Pleurotus species as a source of natural preservatives: mycelia production to obtain tocopherols used as antioxidants in yogurts

Mestrado com dupla diplomação com o High Institute of Biotechnology of Monastir (ISBM), TunisiaMushrooms are consumed worldwide not only as a part of the normal diet, but also as a delicacy due to their highly desirable taste and aroma. In addition to their nutritional value, mushrooms have been considered functional foods and even as adjuvants in some therapies, namely chemotherapy, because they are rich in bioactive molecules, such as phenolic compounds, tocopherols, ascorbic acid, or carotenoids. In particular, tocopherols are powerful antioxidants that can be explored as natural food preservatives, in order to replace the widely used synthetic counterparts. With these aspects in mind, and given the evidence that the in vitro culture of mushroom mycelia promotes the production of tocopherols, the present work aimed to sub-culture two edible species, Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm. and Pleurotus eryngii (DC.) Quél., in different culture media (i.e., Melin–Norkans medium, MMN; modified Melin–Norkans medium, MMNm; and Potato dextrose agar medium, PDA) in order to enhance the production of tocopherols, and use the mycelia as sources of preservative ingredients for foodstuff. Since the best growth was obtained on PDA medium, both species were cultivated in Potato dextrose broth liquid medium (PDB), in order to obtain the amount of biomass required for the assays. The tocopherols content was evaluated by high performance liquid chromatography coupled to a fluorescence detector (HPLC-fluorescence). A formulation enriched in tocopherols was incorporated in yogurts and its preservative capacity was assessed, through the evaluation of the antioxidant properties before and after incorporation in the foodstuff. The results were compared with commercial available and used preservatives (i.e., α-tocopherol - natural antioxidant (E307) and potassium sorbate - synthetic preservative (E202)). The results showed that the mycelium content of tocopherols was particularly high in β-tocopherol and, in the case of P. ostreatus, it was higher than in P. eryngii. Despite the similarity showed in the tocopherol profile for both mushrooms, P. ostreatus mycelium revealed a slightly high DPPH radical scavenging activity, while P. eryngii showed higher reducing power. The DPPH radical scavenging activity measured in yogurts fortified with P. ostreatus and P. eryngii extracts was similar to that achieved in yogurts prepared with potassium sorbate, despite not as strong as yogurts with α-tocopherol. Regarding the reducing Pleurotus species as a source of natural preservatives Abstract VIII power, yogurts with Pleurotus species extracts revealed approximate results of those obtained in yogurts with α-tocopherol, reaching best results than those obtained in yogurts containing potassium sorbate. In neither case were observed significant changes induced by the storage time.Os cogumelos são consumidos no mundo inteiro, não só como parte da dieta normal, mas também como uma iguaria devido ao seu gosto e aroma altamente desejáveis. Além do seu valor nutricional, os cogumelos são considerados alimentos funcionais, sendo mesmo adjuvantes em algumas terapias, nomeadamente a quimioterapia, uma vez que são ricos em moléculas bioativas, como compostos fenólicos, tocoferóis, ácido ascórbico ou carotenóides. Em particular, os tocoferóis são poderosos antioxidantes que podem ser explorados como conservantes de alimentos naturais, podendo substituir os equivalentes conservantes sintéticos utilizados atualmente. Tendo em conta estes aspetos, e a evidência de que a cultura in vitro de micélio de cogumelos promove a produção de tocoferóis, o presente trabalho pretende sub-cultivar duas espécies comestíveis, Pleurotus ostreatus (Jacq. ex P.) P. Kumm. e Pleurotus eryngii (DC.) Quél. em diferentes meios de cultura (isto é, meio Melin-Norkans, MMN; meio Melin-Norkans modificado, MMNm; e meio de agar de dextrose de batata, PDA). Uma vez que o melhor crescimento foi obtido no meio PDA, as duas espécies foram cultivadas em meio líquido de dextrose de batata (PDB), de forma a obter a quantidade de biomassa necessária para a realização dos ensaios. O teor de tocoferóis foi avaliado por cromatografia líquida de alta performance acoplada a um detector de fluorescência (HPLC-fluorescência). Uma formulação enriquecida em tocoferóis foi incorporada em iogurtes e sua capacidade de conservação foi avaliada através da avaliação das propriedades antioxidantes antes e depois da incorporação no género alimentício. Os resultados foram comparados com os conservantes comercialmente disponíveis e utilizados (nomeadamente, α-tocoferol - antioxidante natural (E307) e sorbato de potássio - conservante sintético (E202)). Os resultados mostraram que o perfil de tocoferóis no micélio era praticamente β-tocoferol e, no caso de P. ostreatus, a concentração era maior do que em P. eryngii. Apesar da semelhança evidenciada no perfil de tocoferóis em ambos os cogumelos, o micélio de P. ostreatus foi o que revelou uma actividade captadora de radicais DPPH ligeiramente superior, enquanto o micélio de P. eryngii apresentou maior poder redutor. A atividade captadora de radicais DPPH medida em iogurtes fortificados com extratos de P. ostreatus e P. eryngii foi semelhante à obtida em iogurtes preparados com sorbato de potássio, embora não tão elevada quanto em iogurtes com α-tocoferol. Em relação ao poder redutor, os iogurtes com extratos de Pleurotus species as a source of natural preservatives Resumo X espécies de Pleurotus revelaram resultados aproximados aos obtidos em iogurtes com α-tocoferol, atingindo melhores resultados do que os obtidos em iogurtes contendo sorbato de potássio. Em nenhum dos casos foram observadas alterações significativas induzidas pelo tempo de armazenamento

