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1.
Molecules ; 28(3)2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36770821

RESUMO

Essential oils (EOs) are mixtures of volatile plant secondary metabolites and have been exploited by humans for thousands of years for various purposes because of their many bioactivities. In this study, the EO from Thymus capitatus, a thyme species organically cultured on the Greek Island of Lemnos, was analyzed for its chemical composition (through GC-FID and GC-MS), antioxidant activity (AA), and total phenolic content (TPC), as well as its antimicrobial and antibiofilm actions against three important foodborne bacterial pathogens (Salmonella enterica ser. Typhimurium, Listeria monocytogenes, and Yersinia enterocolitica). For the latter investigations, the minimum inhibitory concentrations (MICs) and minimum biofilm inhibitory concentrations (MBICs) of the EO against the planktonic and biofilm growth of each pathogen were determined, together with the minimum biofilm eradication concentrations (MBECs). Results revealed that T. capitatus EO was rich in thymol, p-cymene, and carvacrol, presenting high AA and TPC (144.66 µmol TroloxTM equivalents and 231.32 mg gallic acid equivalents per g of EO, respectively), while its MICs and MBICs ranged from 0.03% to 0.06% v/v and 0.03% to 0.13% v/v, respectively, depending on the target pathogen. The EO was able to fully destroy preformed (mature) biofilms of all three pathogenic species upon application for 15 min, with MBECs ranging from 2.00 to 6.25% v/v. Overall, the results demonstrate that the EO of organically cultured T. capitatus presents strong antioxidant, antibacterial, and antibiofilm properties and could, therefore, be further exploited as a functional and antimicrobial natural formulation for food and health applications.


Assuntos
Anti-Infecciosos , Óleos Voláteis , Thymus (Planta) , Humanos , Óleos Voláteis/farmacologia , Óleos Voláteis/química , Antioxidantes/farmacologia , Antioxidantes/química , Thymus (Planta)/química , Grécia , Anti-Infecciosos/farmacologia , Antibacterianos/farmacologia , Antibacterianos/química , Biofilmes , Fenóis/farmacologia , Salmonella typhimurium , Testes de Sensibilidade Microbiana
2.
J Sci Food Agric ; 100(8): 3319-3327, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32112412

RESUMO

BACKGROUND: The aim of the present study was to evaluate the fermentation efficiency of freeze-dried immobilized kefir culture on natural supports (apple pieces, delignified cellulosic material) in cider making at various temperatures (5-45 °C) in comparison with freeze-dried free cells. Freeze-dried cells were initially tested in apple juice fermentations at 30 °C, and then the freeze-dried cultures produced with no cryoprotectants were assessed in repeated batch fermentations. RESULTS: Repeated batch fermentations lasted for longer than 5 months. High malic acid conversion rates (up to 78.5%) and ethanol productivity values (up to 37.9 g L-1 day-1 ) were recorded for freeze-dried immobilized cells. Polymerase chain reaction - denaturing gradient gel electrophoresis (PCR-DGGE) analysis showed that freeze-drying had no effect on the microbial diversity of kefir culture. Higher alcohols were significantly reduced at low fermentation temperatures. Application of principal component analysis (PCA) revealed that both the fermentation temperature and the nature of the freeze-dried kefir culture affected significantly the minor volatiles determined by gas chromatography/mass spectrometry (GC/MS). Notably, all ciders produced were of high quality and were accepted by the tasting panel. CONCLUSIONS: Freeze-dried immobilized kefir culture on natural supports with no cryoprotectants was found to be suitable for simultaneous alcoholic and malolactic cider fermentation at various temperatures (5-45 °C). The high operational stability of the systems was confirmed and the results obtained are of great interest for the industrial sector as they could be exploited for cider, low-alcohol cider, or 'soft' cider production. © 2020 Society of Chemical Industry.


