition of another glycosidic enzyme, such as a-L-arabinofuranosidase, to the genome of
the wine yeast to aid the further breakdown of glycosidic bonds. The cloning or engineering
of a j3-glucosidase enzyme that is more active at low temperatures would also yield better
results and release even more of the aroma of the wine. / AFRIKAANSE OPSOMMING: Monoterpeenalkohole (monoterpenole) speel 'n belangrike rol in die geur en aroma van
druiwe en wyn. Dit is veral van toepassing op wyne van Muskaat-varieteite, maar hierdie
geurkomponente is ook teenwoordig in ander nie-Muskaat druifsoorte, waar dit bydra tot
die varieteitsqeur en aroma. Hierdie monoterpenole kom voor in druiwe as vry, vlugtige en
aromatiese molekules, of as geurlose, nie-vlugtige glikosidies-gebonde komplekse. Hierdie
komplekse is meestal in die vorm van 6-0-a-L-arabinofuranosiel-~-D-glukopiranosiede, 6-
O-~-D-xilopiranosiel-~-D-glukopiranosiede (primverosiede), 6-0-~-D-glukopiranosiel-~-Dglukopiranosiede
(gentiobiosiede), 6-0-a-L-ramno-pyranosiel-~-D-glukopiranosiede
(rutinosiede), of 6-0-~-D-apiofuranosiel-~-D-glukopirano-siede van hoofsaaklik linalool,
geraniol, nerol, a-terpineol en hotrienol. Hierdie geurvoorlopers word egter slegs tot In
beperkte mate tydens die proses van fermentasie deur die endogene glikosidase ensieme
gehidroliseer, aangesien hulle baie min aktiwiteit toon onder wynbereidingstoestande.
Die monoterpenole kan op een van twee wyses van hul suikermolekules vrygestel
word: 'n suurhidrolise, of ensiematiese hidrolise. Die ensiematiese hidroliseproses word
baie goed begryp en behels twee opeenvolgende stappe: eerstens, afhangende van die
aard van die voorloper, word die glikosidiese verbinding deur In a-L-arabinofuranosidase, In
a-L-ramnosidase, In ~-D-xilosidase, of 'n ~-D-apiosidase gebreek. In die tweede stap word
die monoterpeenalkohol deur In ~-glukosidase vrygestel. Hierdie ensiematiese
afbraakproses verander nie die intrinsieke aromatiese kenmerke van die wyn, soos wat met
suurhidrolise die geval is nie.
Omdat die endogene glikosidases van Vitis vinifera en die van die gis
Saccharomyces cerevisiae baie lae aktiwiteit ten opsigte van die aromatiese voorlopers
gedurende die hantering van die druiwesap en wynmaakprosesse toon, val die fokus al hoe
meer op die inkorporering van eksogene ~-glukosidases in wyn en sappe. Gene wat vir ~-
glukosidases en a-L-arabinofuranosidases kodeer, is al vanuit verskeie organismes
gekloneer, insluitende bakteriee, fungi en giste. Die aktiwiteite en kenmerke van hierdie
ensieme is egter nie altyd wenslik vir hul gebruik in wyn nie, aangesien dit In omgewing is
met 'n lae pH, lae temperatuur, en hoe etanolvlakke en glukose-konsentrasies. In geneties
veranderde wyngis van S. cerevisiae wat in staat is om glikosidases uit te druk wat onder
hierdie kondisies aktief is, sal baie handig te pas kom in die verbetering van die geur en
aroma van wyne, om daardeur die kompleksiteit en die waarde van die wyn te verhoog.
Twee ~-glukosidasegene, BGL 1 en BGL2 vanaf die gis Saccharomycopsis
fibuligera , is in twee afsonderlike Esccherichia coli-gis-pendelplasmiede gesubkloneer. In
Dominante selekteerbare merkergeen (SMR1) is ook in hierdie plasmiede gekloneer.