Does The Financing Decision Help To Understand Market Reaction Around Mergers And Acquisitions?

Few studies distinguish between the method of payment and the means of financing in mergers and acquisitions. This paper aims to test if the financing means has incremental information beyond that contained in the payment means. To answer this question, we consider a sample of 265 deals undertaken by French listed acquires between January 1997 and December 2008. We decompose our sample according to the method of payment (cash, stock or mixed payment). The difference of means test shows that the impact of the three methods of payment is not statistically significant. In order to take the analysis further, we then broke our sample down according to both the method of payment and the means of financing (debt, equity or internal funds). The difference of means test, the event study methodology and OLS regressions reveal that takeovers financed by debt outperform those financed by other means of financing. These findings confirm the monitoring role of debt and support the pecking order preferences. Finally, our OLS regressions highlight that market reaction depends also on legal environment (common law vs. non common law) on acquisition characteristics such as deal size and on acquirer specific factors such as size and growth opportunities

Experimental determination of the growth rate of Richtmyer-Meshkov induced turbulent mixing after reshock

The time evolution of the width of the turbulent mixing zone arising from the late development of Richtmyer-Meshkov instability is investigated in this work. This is achieved by means of the analysis of time-resolved Schlieren images obtained with a given set of shock-tube experiments. The post-reshock growth rate of the mixing zone width is found to be nearly insensitive to the development state of the mixing at the time of reshock

Study of the turbulent mixing zone induced by the Richtmyer-Meshkov instability using Laser Doppler Velocimetry and Schlieren visualizations

An experimental study of the compressible mixing generated by the Richtmyer-Meshkov instability (RMI) is carried out in a vertical shock tube by means of two-components Laser Doppler Velocimetry (2C-LDV) measurements and Time-resolved Schlieren visualizations. An attempt is made to quantify the RMI-induced air/sulphurhexafluoride (SF6) mixing by measuring turbulence levels inside the mixing zone at a given stage of its development and by extracting the growth rate of the mixing zone from the Schlieren images

Experimental Determination of Delimbing Forces and Deformations in Hardwood Harvesting

Delimbing is the process used to cut the branches off the trunk during tree processing by forest harvester. This process can be described as chipless cutting of green wood at a feed speed of 3 to 7 ms-1.This work aims to identify the parameters influencing the efficiency of the delimbing process. To this end, the main parameters are defined, and different experimental tests are presented. The first experiment was conducted using a dynamometric pendulum that can reach cutting speeds of 10 ms-1. A Digital Image Correlation method was used in order to compute the deformation field in the branch. The deformation fields observed are consistent with previous studies in the literature. The second experimental device was a slow speed test bench. It uses a hydraulic actuator to translate the knife through the branch while measuring force and displacement. Tests were conducted, varying the diameter of branches, to analyze its effect on the cutting force. Proportionality between branch area and cutting forces were verified, and empirical coefficients were obtained for both speeds

0380: Study of anatomical features of pulmonary veins assessed by computed tomography according to age