Assuntos
Bebidas Alcoólicas/microbiologia , Microbiologia de Alimentos/métodos , Kefir/microbiologia , Lactobacillales/metabolismo , Malus/química , Células Imobilizadas/química , Células Imobilizadas/metabolismo , Etanol/metabolismo , Fermentação , Kefir/análise , Lactobacillales/química , Malatos/metabolismo , Malus/microbiologia , Temperatura
3.
Molecules ; 23(1)2018 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-29329229

RESUMO

The aim of the study was to characterize the chemical composition and biological properties of the essential oil from the plant Lippia citriodora grown in Greece. The essential oil volatiles were analyzed by gas chromatography-mass spectrometry GC-MS indicating citral as the major component. Τhe antimicrobial properties were assayed using the disk diffusion method and the minimum inhibitory and non-inhibitory concentration values were determined. Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus, Saccharomyces cerevisiae, and Aspergillus niger were sensitive to Lippia citriodora oil, but not Escherichia coli, Salmonella Enteritidis, Salmonella typhimurium, and Pseudomonas fragi. Adversely, all microbes tested were sensitive to citral. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays were used to assess direct antioxidant activity, which proved to be weak for both agents, while comet assay was utilized to study the cytoprotective effects against H2O2-induced oxidative damage in Jurkat cells. Interestingly, the oil showed a more profound cytoprotective effect compared to citral. The antiproliferative activity was evaluated in a panel of cancer cell lines using the sulforhodamine B (SRB) and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-S-(phenylamino) carbonyl-2-tetrazolium hydroxide (XTT) assays and both agents demonstrated potent antiproliferative activity with citral being more cytotoxic than the oil. Taken together, the essential oil of Lippia citriodora and its major component, citral, exert diverse biological properties worthy of further investigation.


Assuntos
Lippia/química , Óleos Voláteis/química , Compostos Fitoquímicos/química , Óleos de Plantas/química , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/química , Antifúngicos/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Óleos Voláteis/farmacologia , Compostos Fitoquímicos/farmacologia , Óleos de Plantas/análise , Óleos de Plantas/farmacologia
4.
Curr Microbiol ; 74(9): 1061-1067, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28634689

RESUMO

Survival during transit through the gastrointestinal track, intestinal mucosa adhesion, and a potential immunomodulatory effect of Lactobacillus plantarum strains 2035 and ACA-DC 2640 were investigated in a rat model. According to microbiological and multiplex PCR analysis, both strains were detected in feces 24 h after either single-dose or daily administration for 7 days. Intestinal mucosa adhesion of L. plantarum 2035 was noted in the large intestine at 24 h after single-dose administration, while it was not detected at 48 h. Daily dosing, prolonged detection of the strain up to 48 h post-administration, and expanded adhesion to the small intestine. Adhesion of L. plantarum ACA-DC 2640 to the intestinal mucosa after single-dose administration was prolonged and more extended compared to L. plantarum 2035. Daily dosing increased both the levels and the rate of positive cultures of the strains compared to those of the single-dose scheme. In addition, both strains increased total IgG while decreased IgM and IgA serum levels. In conclusion, L. plantarum 2035 and L. plantarum ACA-DC 2640 survived transit through the gastrointestinal track, exhibited transient distinct adhesion to the intestinal mucosa and modulated the systemic immune response.


Assuntos
Aderência Bacteriana , Mucosa Intestinal/microbiologia , Lactobacillus plantarum/imunologia , Lactobacillus plantarum/fisiologia , Viabilidade Microbiana , Animais , Anticorpos Antibacterianos/sangue , Fezes/microbiologia , Imunoglobulina A/sangue , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Fatores Imunológicos/administração & dosagem , Fatores Imunológicos/farmacologia , Intestino Grosso/microbiologia , Intestino Delgado/microbiologia , Lactobacillus plantarum/isolamento & purificação , Reação em Cadeia da Polimerase , Probióticos/administração & dosagem , Probióticos/farmacologia , Ratos , Fatores de Tempo
5.
Int J Mol Sci ; 17(5)2016 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-27153065

