First assessment of diffusion coefficients in model cheese by fluorescence recovery after photobleaching (FRAP)

Floury, Juliane; Madec, M-N.; Waharte, François; Jeanson, Sophie; Lortal, Sylvie

doi:10.1016/j.foodchem.2012.01.030

Cited by 40 publications

(46 citation statements)

References 22 publications

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“…As shown in Fig. 1 (Supplementary material), the position of the ROI has been chosen in order to only photobleach the protein network, and over a sufficiently large and homogeneous region to be able to further extract the profile width in the radial direction from image processing routines as described in Floury et al (2012). Each FRAP measurement started with the acquisition of 3 image scans acquired at 0.1% of the maximum laser intensity, followed by a bleach pulse of 5 image scans at 100% intensity on a ROI spot with a 5.2 lm radius.…”

Section: Frap Analysismentioning

confidence: 99%

“…Cheese ripening involves complex microbiological and biochemical reactions that take place within this protein gel resulting in the development of flavor and texture characteristics, specific to each cheese variety (McSweeney, 2004). Such protein gel structure (also referred to as a protein network) acts like a sieve, where the gel strands impedes the diffusing molecules; a denser gel structure leading to a greater obstruction Floury, Madec, Waharte, Jeanson, & Lortal, 2012;Jeanson et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…The alternative approach of Fluorescence Recovery After Photobleaching (FRAP), coupled to a confocal scanning laser microscope (CSLM), was recently developed to determine effective diffusion coefficients of labeled macromolecules in a model cheese (Floury et al, 2012;Silva, Peixoto, Lortal, & Floury, 2013).This technique is non-destructive and has a good spatio-temporal resolution, unlike the established method which is based on concentration profiles. The model cheese was made from a fat-free dairy gel obtained from an ultrafiltered milk protein concentrate.…”

Section: Introductionmentioning

confidence: 99%

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The influence of cheese composition and microstructure on the diffusion of macromolecules: A study using Fluorescence Recovery After Photobleaching (FRAP)

et al. 2016

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Section: Frap Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The influence of cheese composition and microstructure on the diffusion of macromolecules: A study using Fluorescence Recovery After Photobleaching (FRAP)

et al. 2016

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“…A condição de equilíbrio, no qual o sal se encontra distribuí-do homogeneamente no queijo, é atingida durante o período de maturação (FONTAN et al, 2004;GUINEE, 2004). Tanto a fabricação quanto a maturação são influenciadas pelo transporte de solutos aquosos e de água dentro do queijo (FLOURY et al 2012). O NaCl e a umidade têm papel importante nas rea ções bioquímicas, microbiológicas e na qua lidade sensorial do queijo (GUINEE; FOX, 2004), e, por este motivo, devem ser te mas de pesquisas.…”

Section: Introductionunclassified

DISTRIBUIÇÃO DE NaCl NO QUEIJO REINO AO LONGO DA MATURAÇÃO

Taveira¹,

Costa²,

Júnior³

et al. 2015

Revista do ILCT

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RESUMOO objetivo foi determinar o tempo mínimo necessário para a distribuição igualitária do sal em todas as partes do queijo Reino, ou seja, desde a superfície até o centro, e verificar se houve diferença significativa nessa distribuição em diferentes condições de maturação. Os queijos de um mesmo lote foram submetidos a dois tratamentos, com diferentes temperaturas, umidade relativa do ar e também com e sem embalagem. No primeiro tratamento o queijo foi maturado sem embalagem termoencolhível, à temperatura de 18 °C a 22 °C, com 55% -65% de URA. Já no segundo tratamento, o queijo inicialmente foi maturado sem embalagem (apenas nos cinco primeiros dias) e nas mesmas condições do primeiro tratamento e, após este período, foi embalado em película termoencolhível e maturado a 5 °C -10 °C, com 70% -80% de URA, até completar o tempo de maturação total estipulado. A caracterização do perfil de distribuição de sal nos queijos Reino foi conduzida por meio da determinação do teor percentual de cloreto de sódio (m/m) nas porções centrais, intermediárias e superficiais. A análise de variância indicou que não houve diferença entre os tratamentos na distribuição de sal no queijo Reino, porém, houve diferença entre a porção de queijo analisada e o tempo de maturação, o que demonstrou a dependência da distribuição do sal em função destas variáveis. Concluise que a partir do 27º dia após a fabricação, o sal se distribui homogeneamente em todas as partes do queijo Reino, independentemente das diferentes condições empregadas na maturação.Palavras-chave: embalagem; salga; difusão.

