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See detailStabilité oxydative des viandes blanc bleu belge conditionnées sous atmosphère riche en oxygène après maturation sous vide ou en carcasse
Didimo Imazaki, Pedro Henrique ULg; Douny, Caroline ULg; Scippo, Marie-Louise ULg et al

in Viandes et Produits Carnés (2014, November)

The aim of this study was to evaluate the physico-chemical stability of Belgian Blue beef packaged under high-oxygen atmosphere as a function of a previous aging technique (wet-aging in vacuum conditions ... [more ▼]

The aim of this study was to evaluate the physico-chemical stability of Belgian Blue beef packaged under high-oxygen atmosphere as a function of a previous aging technique (wet-aging in vacuum conditions vs. carcass-aging). Two muscles (longissimus dorsi vs. rectus femoris) were studied. After a seven-day wet- or carcass-aging step, muscle cuts from 4 Belgian Blue cows were vacuum packaged and stored at −1 °C for up to 28 days. Each 14 days, part of these samples was repackaged under modified atmosphere (70 % O2:30 % CO2), and stored during 7 days at +4 °C. The following parameters were evaluated: color, metmyoglobin %, metmyoglobin reducing activity, fat content, fatty acid profile, lipid oxidation, antioxidant enzyme activities and alpha-tocopherol content. The sensitivity of modified atmosphere repacked meat cuts to oxidation was influenced by the conditions of the previous aging period (wet > carcass conditions), muscle (rectus femoris > longissimus dorsi) and length of the vacuum storage. [less ▲]

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See detailCarnobacterium maltaromaticum isolated from vacuum-packed beef with long shelf life: morphological and functional characterization
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Ndedi Ekolo, François et al

Poster (2014, September)

This study was conducted as part of a research project on meat conservability, in particular vacuum packaged beef displaying very long shelf lives at a temperature close to the freezing point, and its ... [more ▼]

This study was conducted as part of a research project on meat conservability, in particular vacuum packaged beef displaying very long shelf lives at a temperature close to the freezing point, and its objective was to perform a morphological and functional characterization of C. maltaromaticum with potential bioprotective effect isolated from vacuum packaged long shelf life beef. The isolated C. maltaromaticum strain presented similar morphological, biochemical and enzymatic profiles as those of two reference strains (LMG 11393 and LMG 22902). Among the studied conditions, a temperature of +12 °C and an atmosphere poor in oxygen (100 % N2) were the optimal conditions for the growth of C. maltaromaticum. Nevertheless, growth on lower temperatures is also possible. After inoculation of beef samples with C. maltaromaticum and 7 days of storage under vacuum at −1 °C, no effect was observed on the total viable count and on the count of lactic acid bacteria. A reduction of Pseudomonas sp. and Brochothrix thermosphacta was observed during the first week of storage under vacuum conditions. After 7 days of subsequent storage of the same samples under modified atmosphere at +4 °C, the inoculant favored the growth of B. thermosphacta and inhibited the growth of Enterobacteriaceae under 100 % N2. No effect of the inoculant was observed when an atmosphere rich in oxygen was applied. The evaluation of the influence of different atmospheres showed that the growth of C. maltaromaticum was slower in an atmosphere containing O2 and CO2. Long-term storage under vacuum at low temperatures are therefore suitable for the growth of this bacterium. An antimicrobial effect against Enterobacteriaceae was highlighted on inoculated fresh meat stored under N2. The functional characterization of this strain will be further pursued by genotypic characterization. Special attention will be taken to study its bioprotective properties. [less ▲]

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See detailMorphological and functional characterization of Carnobacterium maltaromaticum isolated from vacuum-packed beef with long shelf life
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Ndedi Ekolo, François et al

Poster (2014, August)

The aim of this study was to perform a morphological and functional characterization of a Carnobacterium maltaromaticum strain with a potential bioprotective effect isolated from vacuum packaged long ... [more ▼]

