This study was conducted to compare and contrast potential aroma compounds in the headspace and small molecule metabolites produced as a result of starter culture metabolism in a full-fat and low-fat cheddar cheese model system. Past studies have indicated differences in the headspace flavor compound profiles between full-fat and low-fat Cheddar cheeses with no indication as to what compounds were produced as a result of starter culture metabolism. Starter cultures were incubated in a Cheddar cheese extract environment that was made up of the water-soluble portion of Cheddar cheese with environmental conditions mimicking full-fat and low-fat Cheddar cheese by altering the levels of salt and milk fat globular membrane in the system. Incubation times were up to 14 days at 30°C and samples were taken at days 0, 1, 7, and 14. Headspace analysis was accomplished using solid phase micro-extraction coupled with GC-MS and small metabolites were monitored using metabolomic methods coupled with GC-MS. Results indicate that the starter culture was responsible for an increase in the concentration of propan-2-one, heptan-2-one, 3-methylbutanal, heptanal, benzaldehyde, 2-ethylhexanal, and dimethyl trisulfide in both the full-fat and low-fat medias when compared to their respective controls. While heptanal was present at a higher concentration in the full-fat treatments compared to the low-fat treatments and 2- ethylhexan-1-ol and isothiocyanato cyclohexane were present at higher concentrations in the low-fat treatments compared to the full-fat treatments. Principal component analysis for the headspace compounds showed a clear separation of the treatments with heptanal, p-cymene, nonan-2-one, and undecan-2-one contributing the most to the variation between the full-fat and low-fat samples, while 3- methylbutanal, heptan-2-one, benzaldehyde, 2-ethylhexan-1-ol, 2,6-dimethylheptan-4-ol, and 3-methylbutanol contributed the most to the variation between the controls and treatments. The metabolomics data for both the bacteria and Cheddar cheese extract did not provide a clear separation between the full-fat and low-fat samples.

Modern, large scale Cheddar cheese manufacture is dependent on reliable acid production by Lactococcus lactis subspecies cremoris and subspecies lactis starter cultures. Any inhibition of acid production may affect cheese quality, disrupt production schedules and reduce profitability. The presence of antibiotic residues in manufacturing milk resulting from the treatment of mastitis in lactating cattle is a potential source of starter culture inhibition. Therefore, a range of antibiotic concentrations was assessed for measurable inhibitory effects on acid production and compared to the minimum detectable concentrations by approved screening test procedures. Antibiotics were selected from formulations approved for use on lactating cattle for the treatment of mastitis. Novobiocin, lincomycin, oleandomycin and oxytetracyline HCl, all non-b-lactam antibiotics, inhibited acid production of one or more L. lactis strains at antibiotic concentrations below the detectable limit of standard screening procedures. / Depending on the antibiotic, either or both the Bacillus stearothermophilus (var. calidolactis) disk assay and/or the Delvo SP assay were ineffective at detecting the antibiotics at concentrations required to inhibit the starter strains. Consequently, antibiotic residues below the detectable limits of these testing procedures could cause significant starter culture inhibition, disrupting cheese making schedules. Another potential source of starter culture inhibition is related to raw milk quality and the practice of refrigerated storage prior to processing. Previous studies differed as to whether the growth of psychrotrophic organisms would have a detrimental impact on subsequent acid production by starter bacteria employed in cheese manufacture. In this study, no inhibition of acid production by a commercial L. lactis subsp. cremoris strain was evident when grown in milk that had undergone short term temperature abuse. Antimicrobial systems native to bovine milk may also have an adverse impact on starter culture performance. The present study assessed the inhibitory effect of an activated lactoperoxidase system (LPS) on a range of L. lactis cultures. All of the strains were significantly inhibited when grown on reconstituted skim milk in the presence of an active LPS. Inhibition of acid production by strains grown on glucose was also observed, leading to further investigations to describe the inhibitory process. A non-phosphoenolpyruvate phosphotransferase (PEP/PTS) dependent glucose transport system, first observed in 1980 in one L. lactis subsp. lactis strain, was hypothesised as a link in strain variations in LPS sensitivity. However, the LPS sensitive L. lactis subsp. cremoris strains tested did not take up glucose in a PEP depleted state, most likely due to their inability to utilise arginine as an ATP generating energy source. The