Acompanhamento da tecnologia de produção de vinhos da Adega da Cartuxa - Fundação Eugénio de Almeida
Pimenta, José Francisco de Jesus Canhoto Alves
1997
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17 records were found.
Whey protein isolate and glycerol were mixed to form a matrix to incorporate antimicrobial agents and produce edible films with antimicrobial activity against Listeria monocytogenes strains isolated from cheeses. Various organic acids were used to decrease pH down to approximately 3. In a preliminary assay without nisin, the effect of each organic acid was evaluated with respect to the rheological properties of the film solutions and the inhibitory and mechanical properties of the films. Lactic, malic, and citric acids (3%, wt/vol), which were used in a subsequent study of their combined inhibitory effect with nisin (50 IU/ml), had significantly higher antilisterial activity (P , 0.05) compared with the control (2 N HCl, 3% [wt/vol], with nisin). The largest mean zone of inhibition was 4.00 6 0.92 mm for malic acid with nisin. Under small-amplitude oscillatory stress, the proteinglycerol-acid film solutions exhibited a predominantly viscous behavior or a weak gel behavior, with the storage modulus (G9) slightly higher than the loss modulus (G0). The malic acid–based solution was the only one whose viscosity was not influenced by the addition of nisin. The addition of nisin resulted in a nonsignificant (P . 0.05) increase in the percentage of elongation at break. Results from tensile and puncture stress were variable, but in general no significant differences were found after the incorporation of nisin. The overall results support the use of malic acid with nisin to produce effective antimicrobial films to control L. monocytogenes growth.
The inhibitory effects of nisin, natamycin and malic acid, incorporated in whey protein films with pH 3,
were investigated alone or with addition of sucrose esters, Tween80 or EDTA. Water vapour permeability
measurements and mechanical and rheological tests were also assessed. EDTA and Tween80 did not significantly (P < 0.05) influence the inhibitory activity of films against Pseudomonas aeruginosa and Yarrowia lipolytica in contrast with the improved effect against Listeria monocytogenes, Penicillium commune and
Penicillium chrysogenum. Sucrose esters reduced significantly (P < 0.05) the inhibitory effect for Y. lipolytica and Penicillium spp. The present work provides an antimicrobial film formulation with potential to be
a hurdle against spoilage and pathogenic microorganisms isolated from cheese surface.
Comunicação oral da qual só está disponível o resumo.
Laboratório de Microbiologia.
Com este trabalho foi possível implementar na ESACB a técnica de biologia molecular Amplified Fragment Length Polymorphisms (AFLP), com vista à tipagem molecular de culturas de Listeria monocytogenes e outras Listeria spp., as quais tinham sido isoladas maioritariamente de queijo, leite cru e ambiente de uma queijaria.
A técnica apresentou uma boa reprodutibilidade e poder discriminatório para Listeria monocytogenes e L. innocua. Relativamente à espécie L. ivanovii, obtiveram-se perfis com um reduzido número de bandas. Verificou-se a presença de uma banda com aproximadamente 850 pb, comum às amostras estudadas de L. monocytogenes e L. innocua.
Só está disponível o resumo.
L. stoechas subsp. luisieri is one of the five spontaneous species of the genus Lavandula that occurs spontaneously in Portugal. The chemical profile and antifungal activity of L. stoechas subsp. luisieri essential oils were investigated. The essential oil of two phenological stages was isolated by hydrodistillation and their chemical components analyzed by GC-FID/GC-MS. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of both essential oils were determinate to verify antifungal activity against different strains of fungi isolated from strawberry tree. The fungi tested were Aspergillus carbonarius, Rhizopus stolonifer, Penicillium brevicompactum, Aureobasidium pullulans and Saccothecium rubi. Essential oils were
characterized by a high percentage of oxygenated monoterpenes (46-64%) such as trans-α-necrodyl acetate (12.58%), fenchone (5.97%), 1,8-cineole (4.84%) and 5-methylene-2,3,4,4-tetramethylcyclopenten-2-enone (10.97%) were the major compounds in essential oil from dormancy stage, while the main compounds in flowering stage were trans-α-necrodyl acetate (26.90%), trans-α-necrodol (13.02%), lavandulyl acetate (6.53%) and linalool (5.82%). A strong antifungal activity of the essential oils was found against all strains, with MIC and MFC values ranged from 0.07-0.29 µL/mL and 0.58-9.33 µL/mL, respectively.
A survey was made in 1995–1996 for Listeria spp. in 63 soft cheeses, made from raw ewe’s milk using traditional methods, in the
Province of Beira Baixa (Portugal). Listeria spp. were isolated from 47 (75%) of the cheeses, L.monocytogenes was isolated from 29
(46%), and L.innocua but not L.monocytogenes from 18 (29%). Of 24 isolates of L.monocytogenes that were serotyped, 20 were
serotype 4b, three were serotype 1/2b and one was serotype 1/2a. Phage typing of isolates of L.monocytogenes and L.innocua showed
that in some cases a particular phage type was associated with cheese from a particular source. Twenty four strains of
L.monocytogenes tested were able to grow at 30 Cin culture medium adjusted with HCl to a pH in the range from 4.4 to 6.0 within 3
days; in the pH range 4.4–6.8 a representative strain grew most rapidly at pH 6.8. The pH range in the cheeses during maturation
was between about 5.2–6.4. Whether L.monocytogenes could multiply in the cheeses would depend on factors such as concentration
of organic acids and of salt, and storage temperature.