The aim of this study was to perform a morphological and functional characterization of a Carnobacterium maltaromaticum strain with a potential bioprotective effect isolated from vacuum packaged long shelf life beef. The morphological, biochemical and enzymatic profiles, the influence of different temperatures and atmospheres, and the microbial stability of fresh beef inoculated with the C. maltaromaticum strain were evaluated. The isolated C. maltaromaticum strain presented similar morphological, biochemical and enzymatic profiles as those of two reference strains (LMG 11393 and LMG 22902). The growth of C. maltaromaticum was slower in an atmosphere containing O2 and CO2. Vacuum packing is therefore suitable for this bacterium. An antimicrobial effect against Enterobacteriaceae was highlighted on inoculated fresh meat stored under N2. The functional characterization of this isolate will be further pursued by a genotypic characterization to better understand its potential bioprotective effect. [less ▲]

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See detailInfluence of aging technique and muscle on physicochemical stability and antioxidant capacity of high-oxygen atmosphere packed beef
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Thimister, Jacqueline ULg et al

Poster (2014, August)

The aim of this study was to compare the effect of aging technique (wet-aging vs. carcass-aging), muscle (longissimus dorsi vs. rectus femoris) and previous vacuum storage time on color and lipid ... [more ▼]

The aim of this study was to compare the effect of aging technique (wet-aging vs. carcass-aging), muscle (longissimus dorsi vs. rectus femoris) and previous vacuum storage time on color and lipid stability of beef packaged in high-oxygen atmosphere. After a seven-day wet- or carcass-aging step, longissimus dorsi and rectus femoris muscle cuts from 4 Belgian Blue cows were vacuum packaged and stored at −1 °C for up to 28 days. At different times, part of these samples was repackaged under modified atmosphere – 70 % O2:30 % CO2 –, and stored during 7 days at +4 °C. The following parameters were evaluated at different intervals: color (CIE L*a*b*), metmyoglobin %, lipid oxidation (TBARS), antioxidant enzyme activities (catalase, glutathione peroxidase and superoxide dismutase), alpha-tocopherol and fat content. The sensitivity of modified atmosphere repacked meat cuts to oxidation was influenced by the conditions of the previous aging period (wet > carcass conditions), muscle (rectus femoris > longissimus dorsi) and length of the vacuum storage. Oxidation stability could be associated with catalase activity, and no association could be established with the alpha-tocopherol content. [less ▲]

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See detailEvaluation of the bacterial diversity and its evolution during storage of fresh beef from British and Belgian origins under different atmosphere and temperature conditions
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Taminiau, Bernard ULg et al

Conference (2013, December 10)

The purpose of this study was to evaluate the bacterial diversity and its evolution during storage of fresh beef, depending on its origin, packaging and storage temperature, by using a metagenomic ... [more ▼]

The purpose of this study was to evaluate the bacterial diversity and its evolution during storage of fresh beef, depending on its origin, packaging and storage temperature, by using a metagenomic approach. Metagenomic analyzes revealed that the origin, atmosphere and temperature conditions influenced the selection of the predominant flora. Vacuum-packaged British samples presented higher concentrations of Lactobacillus algidus at the begging of the experiment than Belgian samples. Furthermore, the development of Lactobacillus algidus was favored in British and Belgian samples preserved under vacuum at −1 °C, while a predominance of Lactococcus piscium was observed for samples stored at +4 °C. These microorganisms have already been isolated from beef, but taking into account that the knowledge about these two species is currently limited, it is still not possible to state if the conservability of the tested samples was influenced by the presence of these bacteria. Moreover, storage under modified atmosphere favored the development of Leuconostoc gasicomitatum in both British and Belgian samples. This specie is often associated with spoilage of cold-stored modified-atmosphere-packaged (MAP) nutrient-rich foods. This result can partially explain the short shelf-life of the samples once they are stored under this condition. Metagenomics showed to be a useful tool to study the microbial population of a complex matrix since some of the identified genera could not have grown or have grown slowly in culture media commonly used. In addition, it helped to clarify the evolution of the bacterial ecosystem associated to meat during its storage. [less ▲]

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See detailInfluence of two breeds (Belgian Blue and Limousin) and previous storage time on pigment and lipid stability of high-oxygen atmosphere packaged beef
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Thimister, Jacqueline ULg et al

Poster (2013, December 10)

The aim of this study was to evaluate the effect of two breeds (Belgian Blue vs. Limousin) and previous storage time in vacuum conditions on color and lipid stability of meat packaged in high-oxygen ... [more ▼]

