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1.
Int J Food Microbiol ; 324: 108615, 2020 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-32371236

RESUMO

In recent years, CRISPR/Cas9-based genetic editing has become a mainstay in many laboratories including manipulations done with yeast. We utilized this technique to generate a self-cloned wine yeast strain that overexpresses two genes of oenological relevance i.e. the glycerol-3-phosphate dehydrogenase 1 (GPD1) and the alcohol acetyltransferase 1 (ATF1) directly implicated in glycerol and acetate ester production respectively. Riesling wine made from the resulting strain showed increased glycerol and acetate ester levels compared to the parental strain. In addition, significantly less acetic acid levels were measured in wine made with yeast containing both genetic alterations compared to wine made with the strain that only overexpresses GPD1. Thus, this strain provides an alternative strategy for alleviating the accumulation of acetic acid once glycerol production is favoured during alcoholic fermentation with the addition of dramatically increasing acetate esters production.


Assuntos
Sistemas CRISPR-Cas , Saccharomyces cerevisiae/genética , Vinho/microbiologia , Ácido Acético/análise , Ácido Acético/metabolismo , Fermentação , Edição de Genes , Glicerol/análise , Glicerol/metabolismo , Glicerol-3-Fosfato Desidrogenase (NAD+)/genética , Glicerol-3-Fosfato Desidrogenase (NAD+)/metabolismo , Fenótipo , Proteínas/genética , Proteínas/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Vinho/análise
2.
Int J Food Microbiol ; 321: 108551, 2020 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-32078867

RESUMO

Sourdough is a very interesting natural preservation system to prolong mould free shelf-life of bread. Numerous studies have reported that the antifungal activity of sourdough is mainly correlated with the presence of lactic (LA) and acetic acid (AA), but very few information is available on the effect of undissociated acid concentrations in the aqueous phase of bread (CHA; mmole/L). This study was conducted to provide additional information about the mode of action of the acids in sourdough bread, enabling a better shelf-life prediction. This study was divided into two parts. In part 1, three industrial biological sourdoughs were characterized (dough yield, pH, aw, fermentation quotient, microbiota). During 7 weeks, a shelf-life test with natural flora was conducted with daily checks of visible mould growth (21 °C). In part 2, the effect of the acids present in the antifungal active sourdough breads was validated in chemically acidified wheat breads. Complete growth inhibition was observed in full-baked sourdough bread (30 g/100 g dough) containing Lactobacillus sanfranciscensis and Saccharomyces cerevisiae as dominant sourdough micro-organisms, whereas in control bread the shelf-life was limited to 4.4-9.2 days. These full-baked sourdough breads contained 36 mmole undissociated LA/L and 220 mmole undissociated AA/L. The data were used to make General Linear Regression models for shelf-life prediction and resulted in a fit of R2 = 0.79 when expressing the shelf-life in function of CHA,LA and CHA,AA. In acidified breads, the role of lactic acid was not significant and only impacted shelf-life indirectly through acidification. No difference between antifungal activity of sourdough breads and chemically acidified bread with comparable CHA,AA concentrations was observed. Shelf-life increased when 150-200 mmole undissociated AA/L aqueous phase in bread was present. To conclude, this study showed the importance of the undissociated acid fraction of acetic acid in relation to bread shelf-life, together with bread pH and moisture content.


Assuntos
Ácido Acético/farmacologia , Antifúngicos/farmacologia , Pão/análise , Conservação de Alimentos/métodos , Ácido Láctico/farmacologia , Ácido Acético/análise , Antifúngicos/análise , Pão/microbiologia , Fermentação , Fungos/efeitos dos fármacos , Fungos/crescimento & desenvolvimento , Ácido Láctico/análise , Lactobacillus/efeitos dos fármacos , Lactobacillus/crescimento & desenvolvimento , Triticum/microbiologia , Água/análise
3.
Food Chem ; 317: 126424, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32088405

