How do smoothing conditions and storage time change syneresis, rheological and microstructural properties of nonfat stirred acid milk gel?

Nonfat acid milk gel, acidified by GDL, was used to simulate microbial fermentation of milk to produce stirred yoghurt. Acid milk gel preparation at laboratory scale included stirring, pumping, smoothing and cooling operations. Two filters (pre-smoothed, 1 mm; smoothed, 500 μm), three smoothing temperatures (13, 22 and 35 °C) and two storage times (1 and 22 days) were studied. Syneresis, microgels size and smoothness of microgels were analysed for pre-smoothed and smoothed gels; viscosity, storage modulus, firmness and total pore area were only analysed for smoothed gel. After 1 and 22 days of storage, pre-smoothed gels developed lower syneresis and smaller microgels than smoothed gels at 22 °C. For smoothed gels, regardless of the smoothing temperature, syneresis, firmness, microgels size and smoothness increased during storage, while total pore area decreased and viscosity remained stable. Viscosity was lower when smoothing was performed at 35 °C and was correlated to rougher microgels

Ferulic Acid and Eugenol Have Different Abilities to Maintain Their Inhibitory Activity Against Listeria monocytogenes in Emulsified Systems

Natural phenolic compounds are found in large quantities in plants and plant extracts and byproducts from agro-industries. They could be used to ensure food quality and safety due to their antimicrobial properties demonstrated in systems such as culture media. The aim of this study was to evaluate the ability of two natural phenolic compounds, ferulic acid and eugenol, to maintain their inhibitory activity against the growth of Listeria monocytogenes in an oil-in-water emulsion, simulating a complex food system. The minimum inhibitory concentration (MIC) of each phenolic compound was first determined in culture medium, consisting of TS broth and an added emulsifier. Whey proteins and Tween 80 increased the MIC of the antimicrobial activity of eugenol. The MIC of ferulic acid was less affected by the addition of Tween 80. The inhibitory activities of both phenolic compounds were then compared at the same concentration in emulsions and their corresponding aqueous phases by following the growth of L. monocytogenes by plate counting. In emulsified systems, eugenol lost the high inhibitory activity observed in the aqueous phase, whereas ferulic acid retained it. The partition coefficient (logPoct/wat) appears to be a key factor. Eugenol (logPoct/wat = 2.61) dispersed in the aqueous phase intercalates into the bacterial membrane and has high antimicrobial activity. In contrast, it likely preferentially partitions into the lipid droplets when dispersed in an emulsion, consequently losing its antimicrobial activity. As ferulic acid is more hydrophilic, a higher proportion probably remains in the aqueous phase of the emulsion, retaining its antimicrobial activity

Oxidative Phosphorylation Fueled by Fatty Acid Oxidation Sensitizes Leukemic Stem Cells to Cold

Dependency on mitochondrial oxidative phosphorylation (OxPhos) is a potential weakness for leukemic stem cells (LSC) that can be exploited for therapeutic purposes. Fatty acid oxidation (FAO) is a crucial OxPhos-fueling catabolic pathway for some acute myeloid leukemia (AML) cells, particularly chemotherapy-resistant AML cells. Here, we identified cold sensitivity at 4◦C (cold killing challenge; CKC4), commonly used for sample storage, as a novel vulnerability that selectively kills AML LSCs with active FAO-supported OxPhos while sparing normal hematopoietic stem cells. Cell death of OxPhos-positive leukemic cells was induced by membrane permeabilization at 4◦C; by sharp contrast, leukemic cells relying on glycolysis were resistant. Forcing glycolytic cells to activate OxPhos metabolism sensitized them to CKC4. Lipidomic and proteomic analyses showed that OxPhos shapes the composition of the plasma membrane and introduces variation of 22 lipid subfamilies between cold-sensitive and cold-resistant cells. Together, these findings indicate that steady-state energy metabolism at body temperature predetermines the sensitivity of AML LSCs to cold temperature, suggesting that cold sensitivity could be a potential OxPhos biomarker. These results could have important implications for designing experiments for AML research to avoid cell storage at 4◦C.</p

Diversité des agricultures familiales

Dans un contexte d’interrogation sur les modèles agricoles et de profondes transformations des agricultures et des marchés, cet ouvrage s’attache à revisiter la diversité des formes familiales de production et leurs mutations de par le monde. Dès lors, l’analyse intègre les liens aux marchés, aux territoires et à l’Ailleurs — par le fait migratoire — les enjeux d’autonomie et de sécurité alimentaire, les stratégies de survie et d’accumulation ainsi que les formes d’action collective et politique. L’ouvrage est construit autour de dix-huit études de cas, menées dans les cinq continents. Elles ont toutes été conduites avec un cadre méthodologique, identique et original, inspiré du Sustainable Rural Livehoods (cadre d’identification des moyens de subsistance durables en milieu rural). Revisitée pour cet ouvrage, cette méthode d’observations et d’analyses permet aux auteurs de préciser finement « ce qui fait famille », d’analyser les adaptations du travail des actifs familiaux et les mettre en perspective avec le contexte territorial et les politiques publiques de chaque pays. Écrit à plusieurs mains, par un réseau de chercheurs, cet ouvrage contribue autant à l’approfondissement des savoirs scientifiques sur les agricultures familiales dans le monde qu’à la mise à l’épreuve d’un cadre méthodologique d’analyse et d’observations en milieu rural. Il vise un public de chercheurs, d’enseignants et d’étudiants, agronomes, économistes, sociologues et historiens. Les experts du développement agricole et rural y trouveront un grand intérêt. Plus largement, toute personne qui s’intéresse aux agricultures familiales et à leurs évolutions dans divers contextes sociaux trouvera avantage à cette lecture. Les chercheurs qui ont coordonné cet ouvrage sont agronomes, économistes et géographes, au Cirad ou à l’Inra où ils mènent des recherches sur les systèmes agricoles familiaux à des échelles locales, nationales ou internationales. Cet ouvrage est le fruit d’une démarche de recherche collective et partagée permettant à de nombreux scientifiques des pays du Sud d’exprimer la diversité des réalités agraires contemporaines. Certains coordinateurs ou auteurs de cet ouvrage ont également collaboré à Agricultures familiales et mondes à venir, titre paru en 2014 chez Quae. Ce livre est également disponible en anglais sous le titreDiversity of Family Farming Around the Worldauprès des éditions Springer -www.springer.co