Hierdie plasmiede word onderskeidelik pBGL 1 (met die BGL 1-geen) en pBGL2 (bevattende die BGL2-geen) genoem. Hierdie twee plasmiede is hierna apart na twee rasse van
S. cerevisiae getransformeer. Eerstens is 'n laboratoriumras, L1278, getransformeer om te
bevestig dat effektiewe sekresie en uitdrukking van die proteTen plaasvind. Hierna is 'n
industriele gisras, VIN13, getransformeer deur gebruik te maak van die selektiewe merker
(bestandheid teen sulfometuron). Ensiem-bepalings met behulp van die sintetiese
substraat p-nitrofeniel-p-O-glukopiranosied (pNPG) is gedoen om die aktiwiteit van die
p-glukosidqses oor 'n aantal dae te bepaal, asook om die aktiwiteit by sekere temperature
en pH-vlakke te meet. Die stabiliteit van die ensieme is ook bepaal.
Hierdie rekombinante giste was in staat om pNPG effektief af te breek. Hulle het
belowende resultate betreffende die pH-optima getoon, met 'n aansienlike hoeveelheid
aktiwiteit by die pH-vlakke soos dit in die wynomgewing voorkom. Daar was ook 'n effense
verhoging in die ensieme se aktiwiteite by laer temperature. Die rekombinante gisrasse is
ook in kleinskaalse wynfermentasies gebruik. Drie verskillende wyne is gemaak, waarvan
twee wit kultivars was (Chenin blanc en GewOrtztraminer) en een 'n rooi kultivar (Pinotage).
Resultate wat deur die mikro-ekstraksie van die voltooide wyne verkry is, het getoon dat die
terpenolinhoud wei verhoog het, alhoewel dit nie die enigste wynkomponente was wat
beinvloed is nie. Ander geurkomponente het ook 'n verhoging in konsentrasie getoon, veral
die esters. Hierdie verbindings het ook 'n rol in die verhoging van geur in die wyne gespeel.
Toekomstige werk sal die beskikbare resultate verder optimaliseer. Dit sal insluit die
byvoeging van nog 'n glikosidiese ensiem, soos a.-L-arabinofuranosidase, tot die genoom
van die wyngis, om verdere afbraak van glikosidiese verbindings teweeg te bring. Die
klonering of verandering van 'n p-glukosidase-ensiem met verhoogde aktiwiteit by laer
temperature sal ook beter resultate toon en meer geur in die wyn kan vrystel.
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Characterisation of biogenic amine genes in lactic acid bacteria isolated from wineDowning, Lynn,1978- 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The winemaking process involves a complex microbial flora where the interaction of
yeasts, lactic acid bacteria and acetic acid bacteria play an important role in the
quality and wholesomeness of the final product. Yeasts are primarily responsible for
alcoholic fermentation. Malolactic fermentation follows alcoholic fermentation and is
conducted by lactic acid bacteria. These bacteria are important in winemaking and
can have a positive or negative effect on the wine quality. Biogenic amines are one
of the compounds produced by lactic acid bacteria, which affect the hygienic quality
and wholesomeness of the wine negatively and directly pose a health risk to the
consumer. The demand of consumers for higher quality and healthier foods has led
to renewed interest in studies on biogenic amines. Biogenic amines occur in a wide
variety of food products, such as cheese, dried sausage, sauerkraut, fishery
products, chocolates, wine and beer. This thesis focussed on the presence of
biogenic amines in wine.
The first objective of the study was to determine the ability of lactic acid bacteria
isolated from South African wine to produce biogenic amines, using a decarboxylase
screening plate method. The potential to produce the biogenic amines histamine,
tyramine, putrescine and cadaverine was investigated. The results obtained showed
that Lactobacillus species (Lactobacillus brevis and Lactobacillus hilgardil) might be
the lactic acid bacteria responsible for tyramine and putrescine production and that it
can contribute significantly to the overall biogenic amine content in wines. The
results also suggest that amine production is strain dependent and not species
specific. None of the lactic acid bacteria tested had the ability to produce histamine
or cadaverine. It is important to remember that the ability of the lactic acid bacteria to
produce biogenic amines has only been investigated in synthetic media and that it
does not necessarily imply similar behaviour in wine. Wine represents a complex
environment with a wide number of factors influencing microbial growth and
decarboxylase activity and, thus, further investigation is necessary to determine if
these amine-producing bacteria behave similarly in wine conditions.