questions remain unanswered whether cremoris strains possess this glucose transport mechanism and whether it could contribute to strain variations in LPS sensitivity. / In a subsequent investigation, galactose phosphotransferase system (PTS) deficient L. lactis strain ATCC 7962 demonstrated log phase growth inhibition when grown on galactose in the presence of the model LPS. Previously reported LPS mediated effects on the glycolytic enzyme hexokinase do not appear to explain this result. The present study confirmed strain variability in sensitivity to the model LPS among both Lactococcus lactis subspecies lactis and subspecies cremoris strains. Further, the observation that dithiothreitol significantly alleviated the inhibition of a highly sensitive cremoris strain, implicated the involvement of sulphydryl groups as the target of the transient inhibitory factors. Data collected excluded the possibility that portions of the metabolic pathways involved in fructose and galactose metabolism are sensitive to the LPS in cells possessing PEP/PTS capability. This study also identified potential directions of further work to elucidate the mechanism(s) of LPS inhibition.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Barley malt is the predominant raw material for beer brewing world-wide. To meet consumer demand, a constant high quality malt product is required. Malt quality is determined by the degree of substrate hydrolysis during germination and mashing which serves as fermentable substrates for alcoholic fermentation during brewing. It is often difficult to sustain malt of high quality due to inconsistent malt batches and poor germination capacities of dormant barley. External additives such as chemicals and gibberellic acid have been used to overcome these difficulties but are unwanted in the beverage industry. Maltsters are consequently always in search of alternative solutions. Microbes produce diverse enzymes which can contribute to substrate hydrolysis during germination. The development of such starter cultures might provide a natural and economically feasible alternative to augment barley germination. Starter culture technology has been employed in the malting industry, although the main focus has been to improve the microbial stability of malt. The exploitation of cultures with hydrolytic capabilities to augment barley germination is consequently largely unexplored. The aim of this study was to develop a starter culture which can contribute to the enzymatic degradation of barley polymers. Geotrichum spp. and Lactobacillus plantarum were isolated from substrates rich in polymers present in barley and screened for enzymatic capabilities. Geotrichum spp. produced cellulase, xylanase, protease and β-glucanase activities, while L. plantarum harboured cell-bound and extracellular α-amylase activities. These cultures were added in different combinations during the malting of Erica and SSG 564 cultivars, but did not enhance germination significantly. Improved malt parameters did not correlate with microbial enzyme activities and the data were not repeatable. Preliminary plate assays could thus not be used to predict enzyme production in a malting environment. Cell-free supernatants with known enzyme activities of Aspergillus sp., Trichoderma reesei and Rhizopus sp. significantly enhanced malt quality. To our knowledge, the use of fungal supernatant to augment malt modification is a novel concept. Supernatant is more convenient than starter cultures and will aid to deliver more constant malt products than live cultures, as known enzyme levels are added. / AFRIKAANSE OPSOMMING: Garsmout is wêreldwyd die oorheersende roumateriaal vir bier brou. Om die aanvraag van verbruikers te bevredig, word 'n konstante hoë gehalte mout produk vereis. Die kwailiteit van mout word bepaal deur die graad van substraathidrolise gedurende ontkieming, wat dien as fermenteerbare substraat vir alkoholiese fermentasie tydens verbrouing. Dit is dikwels moeilik om ʼn konstante, hoë gehalte, moutproduk te lewer as gevolg van variasie in mout en die swak ontkiemingsvermoë van dormante gars. Hierdie probleem kan oorbrug word met eksterne toevoegings soos chemikalieë en gibberelliensuur, maar dit is nie ʼn gewensde praktyk in die broubedryf nie. Vermouters is gevolglik gedurig op soek na alternatiewe oplossings. Mikroörganismes produseer diverse ensieme wat kan bydra tot substraathidrolise gedurende ontkieming. Die ontwikkeling van sodanige suurselkulture is moontlik 'n natuurlike en ekonomies praktiese alternatief om die ontkieming van gars te stimuleer. Suurselkulture is reeds in die moutindustrie gebruik, alhoewel die fokus hoofsaaklik was om die mikrobiese stabiliteit van mout te verbeter. Die konsep om kulture met hidrolitiese vermoëns te gebruik om garsontkieming aan te vul is gevolglik grootliks onverken. Die doel van hierdie studie was om 'n suurselkultuur te ontwikkel wat kan bydra tot 'n ensiematiese afbraak van die polimere in gars. Geotrichum spp. en