Analyzing the microstructure of a fresh sorbet with X-ray micro-computed tomography: Sampling, acquisition, and image processing

International audienceX-ray micro-computed tomography and image processing techniques were used to analyze fresh frozen sorbets at the outlet of a batch freezer. Sorbets made from water and sucrose were visualized and their microstructure was quantified with a resolution of 9 μm. Sodium iodide was confirmed to enhance the contrast between the unfrozen water and ice in sorbets. A thermostated box was employed to keep the samples at frozen state and constant temperature (close to − 6 • C) during imaging. A reproducible quantification of size distributions and volume fractions of ice crystals and air bubbles were obtained. Data concerning ice crystals were in agreement with cryo-SEM imaging. Ice crystals represented approximately 50%wt of the product and their mean size was about 60 μm whereas air bubbles represented about 6% of the volume. Finally, X-ray microtomography equipped with a thermostated box was found to be a particularly relevant technique for the analysis of the microstructure of frozen desserts

Marketing authorisation application for biotechnology-derived medicinal products (the centralised procedure)

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Rheological properties of stabilizers at low temperatures in concentrated sucrose solutions

International audienceDuring the freezing of sorbets, the concentration of sucrose and stabilizing macromolecules increases in the unfrozen phase. Rheological properties of this unfrozen phase were studied, depending on nature and concentration of hydrocolloids in sucrose solutions at temperatures below zero. Three stabilizers were tested individually in sucrose-rich solutions: locust bean gum (LBG), hydroxypropylmethylcellulose (HPMC) and carboxymethylcellulose (CMC). The parameters of the Ostwald-de Waele model were determined and apparent viscosities of solutions were calculated at shear rates encountered during the process. Intrinsic viscosities and critical concentrations of entanglement were determined to evaluate the expansion of polymers in solutions and the transition of concentration regimes according to process conditions. Viscoelastic properties were also tested to study the possible cryogelation. For HPMC and LBG, the shear thinning behavior increased quite linearly with the concentration in stabilizer whereas CMC was highly shear thinning. Increasing sugar did not reveal large effect on these properties. The increase in apparent viscosity of the unfrozen matrix in process conditions was dependent on stabilizers; solutions containing LBG were less viscous than the others. Intrinsic viscosities revealed that HPMC and LBG became progressively less expanded as the concentration of sucrose increased whereas CMC tended to aggregate. Measurements of viscoelastic properties evidenced a dominant viscous behavior for HPMC and LBG systems whereas CMC systems showed dominant elastic behavior at frequencies higher than 0.1 Hz. The next challenge will be to better understand the potential link between the particular rheological behavior of hydrocolloids in process conditions and their possible influence on crystallization mechanisms

Adhésion entre des gels de biopolymères et des surfaces solides : effet des propriétés rhéologiques et de surfaces

Adhésion entre des gels de biopolymères et des surfaces solides : effet des propriétés rhéologiques et de surfaces. 47. Colloque du Groupe Français de Rhéologie : Rhéologie, Confinement et Interfac

Evaluation of ready-to-use SMLS and DWS devices to study acid-induced milk gel changes and syneresis

The aim of this study was to examine the potential of ready-to-use multi-speckle diffusing wave spectroscopy (MS-DWS) and static multiple light scattering (SMLS) devices to follow the acid-induced gelation of milk, as well as to detect the appearance of gel syneresis. These light-scattering techniques, MS-DWS and SMLS, have been used in comparison to the classical rheology to study acid milk gel formation and syneresis detection. A systematic study of the effects of heat treatment of milk on the formation of acid gels was conducted. Results obtained by DWS and rheology showed excellent correlation in good agreement with the existence of a link between particle dynamics measured by DWS and the macroscopic viscoelastic response of the gel. Moreover, both light scattering techniques showed ability to detect gel shrinkage due to their high sensitivity to particle mobility. DWS allowed evidencing wheying-off along the tubes' glass walls, while SMLS performed well in detecting syneresis on gel surface or confined in localized zones of the glass walls. The results were discussed in light of a proposed model considering gel syneresis as regards of gel properties. Light-scattering techniques proved to be very efficient tools to detect syneresis in acid milk gels and thus can be of great interest in preventing this mechanism