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1.
Molecules ; 26(1)2021 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-33406782

RESUMO

Flavor is amongst the major personal satisfaction indicators for meat products. The aroma of dry cured meat products is generated under specific conditions such as long ripening periods and mild temperatures. In these conditions, the contribution of Maillard reactions to the generation of the dry cured flavor is unknown. The main purpose of this study was to examine mild curing conditions such as temperature, pH and aw for the generation of volatile compounds responsible for the cured meat aroma in model systems simulating dry fermented sausages. The different conditions were tested in model systems resembling dry fermented sausages at different stages of production. Three conditions of model system, labeled initial (I), 1st drying (1D) and 2nd drying (2D) and containing different concentrations of amino acid and curing additives, as well as different pH and aw values, were incubated at different temperatures. Changes in the profile of the volatile compounds were investigated by solid phase microextraction and gas chromatography mass spectrometry (SPME-GS-MS) as well as the amino acid content. Seventeen volatile compounds were identified and quantified in the model systems. A significant production of branched chain volatile compounds, sulfur, furans, pyrazines and heterocyclic volatile compounds were detected in the model systems. At the drying stages, temperature was the main factor affecting volatile production, followed by amino acid concentration and aw. This research demonstrates that at the mild curing conditions used to produce dry cured meat product volatile compounds are generated via the Maillard reaction from free amino acids. Moreover, in these conditions aw plays an important role promoting formation of flavor compounds.

2.
J Sci Food Agric ; 100(13): 4940-4949, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32474932

RESUMO

BACKGROUND: Three yeast strains with probiotic potential, Hanseniaspora opuntiae, Pichia kudriavzevii, and Wickerhamomyces anomalus were inoculated in the fermentation of Guajillo chilli pepper (Capsicum annuum L.) sauce, and the different aroma profiles were investigated. Using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis and gas chromatography-olfactometry (GCO), flavour compound production was evaluated during the fermentation of the Guajillo chilli pepper sauces. RESULTS: A total of 78 volatile compounds were identified during the yeast fermentation of the sauce. Most aldehydes and terpenes detected were present at the beginning of the fermentation, indicating a Guajillo chilli pepper origin. Among the 34 active aroma compounds detected by GCO, propanoic acid (cheesy), 3-methylbutanoic acid (sharp, cheese), ethyl 2-methylbutanoate (fruity), and 6-methyl-5-hepten-2-one (strong, citrus) were identified as key aroma contributors produced by the inoculation of the yeasts. A different aroma profile was produced by probiotic yeast. Hanseniaspora opuntiae produced an aroma profile with herbal and green notes based on high production of aldehydes, ketones, and acetic acid. Pichia kudriavzevii and W. anomalus produced fruity, green-herbal, and cheesy notes based on ester compounds, alcohol and branched-chain acids production although, the production of propanoic acid by W. anomalus increased the cheesy character in the sauces. CONCLUSION: The aroma profile of fermented chilli pepper sauces depends not only on the chili pepper varieties used but also on the fermentation process as a source of aroma compounds. The use of probiotic yeast can be used to improve and diversify the aroma profile of fermented chilli pepper sauces. © 2020 Society of Chemical Industry.

3.
Meat Sci ; 164: 108103, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32145603

RESUMO

The reduction of ingoing amounts of nitrate and nitrite in dry fermented sausages was studied together with the impact of Debaryomyces hansenii inoculation on aroma generation. Three different formulations of sausages were manufactured: control (C), reduced in nitrate and nitrite ingoing amounts (R) and reduced R inoculated with D. hansenii (RY). Changes in physicochemical and microbiological parameters, volatile compounds and aroma were investigated at different drying times. Nitrite/nitrate reduction did not seem to affect microbial growth but affected their metabolic activity. Moreover, nitrite/nitrate reduction decreased lipid oxidation and generation of derived volatile compounds. Yeast inoculation limited lipid oxidation and prevented nitrite oxidation. Sausage aroma profile was positively affected by D. hansenii inoculation which contributed to the generation of potent aroma compounds like ethyl ester compounds and 3-methylbutanal. Long drying time impacted sausage aroma profile as well as yeast metabolism. Yeast inoculation counteracted the negative influence of nitrite/nitrate reduction due to its antioxidant capacity, aroma generation and hindered nitrite oxidation.