In addition, the polymerase chain reaction (PCR) amplification method was
used for the identification of the tyrosine decarboxylase (TOe) gene in some of the
tyramine-producing lactic acid bacteria. This was followed by the sequencing of the
amplified products, which are partial TOe gene sequences, of two L. brevis strains
and of a L. hilgardii strain. Only one tdc gene sequence has been described for
bacteria (Enterococcus faecalis), while a partial TOC gene sequence from L. brevis
lOEB 9809 was described. An amino acid sequence alignment of the three TOe
gene fragments, obtained in this study, with the known TOe gene fragment of
L. brevis lOEB 9809 and the tdc gene of E. faecalis showed a high degree of
relatedness and conserved regions.
To meet consumer demands, procedures are necessary to prevent the
formation of amines in food products. One way of preventing the formation of biogenic amines is to relate amine production with certain lactic acid bacteria species
involved in the winemaking process. Another possible way would be to develop a
rapid detection method for bacteria carrying amino acid decarboxylase genes. The
results of this study provide knowledge about which lactic acid bacteria in the
winemaking process could contribute to the production of biogenic amines and the
sequencing of additional partial TOe genes could possibly assist in the development
of a rapid detection method for tyramine-producing lactic acid bacteria in food
products. / AFRIKAANSE OPSOMMING: Die wynmaakproses behels 'n komplekse mikrobiese flora waar die interaksie van
giste, melksuurbakterieë en asynsuurbakterieë 'n belangrike rol speel in die kwaliteit
en heilsaamheid van die finale produk. Giste is primêr verantwoordelik vir
alkoholiese fermentasie. Appelmelksuurgisting volg op alkoholiese fermentasie en
word deur melksuurbakterieë uitgevoer. Hierdie bakterieë is belangrik in die maak
van wyn en kan 'n positiewe of negatiewe uitwerking op die kwaliteit van wyn hê.
Biogeniese amiene is een van die komponente wat deur melksuurbakterieë
geproduseer kan word en wat die higiëniese kwaliteit en heilsaamheid van die wyn
benadeel. Dit hou ook 'n gesondheidsrisiko vir die verbruiker in. Die vereiste van
verbruikers vir hoër kwaliteit en gesonder voedselprodukte het nuwe belangstelling in
studies op biogeniese amiene ontlok. Biogeniese amiene kom in 'n wye
verskeidenheid voedselprodukte voor, soos kaas, droëwors, suurkool, vis, sjokolade,
wyn en bier. Hierdie tesis fokus op die teenwoordigheid van biogeniese amiene in
wyn.
Die eerste doelwit van die studie was om melksuurbakterieë, wat uit Suid-
Afrikaanse wyn geïsoleer is, se vermoë te bepaal om biogeniese amiene op
dekarboksilase-agarplate te produseer. Die potensiaal om die biogeniese amiene
histamien, tiramien, putresien en kadawerien te produseer, is bestudeer. Die
resultate wat verkry is, toon dat Lactobacillus-spesies (Lactobacillus brevis en
Lactobacillus hilgardit) vir tiramien- en putresienproduksie verantwoordelik is en dat
hulle 'n belangrike bydrae kan lewer tot die totale biogeniese amienkonsentrasie in
wyn. Die resultate dui ook daarop dat die produksie van amiene afhanklik is van die
ras, en nié 'n spesifieke spesie nie. Geen melksuurbakterieë wat getoets is, het die
vermoë getoon om histamien of kadawerien te produseer nie. Dit is belangrik om in
ag te neem dat die vermoë van die melksuurbakterieë om amiene te produseer slegs
in sintetiese media bestudeer is en dat dit nie noodwendig dieselfde gedrag in wyn
sal toon nie. Wyn is 'n komplekse omgewing met 'n wye verskeidenheid faktore wat
die mikrobiese groei en dekarboksilase-aktiwiteit kan beïnvloed, daarom is verdere
studie nodig om vas te stelof hierdie amien-produserende bakterieë dieselfde
gedrag in wyn sal toon.