Lactobacillus plantarum is uit substrate ryk aan polimere teenwoordig in gars geïsoleer en vir hul ensiem aktiwiteite getoets. Geotrichum spp. het sellulase, xylanase, protease en β-glukanase aktiwiteit getoon, terwyl L. plantarum sel-gebonde en ekstrasellulêre α-amilase aktiwiteit getoon het. Hierdie kulture is in verskillende kombinasies tydens die vermouting van Erica en SSG 564 kultivars bygevoeg, maar het nie tot ʼn verbetering in die ontkieming van die gars gelei nie. Geen korrelasie is gevind tussen verbeterde mout parameters en mikrobiese ensiemaktiwiteit nie. Die resultate was ook nie herhaalbaar nie. Voorlopige plaattoetse kan dus nie as 'n maatstaf gebruik word om ensiem produksie deur suurselkulture in vermounting te voorspel nie. Sel-vrye supernatante van Aspergillus sp., Trichoderma reesei en Rhizopus sp., met bekende ensiem aktiwiteit, het die gehalte van mout aansienlik verbeter. Sover ons kennis strek is die gebruik van supernatante van fungi om die ontkieming van gars te stimuleer ʼn nuwe konsep. Supernatant is meer gerieflik as suurselkulture en sal help om konstante mout produkte te lewer aangesien ensiemvlakke beter beheer kan word.

Yoghurt is a fermented milk product which is produced by Streptococcus thermophilus and Lactobacillus delbrueckii spp. bulgaricus. The production of yoghurt has started in Middle East and spread all over the world. The aim of this study is to select the culture combination which is appropriate to Turkish taste and have the best yoghurt characteristics by means of post-acidification and whey separation properties, texture of gel formation, exopolysaccharide and acetaldehyde content / and to observe the effect of freeze-drying of cultures on these yoghurt properties. At the first part of this study, six L.delbrueckii spp. bulgaricus isolates and six S.thermophilus isolates were used with different combinations to produce 36 yoghurt samples. These isolates were selected among a strain collection which contains 111 L.delbrueckii spp. bulgaricus and 56 S.thermophilus isolates which were isolated from traditional Turkish yoghurt according to their acidification activity and acetaldehyde production properties. In addition, two commercial S.thermophilus isolates and one commercial L.delbrueckii spp. bulgaricus isolate were used to produce two commercial yoghurt samples. 38 yoghurt samples were examined in terms of pH and total titratable acidity changes during 21-day storage, syneresis and hardness. According to these three analyses, six yoghurt samples were chosen, which give the best results, for the determination of exopolysaccharide and acetaldehyde content. In addition, two yoghurt samples produced by commercial cultures and one sample, which gives average results in experiments, were also examined for these compounds to provide a good comparison. In the second part of the study the amount of exopolysaccharide and acetaldehyde of nine yoghurt samples were determined. In addition, sensory analysis was conducted to see consumer perception. According to the results, one culture combination was obtained as the best combination which produces the appropriate yoghurt to Turkish taste with the closest chemical analysis results to the commercial samples. In the last part, freeze drying process was examined if this has a significant effect on the selected LAB combination as well as yoghurt produced by using this.

In this study, the physico-chemical chances occurring in white cheese and possible effects of starter culture combinations to the ripening period during 30 days storage examinated. A total of thirty six lactic acid bacteria were isolated from a cheese made witohout using starter culture. For identification gram staining, catalase, gas production and coagulation tests were performed. For determination of species API50 CH (BioM&eacute / rieux) and partial 16S rDNA gene sequence analysis were used. Four cheese were produced, one by using commercial starter culture [Lyofast CMS (Lactococcus lactic subs. lactis and Lactococcus lactis subs. cremoris)]as control the other three by using different combinations of isolates [Lactococcus lactic subs. lactis (13%) +Lactobacillus brevis (40%)+Lactobacillus paracasei (47%) / Lactococcus lactic subs. lactis (36%)+Lactobacillus paracasei (64%) / Lactococus lactis subs. lactis (24,5%)+ Lactobacillus paracasei (28,5%) + Lactobacillus brevis (47%)] Cheese were ripened in 15% saline solution 4 C for 30 days.Samples were taken from each treatment and analyzed on 2nd,15th and 30th days Sensory ,microbiological and chemical properties of the cheese preparations as pH, acidity ,salt,fat,moisture,protein contents during storage period were determined. In this respect effect of using different starter culture combinations on quality of Turkish white chee was determined and Lactococcus lactis subs. lactis(13%)+Lactobacillus brevis (40%)+Lactobacillus paracasei(47%) combination was found as the best and can be suggested as ideal combination for white cheese production.