The aim of this study was to evaluate the effect of two breeds (Belgian Blue vs. Limousin) and previous storage time in vacuum conditions on color and lipid stability of meat packaged in high-oxygen atmosphere. Limousin meat samples of this study presented a higher sensitivity to myoglobin and lipid oxidation than Belgian Blue samples. The higher content of fat in those samples was one of the factors that could explain this higher sensitivity. Lipid oxidation and myoglobin oxidation appear to be linked, and further studies to understand the interaction between both processes are still needed. An understanding of the oxidative processes and their interaction would provide a basis for explaining quality deterioration in meat and also for developing strategies (e.g. antioxidant supplementation) to maintain sensory qualities. [less ▲]

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See detailBacterial diversity and its evolution during storage of fresh beef from different origins under different atmosphere and temperature conditions
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Taminiau, Bernard ULg et al

Poster (2013, October 11)

The purpose of this study was to evaluate the bacterial diversity and its evolution during storage of fresh beef, depending on its origin, packaging and storage temperature. Two batches of three vacuum ... [more ▼]

The purpose of this study was to evaluate the bacterial diversity and its evolution during storage of fresh beef, depending on its origin, packaging and storage temperature. Two batches of three vacuum packed striploins from United Kingdom and Belgium were obtained from a food wholesaler located in the Walloon Region. Fifteen days after slaughter, the striploins were sliced and individually kept under vacuum for 30 days: i) at −1 °C; ii) at +4 °C and iii) at −1 °C for 15 days and then at +4 °C for 15 days. The bacterial diversity was evaluated by metagenomic approach 15, 30 and 45 days after slaughter. Furthermore, each 15 days part of the vacuum packed striploin slices were repacked under modified atmosphere (70 % O2/30 % CO2), stored at +4 °C for 2 days and at +8 °C for 5 days, and then analyzed. Metagenomic analysis revealed a selection of the initial flora depending on atmosphere and temperature conditions. The development of Lactobacillus algidus was favored in samples preserved under vacuum at −1 °C, while a predominance of Lactococcus piscium was observed for samples stored at +4 °C. Moreover, storage under modified atmosphere favored the development of Leuconostoc gasicomitatum. These microorganisms have already been isolated from beef, but no study has evaluated their role in food conservation. The next step of this study will be to isolate and characterize strains of Lactobacillus algidus from meat and to assess their bioprotective potential. [less ▲]

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See detailInfluence of breed and previous storage time on color and lipid stability of beef packaged in high-oxygen atmosphere
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Thimister, Jacqueline ULg et al

Poster (2013, August 20)

The aim of this study was to compare the effect of two breeds (Belgian Blue vs. Limousin) and previous vacuum storage time on color and lipid stability of meat packaged in high-oxygen atmosphere. Vacuum ... [more ▼]

The aim of this study was to compare the effect of two breeds (Belgian Blue vs. Limousin) and previous vacuum storage time on color and lipid stability of meat packaged in high-oxygen atmosphere. Vacuum packaged striploins from Belgian Blue and Limousin cows were stored at −1 °C and +4 °C for up to 60 days and analyzed. Part of these samples were repackaged under modified atmosphere – 70 % O2/30 % CO2 – at different times, stored 2 days at +4 °C and 5 d at +8 °C, and then analyzed. The following parameters were evaluated: color (CIE L*a*b*), metmyoglobin %, lipid oxidation (TBARS) and fat content. Color measurement and metmyoglobin % determination showed greater pigment stability in Belgian Blue samples than in Limousin. Belgian Blue also presented higher lipid stability (TBARS). A positive correlation between pigment oxidation and lipid oxidation was highlighted. The greater amount of fat in meat of Limousin could partially explain its higher sensitivity to oxidation. Nevertheless, other factors may be involved in oxidative stability such as metmyoglobin reducing activity and antioxidant capacity. An understanding of the oxidative processes and their interaction would provide a basis for explaining quality deterioration in meat and for developing strategies to maintain sensory qualities. [less ▲]

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See detailLa diversité bactérienne et son évolution pendant la conservation de viandes bovines fraîches de différentes origines conditionnées sous vide
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Taminiau, Bernard ULg et al

Poster (2012, December)

Le but de cette étude à été d'évaluer la diversité bactérienne et son évolution pendant la conservation de viandes bovine fraîches sous vide, en fonction de leur origine et du respect ou non d’une ... [more ▼]