Essential oils of Lavandula stoechas subsp. luisieri as antifungal agent against fungi from strawberry tree fruit
Os queijos produzidos com leite cru são produtos de elevado valor económico e patrimonial mas que estão sujeitos à ação de microrganismos que comprometem a sua qualidade e a segurança do consumidor. A utilização de revestimentos edíveis antimicrobianos poderá ser uma opção eficaz e sustentável. Pretendeu-se avaliar a aplicação de um revestimento à base de quitosano e óleo essencial de Origanum vulgare subsp. virens, para controlar bactérias e fungos indesejáveis à superfície dos queijos. Foi usado Queijo da Beira Baixa DOP – Tipo Amarelo, não inoculado (NI) e inoculado (I) aos 3 e 16 dias de cura, com agentes de defeitos de cor e de alteração (P. fluorescens, Y.lipolytica, P. commune) e de agentes patogénicos (L. monocytogenes). Cada grupo de queijos (NI e I) foi dividido tendo uma parte sido revestida (R) e a outra não revestida (NR). Durante o período de maturação foram realizados registos fotográficos semanais e, após 45 dias, efetuou-se a contagem (UFC/g) de bolores, leveduras, Listeria, Pseudomonas e Enterobacteriaceae. Observou-se de um modo geral uma menor incidência de manchas escuras nos queijos revestidos, mais notória nos queijos inoculados com 3 dias de maturação. Destaca-se ainda uma redução de Enterobacteriaceae e de Pseudomonas nos queijos revestidos. O revestimento testado mostrou potencial para ser aplicado em queijos, no entanto terá de ser melhorada a sua formulação para a obtenção de um maior espetro de ação antifúngica.
For 5 months, the udders of milking ewes, raw ewe’s milk, cheese, and the plant and environment of a cheese
manufacturer in Portugal were investigated using standard methods for the presence of Listeria spp. An association between subclinical mastitis and Listeria monocytogenes in a single lactating sheep was investigated by
visual inspection of udders for signs of inflammation, application of somatic cell counts, the California mastitis
test, pH measurement to milk, and culture of L. monocytogenes and Staphylococcus spp. To track the routes of
contamination by L. monocytogenes, 103 isolates were characterized by molecular serotyping and amplified
fragment length polymorphism, and a selection was further tested by pulsed-field gel electrophoresis. This study
provides molecular and epidemiological evidence tracking the persistence of a single L. monocytogenes strain
causing a subclinical udder infection without obvious inflammation in a single ewe. This infection was the
likely source of contamination of raw milk that was subsequently used to produce unpasteurised milk cheese
and resulted in a single strain of this bacterium colonizing the processing environment and the final cheese
product.
Pigments are compounds of importance to several industries, for instance, the food industry,
where they can be used as additives, color intensifiers, and antioxidants. As the current trend around
the world is shifting to the use of eco-friendly commodities, demand for natural dyes is increasing.
Melanins are pigments that are produced by several microorganisms. Pseudomonas putida ESACB 191,
isolated from goat cheese rind, was described as a brown pigment producer. This strain produces
a brown pigment via the synthetic Müeller-Hinton Broth. This brown compound was extracted,
purified, analyzed by FTIR and mass spectrometry, and identified as eumelanin. The maximum
productivity was 1.57 mg/L/h. The bioactivity of eumelanin was evaluated as the capacity for
scavenging free radicals (antioxidant activity), EC50 74.0 ± 0.2 µg/mL, and as an acetylcholinesterase
inhibitor, with IC50 575 ± 4 µg/mL. This bacterial eumelanin did not show cytotoxicity towards
A375, HeLa Kyoto, HepG2, or Caco2 cell lines. The effect of melanin on cholesterol absorption and
drug interaction was evaluated in order to understand the interaction of melanin present in the
cheese rind when ingested by consumers. However, it had no effect either on cholesterol absorption
through an intestinal simulated barrier formed by the Caco2 cell line or with the drug ezetimibe.
Chemical investigations of L. stoechas subsp. luisieri and L. pedunculata essential oils were
analyzed by GC-MS, and the antimicrobial activity was performed against bacteria and fungi isolated
from food sources. The cytotoxicity of the essential oil was performed in NHDF cells using the
MTT method. According to the results, the main compounds of L. stoechas subsp. luisieri essential
oil were trans-α-necrodyl acetate (40.2%), lavandulyl acetate (11%), and trans-α-necrodol (10.4%),
while fenchone (50.5%) and camphor (30.0%) in L. pedunculata essential oil. The antifungal activity
of essential oils was confirmed with MIC values ranging from 1.2 to 18.7 µL/mL; for bacteria, it
ranged from 4.7 to 149.3 µL/mL. Both the Lavandula species tested showed low or equal MIC and
MBC/MFC values for L. stoechas subsp. luisieri essential oil, revealing greater efficacy in antimicrobial
activity. The L. stoechas subsp. luisieri essential oil revealed cytotoxic effects (30 ± 2% of cell viability)
in NHDF cells at all concentrations tested.
Comunicação apresentada no III Simpósio Nacional de Olvicultura que decorreu em Castelo Branco, na Escola Superior Agrária do Instituto Politécnico de Castelo Branco, de 289 a 31 de Outubro de 2003.
Artigo apresentado como comunicação no IV Simpósio Nacional de Olivicultura que decorreu em Elvas de 22 a 24 de Novembro de 2006.
SOS Valor caracteriza extratos
de folhas e flores de medronheiro
(Arbutus unedo) e testa a sua
capacidade de combater doenças
neurológicas e efeito nematicida