4.
Int J Syst Evol Microbiol ; 70(4): 2420-2425, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32100691

RESUMO

Yeast strains belonging to a novel anamorphic yeast species were isolated from subsoil groundwater contaminated with hydrocarbons in a metal working factory located in northern Spain, and from a human infection in the USA. Comparison of ITS sequences between the isolates revealed 0.2 % divergence between the Spanish isolates and 0.46 % divergence between those and the USA isolate. Phylogenetic analysis based on the D1/D2 domains of the LSU rRNA gene showed that these isolates belong to the Wickerhamiella clade with W. sorbophila and W. infanticola as their closest relatives. Sequence divergence between the new isolates and W. sorbophila and W. infanticola was 1.97 and 1.79 %, respectively. The isolates in the novel species are not fermentative and pseudohyphae were not produced. Sexual reproduction was not observed for individual isolates or in mixtures of isolates. Conjugation between the isolates in the novel species and close relatives W. sorbophila and W. infanticola was not observed. These data support the proposal of Wickerhamiella verensis as a novel species, with CECT 12028T as the holotype.


Assuntos
Água Subterrânea/microbiologia , Micoses/microbiologia , Filogenia , Saccharomycetales/classificação , DNA Fúngico/genética , Fermentação , Georgia , Humanos , Hidrocarbonetos , Lactente , Técnicas de Tipagem Micológica , Saccharomycetales/isolamento & purificação , Análise de Sequência de DNA , Espanha , Poluentes Químicos da Água
5.
J Agric Food Chem ; 67(33): 9335-9343, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31343169

RESUMO

The ability of Debaryomyces hansenii to produce volatile sulfur compounds from sulfur amino acids and the metabolic pathway involved have been studied in seven strains from different food origins. Our results proved that l-methionine is the main precursor for sulfur compound generation. Crucial differences in the sulfur compound profile and amino acid consumption among D. hansenii strains isolated from different food sources were observed. Strains isolated from dry pork sausages displayed the most complex sulfur compound profiles. Sulfur compound production, such as that of methional, could result from chemical reactions or yeast metabolism, while according to this study, thioester methyl thioacetate appeared to be generated by yeast metabolism. No relationship between sulfur compounds production by D. hansenii strains and the expression of genes involved in sulfur amino acid metabolism was found, except for the ATF2 gene in the L1 strain for production of methyl thioacetate. Our results suggest a complex scenario during sulfur compound production by D. hansenii.


Assuntos
Aminoácidos Sulfúricos/metabolismo , Produtos da Carne/análise , Produtos da Carne/microbiologia , Compostos de Enxofre/metabolismo , Animais , Alimentos e Bebidas Fermentados/análise , Alimentos e Bebidas Fermentados/microbiologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Compostos de Enxofre/química , Suínos , Volatilização
6.
Meat Sci ; 147: 100-107, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30219361

RESUMO

Slow fermented sausages with reduced ingoing amounts of sodium nitrate (control, 15% and 25% reduction) were stored under vacuum up to three months. Changes in microbiology, chemical parameters and volatile compounds were studied. Residual nitrate was not affected by vacuum storage and its reduction resulted in a reduction of sausage redness. General microbial counts decreased during vacuum storage, though nitrate reduction increased the growth of total mesophilic bacteria and Gram positive cocci. Long storage time and 25% nitrate reduction affected microbial activity and sausage aroma profile. Short vacuum storage times and moderate nitrate reduction (15%) were related to compounds producing pleasant odours (3-hydroxy-2-butanone, ethyl octanoate, ethyl-3-methylbutanoate and 2,3-pentanedione) and cheesy/buttery odour (2,3-butanedione and ethyl-2-hydroxypropanoate). In contrast, 25% nitrate reduction increased compounds like heptanal (green, unpleasant odour) and those related to unpleasant odours, methanethiol (rotten odour) and methional (cooked potato).