Orientador: Arnaldo Yoshiteru Kuaye, Laura Maria Bruno / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T22:18:13Z (GMT). No. of bitstreams: 1 Carvalho_JulianeDoeringGasparin_D.pdf: 1954120 bytes, checksum: 4ba23fd784559801ff2b5568f4ba02c0 (MD5) Previous issue date: 2007 / Resumo: O conhecimento da microbiota lática dos queijos de Coalho produzidos de forma artesanal a partir de leite cru, e suas propriedades tecnológicas são fundamentais para preservar as características originais do produto tradicional em queijos de Coalho industrializados, elaborados com leite pasteurizado. Para alcançar este conhecimento, foi realizado um trabalho de pesquisa dividido em três etapas: I) caracterização físico-química de queijos de Coalho artesanais produzidos no Ceará e de sua microbiota lática; II) estudo do comportamento das bactérias ácido láticas (BAL) durante o processamento do queijo; III) caracterização de propriedades tecnológicas das culturas láticas isoladas a partir deles. As análises físico-químicas caracterizaram as amostras avaliadas como sendo queijo de médio conteúdo de umidade (42%), baixa acidez (0,24%), com pH de 6,30; elevada atividade de água (0,959) e teor de NaCl de 2,88%. Dentre as BAL (643) isoladas destas amostras, foram encontrados os gêneros Enterococcus (59,6%), Lactobacillus (22%), Streptococcus (12,8%), Lactococcus (1,7%) e Leuconostoc (0,6%). A identificação de gênero não foi conclusiva para 3,3% de isolados. As espécies prevalecentes foram Enterococcus faecium, Lactobacillus paracasei subsp. paracasei, Streptococcus thermophilus e Lactococcus lactis subsp. lactis. O acompanhamento da evolução da microbiota lática em amostras de leite cru, massa de queijo e do produto final, coletadas em duas unidades produtoras, revelou a presença de Lactococcus no leite e sua ausência no queijo. A presença de Enterococcus aumentou das amostras de matéria-prima para o queijo, indicando a transferência e multiplicação destes microrganismos ao longo do processamento. Estes resultados evidenciaram uma seleção de microrganismos resistentes às temperaturas elevadas no processamento do queijo, durante o cozimento da massa. Quanto às propriedades tecnológicas avaliadas, 15 isolados foram considerados produtores rápidos de ácido, com predominância dos Lactococcus e Streptococcus (40% cada). Os Lactobacillus exibiram maior variabilidade e extensão proteolítica, além de maior produção de aroma. As culturas analisadas mostraram boa tolerância a 3 e 4% de sal. As cepas de Enterococcus faecium apresentaram a maior produção de bacteriocinas ativas contra Listeria spp., com potencial de emprego na produção de queijo de Coalho, como cultura protetora / Abstract: Understanding the lactic microbiota of the artisanal Coalho cheeses produced from raw milk, and its technological properties, is important to preserve the characteristics of the traditional product in the industrialized Coalho cheeses, elaborated with pasteurized milk. In order to achieve such knowledge, a research work was carried out in three stages: I) the physical-chemical characterization of the artisanal Coalho cheeses from Ceara-Brazil and its lactic microbiota, II) the study of the behaviour of the lactic acid bacteria (LAB) along the processing of cheese, III) characterization of technological properties of the lactic cultures isolated from the cheese. The physical-chemical analyses characterized the evaluated cheese samples with medium moisture content (42%), low acidity (0.24%), pH of 6.30, high water activity (0.959) and 2.88% NaCl content. Amongst the 643 LAB isolated from these samples, Enterococcus (59.6%), Lactobacillus (22%), Lactococcus (1.7%), Leuconostoc (0.6%) and Streptococcus (12.8%) genera were found. The identification was not conclusive for 3.3% of the isolates. The main species were Lactococcus latis subsp. latis, Lactobacillus paracasei subsp. paracasei, Streptococcus thermophilus and Enterococcus faecium. Following the evolution of lactic microbiota in raw milk, curd and cheese samples collected in two dairies, Lactococcus was found to be present in the milk, but absent in the cheese. The presence of Enterococcus increased from the raw material to the cheese samples, indicating