Le but de cette étude à été d'évaluer la diversité bactérienne et son évolution pendant la conservation de viandes bovine fraîches sous vide, en fonction de leur origine et du respect ou non d’une température proche du point de congélation. Les dénombrements réalisés ont mis en évidence que les viandes d’origines britannique et belge testées présentent un écosystème microbien différent. Les analyses par approche métagénomique permettront d’éclaircir ces différences, surtout en ce qui concerne la présence de bactéries pouvant jouer un rôle "bioprotecteur" permettant d’améliorer la conservabilité des viandes. [less ▲]

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See detailViandes bovines à longue durée de conservation conditionnées sous vide : isolement et caractérisation de souches de Carnobacterium
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Baptista Rodrigues, Ana Lucia ULg et al

Poster (2012, November 13)

The lactic acid bacteria Carnobacterium divergens and Carnobacterium maltaromaticum are often associated to meat and meat products and may be used as a protective culture, improving the microbial ... [more ▼]

The lactic acid bacteria Carnobacterium divergens and Carnobacterium maltaromaticum are often associated to meat and meat products and may be used as a protective culture, improving the microbial stability and the safety of these products. In this context, the aim of this study was to isolate and characterize Carnobacterium from long shelf-life vacuum-packed beef. LAB counts after culture at +22°C remained below 2.0 log UFC/cm², even at the end of shelf life. On the other hand, the ecosystem evaluation performed by metagenomics revealed the predominance of Carnobacterium and Lactobacillus on the samples. After spreading of a peptone water suspension obtained from the samples on PCA, pure isolates were collected and identified by API 50 CHL galleries. Seventy-eight % of isolates were C. maltaromaticum, 3 % C. divergens and 19 % could not be identified. The next step of this work will consist in performing a genotypic and functional characterization of these Carnobacterium isolates. [less ▲]

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See detailValidation of a method for measuring the colour and determining the proportions of myoglobin redox forms on beef
Didimo Imazaki, Pedro Henrique ULg; Salmon, Olivier; Tahiri, Assia ULg et al

Poster (2012, October 19)

The aim of this study was to validate the use of the spectrophotometer Minolta CM-600d for measuring the colour and the proportions of different myoglobin redox forms (oxymyoglobin, deoxymyoglobin, and ... [more ▼]

The aim of this study was to validate the use of the spectrophotometer Minolta CM-600d for measuring the colour and the proportions of different myoglobin redox forms (oxymyoglobin, deoxymyoglobin, and metmyoglobin) on the surface of meat. One vacuum-packaged (VP) striploin was supplied by a Belgian food wholesaler. It was cut in 3 cm thick steaks, repacked under vacuum and stored at −0.5 °C until analyses. The measurement of colour in the C.I.E. L*a*b* space and the determination of oxymyoglobin, deoxymyoglobin, and metmyoglobin were performed on VP and modified atmosphere-packed (70 % O2/30 % CO2 for 24 h) samples (n = 10). Results obtained were compared to two reference methods (colour measurement using a chromameter Minolta CR-400 and spectrophotometric determination of different myoglobin redox forms in aqueous meat extracts) by F-test for precision and t-test for accuracy. Statistic significance level was established at 5 %. The two colour measurement methods presented the same precision, when considering VP samples only, and different accuracies, probably because of the different detectors and observation angles used by both devices. The two methods for determining the different myoglobin forms presented also the same precision but different accuracies, probably due to the fact that oxygenation is favoured during some steps of the reference method (e.g. extraction, filtration). In conclusion, the results for colour measurement obtained by both devices cannot be compared. It is necessary to compare both methods for determining oxymyoglobin, deoxymyoglobin, and metmyoglobin in complete anaerobic conditions in order to eliminate the oxygenation bias. [less ▲]

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See detailEffect of duration and temperature of previous vacuum-packed storage on the microbiological quality of Belgian Blue meat packed in high-oxygen atmosphere
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Daube, Georges ULg et al

Poster (2012, September 05)

The aim of this experiment was to study the effect of duration and temperature of previous vacuum-packed (VP) storage on the microbiological quality of Belgian Blue (BB) beef packed in high-oxygen ... [more ▼]