Assuntos
Conservantes de Alimentos/análise , Armazenamento de Alimentos/métodos , Produtos da Carne/microbiologia , Nitratos/análise , Odorantes/análise , Animais , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Cor , Fungos/crescimento & desenvolvimento , Fungos/isolamento & purificação , Produtos da Carne/análise , Suínos , Vácuo
7.
Int J Food Microbiol ; 282: 84-91, 2018 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-29933128

RESUMO

Slow fermented sausages with reduced ingoing amounts of sodium nitrate were manufactured: control (250 ppm), 15% (212.5 ppm) and 25% (187.5 ppm) reduction. The effect of nitrate reduction on microbiology and chemical parameters, volatile compounds and aroma production was studied. Parameters like, pH, aw and colour decreased during ripening, without being affected by nitrate reduction. Lipid oxidation increased during ripening and it was higher in control sausages due to fat content. Residual nitrite was below the detection limit during the whole process and residual nitrate decreased during ripening, with higher reduction in RN25 sausages. Lactic acid bacteria, total mesophilic bacteria and yeasts and moulds increased during ripening but Gram positive cocci decreased. Microbial counts from nitrate reduced sausages at the end of the manufacturing process were not statistically different from the control sausages with nitrate. Regarding volatile compounds formation, compounds derived from amino acid degradation were increased by nitrate reduction. Aroma compounds derived from amino acid degradation and responsible for strong odours, dimethyl disulphide (toasted, garlic) and methional (cooked potato) and, to a lesser extent, compounds derived from esterase activity producing fruity odours (ethyl acetate, ethyl butanoate, ethyl­2­hydroxypropanoate, ethyl­2­methylbutanoate and ethyl­3­methylbutanoate) and several compounds from carbohydrate fermentation acetic acid (vinegar odour) and 2-butanone (fruity) were related to the high nitrate reduction (25%). Despite nitrate reduction up to 25% produced minor effect on microbial growth, their metabolism is regulated by nitrate content and therefore by nitrite generation affecting the production of key aroma compounds that alter the sausage aroma profile.


Assuntos
Bactérias/metabolismo , Aromatizantes/análise , Conservantes de Alimentos/análise , Fungos/metabolismo , Produtos da Carne/microbiologia , Nitratos/análise , Animais , Bactérias/classificação , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Fermentação , Alimentos e Bebidas Fermentados/análise , Aromatizantes/metabolismo , Fungos/genética , Fungos/crescimento & desenvolvimento , Fungos/isolamento & purificação , Humanos , Produtos da Carne/análise , Nitritos/análise , Odorantes/análise , Cloreto de Sódio , Suínos , Paladar
8.
J Sci Food Agric ; 98(6): 2121-2130, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28941248

RESUMO

BACKGROUND: The use of boar back fat for processing of fermented sausages may cause the presence of abnormal odours. In dry-cured products, ripening time is essential to develop the sensory characteristics. Yeast has been proposed as an alternative to mask boar taint odour through its metabolic activity but it is necessary to elucidate which mechanisms are involved. The aim is to study the effect of Debaryomyces hansenii inoculation on the lipolysis process and generation of aroma compounds in fermented sausages manufactured with boar back fat at two different ripening times. RESULTS: D. hansenii inoculated sausages had a higher degree of lipolysis as demonstrated by higher content of free fatty acids, ester compounds and branched aldehydes which contribute the fruity odour. The increase in lipolysis produced by D. hansenii inoculation was not followed by an increase in oxidation during processing possibly due to the metabolic activity of yeast. The effect of back fat type was scarcely appreciated whereas ripening time had a stronger effect on sausage. Boar sausages were characterised by a lower polyunsaturated fatty acid profile and lesser lipolysis than gilt sausages. CONCLUSION: Yeast inoculation with D. hansenii and long ripening time were appropriate strategies to limit the perception of boar taint in dry fermented sausages. © 2017 Society of Chemical Industry.