the transference and multiplication of these microorganisms throughout the cheesemaking. Such results evidenced a selection of high temperature resistant microorganisms at the curd cooking stage of cheesemaking. According to the technological properties evaluated, 15 isolates were considered fast producers of acid, with predominance of the Lactococcus and Streptococcus (40% each). The Lactobacillus showed high variability and provided the widest range of proteolytic activity and production of flavour. The lactic cultures also showed good tolerance to 3 and 4 % of NaCl. Strains of Enterococcus faecium produced active bacteriocins against Listeria spp., with potential use in the production of Coalho cheese like protective culture / Doutorado / Doutor em Tecnologia de Alimentos

Orientador: Nelson Jose Beraquet / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T02:21:19Z (GMT). No. of bitstreams: 1 Cavenaghi_AngelaDulce_D.pdf: 820135 bytes, checksum: d87ee57cf9506eb8fcb111d97c637bf4 (MD5) Previous issue date: 2005 / Resumo: Face às demandas do mercado é necessário diversificar a elaboração de produtos industrializados à base de carne de frango, particularmente da carne da perna e coxa de frango que tem menor aceitação que o peito. Embutidos fermentados cozidos podem ser elaborados com carne de perna e coxa de frango constituindo-se num novo produto, ainda não disponível no mercado brasileiro. Carne de perna e coxa de frango foi utilizada em substituição às carnes suína e bovina numa formulação padrão de salame, mantendo-se o toucinho, e realizando-se a cocção após o estágio de fermentação quando o pH desejado foi atingido. Foram avaliados os efeitos da adição de dextrose em dois níveis 0,4 e 0,75%, duas misturas de culturas iniciadoras, sendo a cultura 1 (Staphylococcus carnosus e Lactobacillus pentosus) e a cultura 2 (Staphylococcus xylosus e Pediococcus pentosaceus), e adição de gordura suína também em dois níveis 12 e 16%. Essa última variável visa a obtenção de produtos lights e convencionais. O tempo de secagem/maturação foi controlado para obter duas faixas de atividade de água (Aa) no produto final, 0,87-0,88 e 0,90-0,91. O delineamento experimental foi um fatorial completo, totalizando 16 tratamentos efetuados em duplicata. As curvas de queda de pH e Aa foram determinadas a partir de medidas tomadas durante o processamento. Avaliou-se a composição aproximada da massa de embutimento e dos produtos finais. As medidas de L*, a* e b*, força de cisalhamento, nitrito residual, cloretos e acidez lática foram realizadas nos produtos finais e conduziu-se análises sensoriais de aceitação (sabor, firmeza, cor e avaliação global) e descritiva quantitativa (ADQ) (aparência, sabor, textura e aroma). Para a avaliação da segurança microbiológica determinou-se as contagens de coliformes, Salmonella e Staphylococcus coagulase positiva. Os produtos elaborados com 0,4% de dextrose não atingiram pH final abaixo de 5,3 e, portanto seria recomendável a adição de 0,75% de dextrose. O uso da cultura 2 reduziu em cerca de 10 horas o tempo de fermentação, quando comparado à cultura 1. Os produtos elaborados com a cultura 2 e Aa final 0,90-0,91 tiveram o tempo de processamento reduzido em 1 dia em relação aos com Aa 0,87-0,88. Por outro lado, produtos elaborados com a cultura 1 apresentaram aroma mais característico de salame e foram considerados mais suculentos. Os produtos com adição de 12% de gordura poderiam ser classificados como lights de acordo com a legislação brasileira. Para os atributos avaliados todos os tratamentos foram considerados ¿bons¿ com base na análise sensorial de aceitação e na ADQ. Numa segunda fase um produto do tipo light (23,7% de gordura) e outro do tipo convencional (29,5% de gordura) tiveram a sua vida útil determinada sob condições ambientais (temperatura ambiente, seco e fresco). Para este fim, foram conduzidas determinações de pH, Aa, força de cisalhamento, oxidação lipídica e ADQ ao longo do tempo de estocagem. A ADQ mostrou que as características sensoriais dos dois produtos foram praticamente iguais, e na análise de aceitação os dois produtos apresentaram 80% de intenção de compra por parte dos consumidores. A vida útil dos produtos