RESUMO

A molecular method for efficient and accurate detection and identification of two potential probiotic lactobacilli strains isolated from fermented olives, namely Lactobacillus pentosus B281 and Lb. plantarum B282, was developed in the present study. Random Amplified Polymorphic DNA (RAPD) analysis was performed, and strain specific primers were designed and applied in a multiplex polymerase chain reaction (PCR) assay. The specificity of the assay was tested and successfully confirmed in 27 and 22 lactobacilli strains for Lb. pentosus B281 and Lb. plantarum B282, respectively. Moreover, the two strains were used as starter cultures in yogurt production. Cell enumeration followed by multiplex PCR analysis demonstrated that the two strains were present in yogurt samples at levels ≥6 log CFU/g even after 35 days of storage at 4 °C. Microbiological analysis showed that lactobacilli and streptococci were present within usual levels, whereas enterobacteriaceae and yeast/mold counts were not detected as expected. Although the pH values of the novel products were slightly lower than the control ones, the yogurt containing the probiotic cultures scored similar values compared to the control in a series of sensory tests. Overall, these results demonstrated the possible use of the two strains as starter adjuncts in the production of yogurt with potential probiotic properties.


Assuntos
Laticínios/microbiologia , Fermentação , Lactobacillus pentosus/metabolismo , Lactobacillus plantarum/metabolismo , Probióticos/isolamento & purificação , DNA Bacteriano/química , DNA Bacteriano/genética , Laticínios/normas , Ácido Láctico/metabolismo , Lactobacillus pentosus/genética , Lactobacillus pentosus/isolamento & purificação , Lactobacillus plantarum/genética , Lactobacillus plantarum/isolamento & purificação , Probióticos/metabolismo
6.
Molecules ; 21(8)2016 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-27537869

RESUMO

Natural products, known for their medicinal properties since antiquity, are continuously being studied for their biological properties. In the present study, we analyzed the composition of the volatile preparations of essential oils of the Greek plants Ocimum basilicum (sweet basil), Mentha spicata (spearmint), Pimpinella anisum (anise) and Fortunella margarita (kumquat). GC/MS analyses revealed that the major components in the essential oil fractions, were carvone (85.4%) in spearmint, methyl chavicol (74.9%) in sweet basil, trans-anethole (88.1%) in anise, and limonene (93.8%) in kumquat. We further explored their biological potential by studying their antimicrobial, antioxidant and antiproliferative activities. Only the essential oils from spearmint and sweet basil demonstrated cytotoxicity against common foodborne bacteria, while all preparations were active against the fungi Saccharomyces cerevisiae and Aspergillus niger. Antioxidant evaluation by DPPH and ABTS radical scavenging activity assays revealed a variable degree of antioxidant potency. Finally, their antiproliferative potential was tested against a panel of human cancer cell lines and evaluated by using the sulforhodamine B (SRB) assay. All essential oil preparations exhibited a variable degree of antiproliferative activity, depending on the cancer model used, with the most potent one being sweet basil against an in vitro model of human colon carcinoma.


Assuntos
Mentha spicata/química , Ocimum basilicum/química , Óleos Voláteis/química , Óleos Voláteis/farmacologia , Pimpinella/química , Rutaceae/química , Derivados de Alilbenzenos , Anisóis/isolamento & purificação , Anisóis/farmacologia , Aspergillus niger/efeitos dos fármacos , Bactérias/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Monoterpenos Cicloexânicos , Cicloexenos/isolamento & purificação , Cicloexenos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Microbiologia de Alimentos , Humanos , Limoneno , Testes de Sensibilidade Microbiana , Monoterpenos/isolamento & purificação , Monoterpenos/farmacologia , Oxirredução/efeitos dos fármacos , Óleos de Plantas/química , Óleos de Plantas/farmacologia , Saccharomyces cerevisiae/efeitos dos fármacos , Terpenos/isolamento & purificação , Terpenos/farmacologia
7.
Int J Mol Sci ; 16(10): 25141-53, 2015 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-26506345