Assuntos
/metabolismo , Aromatizantes/metabolismo , Produtos da Carne/microbiologia , Animais , Fermentação , Aromatizantes/análise , Microbiologia de Alimentos , Lipólise , Masculino , Produtos da Carne/análise , Odorantes/análise , Sódio/análise , Sódio/metabolismo , Sus scrofa , Suínos
9.
Food Microbiol ; 67: 1-10, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28648286

RESUMO

Diversity and dynamics of yeasts associated with the fermentation of Argentinian maize-based beverage chicha was investigated. Samples taken at different stages from two chicha productions were analyzed by culture-dependent and culture-independent methods. Five hundred and ninety six yeasts were isolated by classical microbiological methods and 16 species identified by RFLPs and sequencing of D1/D2 26S rRNA gene. Genetic typing of isolates from the dominant species, Saccharomyces cerevisiae, by PCR of delta elements revealed up to 42 different patterns. High-throughput sequencing (HTS) of D1/D2 26S rRNA gene amplicons from chicha samples detected more than one hundred yeast species and almost fifty filamentous fungi taxa. Analysis of the data revealed that yeasts dominated the fermentation, although, a significant percentage of filamentous fungi appeared in the first step of the process. Statistical analysis of results showed that very few taxa were represented by more than 1% of the reads per sample at any step of the process. S. cerevisiae represented more than 90% of the reads in the fermentative samples. Other yeast species dominated the pre-fermentative steps and abounded in fermented samples when S. cerevisiae was in percentages below 90%. Most yeasts species detected by pyrosequencing were not recovered by cultivation. In contrast, the cultivation-based methodology detected very few yeast taxa, and most of them corresponded with very few reads in the pyrosequencing analysis.


Assuntos
Bebidas/microbiologia , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Técnicas Microbiológicas/métodos , Leveduras/isolamento & purificação , Leveduras/metabolismo , Zea mays/microbiologia , Argentina , Biodiversidade , DNA Fúngico/genética , DNA Ribossômico/genética , Fermentação , Saccharomyces cerevisiae/classificação , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/isolamento & purificação , Saccharomyces cerevisiae/metabolismo , Leveduras/classificação , Leveduras/genética , Zea mays/metabolismo
10.
J Agric Food Chem ; 65(19): 3900-3909, 2017 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-28447463

RESUMO

A total of 15 Debaryomyces hansenii strains from different food origins were genetically characterized and tested on a culture medium resembling the composition of fermented sausages but different concentrations of nitrifying preservatives. Genetic typing of the D. hansenii strains revealed two levels of discrimination: isolation source or strain specific. Different abilities to proliferate on culture media containing different concentrations of nitrate and nitrite, as sole nitrogen sources and in the presence of amino acids, were observed within D. hansenii strains. Overall metabolism of amino acids and generation of aroma compounds were related to the strain origin of isolation. The best producers of branched aldehydes and ethyl ester compounds were strains isolated from pork sausages. Strains from cheese and llama sausages were good producers of ester compounds and branched alcohols, while vegetable strains produced mainly acid compounds. Nitrate and nitrite reduction affected in different ways the production of volatiles by D. hansenii.


Assuntos
Aromatizantes/metabolismo , Conservantes de Alimentos/análise , Produtos da Carne/microbiologia , Saccharomycetales/química , Animais , Fermentação , Conservantes de Alimentos/metabolismo , Produtos da Carne/análise , Nitratos/análise , Nitratos/metabolismo , Nitritos/análise , Nitritos/metabolismo , Saccharomycetales/genética , Saccharomycetales/isolamento & purificação , Saccharomycetales/metabolismo , Suínos
11.
Mol Phylogenet Evol ; 108: 49-60, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28189617