Die polimerase-kettingreaksie (PKR) amplifikasie-metode is vir die identifikasie
van die tirosiendekarboksilase-geen (TDK) in sommige van die tiramienproduserende
melksuurbakterieë gebruik. Dit is gevolg deur die volgordebepaling
van die geamplifiseerde produkte, wat gedeeltelike TDK-geenvolgordes is, van twee
L. brevis- en van een L. hilgardii-ras. Slegs een tdk-geenvolgorde is al voorheen vir
bakterieë beskryf, nl. Enterococcus faecalis, asook 'n gedeeltelike TDK-geenvolgorde
vir L. brevis lOEB 9809. 'n Vergelyking van die aminosuurvolgordes van die drie
TDK-geenfragmente wat in die studie verkry is, het 'n hoë graad van ooreenkoms en
gekonserveerde areas met die bekende TDK-geenfragment van L. brevis lOEB 9809
en die tdk-geen van E. faecalis getoon. Om verbruikers se behoeftes te bevredig, is dit noodsaaklik dat die vorming van
amiene in voedselprodukte voorkom word. Een manier van voorkoming is om
amienproduksie aan sekere melksuurbakterieë wat in die wynmaakproses betrokke
is, te koppel. 'n Ander manier sal wees om 'n vinnige metode te ontwikkel vir die
opsporing van bakterieë wat aminosuurdekarboksilase-gene dra. Die resultate van
die studie verskaf kennis van watter melksuurbakterieë in die wynmaakproses tot die
produksie van biogeniese amiene kan bydra. Die volgordebepaling van addisionele
gedeeltelike TDK-gene kan moontlik tot die ontwikkeling van 'n vinnige
opsporingsmetode van tiramien-produserende melksuurbakterieë in voedselprodukte
bydra.
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Biochemiese veranderinge in druiwemos veroorsaak deur Botrytis cinerea en Rhizopus nigricansHofmann, Gerhard 12 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 1964. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming
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The effect of oxygen on the composition and microbiology of red wineDu Toit, Wessel Johannes 03 1900 (has links)
Thesis (PhD(Agric) (Viticulture and Oenology))--University of Stellenbosch, 2006. / The winemaking process involves different complex chemical and biochemical
reactions, which include those of oxygen (O2). Oxygen can come into contact with the
wine through various winemaking procedures and can be used by the winemaker to
enhance the quality of red wine. In wine, the main substrates for oxidation are
phenolic molecules, which form quinones. These can influence the sensory
characteristics of the wine. O2 can be used in fresh must to remove oxidisable
phenolic molecules through a process called hyper-oxidation and can also be added
to fermenting must to enhance the fermentation performance of yeast. Controlled O2
additions during ageing can lead to the wine’s colour being increased and the
astringency of the wine decreased. This is due to the formation of acetaldehyde from
the oxidation of ethanol, which induces the polymerisation of tannin and anthocyanin
molecules. The addition of too much O2 to wine can, however, lead to unwanted
over-oxidation, with certain off-odours being formed. It can also enhance the growth
of unwanted spoilage microorganisms, such as Brettanomyces and acetic acid
bacteria. Although research on O2 in wine was started many years ago, many
questions still remain. These include the general effect of O2 on the sensory and
phenolic profile of red wine especially and the microbiology of wine during ageing. An
effective way of measuring oxidation, especially in red wine must also be developed.
In the first part of this study, the effects of O2 and sulfur dioxide (SO2) additions
on a strain of Brettanomyces bruxellensis (also known as Dekkera bruxellensis) and
Acetobacter pasteurianus were investigated. Epifluorescence microscopy and plating
revealed that the A. pasteurianus strain went into a viable but non-culturable state in
the wine after prolonged storage under relative anaerobic conditions. This state,
however, could be negated with successive increases in culturability by the addition
of O2, as would happen during the transfer of wine when air is introduced. The A.
pasteurianus strain was also relatively resistant to SO2, but the B. bruxellensis strain
was more sensitive to SO2. A short exposure time to molecular SO2 drastically
decreased the culturability of the B. bruxellensis strain, but bound SO2 had no effect
on the culturability or viability of either of the two types of microorganisms. Oxygen
addition to the B. bruxellensis strain also led to a drastic increase in viability and
culturability. It is thus clear that SO2 and O2 management in the cellar is of critical
importance for the winemaker to produce wines that have not been spoiled by
Brettanomyces or acetic acid bacteria. This study should contribute to the
understanding of the factors responsible for the growth and survival of
Brettanomyces and acetic acid bacteria in wine, but it should be kept in mind that
only one strain of each microorganism was used. This should be expanded in future
to include more strains that occur in wine.