RESUMO

Lactobacillus plantarum 2035 and Lactobacillus plantarum ACA-DC 2640 are two lactic acid bacteria (LAB) strains that have been isolated from Feta cheese. Both display significant potential for the production of novel probiotic food products. The aim of the present study was the development of an accurate and efficient method for the molecular detection and identification of the above strains in a single reaction. A multiplex PCR assay was designed for each strain, based on specific primers derived from Random Amplified Polymorphic DNA (RAPD) Sequenced Characterized Amplified Region (SCAR) analysis. The specificity of the assay was tested with a total of 23 different LAB strains, for L. plantarum 2035 and L. plantarum ACA-DC 2640. The multiplex PCR assay was also successfully applied for the detection of the above cultures in yogurt samples prepared in our lab. The proposed methodology may be applied for monitoring the presence of these strains in food products, thus evaluating their probiotic character. Moreover, our strategy may be adapted for other novel LAB strains with probiotic potential, thus providing a powerful tool for molecular discrimination that could be invaluable to the food industry.


Assuntos
Lactobacillus plantarum/classificação , Lactobacillus plantarum/genética , Tipagem Molecular/métodos , Reação em Cadeia da Polimerase Multiplex/métodos , Probióticos/química , Técnica de Amplificação ao Acaso de DNA Polimórfico/métodos , Sequência de Bases , Queijo/microbiologia , Clonagem Molecular , Primers do DNA/genética , DNA Bacteriano/análise , DNA Bacteriano/genética , Lactobacillus plantarum/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Iogurte/microbiologia
8.
Microb Ecol Health Dis ; 26: 26543, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25952773

RESUMO

BACKGROUND: Nowadays, there has been an increased interest in essential oils from various plant origins as potential antimicrobial, antioxidant, and antiproliferative agents. This trend can be mainly attributed to the rising number and severity of food poisoning outbreaks worldwide along with the recent negative consumer perception against artificial food additives and the demand for novel functional foods with possible health benefits. Origanum dictamnus (dittany) is an aromatic, tender perennial plant that only grows wild on the mountainsides and gorges of the island of Crete in Greece. OBJECTIVE: The aim of the present study was to investigate the antimicrobial, antioxidant, and antiproliferative properties of O. dictamnus essential oil and its main components and assess its commercial potential in the food industry. DESIGN: O. dictamnus essential oil was initially analyzed by gas chromatography-mass spectrometry (GC-MS) to determine semi-quantitative chemical composition of the essential oils. Subsequently, the antimicrobial properties were assayed and the minimum inhibitory and non-inhibitory concentration values were determined. The antioxidant activity and cytotoxic action against the hepatoma adenocarcinoma cell line HepG2 of the essential oil and its main components were further evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and by the sulforhodamine B (SRB) assay, respectively. RESULTS: The main constituents of O. dictamnus essential oil identified by GC-MS analysis were carvacrol (52.2%), γ-terpinene (8.4%), p-cymene (6.1%), linalool (1.4%), and caryophyllene (1.3%). O. dictamnus essential oil and its main components were effective against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Listeria monocytogenes, Salmonella Enteritidis, Salmonella typhimurium, Saccharomyces cerevisiae, and Aspergillus niger. In addition, the estimated IC50 value for the DPPH radical scavenging activity for O. dictamnus essential oil was 0.045±0.0042% (v/v) and was mainly attributed to carvacrol. The EC50 value for the essential oil in the 72h SRB assay in HepG2 cells was estimated to be 0.0069±0.00014% (v/v). Among the individual constituents tested, carvacrol was the most bioactive compound and accounted for the observed antiproliferative activity of the essential oil. CONCLUSIONS: The results revealed that O. dictamnus essential oil is a noteworthy growth inhibitor against the microbes studied. It also possesses significant antioxidant activity and demonstrated excellent cytotoxicity against HepG2 cells. Taken together, O. dictamnus essential oil may represent an effective and inexpensive source of potent natural antimicrobial agents with health-promoting properties, which may be incorporated in food systems.