RESUMO

Horizontal gene transfer (HGT) in eukaryotic plastids and mitochondrial genomes is common, and plays an important role in organism evolution. In yeasts, recent mitochondrial HGT has been suggested between S. cerevisiae and S. paradoxus. However, few strains have been explored given the lack of accurate mitochondrial genome annotations. Mitochondrial genome sequences are important to understand how frequent these introgressions occur, and their role in cytonuclear incompatibilities and fitness. Indeed, most of the Bateson-Dobzhansky-Muller genetic incompatibilities described in yeasts are driven by cytonuclear incompatibilities. We herein explored the mitochondrial inheritance of several worldwide distributed wild Saccharomyces species and their hybrids isolated from different sources and geographic origins. We demonstrated the existence of several recombination points in mitochondrial region COX2-ORF1, likely mediated by either the activity of the protein encoded by the ORF1 (F-SceIII) gene, a free-standing homing endonuclease, or mostly facilitated by A+T tandem repeats and regions of integration of GC clusters. These introgressions were shown to occur among strains of the same species and among strains of different species, which suggests a complex model of Saccharomyces evolution that involves several ancestral hybridization events in wild environments.


Assuntos
Hibridização Genética , Mitocôndrias/genética , Saccharomyces/genética , Sequência de Bases , Complexo IV da Cadeia de Transporte de Elétrons/genética , Genoma Mitocondrial , Geografia , Haplótipos/genética , Fases de Leitura Aberta/genética , Filogenia , Alinhamento de Sequência , Especificidade da Espécie
12.
Meat Sci ; 123: 1-7, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27579788

RESUMO

Yeast inoculation of dry fermented sausages manufactured with entire male fat was evaluated as a strategy to improve sausage quality. Four different formulations with entire male/gilt back fat and inoculated/non-inoculated with Debaryomyces hansenii were manufactured. The use of entire male back fat produced the highest weight losses, hardness and chewiness in dry sausages. Consumers clearly distinguished samples according to drying time and D. hansenii inoculation while the use of entire/gilt back fat was not highly perceived. The presence of androstenone and skatole was close to their sensory thresholds. Androstenone was not degraded during the process but skatole was affected by yeast inoculation. D. hansenii growth on the surface regulated water release during ripening, reduced hardness and chewiness in entire male sausages and resulted with similar texture to gilt sausages. Yeast inoculation inhibited lipid oxidation providing fruity odours and less oxidized fatty sausages in the sensory analysis. The effectiveness of yeast to mask boar taint was demonstrated by sensory analysis.


Assuntos
Tecido Adiposo/química , Produtos da Carne/análise , Saccharomycetales , Leveduras , Adulto , Androsterona/análise , Cor , Comportamento do Consumidor , Dessecação , Gorduras na Dieta/análise , Feminino , Microbiologia de Alimentos , Qualidade dos Alimentos , Humanos , Lactobacillus , Masculino , Pessoa de Meia-Idade , Escatol/química , Olfato , Cloreto de Sódio na Dieta/análise , Staphylococcus , Paladar , Substâncias Reativas com Ácido Tiobarbitúrico/análise
13.
Int J Food Microbiol ; 233: 1-10, 2016 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-27294555

RESUMO

In the present study, we have analysed the genetic diversity in Kluyveromyces marxianus isolated from Parmigiano Reggiano and Pecorino di Farindola cheesemaking environment. Molecular typing methods inter-RTL fingerprint and mtDNA RFLPs, as well as, sequence diversity and heterozygosity in the intergenic region between KmSSB1 and KmRIO2 genes and analysis of the mating locus were applied to 54 K. marxianus strains. Inter-RTL fingerprint revealed a large degree of genetic heterogeneity and clustering allowed differentiation of K. marxianus strains from different geographical origins. In general, inter-LTR profiles were more discriminating than RFLPs of mtDNA; however our results also indicate that both techniques could be complementary unveiling different degrees of genetic diversity. Sequence analysis of the intergenic region between KmSSB1 and KmRIO2 genes revealed 26 variable positions in which a double peak could be observed in the sequence chromatogram. Further analysis revealed the presence of heterozygous strains in the K. marxianus population isolated from Parmigiano Reggiano. On the other hand, all strains isolated from Pecorino di Farindola were homozygous. Two very different groups of haplotypes could be observed as well as mixtures between them. Phylogenetic reconstruction divided K. marxianus dairy strains into two separate populations. A few heterozygous strains in an intermediate position between them could also be observed. Mating type locus analysis revealed a large population of diploid strains containing both MATa and MATα alleles and few haploid strains, most of them presenting the MATα allele. Different scenarios explaining the presence and maintaining of homozygous and heterozygous diploids as well as hybrids between them in the Parmigiano Reggiano K. marxianus population are proposed. A principal component analysis supported the large differences between K. marxianus isolated from Parmigiano Reggiano and Pecorino di Farindola.