The second part of this study investigated the effect of micro-oxygenation on four
different South African red wines. It was found that the micro-oxygenation led to an
increase in the colour density and SO2 resistant pigments of the two wines in which micro-oxygenation was started just after the completion of malolactic fermentation. In
one of these wines, a tasting panel preferred the micro-oxygenation treated wines to
the control. In the other two red wines, in which the micro-oxygenation was started
seven months after the completion of malolactic fermentation, very little colour
increase was observed. One of these two wines was also matured in an oak barrel,
where the change in phenolic composition was on par with the treated wines. A
prolonged period of micro-oxygenation, however, led to this wine obtaining an
oxidised, over-aged character. Micro-oxygenation and maturation in an oak barrel
also enhanced the survival of acetic acid bacteria and Brettanomyces in this wine.
Micro-oxygenation can hence be used by the wine producer on young red wines to
enhance the quality of the wine, but should be applied with care in older red wines.
Future research into micro-oxygenation should focus on whether it can simulate an
oak barrel. More research into the effect of micro-oxygenation on the sensory profile
of the wine is needed.
As mentioned, the addition of O2 can lead to oxidative degradation of wine. The
brown colour in wine is often used as an indication of oxidation, but oxidative aromas
can be perceived before a drastic increase in the brown colour has been observed in
red wine.
The third part of this study was to assess the possible use of Fourier Transform
Infrared Spectroscopy (FTIR) to measure the progression of oxidation in Pinotage red
wines. Three wines were used in this study and clear separation between the control
and aerated wines was observed by using Principle Component Analysis (PCA).
Sensory analysis of these wines confirmed this observation, with a reduction
especially in berry fruit and coffee characters and an increase first in potato skin and
then acetaldehyde aroma characters as the oxidation progressed. PCA analysis also
revealed that in certain wines the visible spectrum of light did not indicate the
progression of oxidation as sensitively as with the use of FTIR. This also correlated
with the inability of the panel to observe a drastic colour change. FTIR should be
further investigated as a possible means of monitoring oxidation in wine and this
study should be expanded to wines made from other cultivars as well.
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Comparative 'omic' profiling of industrial wine yeast strainsRossouw, Debra 12 1900 (has links)
Thesis (PhD(Agric) Viticulture and Oenology. Wine Biotechnology))--University of Stellenbosch, 2009. / The main goal of this project was to elucidate the underlying genetic factors responsible for the
different fermentation phenotypes and physiological adaptations of industrial wine yeast strains. To
address this problem an ‘omic’ approach was pursued: Five industrial wine yeast strains, namely
VIN13, EC1118, BM45, 285 and DV10, were subjected to transcriptional, proteomic and exometabolomic
profiling during alcoholic fermentation in simulated wine-making conditions. The aim
was to evaluate and integrate the various layers of data in order to obtain a clearer picture of the
genetic regulation and metabolism of wine yeast strains under anaerobic fermentative conditions.
The five strains were also characterized in terms of their adhesion/flocculation phenotypes,
tolerance to various stresses and survival under conditions of nutrient starvation.
Transcriptional profiles for the entire yeast genome were obtained for three crucial stages during
fermentation, namely the exponential growth phase (day 2), early stationary phase (day 5) and late
stationary phase (day 14). Analysis of changes in gene expression profiles during the course of
fermentation provided valuable insights into the genetic changes that occur as the yeast adapt to
changing conditions during fermentation. Comparison of differentially expressed transcripts
between strains also enabled the identification of genetic factors responsible for differences in the
metabolism of these strains, and paved the way for genetic engineering of strains with directed
modifications in key areas. In particular, the integration of exo-metabolite profiles and gene
expression data for the strains enabled the construction of statistical models with a strong predictive
capability which was validated experimentally.