RESUMO

In this study, a simple, efficient, and green effervescence tablet-assisted microextraction method based on the solidification of deep eutectic solvent (ETA-ME-SDES) was developed to determine picoxystrobin, pyraclostrobin, and trifloxystrobin in water, juice, wine, and vinegar samples by HPLC. An eco-friendly, hydrophobic, deep eutectic solvent (DES, acting as the extraction solvent) was synthesized by thymol and octanoic acid in the molar ratio of 1:5. The extraction solvent dispersed in sample solutions with the assistance of pH adjustment and effervescence reaction, and was collected after solidification in an ice bath. Several essential conditions, including the type and the volume of DESs, the amount of ammonia hydroxide, and the components of effervescence tablets were optimized. The limits of detection ranged from 0.15 to 0.38 µg L-1. Extraction recovery ranged from 77.4 to 106.9%. The proposed method was successful in determining the amount of strobilurin fungicides in water, juice, wine, and vinegar samples.


Assuntos
Ácido Acético/análise , Cromatografia Líquida de Alta Pressão , Sucos de Frutas e Vegetais/análise , Fungicidas Industriais/análise , Estrobilurinas/análise , Poluentes Químicos da Água/análise , Vinho/análise , Acetatos/análise , Fungicidas Industriais/química , Concentração de Íons de Hidrogênio , Iminas/análise , Limite de Detecção , Microextração em Fase Líquida/métodos , Sais/química , Estrobilurinas/química , Poluentes Químicos da Água/química
4.
Food Chem ; 309: 125664, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31699553

RESUMO

In this study, it was aimed to determine the bioactive compounds and volatile aroma compounds of the sour cherry vinegar, and to investigate the usability of concentrated juice instead of the fresh fruit juice in vinegar production. And, two sour cherry vinegars were produced using juices prepareted fresh fruit (FSCJ) and concentrate juice (CSCJ), analyzed for functional and organoleptic aspects. The finding shown that both vinegars produced have rich functional compounds (gallic and chlorogenic acids) and volatile aroma compounds, and sour cherry is ideal for vinegar production. However, the vinegar produced using the CSCJ was more prominent, according to aromatic aspect. These aroma compounds were 3-methyl-1-butanol and eugenol, phenethyl alcohol, 2-phenethyl acetate, acetic, isobutyric, isovaleric, hexanoic and octanoic acids. Within this study, a new way for sour cherry usage, independently of the season were proposed. And, aromatic and functional aspects of sour cherry vinegar were revealed for the first time.


Assuntos
Ácido Acético/análise , Antioxidantes/química , Sucos de Frutas e Vegetais/análise , Prunus avium/química , Compostos Orgânicos Voláteis/química , Frutas/química , Frutas/metabolismo , Concentração de Íons de Hidrogênio , Fenóis/química , Prunus avium/metabolismo , Refratometria , Espectrofotometria
5.
Food Chem ; 311: 126012, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855771

RESUMO

The aroma profiles of Spanish wine vinegars with Protected Designation of Origin (PDO) were described and compared for the first time by gas chromatography-mass spectrometry-olfactometry (GC-MS-O), odor-active values (OAVs) and quantitative descriptive analysis (QDA). Vinagre de Jerez Reserva (JRE) showed higher percentage of 'grassy-vegetal' impact odorants, while 'spicy' compounds highlighted the Pedro Ximénez category (JPX). Vinagre de Montilla-Moriles Reserva (MRE) had 'buttery-lactic' impact odorants, while 'empyreumatic' and 'sweet' aromas stood out for Pedro Ximénez category (MPX). Vinagre de Condado de Huelva Reserva (CRE) showed a stronger percentage of 'chemical' impact odorants. The key odorants were ethyl propionate, ethyl octanoate, propanoic acid and 4-ethylphenol for JRE, diacetyl and methional/furfural for JPX, acetoin for MRE, ethyl phenylacetate and vanillin for MPX and acetaldehyde diethyl acetal, isobutyl acetate, ethyl isovalerate and guaiacol for CRE. A good relation among the impact odorants and the sensory descriptors was observed.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Odorantes/análise , Compostos Orgânicos Voláteis/análise , Vinho/análise , Ácido Acético/análise , Feminino , Humanos , Masculino , Olfatometria , Análise de Componente Principal , Paladar
6.
J Dairy Sci ; 103(1): 215-219, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31733842