9.
J Dairy Sci ; 97(8): 4675-85, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24931523

RESUMO

The use of free and immobilized Lactobacillus casei ATCC 393 on whey protein as starter culture in probiotic Feta-type cheese production was evaluated. The probiotic cultures resulted in significantly higher acidity; lower pH; reduced counts of coliforms, enterobacteria, and staphylococci; and improved quality characteristics compared with cheese with no culture. Microbiological and strain-specific multiplex PCR analysis showed that both free and immobilized L. casei ATCC 393 were detected in the novel products at levels required for conferring a probiotic effect at the end of the ripening. The effect of starter culture on production of volatile compounds was investigated by the solid-phase microextraction gas chromatography-mass spectrometry analysis technique. The immobilized cells resulted in an improved profile of aroma-related compounds and the overall high quality of the novel products was ascertained by the preliminary sensory test. Finally, the high added value produced by exploitation of whey, which is an extremely polluting industrial waste, was highlighted and assessed.


Assuntos
Queijo/microbiologia , Microbiologia de Alimentos , Lacticaseibacillus casei , Proteínas do Leite/metabolismo , Probióticos , Animais , Células Imobilizadas , Fenômenos Químicos , Contagem de Colônia Microbiana , Comportamento do Consumidor , Enterobacteriaceae/isolamento & purificação , Manipulação de Alimentos , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Concentração de Íons de Hidrogênio , Viabilidade Microbiana , Análise de Componente Principal , Staphylococcus/isolamento & purificação , Paladar , Compostos Orgânicos Voláteis/análise , Proteínas do Soro do Leite
10.
J Sci Food Agric ; 94(3): 404-14, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24037649

RESUMO

Grape brandy is a spirit drink produced by wine distillation and is matured in wooden casks. According to legislation, it can be characterised by the geographical area where the grapes were produced, the grape variety used and the selected distillation and ageing techniques. Distillation increases ethanol concentration and aromatic constituents which are already present in grapes or are developed during fermentation and distillation. During maturation in wooden casks, compounds that contribute to the aroma and taste are extracted from the wood. Hence the spirit acquires the desired softer mouth feel, aromatic complexity and overall quality. Different methods of analysis are used in order to pursuit this process by analysing volatile and non-volatile substances and correlate composition with quality. Analysis can also be useful in identification of brandy safety, potential adulterations, provenance and differentiation from other spirits drinks.


Assuntos
Bebidas Alcoólicas/análise , Odorantes/análise , Paladar , Vitis/química , Compostos Orgânicos Voláteis/análise , Madeira/química , Destilação , Etanol/análise , Fermentação , Humanos , Vinho
11.
Microorganisms ; 12(2)2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38399636

RESUMO

As the food and pharmaceutical industry is continuously seeking new probiotic strains with unique health properties, the aim of the present study was to determine the impact of short-term dietary intervention with novel wild-type strains, isolated from various sources, on high-fat diet (HFD)-induced insulin resistance. Initially, the strains were evaluated in vitro for their ability to survive in simulated gastrointestinal (GI) conditions, for adhesion to Caco-2 cells, for bile salt hydrolase secretion, for cholesterol-lowering and cellular cholesterol-binding ability, and for growth inhibition of food-borne pathogens. In addition, safety criteria were assessed, including hemolytic activity and susceptibility to antibiotics. The in vivo test on insulin resistance showed that mice receiving the HFD supplemented with Pediococcus acidilactici SK (isolated from human feces) or P. acidilactici OLS3-1 strain (isolated from olive fruit) exhibited significantly improved insulin resistance compared to HFD-fed mice or to the normal diet (ND)-fed group.