Proteomic analysis enabled correlations to be made between relative transcript abundance and
protein levels for approximately 450 gene and protein pairs per analysis. The alignment of
transcriptome and proteome data was very accurate for interstrain comparisons. For intrastrain
comparisons, there was almost no correlation between trends in protein and transcript levels, except
in certain functional categories such as metabolism. The data also provide interesting insights into
molecular evolutionary mechanisms that underlie the phenotypic diversity of wine yeast strains.
Overall, the systems biology approach to the study of yeast metabolism during alcoholic
fermentation opened up new avenues for hypothesis-driven research and targeted engineering
strategies for the genetic enhancement/ modification of wine yeast for commercial applications.
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The development of yeasts for the optimal production of flavor-active esters and higher alcohols in wine and distillatesLilly, Mariska 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Yeasts produce a broad range of aroma-active volatile esters and higher alcohols during
alcoholic fermentation. Some of these esters and higher alcohols are important for the fruity
flavors and therefore the final quality of wine and other fermented beverages. Esters are
produced and hydrolyzed by alcohol acetyltransferases and esterases, respectively. In yeast,
ester-synthesizing activities are represented by two alcohol acetyltransferases encoded by the
ATFI and ATF2 genes, and by an ethanol hexanoyl transferase encoded by the EHTI gene.
Atfl p and Atf2p appear responsible for the production of ethyl acetate and isoamyl acetate,
while Ehtl p synthesizes ethyl hexanoate from ethanol and hexanoyl-CoA. Although a fair
amount of information is available regarding the ATF 1 gene, limited information is available
on the remaining alcohol acetyltransferases. Only two genes that code for esterases have been
identified in yeast, namely lAHI and TIPI. It has also been shown that the balance between
alcohol acetyltransferases and esterases is important for the net rate of ester accumulation.
Higher alcohols are synthesized from the a-keto-acids in the branched-chain amino acid
metabolic pathway by decarboxylation and reduction. The transamination of the amino acid to
the respective a-keto-acid is catalyzed by mitochondrial and cytosolic branched-chain amino
acid transferases, which are encoded by the BATI and BAT2 genes, respectively.
In recent years, a strong scientific and industrial interest in the metabolism of flavoractive
compounds has emerged, but information regarding the roles of specific enzymes and
the physiological relevance of their metabolism remains limited. The aim of this project was
to investigate the physiological and metabolic consequences of changes in the expression
levels of some of the key enzymes involved in aroma compound production. The
consequences of these changes on the chemical composition and the fermentation bouquet of
wines and distillates were also investigated.
The first part of the section on the results in this dissertation reports on the role and
relative importance of the Saccharomyces cerevisiae enzymes involved in ester metabolism,
namely Atflp, Atf2p, Ehtlp, Iahlp and Tiplp. The corresponding genes were overexpressed
in a laboratory strain of S. cerevisiae, BY4742, and in a widely used commercial wine yeast
strain, VIN13. Table wine and base wines for distillation were prepared with these VIN13
transformed strains. The ester concentrations and aroma profiles of the wines and distillates
were analyzed and compared. The data indicated that the overexpression of ATF 1 and ATF2
increased the concentrations of ethyl acetate, isoamyl acetate, 2-pheylethyl acetate and ethyl
caproate, while the overexpression of JAHI resulted in a significant decrease in the
concentrations of ethyl acetate, isoamyl acetate, hexyl acetate and 2-phenylethyl acetate. The
overexpression of EHTI resulted in a marked increase in the concentrations of ethyl caproate,
ethyl caprylate and ethyl caprate, while the overexpression of TJP1 did not decrease the
concentrations of any of the esters. In most cases, there was a correlation between the increase
in esters and the decrease in higher alcohols. The data suggest that yeast balances the amount
of different esters produced through alcohol acetyltransferases and esterases, and that, in some
cases, these enzymes appear to overlap in function and/or influence each other's activity. In the second part of the results section, the consequences of the deletion and the
overexpression of two genes, BATl and BAT2, which encode transaminases that contribute to
the metabolism of higher alcohols, were investigated. The genes were both disrupted in a
S. cerevisiae BY4742, and overexpressed in both this laboratory strain and in the VIN13 wine
yeast strain. The effects of these modifications on the general physiology of the corresponding
yeast strains and on higher alcohol metabolism were assessed in a range of growth conditions,
including aerobic and anaerobic growth conditions, in the presence of glucose or raffinose as
sole carbon source and growth in the presence of various concentrations of amino acids. Table
wine and base wines for distillation were prepared with the modified industrial strains and the
concentrations of the higher alcohols and the aroma profiles of the wine and distillates were
analyzed and compared. Batl deletion seemed to be lethal under the conditions that were
created, and therefore only the bat2!:!.strain, together with the BATI and BAT2 overexpression
strains, were investigated. These modifications did not appear to significantly affect the
general physiology of the strains. The results obtained indicated that the overexpression of
BATI increased the concentrations of isoamyl alcohol and isoamyl acetate, and, to a lesser
extent, the concentrations of isobutanol and isobutyric acid. The overexpression of the BAT2
gene resulted in a substantial increase in the levels of isobutanol, isobutyric acid and
propionic acid production, and a modest increase in the level of propanol and isovaleric acid.