IntroductionPulmonary veins (PV) play a crucial role in triggering and generating atrial fibrillation (AF). Isolation of PVs is fundamental in the AF ablation whether paroxysmal or persistent. The presence of four distinct pulmonary veins (two left PVs and two right PVs) has been described as the normal variant.AimThe purpose of our study was to investigate whether the age of the patients had an influence on the incidence of anatomical abnormalities of PVs.MethodsOur study was a prospective study which has included 38 patients followed for AF in the cardiology’s department of our hospital. All patients underwent a CT scan of PVs in order to characterize their anatomy. PVs’ size was represented by the largest diameter. We have divided our cohort into two groups: group 1: patients aged more than 50 years and group 2: patients aged less than 50 years.ResultsOur patients had a mean age of 50.5±13 years. The majority of our patients had paroxysmal AF (65%), 4 had persistent AF (10%), 9 had prolonged persistent AF (25%).CT Scan of PV results according to age are summarized in table.ConclusionIn our study, we found no significant relationship between age and anatomical abnormalities of the PVs. Hence, it is important to look for these anatomical anomalies whatever was the age of the patients to increase the success rate and to avoid complications during the AF ablation procedures.Abstratct 0380 – Table: Comparison of PV features evaluated by CT scan according to ageGroup 1 Age>50 years old N=20 patientsGroup 2 Age≤50 years old N=18 patientsPThe average left atrium volume140.8±75.78ml75.72±29.10mLP=0.01Mean number of PV3.85±0.484±0.65NSAverage diameter of left PV26.82±8.6825.03±12.29NSAverage diameter of right PV20.58±5.3522.81±6.05NSLeft single ostium forming a core collector4 (20%)3 (16.6%)NSRight single ostium forming a core collector1 (5%)4 (22%)N

Evaluation of the efficacy of endovascular treatment of pelvic congestion syndrome

AbstractAimTo assess the efficacy of venous embolization treatment for the pelvic congestion syndrome (PCS).Patients and methodsRetrospective study of 33 female patients undergoing pelvic venous embolization between January 2008 and May 2012 in Bordeaux. The inclusion criteria were clinical symptoms of PCS documented by transabdominal Doppler ultrasound and/or pelvic magnetic resonance imaging. Patients with pelvic varicose veins feeding saphenous varicose veins were excluded. The efficacy of treatment was assessed on a Visual Analog Scale (VAS).ResultsThirty-three patients were included and the mean follow up period was 26months (3–59months). The VAS was 7.37 (standard deviation: 0.99) before embolization and 1.36 (standard deviation: 1.73) after embolization (P<0.0001). Twenty patients reported that their symptoms had completely disappeared, 11 had partially disappeared and two had gained no improvement. A significant fall was found in the number of patients with dyspareunia (P<0.0001). A single technical embolization failure was reported.ConclusionOur series demonstrates the efficacy of embolization treatment with a significant fall in the VAS in patients with PCS

Ergonomic Evaluation of Thermal Stress in a Tunisian Steel Industry

This work aims to assess thermal stress based on the various measurable thermal stress parameters (wet bulb temperature, air speed, radiation temperature, black globe temperature…). A cross-sectional study was carried in a steel company. The evaluation of thermal stress was made by physical parameters measurment (air temperature, relative humidity, air velocity, globe temperature, clothing insulation, metabolism of work) and analyzed according to the International Standard Organization (ISO) 7933 “Analytical determination and interpretation of heat stress using calculation of the predicted heat strain”. Eighty male workers were mean ageed of 37.9 ± 9.25 years. The climatic conditions category was three (meaning a Long-term stress) in 68.18% of the workers and four (Short-term stress meaning the occurrence of health problems within 30 to 120 minutes of exposure) in 30.3% of workers. The long and short-term thermal stress identified in this study spearhead a prevention strategy (automation of manufacturing processes, improvement of the organization of tasks, and the strengthening of medical surveillance of workers)

Pédagogie et recherche pour une bibliothèque numérique de machines et mécanismes au sein du projet européen thinkMotion

Ce projet pédagogique associe des étudiants de niveau BAC+3 à un travail de recherche dans le cadre du projet européen thinkMotion, future grande bibliothèque numérique libre sur le thème des machines et mécanismes. En effet, une bonne part du riche patrimoine mécanique européen tombe dans l'oubli. Or, nos jeunes concepteurs doivent mettre en pratique méthodes de conception et outils de CFAO sur des exemples concrets. Voici comment ils analysent brevets et ouvrages anciens, modélisent géométrie et cinématique des machines et produisent du contenu multimédia à l'aide d'outils TICE

COST EFFICIENCY OF FRENCH COMMERCIAL BANKS: DOMESTIC VERSUS FOREIGN BANKS

ABSTARCT (Berger et al. 2000) . This suggests the decision to practice retail banking activities by domestic banks implies high fixed costs