RESUMO

Kefir is an artisanal product that is gaining scientific attention due to its increase in consumption attributed to its potential health benefits. The effect on the quality attributes of kefir grains of different origin (household and commercial) and preserved with different methods (drying and freezing) was evaluated to standardize a domestic and semi-industrial process. Chemical (protein, lactose. lactic acid, ethanol, and acetic acid) as well as microbial properties (total plate count and total yeast count) were monitored during the experiment. Results show a statistical difference between the kefir grains in terms of acetic acid and ethanol percentages, which leads to the conclusion that there is a difference in the microbial populations that produce these products. Lactic acid, protein, and lactose parameters are statistically the same as well as the growth in biomass and the total population of yeast. Our results suggest that both types of kefir grains maintain a similar performance and that their metabolic capabilities are stable throughout time (taking into account that the household grains have been productive for years), meaning that domestic or semi-industrial processes could be easily standardized.


Assuntos
Ácido Acético/análise , Etanol/análise , Kefir/análise , Animais , Costa Rica , Fermentação
7.
Food Chem Toxicol ; 134: 110829, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31542431

RESUMO

The development and validation of a simple, low-cost, and sensitive method for the determination of nine compounds expected in beverages and vinegar as a result of migration from food contact material (parabens, phenolic antioxidants, sulfonamide plasticizer, and flame retardant) is presented. The analytes were preconcentrated using solid-phase microextraction and analyzed by gas chromatography - tandem mass spectrometry. The method required no derivatization procedure and an affordable chemical was used as internal standard. The LODs were in the range of 0.005-0.2 µg/L, the relative standard deviations 0.8-5.4%, and the mean recoveries 98-109%. Different alcoholic beverages and vinegars were analyzed. A crown cap migration study using several food simulants was conducted for 6 months. Moreover, migration from a home brewing plastic fermenter in a time span of 4 weeks was studied. Analyte concentrations up to 2220.99 µg/L were detected in real samples and up to 4.75 µg/L in migration experiments.


Assuntos
Ácido Acético/análise , Bebidas Alcoólicas/análise , Contaminação de Alimentos/análise , Embalagem de Alimentos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Microextração em Fase Sólida/métodos
8.
Food Funct ; 10(8): 4877-4887, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31334505

RESUMO

Catechin, a natural antiglycative agent, was incorporated into fermented vinegar, and has high potential to lower the risk of diabetes. In this study, vinegar containing 5% catechin as a substrate for acetous fermentation significantly inhibited the formation of total fluorescent advanced glycation end-products (AGEs), as well as Nε-(carboxymethyl)lysine (CML)/Nε-(carboxyethyl)lysine (CEL), especially when added during acetic fermentation. Further study proved that catechin could not only significantly suppress the increase of blood glucose levels, but also inhibit α-amylase, α-glucosidase and ß-glucosidase strongly with IC50 values of 0.533 mg mL-1, 0.307 mg mL-1 and 0.413 mg mL-1, respectively. Moreover, 32 volatile compounds were finally identified by headspace solid phase microextraction gas chromatography-mass spectrometry (HSPM-GC-MS) and electronic nose. The flavor of the catechin-vinegars, which possess relatively high ester and low acid contents, was superior to that of traditional vinegar. Therefore, it was helpful to use catechin as a functional food ingredient in vinegar to prevent AGE-associated diseases and alleviate postprandial hyperglycemia, through limiting the digestion of starch and inhibiting the uptake of glucose. Meanwhile, the pleasant flavor and safety of catechin-vinegar were better than traditional vinegar, which represents prominent value to attract consumers.


Assuntos
Ácido Acético/análise , Catequina/análise , Produtos Finais de Glicação Avançada/análise , Ácido Acético/metabolismo , Acetobacter/metabolismo , Fermentação , Aditivos Alimentares/análise , Tecnologia de Alimentos , Alimento Funcional/análise , Cromatografia Gasosa-Espectrometria de Massas , Saccharomyces cerevisiae/metabolismo , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/metabolismo
9.
Sensors (Basel) ; 19(14)2019 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-31336702

RESUMO

Photonic nanoarchitectures in the wing scales of butterflies and moths are capable of fast and chemically selective vapor sensing due to changing color when volatile vapors are introduced to the surrounding atmosphere. This process is based on the capillary condensation of the vapors, which results in the conformal change of the chitin-air nanoarchitectures and leads to a vapor-specific optical response. Here, we investigated the optical responses of the wing scales of several butterfly and moth species when mixtures of different volatile vapors were applied to the surrounding atmosphere. We found that the optical responses for the different vapor mixtures fell between the optical responses of the two pure solvents in all the investigated specimens. The detailed evaluation, using principal component analysis, showed that the butterfly-wing-based sensor material is capable of differentiating between vapor mixtures as the structural color response was found to be characteristic for each of them.