The aim of this experiment was to study the effect of duration and temperature of previous vacuum-packed (VP) storage on the microbiological quality of Belgian Blue (BB) beef packed in high-oxygen atmosphere. VP striploins from bulls (B) and cows (C) were stored at −1 °C and +4 °C for up to 80 days. These meats were subsequently repackaged under modified atmosphere (MA) – 70 % O2/30 % CO2 – at different times, and stored 2 d at +4 °C and 5 d at +8 °C. The average initial counts in VP meats were 3.6 log CFU/cm² (B) and 2.7 log CFU/cm² (C) for total viable count (TVC) at +22 °C; < 2.0 log CFU/cm² (B and C) for lactic ac id bacteria (LAB) at +22 °C; 1.1 log CFU/cm² (B) and 1.3 log CFU/cm² (C) for Enterobacteriaceae at +30 °C and < 1.0 log CFU/cm² (B and C) for Pseudomonas spp. and Brochothrix thermosphacta. During the first 40 days of VP storage, temperature had a striking influence on microbial growth. The maximum count differences between storage temperatures were obtained at the 20th day of storage: 2.7 log CFU/cm² (B) and 2.9 log CFU/cm² (C) for TVC, 4.0 log CFU/cm² (B and C) for LAB and 3.6 log CFU/cm² (B and C) for Enterobacteriaceae. The difference in TVC between temperatures at the 20th day tended to disappear once the meats were repacked under MA and stored during seven days. Conversely, the difference in LAB and Enterobacteriaceae counts tended to be maintained after MA repackaging, showing that duration and temperature of VP storage had influence on microbiological quality of BB meat subsequently stored in high-oxygen atmosphere. Moreover, chilling at temperatures very close to the freezing point of meat during VP storage, which has already showed innumerous advantages for physicochemical quality of meat, was capital to maintain the microbiological quality of BB fresh meat during subsequent MA-packed storage. [less ▲]

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See detailEffect of duration and temperature of previous vacuum-packed storage on the oxidative stability of Belgian Blue meat packed in high-oxygen atmosphere
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Thimister, Jacqueline ULg et al

Poster (2012, August 13)

The aim of this experiment was to study the effect of duration and temperature of previous vacuum-packed (VP) storage on the oxidative stability of Belgian Blue meat packed in high-oxygen atmosphere. VP ... [more ▼]

The aim of this experiment was to study the effect of duration and temperature of previous vacuum-packed (VP) storage on the oxidative stability of Belgian Blue meat packed in high-oxygen atmosphere. VP striploins from bulls and cows were stored at −1 °C and +4 °C for up to 80 days and analyzed. These same meat samples were also repackaged under modified atmosphere (MA) – 70 % O2/30 % CO2 – at different times, stored 2 d at +4 °C and 5 d at +8 °C, and then analyzed. Meat from cows presented a lower loss of redness than meat from bulls. A low lipid oxidation was observed in VP samples, but an increase of lipid oxidation took place after MA repackaging. Meat from cows presented a higher -tocopherol content. A decrease of α-tocopherol content during storage was observed as well. The fat content was also higher in meat from cows than in meat from bulls. The duration and temperature of vacuum-packed storage influenced the sensitivity of Belgian Blue beef to pigment and lipid oxidation during subsequent high-oxygen storage. [less ▲]

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See detailStudy of the microbial diversity in vacuum-packed chilled beef from different origins through a metagenomics approach
Didimo Imazaki, Pedro Henrique ULg; Taminiau, Bernard ULg; Nezer, Carine et al

Poster (2012, April)

Despite a diverse initial microbial population, bacterial spoilage of vacuum-packed chilled beef is mainly due to the growth of psychrotrophic bacteria. The study of the microflora of vacuum-packed ... [more ▼]