12.
Foods ; 13(7)2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38611440

RESUMO

Lactic acid bacteria (LAB) are widely applied for fermentation purposes in dairy and non-dairy food matrices with beneficial technological and health-promoting properties. This study describes the effect of two lactic acid bacteria, namely, Lactiplantibacillus paracasei SP5 and Pediococcus pentosaceus SP2, on the phenolic profiles, antioxidant activities, total phenolic content (TPC), carotenoid content, and sensorial profile of two different mixed fruit juices. After 48 h of fermentation, both LABs retained viability over 9 Log CFU/mL in both juices. The TPC, zeaxanthin + lutein, ß-carotene content, and antioxidant activity (AA) were elevated for both LABs and mixed juices after 48 h of fermentation compared to control samples. Regarding the phenolic profile, both juices exhibited a significant decrease in chlorogenic acid levels, while quinic acid and tyrosol concentrations showed notable increases.

13.
Food Chem ; 441: 138175, 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38194793

RESUMO

Salvia officinalis L. has attracted scientific and industrial interest due to its pharmacological properties. However, its detailed phytochemical profile and its correlation with beneficial effects in the human microbiome and oxidative stress remained elusive. To unveil this, S. officinalis was collected from the region of Epirus and its molecular identity was verified with DNA barcoding. Phytochemical profile for both aqueous and ethanol-based extracts was determined by high-pressure liquid chromatography-tandem mass spectrometry and 103 phytochemicals were determined. The effect of S. officinalis extracts as functional regulators of food microbiota by stimulating the growth of Lacticaseibacillus rhamnosus strains and by suppressing evolution of pathogenic bacteria was verified. Furthermore, we recorded that both extracts exhibited a significant cellular protection against H2O2-induced DNA damage. Finally, both extracts exhibited strong inhibitory effect towards LDL oxidation. This study provides a comprehensive characterization of S. officinalis on its phytochemical components as also its potential impact in human microbiome and oxidative stress.


Assuntos
Salvia officinalis , Humanos , Salvia officinalis/química , Peróxido de Hidrogênio , Extratos Vegetais/química , Compostos Fitoquímicos/análise , Antioxidantes/química
14.
J Dairy Sci ; 96(5): 3369-77, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23498002

RESUMO

The aim of the present study was to monitor the survival of the probiotic strain Lactobacillus casei ATCC 393 during refrigerated storage of natural regular yogurts compared with Lactobacillus delbrueckii ssp. bulgaricus. Both free and immobilized cells on supports of high industrial interest, such as fruits and oat pieces, were tested. Microbiological and strain-specific multiplex PCR analysis showed that both free and immobilized Lb. casei ATCC 393 were detected in the novel products at levels required to confer a probiotic effect (at least 6 log cfu/g) for longer periods than required by the dairy industry (≥ 30 d) during storage at 4°C. In contrast, the viable bacterial density of Lb. delbrueckii ssp. bulgaricus decreased to levels <6 log cfu/g after 14 d of cold storage. Of note, the final pH of all products was 4.2 to 4.3. Acid resistance or cold tolerance of Lb. casei ATCC 393 apparently allows for increased survival compared with Lb. delbrueckii ssp. bulgaricus in these yogurt formulations.


Assuntos
Lacticaseibacillus casei/fisiologia , Probióticos , Iogurte/microbiologia , Armazenamento de Alimentos , Concentração de Íons de Hidrogênio , Lactobacillus delbrueckii/fisiologia , Reação em Cadeia da Polimerase Multiplex/métodos , Probióticos/normas , Fatores de Tempo , Iogurte/normas
15.
Microorganisms ; 11(3)2023 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-36985219