Assuntos
Borboletas , Mariposas , Compostos Orgânicos Voláteis , Asas de Animais/química , Asas de Animais/fisiologia , Ácido Acético/análise , Ácido Acético/química , Animais , Borboletas/fisiologia , Etanol , Masculino , Mariposas/fisiologia , Óptica e Fotônica , Pigmentação , Análise de Componente Principal , Espectrofotometria/instrumentação , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Asas de Animais/anatomia & histologia
10.
Molecules ; 24(13)2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31284387

RESUMO

(1) Background: The continuously increasing demand for renewable energy sources renders anaerobic digestion as one of the most promising technologies for renewable energy production. Due to the animal production intensification, manure is being used as the primary feedstock for most biogas plants. Their economical profitable operation, however, relies on increasing the methane yield from the solid fraction of manure, which is not so easily degradable. The solid fraction after anaerobic digestion, the so-called digested fibers, consists mainly of hardly biodegradable material and comes at a lower mass per unit volume of manure compared to the solid fraction before anaerobic digestion. Therefore, investigation on how to increase the biodegradability of digested fibers is very relevant. So far, Aqueous Ammonia Soaking (AAS), has been successfully applied on digested fibers separated from the effluent of a manure-fed, full-scale anaerobic digester to enhance their methane productivity in batch experiments. (2) Methods: In the present study, continuous experiments at a mesophilic (38 °C) CSTR-type anaerobic digester fed with swine manure first and a mixture of manure with AAS-treated digested fibers in the sequel, were performed. Anaerobic Digestion Model 1 (ADM1) previously fitted on manure fed digester was used in order to assess the effect of the addition of AAS-pre-treated digested manure fibers on the kinetics of anaerobic digestion process. (3) Results and Conclusions: The methane yield of AAS-treated digested fibers under continuous operation was 49-68% higher than that calculated in batch experiments in the past. It was found that AAS treatment had a profound effect mainly on the disintegration/hydrolysis rate of particulate carbohydrates. Comparison of the data obtained in the present study with the data obtained with AAS-pre-treated raw manure fibers in the past revealed that hydrolysis kinetics after AAS pre-treatment were similar for both types of biomasses.


Assuntos
Amônia/farmacologia , Esterco/análise , Água/química , Ácido Acético/análise , Anaerobiose , Animais , Biocombustíveis/análise , Ácido Butírico/análise , Modelos Teóricos , Propionatos/análise , Suínos
11.
Int J Food Microbiol ; 305: 108255, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31252247