Despite a diverse initial microbial population, bacterial spoilage of vacuum-packed chilled beef is mainly due to the growth of psychrotrophic bacteria. The study of the microflora of vacuum-packed chilled beef remains a challenge since some members of the microflora may be missed or not identified by cultivation-based methods. The aim of this study was to evaluate the microbial diversity in eight batches of vacuum-packed chilled beef from different origins (Australia, Belgium, Brazil, Ireland and United Kingdom) by metagenomics. Longissimus dorsi muscle samples were homogenized and analysed in early and late stages of their shelf life by metagenomics. The metagenomic assays consisted in DNA extraction, 16S ribosomal RNA gene amplification, pyrosequencing and data analysis. All samples, except for two batches from Australia, presented a high microbial diversity in the beginning of their shelf life. Enterobacteriaceae, Pseudomonas, Burkholderia, Lactobacillus and Sterotrophomonas were some of the major bacteria identified at this stage of storage. The dominant flora (> 80 % of relative abundance) in two Australian batches was composed by Carnobacterium. At the end of the shelf life of the samples, a decrease in microbial diversity was observed in almost all batches. At this stage of storage, Carnobacterium, Lactobacillus, Lactococcus and Enterococcus were some of the major genera identified. Carnobacterium remained the dominant flora in the two Australian batches cited above, which could explain the long shelf life applicable to this meat (140 days) as some Carnobacterium strains induce a biopreservative effect especially by producing bacteriocins with a wide inhibition spectrum. Metagenomics showed to be a very useful tool to study the microbial population of a complex matrix such as meat since some of the identified genera such as Lactobacillus and Carnobacterium are known not to grow or to grow slowly in media commonly used for the isolation and cultivation of total viable counts. [less ▲]

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See detailIn vivo and in vitro estrogenic activity of the antidepressant fluoxetine.
Muller, JC; Didimo Imazaki, Pedro Henrique ULg; Boareto, AC et al

in Reproductive Toxicology (2012), 34(1), 80-85

Recent years have seen an increase in the use of antidepressant drugs, especially fluoxetine (FLX), in sensitive populations, such as pregnant and lactating women. Although some evidence suggests a ... [more ▼]

Recent years have seen an increase in the use of antidepressant drugs, especially fluoxetine (FLX), in sensitive populations, such as pregnant and lactating women. Although some evidence suggests a possible endocrine action of FLX, no specific studies have been performed to investigate this hypothesis. In the present study, we investigated the possible (anti)androgenic and (anti)estrogenic actions of FLX using Hershberger, uterotrophic (0.4, 1.7, and 17mg/kg), and reporter gene (7.6-129muM) assays. In the Hershberger assay, no differences were observed in androgen-dependent organ weights. However, the uterotrophic and gene reporter assays indicated a possible estrogenic action of FLX. Uterine weight increased in the 1.7 and 17mg/kg/day groups in the 3-day uterotrophic assay in immature rats. Additionally, noncytotoxic concentrations of FLX induced estrogenic responses and increased the estrogenic response of estradiol in MCF-7 breast cancer cells transfected with luciferase. [less ▲]

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See detailCaractérisation des viandes bovines à très longue durée de conservation sous vide
Didimo Imazaki, Pedro Henrique ULg; Nezer, Carine ULg; Taminiau, Bernard ULg et al

Poster (2011, December 09)

Le but de cette étude a été d’évaluer la conservabilité de viandes bovines de différentes origines (Royaume-Uni et Irlande, Australie et Brésil) et l’influence sur celle-ci de la température de ... [more ▼]

Le but de cette étude a été d’évaluer la conservabilité de viandes bovines de différentes origines (Royaume-Uni et Irlande, Australie et Brésil) et l’influence sur celle-ci de la température de conservation (1 °C vs. +4 °C). Des paramètres physico-chimiques (pH, couleur, proportion des différentes formes redox de la myoglobine (FRMb), indice TBARS et acides organiques) et microbiologiques (flore aérobie totale, flore lactique, Enterobacteriaceae, Pseudomonas spp. et Brochothrix thermosphacta) ont été mesurés sur sept lots de contre-filet conditionnés sous vide : aux ⅔ de la DLC et à la fin de la DLC. La diversité bactérienne a été évaluée par galeries API50 CHL et par métagénomique. Le pH a diminué au cours de la conservation dans deux lots. La couleur et la proportion des FRMb sont restées stables. Une augmentation de l’indice TBARS, plus prononcée à +4 °C, a été observée. Les viandes australiennes et brésilienne ont présenté des taux en acides acétique et citrique plus élevés. Tous les lots conservés à 1 °C ont présenté une qualité microbiologique satisfaisante à la fin de leur DLC (viandes britanniques et irlandaises = 35 ~ 45 jours; australiennes = 140 jours et brésilienne = 120 jours). La conservation à +4 °C a favorisé la croissance d’entérobactéries, facteur limitant de la conservation de plusieurs lots. L’identification bactérienne a révélé la présence de bactéries connues pour leur effet bioprotecteur. La phase ultérieure de ce travail consistera à étudier la dynamique de la flore microbienne endogène en fonction des conditions environnementales appliquées (température, atmosphère). [less ▲]