RESUMO

During the last decade, a rising interest in novel functional products containing probiotic microorganisms has been witnessed. As food processing and storage usually lead to a reduction of cell viability, freeze-dried cultures and immobilization are usually recommended in order to maintain adequate loads and deliver health benefits. In this study, freeze-dried (free and immobilized on apple pieces) Lacticaseibacillus rhamnosus OLXAL-1 cells were used to fortify grape juice. Juice storage at ambient temperature resulted in significantly higher (>7 log cfu/g) levels of immobilized L. rhamnosus cells compared to free cells after 4 days. On the other hand, refrigerated storage resulted in cell loads > 7 log cfu/g for both free and immobilized cells for up to 10 days, achieving populations > 109 cfu per share, with no spoilage noticed. The possible resistance of the novel fortified juice products to microbial spoilage (after deliberate spiking with Saccharomyces cerevisiae or Aspergillus niger) was also investigated. Significant growth limitation of both food-spoilage microorganisms was observed (both at 20 and 4 °C) when immobilized cells were contained compared to the unfortified juice. Keynote volatile compounds derived from the juice and the immobilization carrier were detected in all products by HS-SPME GC/MS analysis. PCA revealed that both the nature of the freeze-dried cells (free or immobilized), as well as storage temperature affected significantly the content of minor volatiles detected and resulted in significant differences in the total volatile concentration. Juices with freeze-dried immobilized cells were distinguished by the tasters and perceived as highly novel. Notably, all fortified juice products were accepted during the preliminary sensory evaluation.

16.
Pathogens ; 12(12)2023 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-38133332

RESUMO

The emergence of antimicrobial resistance remains one of the greatest public health concerns. Biofilm formation has been postulated as a mechanism of microbial pathogens to resist antimicrobial agents. Lactic Acid Bacteria (LAB) and their metabolites have been proposed to combat bacterial biofilms due to their antimicrobial activity. In this vein, the aim of the present study was to investigate the biofilm removal potential of cell-free supernatants (CFSs) of five wild-type Lacticaseibacillus rhamnosus strains, isolated from Greek natural products, in comparison to the commercially available L. rhamnosus GG strain, against biofilms formed by common foodborne pathogens (Salmonella Enteritidis, Salmonella Typhimurium, Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus). The biofilm removal activity of LAB was assessed on a two-day-old mature biofilm using a microtiter plate-based procedure. Both non-neutralized and neutralized CFSs removed biofilms in a concentration-dependent manner. The biofilm removal activity of the non-neutralized CFSs was significantly higher compared to the neutralized CFSs, as expected, with ranges of 60-89% and 30-80%, respectively. The biofilm removal efficiency of L. rhamnosus OLXAL-3 was significantly higher among the wild-type L. rhamnosus strains tested (20-100% v/v). In conclusion, our results suggest the great potential of the application of wild-type L. rhamnosus strain' CFSs as effective natural agents against pathogenic bacterial biofilms.

17.
Foods ; 12(15)2023 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-37569162

RESUMO

Essential oils (EOs) are plant mixtures that are known to present strong bioactivities, including a wide antimicrobial action. Biofilms are microbial sessile structures that represent the default mode of growth of microorganisms in most environments. This study focused on the antimicrobial action of the EO extracted from one of the most representative oregano species, that is, Origanum vulgare (subsp. hirtum), against two important foodborne pathogens, Salmonella enterica (serovar Typhimurium) and Listeria monocytogenes. For this, the minimum inhibitory concentrations of the EO against the planktonic and biofilm growth of each bacterium were determined (MICs, MBICs), together with the minimum bactericidal and biofilm eradication concentrations (MBCs, MBECs). The EO was also analyzed for its chemical composition by gas chromatography-mass spectrometry analysis (GC-MS). The influence of EO exposure on the expression of some important virulence genes (hly, inlA, inlB and prfA) was also studied in L. monocytogenes. Results revealed a strong antibacterial and antibiofilm action with MICs and MBICs ranging from 0.03% to 0.06% (v/v) and from 0.06% to 0.13% (v/v), respectively. The application of the EO at 6.25% (v/v) for 15 min resulted in the total eradication of the biofilm cells of both pathogens. The EO was mainly composed of thymol, p-cymene, γ-terpinene and carvacrol. The 3 h exposure of L. monocytogenes planktonic cells to the EO at its MBIC (0.06% v/v) resulted in the significant downregulation of all the studied genes (p < 0.05). To sum, the results obtained advocate for the further exploitation of the antimicrobial action of oregano EO in food and health applications.