RESUMO

The microbial diversity of wine alcoholic fermentation is not restricted to the presence and activity of Saccharomyces yeast strains. Some non-Saccharomyces species have been described as part of the fermentative microbiota, specially found in the initial steps of wine fermentations. These species may play roles from wine spoilage to flavor quality enhancement. From a large number of wine fermentations (429 wine samples), analyzed by ITS-amplicon sequencing to define their mycobiome, 2 non-conventional yeast species (Nakazawaea ishiwadae and Lodderomyces elongisporus) were detected, in a very limited number of samples but in significant levels of relative abundance. One strain of each species was isolated and their technological and enological potential have been characterized in this work. Compared with the Saccharomyces cerevisiae Viniferm Revelacion wine strain, the studied N. ishiwadae BMK17.1 and L. elongisporus BMK12.5 strains showed, as expected, a lower tolerance and growth fitness in high ethanol concentrations. However, N. ishiwadae BMK17.1 was able to grow also at 15% ethanol and L. elongisporus BMK12.5 at 10% reaching, in the latter case, slightly higher efficiency rates than S. cerevisiae at this level. Contrary to most non-Saccharomyces yeasts, these species were able to growth in presence of high doses of potassium-metabisulfite, reaching in both cases higher efficiency rates than S. cerevisiae. A notable affinity of L. elongisporus BMK12.5 for high pH values was clearly observed. Their fermentation kinetics and the final chemical-analytical characterization were studied in micro-fermentation assays, using synthetic grape must. L. elongisporus BMK12.5 was able to complete, in single inoculation, the sugar fermentation after 19 days, but, N. ishiwadae BMK17.1 left about 80 g/L sugars at this time. Co-inoculation assays (in a 1:100 proportion of S. cerevisiae:non-Saccharomyces strains) finished sugar consumption with similar kinetics than the S. cerevisiae single inoculation, in the case of L. elongisporus BMK12.5 co-inoculation, and with lower kinetics when using N. ishiwadae BMK17.1. A remarkable malic acid consumption and a low acetic acid production was associated with L. elongisporus BMK12.5 fermentations, together with a high production of 3-methyl-1-butanol and 2-phenylethanol, and the release of high amounts of proteins into the wines. N. ishiwadae BMK17.1, although unable to finish the fermentation itself, showed a high production of oligosaccharides and volatile compounds such as isobutanol or isobutyric acid. This work reports, for the first time, the occurrence and enological potential of two strains pertaining to the non-conventional yeast genera Lodderomyces and Nakazawaea.


Assuntos
Saccharomycetales/metabolismo , Vitis/microbiologia , Vinho/microbiologia , Ácido Acético/análise , Ácido Acético/metabolismo , Etanol/análise , Etanol/metabolismo , Fermentação , Malatos/análise , Malatos/metabolismo , Saccharomyces cerevisiae , Vitis/metabolismo , Vinho/análise
12.
Food Microbiol ; 83: 141-149, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31202405

RESUMO

This study aimed to investigate bacterial diversity in paocai and Chinese spicy cabbage and compare the microbial communities using high-throughput sequencing. Bacteria representing 26 phyla, 480 genera and 338 species were observed in these Chinese fermented vegetables. Firmicutes and Proteobacteria were the main phyla observed in both paocai and Chinese spicy cabbage. Additionally, Lactobacillus, Pediococcus, Serratia, Stenotrophomonas and Weissella were the major genera observed in both paocai and Chinese spicy cabbage. Overall, the relative abundances of Lactobacillus, Pediococcus and Weissella in Chinese spicy cabbage were much higher than those in paocai, but the proportions of Stenotrophomonas and Serratia in Chinese spicy cabbage were less than those in paocai. The results showed that the composition of the microbial community in Chinese spicy cabbage was positively correlated with total titratable acidity (TA), lactic acid and acetic acid contents but was negatively correlated with salinity. In contrast, the composition of the microbial community in paocai was negatively correlated with TA, lactic acid and acetic acid contents but was positively correlated with salinity. This study provides insights into the relationship between bacterial profiles and environmental factors in Chinese spicy cabbage and paocai, and its findings will aid in guiding future research on fermented vegetables.


Assuntos
Bactérias/classificação , Brassica/microbiologia , Alimentos e Bebidas Fermentados/microbiologia , Microbiologia de Alimentos , Ácido Acético/análise , Bactérias/isolamento & purificação , Fermentação , Sequenciamento de Nucleotídeos em Larga Escala , Ácido Láctico/análise , Microbiota , RNA Ribossômico 16S/genética
13.
Analyst ; 144(14): 4153-4161, 2019 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-31144689

RESUMO

Breast cancer (BC), ranked as the fifth amongst all cancers, remains at the top of women's cancers worldwide followed by colorectal, lung, cervix, and stomach cancers. The main handicap of most of the screening/diagnostic methods is based on their low sensitivity and specificity and the invasive behavior of most sampling procedures. The aim of this study was to establish the volatomic pattern of BC and cancer-free (CF) tissues (n = 30) from the same patients, as a powerful tool to identify a set of volatile organic metabolite (VOM) potential BC biomarkers which might be used together or complement with the traditional BC diagnostics strategies, through the integration of chromatographic data, obtained by solid-phase microextraction followed by gas chromatography-mass spectrometry (SPME/GC-qMS), with chemometric tools. A total of four metabolites: limonene, decanoic acid, acetic acid and furfural presented the highest contribution towards discrimination of BC and CF tissues (VIP > 1, p < 0.05). The discrimination efficiency and accuracy of BC tissue metabolites was ascertained by ROC curve analysis that allowed the identification of some metabolites with high sensitivity and specificity. The results obtained with this approach suggest the possibility of identifying endogenous metabolites as a platform to find potential BC biomarkers and pave the way to investigate the related metabolomic pathways in order to improve BC diagnostic tools. Moreover, deeper investigations could unravel novel mechanistic insights into the disease pathophysiology.