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See detailEvaluation de la diversité bactérienne et de son évolution pendant la conservation de la viande fraîche bovine de différentes origines emballée sous vide
Didimo Imazaki, Pedro Henrique ULg; Maréchal, Aline; Nezer, Carine ULg et al

Poster (2011, November 18)

Un grand nombre de bactéries lactiques associées à la viande sont connues comme d'importants producteurs de bactériocines. Ces bactériocines sont des toxines protéiques présentant une activité bactéricide ... [more ▼]

Un grand nombre de bactéries lactiques associées à la viande sont connues comme d'importants producteurs de bactériocines. Ces bactériocines sont des toxines protéiques présentant une activité bactéricide ou bactériostatique contre des espèces proches de la souche productrice. La présence de certaines bactéries lactiques dans la viande fraîche pourrait donc prolonger la durée de conservation, et améliorer la stabilité microbienne et la sécurité de ce produit. Dans ce contexte, une étude a été réalisée sur des échantillons de contre-filet de différentes origines emballés sous vide, dans le but d’évaluer la diversité bactérienne et son évolution pendant la conservation. L’étude a été réalisée sur trois lots provenant d’Irlande, du Brésil et d’Australie, affichant respectivement une DLC de 35 jours, 120 jours et 140 jours. Après réception dans le laboratoire, les échantillons ont été conservés à 1 °C. Ensuite, pendant le dernier tiers de leur DLC, ils ont été conservés à 1 °C ou à +4 °C. Des dénombrements ont été réalisés : 1) aux ⅔ de la DLC et 2) à la fin de la DLC. Les germes dénombrés ont été : la flore aérobie totale à +22 °C, la flore lactique à +22 °C et les Enterobacteriaceae à +30 °C en utilisant le système automatique de dénombrement TEMPO®. Tous les échantillons conservés à 1 °C ont présenté une qualité microbiologique satisfaisante à la fin de la conservation. Par contre, la conservation à +4 °C a favorisé une croissance plus importante des bactéries lactiques et des Enterobacteriaceae. Dans le cas des Enterobacteriaceae, le seuil défini pour évaluer l’acceptabilité des différents lots a été dépassé. Les dénombrements ont permis de caractériser la dynamique de croissance des populations bactériennes, mais n’ont donné que très peu d’information sur la diversité bactérienne des échantillons. Dans le but de caractériser celle-ci, une étude métagénomique a été réalisée. Ce champ relativement nouveau de la génétique permet d'étudier les communautés de microorganismes dans leur environnement naturel, en contournant la nécessité de culture et isolement en laboratoire. Les résultats préliminaires révèlent qu’aux ⅔ de la DLC, Aquabacterium était le genre dominant dans les lots d’origines irlandaise et brésilienne, Pseudomonas était le genre dominant dans le lot d’origine australienne. A la fin de la DLC (après conservation à +4 °C), Aquabacterium et Escherichia étaient les genres dominants dans le lot d’origine irlandaise. L’ordre Lactobacillales était le plus abondant dans les lots d’origines brésilienne et australienne. Les différences dans la composition de la population bactérienne de la viande, en particulier en ce qui concerne les bactéries lactiques, pourraient expliquer les longues DLC appliquées dans certains pays. Ces recherches doivent être poursuivies pour identifier les populations bactériennes (et leur source) présentes dans ces viandes et pour étudier leur dynamique au cours de la conservation. [less ▲]

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See detailInfluence of temperature on conservability of chilled vacuum packed beef from different origins
Didimo Imazaki, Pedro Henrique ULg; Maréchal, Aline; Nezer, Carine ULg et al

Poster (2011, August 07)

The objective of this experiment was to study the conservability of chilled vacuum-packed meat depending on storage temperature (–1 °C vs. +4 °C) during the last third of their shelf life. Physicochemical ... [more ▼]