18.
Foods ; 12(1)2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36613407

RESUMO

Non-Saccharomyces (NS) yeasts are gaining popularity in modern winemaking for improving wine quality. Climate change is one of the biggest challenges winegrowing now faces in warm regions. Here, Lachancea thermotolerans LtS1 and Torulaspora delbrueckii TdS6 combined with Saccharomyces cerevisiae ScS13 isolated from Assyrtiko grapes from Santorini island were evaluated in grape must fermentation with the aim to mitigate major consequences of temperature rise. Different inoculation protocols were evaluated, including simultaneous and sequential mixed-strain inoculations, displaying significant variation in the chemical and kinetic characteristics. Both LtS1 and TdS6 could raise the titratable acidity (TA). TdS6 also reduced the volatile acidity (VA) and was thus chosen for further evaluation in microvinifications and pilot-scale fermentations. Consistent with lab-scale trials, sequential inoculation exhibited the longest persistence of TdS6 resulting in minimum VA levels. Diethyl succinate, ethyl propanoate, and ethyl isobutyrate were significantly increased in sequential inoculations, although a decline in the net total ester content was observed. On the other hand, significantly higher levels of TA, succinic acid, and 2-methylpropanoic were associated with sequential inoculation. The overall performance of TdS6 coupled with a high compatibility with S. cerevisiae suggests its use in the fermentation of Santorini-Assyrtiko or other high sugar musts for the production of structured dry or sweet wines.

19.
Biomedicines ; 11(2)2023 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-36831029

RESUMO

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory diseases of the gastrointestinal tract affecting millions of patients worldwide. The gut microbiome partly determines the pathogenesis of both diseases. Even though probiotics have been widely used as a potential treatment, their efficacy in inducing and maintaining remission is still controversial. Our study aims to review the present-day literature about the possible role of probiotics in treating inflammatory bowel diseases in adults. This research was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. We included studies concerning adult patients who compared probiotics with placebo or non-probiotic intervention. We identified thirty-three studies, including 2713 patients from fourteen countries. The role of probiotics in Crohn's disease was examined in eleven studies. Only four studies presented statistically significant results in the remission of disease, primarily when used for three to six months. On the other hand, in twenty-one out of twenty-five studies, probiotics proved effective in achieving or maintaining remission in ulcerative colitis. Supplementation with Bifidobacterium sp. or a combination of probiotics is the most effective intervention, especially when compared with a placebo. There is strong evidence supporting the usage of probiotic supplementation in patients with ulcerative colitis, yet more research is needed to justify their efficacy in Crohn's disease.

20.
Microorganisms ; 11(2)2023 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-36838401

RESUMO

This study aimed to utilize two by-products, acid whey and apple pomace, as well as an indigenous Lactococcus lactis LL16 strain with the probiotic potential to produce a sustainable cheese with functional properties. Acid whey protein cheese was made by thermocoagulation of fresh acid whey and enhancing the final product by adding apple pomace, L. lactis LL16 strain, or a mixture of both. The sensory, the physicochemical, the proteolytic, and the microbiological parameters were evaluated during 14 days of refrigerated storage. The supplementation of the cheese with apple pomace affected (p ≤ 0.05) the cheese composition (moisture, protein, fat, carbohydrate, and fiber), the texture, the color (lightness, redness, and yellowness), and the overall sensory acceptability. The addition of the presumptive probiotic L. lactis LL16 strain decreased (p ≤ 0.05) the concentration of glutamic acid, thus increasing γ-aminobutyric acid (GABA) significantly in the acid whey cheese. The supplementation with apple pomace resulted in slightly (p < 0.05) higher counts of L. lactis LL16 on day seven, suggesting a positive effect of apple pomace components on strain survival. The symbiotic effect of apple pomace and LL16 was noted on proteolysis (pH 4.6-soluble nitrogen and free amino acids) in the cheese on day one, which may have positively influenced the overall sensory acceptance.

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