Assuntos
Biomarcadores Tumorais/análise , Neoplasias da Mama/diagnóstico , Compostos Orgânicos Voláteis/análise , Ácido Acético/análise , Adulto , Idoso , Idoso de 80 Anos ou mais , Ácidos Decanoicos/análise , Feminino , Furaldeído/análise , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Limoneno/análise , Metabolômica/métodos , Pessoa de Meia-Idade , Análise Multivariada , Curva ROC
14.
Acta Diabetol ; 56(5): 569-579, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30888539

RESUMO

AIMS: To investigate the interactions among fecal and plasma glutamate levels, insulin resistance cognition and gut microbiota composition in obese and non-obese subjects. METHODS: Gut microbiota composition (shotgun) and plasma and fecal glutamate, glutamine and acetate (NMR) were analyzed in a pilot study of obese and non-obese subjects (n = 35). Neuropsychological tests [Trail making test A (TMT-A) and Trail making test B (TMT-B)] scores measured cognitive information about processing speed, mental flexibility and executive function. RESULTS: Trail-making test score was significantly altered in obese compared with non-obese subjects. Fecal glutamate and glutamate/glutamine ratio tended to be lower among obese subjects while fecal glutamate/acetate ratio was negatively associated with BMI and TMT-A scores. Plasma glutamate/acetate ratio was negatively associated with TMT-B. The relative abundance (RA) of some bacterial families influenced glutamate levels, given the positive association of fecal glutamate/glutamine ratio with Corynebacteriaceae, Coriobacteriaceae and Burkholderiaceae RA. In contrast, Streptococaceae RA, that was significantly higher in obese subjects, negatively correlated with fecal glutamate/glutamine ratio. To close the circle, Coriobacteriaceae/Streptococaceae ratio and Corynebacteriaceae/Streptococaceae ratio were associated both with TMT-A scores and fecal glutamate/glutamine ratio. CONCLUSIONS: Gut microbiota composition is associated with processing speed and mental flexibility in part through changes in fecal and plasma glutamate metabolism.


Assuntos
Cognição/fisiologia , Fezes/química , Microbioma Gastrointestinal/fisiologia , Ácido Glutâmico/análise , Resistência à Insulina , Obesidade/fisiopatologia , Ácido Acético/análise , Ácido Acético/sangue , Bactérias/isolamento & purificação , Feminino , Ácido Glutâmico/sangue , Glutamina/análise , Glutamina/sangue , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Obesidade/complicações , Obesidade/microbiologia , Projetos Piloto , Teste de Sequência Alfanumérica
15.
Food Chem ; 286: 141-145, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30827587

RESUMO

The concentration of tetramethylpyrazine (TMP) in vinegar is an active indicator of vinegar quality. Dispersive liquid-liquid microextraction (DLLME) was first applied to vinegar as a clean-up pre-treatment for the rapid (5 min) determination of TMP by high-pressure liquid chromatography with ultraviolet detection (HPLC-UV), and may serve as an alternative to solid-phase extraction (SPE) or solid-phase microextraction (SPME). High sensitivity of HPLC for TMP determination was obtained using the DLLME pretreatment, with a limit of detection (LOD) of 0.001 mg L-1 and limit of quantification (LOQ) of 0.005 mg L-1. The developed method exhibited excellent linearity in the concentration range of 0.050-80.000 mg L-1, with a correlation coefficient R2 > 0.999. Furthermore, the percentage recovery of TMP in vinegar using the developed method was within the range 97.97-105.24%. Therefore, DLLME coupled with HPLC-UV is a sensitive and promising method for vinegar clean-up and TMP assay.