foi estimada em aproximadamente 90 dias uma vez que as primeiras alterações dos atributos sensoriais só ocorreram após 120 dias de estocagem / Abstract: Taking into account the market demands, it is necessary to develop a wider array of industrialized chicken products, with special emphasis on the use of leg and thigh meat since they do not have a consumer acceptance as high as breast meat. Cooked fermented sausages can be made by using chicken leg and thigh meat, creating then a new product not yet available to the Brazilian market. Chicken leg and thigh meat was used to replace pork and beef on a standard salami formulation, maintaining the swine fat cubes and cooking the sausages after the fermentation stage and after they had reached the desired pH level. The effects of two levels of dextrose addition (0.4 and 0.75%) and the development of two different starter cultures (Culture 1 Staphylococcus carnosus and Lactobacillus pentosus, and culture 2 Staphylococcus xylosus and Pediococcus pentosaceus) were evaluated. The salamis also had different added swine fat contents (12 and 16%) in order to result in light e regular products, and the drying/maturation period was controlled in order to obtain two water activity levels (Aw) in the final product (0.87-0.88 and 0.90-0.91). The experimental design was a complete factorial, with a total of 16 treatments in duplicate. The pH and Aw fall curves were determined daily, as were the proximate composition of the initial and final product. The measurements of L*, a* and b* colour values, shear force, residual nitrote, chlorides, and lactic acidity were performed on the final product. Also, sensorial analysis of overall acceptance (taste, firmness, color and overall rating) as well as quantitative descriptive analysis (QDA) (appearance, taste, texture and aroma), were performed on the final product. The microbiological safety of those products was determined through the counting of coliforms, Salmonella, and Staphylococcus aureus. The products made with 0.4% dextrose addition did not reach a pH below 5.3. Therefore the 0.75% level is recommended. The use of culture 2 reduced in 10 hours the fermentation period, comparing to culture 1. The products made using culture 2 and with Aw 0.90-0.91 had the processing time reduced by one day when compared to Aw 0.87-0.88. On the other hand, products made using culture 1 were described as having an aroma more typical of salami and were considered juicier. The products with a 12% fat addition would be classified as light according to the Brazilian legislation. All treatments, considering both the sensorial analyses of overall acceptance and QDA methods, were considered ¿good¿ in terms of the attributes studied. On a second phase, the light product (23.7% fat content) and the regular one (29.5% fat content) had their shelf-lives determined at room temperature. In order to do so were determined the levels of pH and Aw, the shear force, the lipid oxidation, and the QDA throughout the storage period. The QDA showed that the sensory characteristics of the product were similar and presented 80% purchasing intent from consumers. The shelf-life of both product was around 90 days, although the sensory characteristics remained unchanged during 120th day of storage / Doutorado / Tecnologia de Alimentos / Doutor em Tecnologia de Alimentos

Chocolate is one of the most important products for the food industry, being of economic interest all over the world. The cocoa quality depends directly on the post-harvest processing, being the cocoa-pulp fermentation a crucial step for chocolate quality development. The aim of this work was to study the diversity of aroma-producing yeasts associated with cocoa beans fermentation and to select suitable yeast starter culture to cocoa flavor modulation. A total of 39 cocoa-derived yeast isolates were screened for their capacity to produce volatile aroma compounds in a cocoa pulp simulation medium. The seven highest aroma-producing yeasts were identified by ITS-rRNA gene sequencing as belonging to Pichia kudriavzevii, in spite of exhibiting different metabolic profiles. A computer-assisted analysis of rep-PCR genomic fingerprints of Pichia kudriavzevii