Assuntos
Queijo/microbiologia , Variação Genética , Kluyveromyces/genética , Kluyveromyces/isolamento & purificação , DNA Mitocondrial/genética , Kluyveromyces/classificação , Tipagem de Sequências Multilocus , Filogenia , Polimorfismo de Fragmento de Restrição
14.
Microb Cell Fact ; 14: 128, 2015 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-26336982

RESUMO

BACKGROUND: Aroma is one of the most important attributes defining wine quality in which yeasts play a crucial role, synthesizing aromatic compounds or releasing odourless conjugates. A present-day trend in winemaking consists of lowering fermentation temperature to achieve higher aroma production and retention. S. cerevisiae × S. kudriavzevii hybrids seem to have inherited beneficial traits from their parental species, like fermenting efficiently at low temperature or producing higher amounts of certain aromatic compounds. In this study, allelic composition and gene expression of the genes related to aroma synthesis in two genetically and phenotypically different S. cerevisiae × S. kudriavzevii hybrids, Lalvin W27 and VIN7, were compared and related to aroma production in microvinifications at 12 and 28 °C. In addition, the contribution of the allele coming from each parental to the overall expression was explored by RT-PCR. RESULTS: The results indicated large differences in allele composition, gene expression and the contribution of each parental to the overall expression at the fermentation temperatures tested. Results obtained by RT-PCR showed that in ARO1 and ATF2 genes the S. kudriavzevii allele was more expressed than that of S. cerevisiae particularly at 12 °C. CONCLUSIONS: This study revealed high differences regarding allele composition and gene expression in two S. cerevisiae × S. kudriavzevii hybrids, which may have led to different aroma profiles in winemaking conditions. The contribution of the alleles coming from each parental to the overall expression has proved to differently influence aroma synthesis. Besides, the quantitative contribution to the overall gene expression of the alleles coming from one parental strain or the other was clearly determined by the fermentation temperature for some genes.


Assuntos
Fermentação , Hibridização Genética , Odorantes , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces/genética , Vinho , Perfilação da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Genômica , Redes e Vias Metabólicas/genética , Saccharomyces/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Temperatura
15.
J Dairy Res ; 82(3): 356-64, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26004434

RESUMO

ß-Galactosidases from Kluyveromyces lactis and Kluyveromyces marxianus isolated from artisanal ewes' milk cheeses, were used to transgalactosylate lactose from cheese whey permeate (WP). The content of galactooligosaccharides (GOS) obtained by transgalactosylation was comparable with that formed using pure lactose as substrate. In order to obtain a mixture with higher prebiotic oligosaccharide content, isomerisation of the transgalactosylated WP was carried out using sodium aluminate as catalyst. The transgalactosylated mixtures at 6 h of reaction contained amounts of prebiotic carbohydrates (tagatose, lactulose, GOS and oligosaccharides derived from lactulose, OsLu) close to 50 g/100 g of total carbohydrates for all the strains tested, corresponding to 322 g prebiotics/kg whey permeate. Thus, the suitability of this methodology to produce mixtures of dietary non-digestible carbohydrates with prebiotic properties from WP has been demonstrated, which is interesting for the food industry since it increases the value and the applicability of this by-product from cheese manufacture.