Assuntos
Análise de Alimentos/métodos , Microextração em Fase Líquida/métodos , Pirazinas/análise , Ácido Acético/análise , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Sensibilidade e Especificidade
16.
Food Chem ; 286: 78-86, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30827669

RESUMO

Verjuice is an acidic unfermented unripe grape juice that has recently been proposed as an alternative to vinegar in different food preparations. In this study, pickled cucumber preserves were industrially prepared using two dilutions of verjuice as acidifying agent and compared with the traditional vinegar-pickled samples. Samples were chemically characterized and subjected to sensory analyses using a trained panel and consumers. The different acidifying agents resulted in pickled cucumbers giving different olfactory and gustatory evaluations. No differences in appearance and texture were found. Despite showing chemical and sensory differences, pickles preserved with verjuice and vinegar had similar overall liking scores for visual, olfactory and gustatory aspects. A key feature of pickles prepared with verjuice is their lack of acetic acid potentially conferring them an additional value, suggesting that verjuice represents a viable alternative to vinegar for the production of pickles with distinctive sensorial properties.


Assuntos
Cucumis sativus , Conservação de Alimentos/métodos , Sucos de Frutas e Vegetais , Vitis , Ácido Acético/análise , Cucumis sativus/química , Feminino , Humanos , Masculino , Paladar
17.
Food Chem ; 287: 115-125, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-30857680

RESUMO

A practice in wine vinegar production is the addition of grape-must caramel to correct and unify the final colour of different batches. Although current legislation allows it, the effect in vinegars' quality has not been studied yet and it can become a fraud when it is used to simulate the effect of a longer ageing. Therefore, the aim of this work was to assess multidimensional fluorescence as a cost-effective and fast technique for detecting and quantifying grape-must caramel in vinegars. Different amounts of grape-must caramel and multivariate data analysis, as Parallel Factor Analysis (PARAFAC), N-way partial least squares and partial least squares discrimination and regression (NPLS-DA, PLS-DA and NPLS) were studied. Triangle sensory test was also performed. Results demonstrated the ability of this methodology in the detection and quantification of grape-must caramel (low prediction errors, RMSEP ≈ 0.24) and the effects that grape-must caramel has upon a PDO vinegar's final quality.


Assuntos
Ácido Acético/análise , Extratos Vegetais/química , Espectrometria de Fluorescência/métodos , Vitis/química , Vinho/análise
18.
Luminescence ; 34(3): 341-346, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30784194

RESUMO

New carbon dots (CDs) were prepared by a microwave method using m-trihydroxybenzene and dilute sulphuric acid as raw materials. The as-prepared CDs exhibited excellent water solubility and photoluminesence properties. The optimum excitation and emission wavelengths of the new CDs were at 365 nm and 465 nm, respectively. The fluorescence of the new CDs experienced remarkable changes in the presence of Britton-Robinson (BR) buffer solution with different pH values under 4°C after reacting for 70 min. In addition, a linear relationship between the logarithm of the relative fluorescence intensity ratio [lg(IF /IFo )] of CDs and the pH values of the sensing system ranging 1.81-5.72 was obtained, with a correlation coefficient of 0.9933. Thus, a sensitive and simple method to detect the pH value of solution was developed. Furthermore, the analytical application of detecting the concentration of acetic acid in vinegar was investigated. The detection values were found similar to the reference values, fully demonstrating a good linear relationship between the logarithm of the relative fluorescence intensity ratio of the CDs and the pH value of the system. Hence, the method could be used to detect the concentration of acetic acid in vinegar.