The objective of this experiment was to study the conservability of chilled vacuum-packed meat depending on storage temperature (–1 °C vs. +4 °C) during the last third of their shelf life. Physicochemical parameters (pH and colour) and microbiological growth (total aerobic bacteria, lactic acid bacteria, Enterobacteriaceae, Pseudomonas spp. and Brochothrix thermosphacta) of Longissimus dorsi samples from different origins (United Kingdom and Ireland, Australia and Brazil) were measured at: i) 2/3 of their shelf life and ii) the end of their shelf life. Sample bacteria population growing on MRS was identified by API 50 CHL strips. Unlike Irish and British samples, pH of some Australian and Brazilian samples decreased during conservation. The colour of the samples remained stable and it did not seem to be influenced by temperature. All samples conserved at –1 °C presented a satisfactory microbiological quality at the end of their shelf life (British and Irish meat = 35~45 days; Australian meat = 140 days and Brazilian meat = 120 days). On Australian and Brazilian samples, temperature did not influence total aerobic bacteria growth, but conservation at +4 °C favoured lactic acid bacteria and Enterobacteriaceae growth. API 50 CHL strip identifications revealed the presence of bacteria like Lactobacillus brevis, Carnobacterium maltaromaticum and Lactobacillus fermentum, which occur naturally in fresh meat and are known for their bioprotective effect against other microorganisms. Further analyses are being carried out using molecular methods in order to study the initial bacteria population diversity and it evolution during storage. [less ▲]

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See detailA new tool to control meat products safety: a web based application of predictive microbiology models
Delhalle, Laurent ULg; Adolphe, Ysabelle ULg; Crevecoeur, Sébastien ULg et al

Conference (2011)

Predictive microbiology is considered by the European legislation as a tool to control food safety. Meat and meat products are particularly sensitive to contamination with pathogens. However, development ... [more ▼]

Predictive microbiology is considered by the European legislation as a tool to control food safety. Meat and meat products are particularly sensitive to contamination with pathogens. However, development of predictive microbiology models and interpretation of results require specific knowledge. A free web based model has been developed for an easy use by people who are not experts in this field as industries and public authorities. The model can simulate the growth of Salmonella spp, Listeria monocytogenes and Escherichia coli O157 in minced pork meat and on pork meat product (white pudding) under different environmental conditions. The model provides simulations under static or dynamic conditions over time. The user also has the opportunity to import the specific growth rate and cardinal parameters of a bacterium. Unlike polynomial models currently available, this free web access model is distinguished by the use of secondary square roots and primary logistic model with delay. This model permits to have a real time process management, to prospect new formulation for safer products or to design safer processes, to estimate the shelf life of a food product, etc [less ▲]

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See detailChilling of heavy carcasses from double muscled cattle: time-temperature evolution and predictive modelling of growth of Listeria monocytogenes and Clostridium perfringens
Delhalle, Laurent ULg; Collignon, Bertrand; Dehard, Sandrine ULg et al

Poster (2010, August)

The time/temperature combination during carcass chilling is of concern in order to avoid bacterial growth. The chilling speed is lower in carcasses with high muscular development such as large cattle from ... [more ▼]

The time/temperature combination during carcass chilling is of concern in order to avoid bacterial growth. The chilling speed is lower in carcasses with high muscular development such as large cattle from the Belgian Blue breed. Three slaughterhouses were selected for temperature and pH measurements during the chilling process at 6 different days on 4 half carcasses in order to obtain representative data from heavy carcasses with high muscular development. Predictive microbiology was used to evaluate the potential growth of Listeria monocytogenes and Clostridium perfringens on the surface and in the depth of the carcasses. The gamma concept was chosen as secondary model taking into account the effect of temperature, pH and water activity on the selected bacteria during the chilling process. The predicted growth potential of Listeria monocytogenes is influenced by the different environmental conditions of the selected slaughterhouses and could reach 1.4 log CFU/cm² after the chilling process. The potential growth of Clostridium perfringens is limited due to unfavourable conditions during the first hours and to low temperature later. It can be concluded that when the initial level of contaminating bacteria is not excessive the speed at which the carcass is currently chilled is sufficient to limit the growth of these two pathogens and to ensure the product quality [less ▲]

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