strains clearly differentiated the upper aroma-forming yeast strains (G1 group; P. kudriavzevii LPB06 and P. kudriavzevii LPB07) from the other strains (G2 group). This demonstrates the potential of rep-PCR technique as a promising genotypic tool for rapid and reliable speciation of aromatic yeast strains. In the second stage of this study, two strains with superior aroma production, namely P. kudriavzevii LPB06 and P. kudriavzevii LPB07, were used in cocoa beans fermentation at laboratory scale. They were able to establish an accelerated fermentation process with efficient yeast growth, sugars consumption and ethanol formation compared to the spontaneous process. The resulting cocoa beans were analyzed by diverse chemical analysis methods, including SPME-GC/MS, FTIR spectroscopy and metal and colorimetric analysis. All together, the results indicated that inoculated fermentations generated cocoa beans with better color development and richer aroma composition, suggesting that cocoa-associated yeast diversity at strain level can be exploited for flavor modulation of cocoa beans. / Atualmente, o chocolate é um dos produtos mais importantes para a indústria de alimentos, sendo de interesse econômico em todo o mundo. A qualidade do cacau depende diretamente do processamento pós-colheita, sendo a fermentação da polpa um passo crucial para o desenvolvimento da qualidade do chocolate. O objetivo deste trabalho foi estudar a diversidade de leveduras aromáticas associadas à fermentação de cacau e selecionar uma cultura iniciadora com potencial para modular o flavor de chocolate. Um total de 39 leveduras foram isoladas e caracterizadas quanto à formação de compostos aromáticos. As sete melhores produtoras foram identificadas através do sequenciamento do gene ITS-rRNA como Pichia kudriavzevii, apesar de apresentarem diferentes perfis metabólicos. Análise de impressões digitais (fingerprints) dos isolados pela técnica de rep-PCR claramente distinguiu as cepas com maior produção de compostos aromáticos, demonstrando o potencial desta técnica como uma ferramenta para rápida e confiável seleção de leveduras. Na segunda etapa deste estudo, duas cepas com superior formação de aroma (P. kudriavzevii LPB06 e P. kudriavzevii LPB07) foram testadas como culturas iniciadoras para fermentações de cacau em escala laboratorial. Estas duas cepas foram capazes de estabelecer um acelerado processo fermentativo, com eficiente consumo de açúcares e formação de etanol, em comparação ao método natural. As amêndoas de cacau resultantes destes processos foram analisadas por diferentes métodos químicos, incluindo SPME-GC/MS, espectroscopia FTIR e análises de metal e calorimetria. Os resultados indicaram que as fermentações inoculadas desenvolveram amêndoas de cacau com melhor cor e composição de aroma, sugerindo que a diversidade de levedura em fermentações de cacau pode ser explorada para a modulação do flavor de chocolate.

<p>Kombuha je tradicionalni napitak koji se dobija fermentacijom zaslađenog crnog<br />ili zelenog čaja, fiziolo&scaron;kom aktivno&scaron;ću čajne gljive, koja predstavlja simbiozu<br />autohthonih vrsta kvasaca i bakterija sirćetnog vrenja. Cilj rada je bio da se ispita<br />biolo&scaron;ka aktivnost konzumnih kombuha napitaka (titrabilne kiselosti 3,5-4 g/L) od<br />crnog čaja (<em>Camellia sinensis</em> L), čaja ehinacee (<em>Echinacea purpurea</em> L.) i<br />rtanjskog čaja (<em>Satureja montana</em> L.). Za ispitivanje antimikrobne aktivnosti<br />kombuha napitaka upotrebljeni su sledeći sojevi bakterija, kvasaca i plesni:<br /><em>Pseudomonas aeruginosa</em>, <em>Staphylococcus aureus</em>, <em>Bacillus sp.</em>, <em>Salmonella<br />enteritidis, Proteus mirabilis, Escherichia coli, Sarcina lutea, Saccharomyces<br />cerevisiae, Candida pseudotropicalis, Rhodotorula sp., Penicillium<br />aurantiogriseum, Aspergillus niger i Aspergillus flavus</em>. Antioksidativna aktivnost<br />kombuha napitaka ispitana je na DPPH i OH radikale ESR spektralnom metodom.