Interestingly, the overexpression of BAT2 led to a decrease in isoamyl alcohol and isoamyl
acetate concentrations. Sensory analyses indicated that the wines and distillates produced with
the strains in which the BATl and BAT2 genes were overexpressed had more fruity
characteristics (peach and apricot aromas) than the wines produced by the wild-type strains.
This study offers new prospects for the development of wine yeast starter strains with
optimized ester and higher alcohol-producing capability that could assist winemakers in their
efforts to consistently produce wine to definable specifications and styles and a predetermined
flavor profile. / AFRIKAANSE OPSOMMING: Gedurende fermentasie produseer giste 'n wye verskeidenheid vlugtige aromatiese esters en
hoër alkohole. Sommige van hierdie esters en hoër alkohole is belangrik vir die vrugtige
geure en dra dus by tot die finale kwaliteit van wyn en ander gefermenteerde drankies. Esters
word onderskeidelik deur alkoholasetieltranferases en esterases geproduseer en gehidroliseer.
In giste word die ester-sintetiserende aktiwiteite deur twee alkoholasetieltransferases
verteenwoordig wat deur die ATFI-en ATF2-gene, asook 'n etanolheksanoïeltransferase wat
deur die EHTl-geen, gekodeer word. Dit blyk dat ATFlp en ATF2p verantwoordelik is vir
die produksie van etielasetaat en isoamielasetaat, terwyl Ehtl p-etielheksanoaat vanaf etanol
en heksanoïel-CoA sintetiseer. Alhoewel daar 'n redelike hoeveelheid inligting t.o.v die
ATF I-geen beskikbaar is, is daar weinig inligting oor die res van die aloholasetieltransferases.
Slegs twee gene wat vir esterases kodeer, is in gis geïdentifiseer, naamlik IAHI en TIPI.
Daar is ook bewys dat 'n balans tussen die alkoholasetieltransferases en esterases baie
belangrik is vir die netto-tempo van ester-akkumulasie. Hoër alkohole word gesintetiseer
vanaf a-keto sure in die vertakte-ketting aminosuur metaboliese pad deur dekarboksilasie en
reduksie. Die transaminasie van die aminosuur na die onderkeidelike a-ketosuur word deur
vertakte-ketting aminosuur transferases, geleë in die mitochondrion en sitosol, en gekodeer
deur BATl- en BAT2-gene, gekataliseer.
In die laaste paar jare het daar 'n sterk wetenskaplike, asook industrïele, belangstelling in
die metabolisme van aroma-aktiewe komponente te voorskyn gekom, maar inligting in
verband met die rol van spesifieke ensieme en die fisiologiese belangrikheid van hul
metabolisme is egter beperk. Die doel van hierdie projek was om die fisiologiese en
metaboliese gevolge van veranderinge in die ekspressievlakke van sommige sleutelensieme
betrokke by aromakomponent-produksie te ondersoek. Die gevolge van hierdie veranderinge
op chemiese vlakke, asook hoe die fermentasie-aroma van die wyne en distillate beïnvloed
word, is ook bestudeer.