Assuntos
Queijo/microbiologia , Galactose/metabolismo , Kluyveromyces/enzimologia , Lactulose/metabolismo , Oligossacarídeos/biossíntese , beta-Galactosidase/metabolismo , Compostos de Alumínio/química , Animais , Carboidratos da Dieta , Feminino , Isomerismo , Oligossacarídeos/análise , Prebióticos/análise , Ovinos , Compostos de Sódio/química , Soro do Leite/química
16.
Int J Food Microbiol ; 212: 16-24, 2015 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-25765533

RESUMO

Actual healthy trends produce changes in the sensory characteristics of dry fermented sausages therefore, new strategies are needed to enhance their aroma. In particular, a reduction in the aroma characteristics was observed in reduced fat and salt dry sausages. In terms of aroma enhancing, generally coagulase-negative cocci were selected as the most important group from the endogenous microbiota in the production of flavour compounds. Among the volatile compounds analysed in dry sausages, ester compounds contribute to fruity aroma notes associated with high acceptance of traditional dry sausages. However, the origin of ester compounds in traditional dry sausages can be due to other microorganisms as lactic acid bacteria, yeast and moulds. Yeast contribution in dry fermented sausages was investigated with opposite results attributed to low yeast survival or low activity during processing. Generally, they affect sausage colour and flavour by their oxygen-scavenging and lipolytic activities in addition to, their ability to catabolize fermentation products such as lactate increasing the pH and contributing to less tangy and more aromatic sausages. Recently, the isolation and characterization of yeast from traditional dry fermented sausages made possible the selection of those with ability to produce aroma active compounds. Molecular methods were used for genetic typing of the isolated yeasts whereas their ability to produce aroma compounds was tested in different systems such as in culture media, in model systems and finally on dry fermented sausages. The results revealed that the appropriate selection of yeast strains with aroma potential may be used to improve the sensory characteristics of reformulated fermented sausages.


Assuntos
Fermentação , Microbiologia de Alimentos , Produtos da Carne/microbiologia , Produtos da Carne/normas , Leveduras/fisiologia , Animais , Biodiversidade , Reatores Biológicos , Meios de Cultura , Ésteres/análise , Produtos da Carne/análise , Olfato , Suínos , Leveduras/química , Leveduras/genética , Leveduras/isolamento & purificação
17.
PLoS One ; 9(5): e97626, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24854353

RESUMO

The Saccharomyces genus is the main yeast involved in wine fermentations to play a crucial role in the production and release of aromatic compounds. Despite the several studies done into the genome-wide expression analysis using DNA microarray technology in wine S. cerevisiae strains, this is the first to investigate other species of the Saccharomyces genus. This research work investigates the expression of the genes involved in flavor compound production in three different Saccharomyces species (S. cerevisiae, S. bayanus var. uvarum and S. kudriavzevii) under low (12°C) and moderate fermentation temperatures (28°C). The global genes analysis showed that 30% of genes appeared to be differently expressed in the three cryophilic strains if compared to the reference strain (mesophilic S. cerevisiae), suggesting a very close cold adaptation response. Remarkable differences in the gene expression level were observed when comparing the three species, S. cerevisiae, S. bayanus var. uvarum and S. kudriavzevii, which will result in different aroma profiles. Knowledge of these differences in the transcriptome can be a tool to help modulate aroma to create wines with the desired aromatic traits.


Assuntos
Genes Fúngicos/genética , Odorantes , Saccharomyces/genética , Vinho/análise , Hibridização Genômica Comparativa , Fermentação , Perfilação da Expressão Gênica , Cariotipagem , Análise de Sequência com Séries de Oligonucleotídeos , Especificidade da Espécie , Vinho/microbiologia
18.
Meat Sci ; 96(4): 1469-77, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24423452