Assuntos
Carbono/química , Medições Luminescentes/métodos , Fenol/química , Pontos Quânticos/química , Ácido Acético/análise , Fluorescência , Concentração de Íons de Hidrogênio , Medições Luminescentes/instrumentação
19.
J Dairy Res ; 86(1): 120-128, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30729899

RESUMO

The aim of this work was to evaluate the impact of two factors on the ripening profiles of hard cooked cheeses: (F1) the growth medium for the primary and adjunct cultures, constituted by autochthonous strains: Lactobacillus helveticus 209 (Lh209) and Lactobacillus paracasei 90 (Lp90), respectively, and (F2) the addition of L. paracasei Lp90 as adjunct culture. Four types of cheeses were made: W and M cheeses in which only Lh209 was added after its growth in whey and MRS, respectively; Wa and Ma cheeses in which both strains (Lh209 and Lp90) were added after their growth in whey and MRS, respectively. Physicochemical and microbial composition, proteolysis and profiles of organic acids and volatile compounds were analyzed. According to the methodology of the cultures preparation, W and Wa cheeses showed a higher level of secondary proteolysis and lower level of primary proteolysis (P < 0·05), lower content of citric and acetic acids and higher amount of propionic acid (P < 0·05), in comparison with M and Ma cheeses. The incorporation of Lp90 increased the secondary proteolysis (P < 0·05), decreased the citric acid (P < 0·05), and increased the propionic acid only when was added after their growth in whey (P < 0·05). Both factors significantly modified the percentages of the volatile compounds grouped in chemical families; in addition, for the half of the compounds detected, significant differences were found. Based on the obtained results, the use of Lp90 as an adjunct in hard cooked cheeses, and the preincubation of the cultures in whey are strategies to accelerate the cheese ripening and to enhance the production of some characteristic compounds of this type of cheeses, such as propan-2-one, hexan-2-one, 2- and 3-methyl butanal, heptan-2-ol, acetic and 3-methylbutanoic acids and 3-hydroxy butan-2-one.


Assuntos
Queijo/análise , Queijo/microbiologia , Tecnologia de Alimentos/métodos , Lactobacillus helveticus/crescimento & desenvolvimento , Lactobacillus paracasei/crescimento & desenvolvimento , Ácido Acético/análise , Carboidratos/análise , Fenômenos Químicos , Ácido Cítrico/análise , Meios de Cultura , Fermentação , Manipulação de Alimentos/métodos , Concentração de Íons de Hidrogênio , Lactobacillus helveticus/metabolismo , Lactobacillus paracasei/metabolismo , Propionatos , Proteólise , Compostos Orgânicos Voláteis/análise
20.
J Anim Sci ; 97(4): 1634-1644, 2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30715358

RESUMO

The objective of this study was to evaluate the effects of Lactobacillus inoculants on fermentation, losses, and aerobic stability of a total mixed ration (TMR) silage. A TMR, formulated to meet the requirements of dairy cows producing 25 kg of milk/d, was applied with the following treatments prior to ensiling: 1) Control (CON), 2) Lactobacillus buchneri (105 cfu/g of fresh forage; LB), and 3) Lactobacillus plantarum (105 cfu/g of fresh forage; LP). TMR silages were ensiled for 15 and 60 d in silos equipped with an apparatus for determination of gravimetric DM, gas, and effluent losses. The experiment was performed in a complete randomized design with a 3 × 2 factorial arrangement of the treatments, with 5 replicates per treatment. Chemical changes, microbial counts, fermentation profile, and aerobic stability were measured after opening the silos. Data were submitted to ANOVA, and means were compared by Tukey and T-test and statistical significance was declared at P ≤ 0.05. After 15 d of ensiling, the inclusion of inoculant decreased NDF (P < 0.05) and butyric acid concentrations (P < 0.05) in TMR. LP had the lowest aerobic stability (P < 0.05) and the greatest loss of DM (P < 0.03). Ensiling for 60 d increased ammonia nitrogen (NH3-N), lactic acid bacteria (LAB), aerobic stability, and concentrations of lactic and acetic acid (P < 0.01) and lowered (P < 0.02) total fermentation losses compared to 15 d across all treatments. After 60 d of ensiling, LP lowered pH to the greatest extent. Treatment had no effect on concentrations of DM, CP, ADF, ash, and EE, as well as in vitro DM digestibility. In conclusion, inoculants containing LP or LB did not improve fermentation profile, did not prolong the aerobic stability, nor reduced losses. Furthermore, the 15-d ensiling period was insufficient for adequate bacterial activity.


Assuntos
Bovinos/fisiologia , Lactobacillus , Leite/metabolismo , Silagem/microbiologia , Ácido Acético/análise , Animais , Feminino , Fermentação , Lactobacillus plantarum
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