Die eerste gedeelte van die resultate rapporteer oor die rol en relatiewe belangrikheid van
die Saccharomyces cerevisiae-ensieme betrokke by estermetabolisme, naamlik Atfl p, Atf2p,
Ehtlp, Iahlp en Tiplp. Die gene was ooruitgedruk in 'n laboratoriurnras van S. cerevisiae,
BY4742, asook in 'n kommersïele wyngisras, VIN13. Tafelwyne en basiswyne vir distillasie
is gemaak met die getransformeerde VIN13-rasse. Die esterkonsentrasies en aromaprofiele
van die wyne en distillate is ontleed en vergelyk. Die data het gewys dat die ooruitdrukking
van ATFI- en ATF2-gene 'n verhoging in etielasetaat, isoamielasetaat, 2-fenieletielasetaat en
etielkaproaat veroorsaak het, terwyl ooruitdrukking van !AHI 'n betekenisvolle afname in
etielasetaat-, isoamielasetaat-, heksielasetaat- en 2-fenieletielasetaat-konsentrasies veroorsaak
het. Die ooruitdrukking van EHTI het 'n duidelike verhoging in etielkaproaat, etielkaprilaat
en etielkapraat veroorsaak en die ooruitdrukking van TIPIhet geen van die esterkonsentrasies
verander nie. In die meeste gevalle was daar nie 'n korrelasie tussen die toename in esters en
afname in hoër alkohole nie. Die data stelook voor dat die gis 'n balans tussen die
verskillende esters handhaaf deur middel van die alkoholasetieltrasferases en esterases, en in sommige gevalle blyk dit dat die ensieme dieselfde funksies het en/of mekaar se aktiwiteit
beïnvloed.
In die tweede gedeelte van die resultate is die oorsake van delesie en ooruitdrukking van
twee gene, BAT1 en BAT2, wat kodeer vir transaminases wat tot hoër alkohol metabolisme
bydra, bestudeer. Die gene is uitgeslaan in S. cerevisiae BY4742 en ooruitgedruk in BY4742
en in die wyngisras VIN13. Die effekte van hierdie modifikasies op die algemene fisiologie
van die verskillende gisrasse en op hoëralkoholmetabolisme is onder 'n verskeidenheid
kondisies bestudeer, naamlik aërobies en anaërobiese groeikondisies, in die teenwoordigheid
van glukose of raffinose as die enigste koolstofbron, asook in die teenwoordigheid van 'n
verskeidenheid konsentrasies aminosure. Tafelwyne en basiswyne vir distillasie is gemaak
met die gemodifiseerde industrïele rasse en die konsentrasies van die hoër alkohole en
aromaprofiele van die wyne en distillate is ontleed en vergelyk. Bat1-delesie was dodelik
onder die kondisies, daarom is slegs die batlts-tes tesame met die BAT1 en BAT2 wat in die
rasse ooruitgedruk is, bestudeer. Die modifikasies het nie 'n beduidende effek op die
algemene fisiologie van die rasse getoon nie. Die data het wel getoon dat die ooruitdrukking
van BAT1 'n verhoging in isoamielalkohol- en isoamielasetaatkonsentrasies, en tot 'n mindere
mate isobutielalkohol- en isobottersuur-konsentrasies, veroorsaak het. Die ooruitdrukking
van BAT2 het 'n beduidende toename in isobutanol-, isobottersuur- en propioonsuurkonsentrasies
en 'n kleinere toename in propanol- en isovaleriaansuur veroorsaak. Die
ooruitdrukking van BAT2 het ook gelei tot 'n afname in isoamielalkohol- en isoamielasetaatkonsentrasies.
Sensoriese analises het getoon dat die wyne en distillate wat geproduseer is
met die rasse waarin die BAT1 en BAT2 gene ooruitgedruk is meer vrugtige eienskappe
(perske- en appelkoos-aromas) getoon het as die wyne wat deur die wildetipe rasse
geproduseer is.
Die studie lewer nuwe vooruitsigte vir die ontwikkeling van wyngiste met geoptimiseerde
ester en hoër alkohol produserende eienskappe wat die wynmakers in staat kan stelom wyne
te produseer met gedefinieerde spesifikasies en style en 'n voorafbepaalde aromaprofiel.
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