RESUMO

Debaryomyces hansenii strains, M4 and P2, isolated from natural fermented sausages were inoculated in slow fermented sausages to study their effect on processing parameters, microbial population, volatile compound and sensory characteristics. The inoculation of D. hansenii strains, M4 and P2, did not affect the ripening process as no differences in pH and Aw were detected. The dominance of the inoculated yeast strains along the process was followed by RAPDs of M13 minisatellite. The inoculated yeasts, P2 and M4, were recovered at the end of the ripening process although P2 appeared in higher counts than M4. The sausages inoculated with P2 resulted in a decrease in lipid oxidation values (TBARS) and a reduction of lipid-oxidation derived aldehydes in addition to a highest acid compound abundance. M4 inoculated sausages resulted in highest sulphur containing compound abundance. However, no differences in consumer acceptance were detected. Moreover, both yeast strains were responsible for the generation of ethyl methyl-branched ester compounds in the dry-cured sausages.


Assuntos
Comportamento do Consumidor , Fermentação , Microbiologia de Alimentos , Produtos da Carne/análise , Saccharomycetales , Compostos Orgânicos Voláteis/análise , Ácidos/metabolismo , Aldeídos/metabolismo , Dessecação , Ésteres/metabolismo , Manipulação de Alimentos , Humanos , Peroxidação de Lipídeos , Produtos da Carne/microbiologia , Produtos da Carne/normas , Saccharomycetales/classificação , Especificidade da Espécie , Compostos de Enxofre/metabolismo , Leveduras/classificação
19.
Food Chem ; 151: 364-73, 2014 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-24423545

RESUMO

The ability of seven Debaryomyces hansenii strains to generate aroma compounds in a fermented sausage model system was evaluated. The presence of the yeast, in the inoculated models, was confirmed by PCR amplification of M13 minisatellite. Volatile compounds production was analysed using Solid Phase Micro-Extraction and gas chromatography/mass spectrometry. Forty volatile compounds were detected, quantified and their odour activity values (OAVs) calculated. All volatile compounds increased during time in the inoculated models although significant differences were found amongst them. Ester and sulphur production was strongly dependent on the strain inoculated. D. hansenii P2 and M6 strains were the highest producers of sulphur compounds where dimethyl disulphide and dimethyl trisulfide were the most prominent aroma components identified by their OAVs whereas, M4 showed the highest OAVs for ester compounds followed by the P2 strain. The meat model system has been useful to show the real ability of yeast strains to produce aroma compounds.


Assuntos
/química , Produtos da Carne/microbiologia , Odorantes/análise , Antifúngicos/química , Fermentação , Produtos da Carne/análise
20.
Food Microbiol ; 38: 160-6, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24290639

RESUMO

The yeasts present during the ripening process of ewes' and goats' cheeses produced in a small traditional dairy in Mediterranean Spain were isolated and identified. Five hundred and thirty strains pertaining to eleven yeast species representing eight genera were identified using molecular methods. Debaryomyces hansenii was the yeast species most frequently isolated in all cheeses. Other yeast species commonly found in dairy products were present at the first maturing weeks. Two yeast species Trichosporon coremiiforme and Trichosporon domesticum have been reported in cheeses for the first time, and Meyerozyma guilliermondii has been newly isolated from goats' cheeses. Yeast species composition changed greatly along the process; although, D. hansenii dominated at the end of ripening in all cheeses. Most yeast isolates were able to hydrolyze casein and fatty acid esters. One hundred and eighty seven D. hansenii isolates were genotyped by PCR amplification of M13 satellites and an UPGMA dendrogram was constructed. The majority of isolates were grouped in 5 clusters while 7 profiles were represented by 1-3 isolates. These results demonstrate the genetic heterogeneity present in D. hansenii strains isolated from raw milk cheeses.


Assuntos
Queijo/microbiologia , Heterogeneidade Genética , Leite/microbiologia , Saccharomycetales/genética , Leveduras/genética , Animais , Fermentação , Microbiologia de Alimentos , Cabras , Filogenia , Saccharomycetales/classificação , Saccharomycetales/isolamento & purificação , Saccharomycetales/metabolismo , Ovinos , Leveduras/classificação , Leveduras/isolamento & purificação , Leveduras/metabolismo
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