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“…Model cheeses were made from ultrafiltrated (UF) milk retentate both in 15-ml flasks and 1-ml cassettes as described by Floury et al (11), except that we used CoverWell imaging chambers (SigmaAldrich, Saint-Quentin Fallavier, France). The model cheese produced is a soft-type cheese, similar to a Pavé d'Affinois cheese without fat.…”

mentioning

confidence: 99%

Microgradients of pH Do Not Occur around Lactococcus Colonies in a Model Cheese

Jeanson

Floury

Issulahi

et al. 2013

Appl Environ Microbiol

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Lactococci inoculated into cheese grow as colonies producing lactic acid. The pH microgradients were investigated around colonies in a complex food such as cheese. The results, obtained using a nondestructive technique, demonstrated that pH microgradients did not occur regardless of the acidification kinetics and the size of the colony. Lactic acid bacteria are used as starters in cheese manufacture. They are immobilized within the cheese curd during the coagulation step regardless of the cheese-making process. Immobilized cells then grow as colonies (1), producing lactic acid within the cheese matrix. The hypothesis of an accumulation of lactic acid around bacterial colonies has been formulated as a consequence of mass transfer limitations from the colony (2, 3), lowering the pH on the edge of the colony. Since low pH is known to modify the metabolic activity of lactic acid bacteria (4, 5) and to have even more influence when cells are immobilized (5), it is important to determine whether or not, in solid and complex foods such as cheese, the local pH around colonies differed from the "global" pH usually measured. Microgradients of pH occur in gelatin media around large colonies of Salmonella enterica serovar Typhimurium (diameters from 450 m to 2.5 mm) (3, 6) and Lactobacillus curvatus (diameters from 380 m to 430 m) but do not occur around L. curvatus colonies with a diameter of 155 m (7). These results, obtained in gelatin medium, cannot be applied to cheese since the diffusion coefficients have been shown to depend on the microstructure (8).Different techniques have been used to monitor pH in and around bacterial colonies. Microelectrodes were first used to measure pH in and around submerged colonies of S. Typhimurium (3). Later, a nondestructive technique based on fluorescence microscopy was developed to describe the pH microgradient around colonies of L. curvatus (7). More recently, the pH-sensitive fluoroprobe, C-SNARF-4F, has been applied to measure the pH within biofilms using a ratiometric correlation to pH (9). Our final aim is to explore the pH microenvironment around bacterial colonies in a complex and solid food such as cheese. Our strategy, in this first study, was to use a nonfat model cheese which was a reproducible and homogeneous cheese matrix directly molded in imaging chambers for nondestructive microscopic examination. As we previously demonstrated that the size of colonies depends on the inoculation level in cheese (10), the model cheeses were inoculated at three different levels with Lactococcus lactis, generating three different sizes of colonies. Bigger colonies (lower inoculation levels) than in traditional cheeses were generated in order to enhance the phenomenon of lactic acid accumulation. We monitored the pH both at the macroscopic scale, so called here macropH, and at the microscopic scale, so called here micro-pH, using a nondestructive microscopic examination.Monitoring macro-pH and micro-pH in model cheeses. Model cheeses were made from ultrafiltrated (UF) milk retentate both ...

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First assessment of diffusion coefficients in model cheese by fluorescence recovery after photobleaching (FRAP)

Cited by 40 publications

References 22 publications

The influence of cheese composition and microstructure on the diffusion of macromolecules: A study using Fluorescence Recovery After Photobleaching (FRAP)

The influence of cheese composition and microstructure on the diffusion of macromolecules: A study using Fluorescence Recovery After Photobleaching (FRAP)

DISTRIBUIÇÃO DE NaCl NO QUEIJO REINO AO LONGO DA MATURAÇÃO

Microgradients of pH Do Not Occur around Lactococcus Colonies in a Model Cheese

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