<br />Antiproliferativna aktivnost čajeva i kombuha napitaka od crnog i rtanjskog čaja<br />ispitana na tri ćelijske linije humanih karcinoma: HeLa (epitelni karcinom<br />cerviksa), MCF-7 (adenokarcinom dojke) i HT-29 (adenokarcinom debelog<br />creva). Pored istraživanja biolo&scaron;ke aktivnosti kombuha napitaka, cilj rada je bio da<br />se ispitaju i neki od osnovnih parametara kombuha fermentacije &ndash; optimalna<br />količina izvora ugljenika i azota u medijumu za kultivaciju, geometrijske<br />karakteristike fermentora, inokulacija starter kulturama. Definisanje kritičnih<br />parametara kombuha fermentacije je bio osnov za izvođenje matematičkog<br />modela za scale-up fermentativnog procesa.</p> / <p>Kombucha is a traditional beverage obtained by fermenting sweetned black or<br />green tea with tea fungus, which represents a symbiotic combination of acetic acid<br />bacteria and autochthonous yeast species. In this study, the antimicrobial,<br />antioxidative and antiproliferative activity of kombucha beverages (titratable<br />acidity 3,5-4 g/L) obtain from black tea (<em>Camellia sinensis</em> L), echinacea tea<br />(<em>Echinacea purpurea</em> L.) and rtanj tea (<em>Satureja montana</em> L.) were tested.<br /><em>Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus sp., Salmonella<br />enteritidis, Proteus mirabilis, Escherichia coli, Sarcina lutea, Saccharomyces<br />cerevisiae, Candida pseudotropicalis, Rhodotorula sp., Penicillium<br />aurantiogriseum, Aspergillus niger i Aspergillus flavus</em> were used as test<br />microorganisms for examination of antimicrobial activity. The antioxidant activity<br />of differently prepared kombucha beverages was examined agains DPPH and OH<br />radicals by ESR-spectrometry. Antiproliferative activity of black tea kombucha<br />and Satureja montana kokmbucka was measured by sulforhodamine B<br />colorimetric assay on HeLa (cervix epitheloid carcinoma), HT-29 (colon<br />adenocarcinoma), and MCF-7 (breast adenocarcinoma) cells line. Also, same<br />parametars of kombucha fermentation &ndash; optimal quantity of source of carbon and<br />nitrogen in cultivation medium, geometric characteristics of reactors and<br />inoculation by starter culture &ndash; were tested. Definition of critical parameters of<br />kombucha fermentation is important for derivation of mathematical model for<br />scaling-up fermentation process.</p>

Yogurt is a characteristic fermented dairy product of Turkey and Bulgaria and its popularity has been increasing all over the world. Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (Lactobacillus bulgaricus) are used together as starter culture in production of yogurt. The objective of this study was to isolate and characterize yogurt cultures from traditionally produced yogurts (i.e. produced without using commercial starter cultures) and to search the genotypic diversity within traditional S. thermophilus isolates. Yogurt cultures were isolated from traditionally produced yogurts collected from different regions of Turkey and identified biochemically. Acidification ability of the isolates was examined and the cultures giving best acidifying rates were further subjected to a selection in terms of their acetaldehyde production ability. Then, phage resistance and proteolytic activity of chosen isolates were tested. Finally, twenty-five L. bulgaricus and twenty-two S. thermophilus isolates were selected as cultures having best technological properties. Furthermore, subtyping studies were carried out to indicate strain diversity among isolates. S. thermophilus was selected as target organism for subtyping in this study. Clustered regularly interspaced short palindromic repeats (CRISPR) loci are highly polymorphic genetic regions, which are composed of partially palindromic direct repeats interspaced by sequences called spacers. In order to characterize S. thermophilus isolates genotypically, CRISPR1 locus of the isolates were analyzed. Additionally, nineteen isolates selected after CRISPR1 analysis were characterized using multilocus sequence typing (MLST). This provided to compare CRISPR1 analysis with MLST as a typing method. According to CRISPR1 analysis S. thermophilus isolates were grouped into 6 main clusters with a total of 15 sub-clusters. MLST results demonstrated an evolutionary relationship among these strains compatible with that derived from the CRISPR1 analysis.