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International audience; High-pressure homogenization (HPH) was applied within a range of 300 to 1000 bar for 2 to 8 cycles. At constant dry matter (6.2%), pulp mass increased from 3.7 to 8%, indicating a change in particle organization. D-90 varied from 197 to 20 mu m depending on the pressure and number of cycles. The aggregation of particles, then destruction of the aggregates depending on the number of cycles, explained viscosity behavior. HPH delayed phase separation by an average 28.5 h. Sedimentation velocity was 10 times higher at 8 cycles than at 3 cycles, at 1000 bar. At 1000 bar, browning was observed, resulting from Maillard reactions, and was linked to the furan-2-pentyl content (10-fold higher) and a 45% loss of carotenoids. This study will help in understanding changes induced in mango nectar by HPH and will be of use in developing processing technologies to preserve mango-based products. Novelty impact statement This study provides some additional scientific indications for understanding the subtility of HPH impacts in stabilizing mango nectar. The optimum pressure treatment for delaying phase separation (1000 bar, 3-6 cycles), i.e., reducing particle size and forming adequate re-aggregation, also causes a Maillard reaction (2-fold color difference, 10-fold furan increase, etc.), hence browning through an increase in local temperature. It will therefore be necessary to find a compromise to limit degradation reactions caused by the process, and to guarantee greater consumer acceptance (phase separation and sensory quality).

Septoria tritici blotch (STB), caused by the fungus Zymoseptoria tritici, is among the most threatening wheat diseases in Europe. Genetic resistance remains one of the main environmentally sustainable strategies to efficiently control STB. However, the molecular and physiological mechanisms underlying resistance are still unknown, limiting the implementation of knowledge-driven management strategies. Among the 22 known major resistance genes (Stb), the recently cloned Stb16q gene encodes a cysteine-rich receptor-like kinase conferring a full broad-spectrum resistance against Z. tritici. Here, we showed that an avirulent Z. tritici inoculated on Stb16q quasi near isogenic lines (NILs) either by infiltration into leaf tissues or by brush inoculation of wounded tissues partially bypasses Stb16q-mediated resistance. To understand this bypass, we monitored the infection of GFP-labeled avirulent and virulent isolates on Stb16q NILs, from germination to pycnidia formation. This quantitative cytological analysis revealed that 95% of the penetration attempts were unsuccessful in the Stb16q incompatible interaction, while almost all succeeded in compatible interactions. Infectious hyphae resulting from the few successful penetration events in the Stb16q incompatible interaction were arrested in the sub-stomatal cavity of the primary-infected stomata. These results indicate that Stb16q-mediated resistance mainly blocks the avirulent isolate during its stomatal penetration into wheat tissue. Analyses of stomatal aperture of the Stb16q NILs during infection revealed that Stb16q triggers a temporary stomatal closure in response to an avirulent isolate. Finally, we showed that infiltrating avirulent isolates into leaves of the Stb6 and Stb9 NILs also partially bypasses resistances, suggesting that arrest during stomatal penetration might be a common major mechanism for Stb-mediated resistances.

International audience; L'utilisation des procédés baromembranaires pour le fractionnement à froid de liquides alimentaires thermosensibles suscite un intérêt grandissant au niveau industriel. De plus en plus d'études portent sur le couplage des procédés de micro, ultra et nanofiltration pour l'élaboration d'extraits naturels à haute ajoutée. Les composés d'arôme (CA) font partie de ces composés fonctionnels d'intérêt. Ils correspondent à l'ensemble des composés volatils qui, en mélange, sont responsables de l'odeur et de l'arôme des aliments. Ils sont particulièrement thermo et chimio-labiles et leur grande volatilité relative par rapport à l'eau les rend difficile à concentrer par des techniques conventionnelles. L'identification sensorielle d'une odeur et d'un arôme est généralement le résultat d'une composition moléculaire complexe qui peut être facilement altérée par le procédé de transformation. Dans ce contexte, l'objectif du travail est d'évaluer la capacité de ces procédés baromembranaires à concentrer les CA contenus dans un extrait hydroalcoolique (10 %vol) de framboise. Couplage micro et nanofiltration tangentielles pour la concentration des composés d'arômes d'un extrait hydroalcoolique de framboise Conception: Cirad, Martine Duportal, mai 2022-© photos Cirad Conclusions Ce travail exploratoire met en avant le potentiel de la nanofiltration associée à la microfiltration pour la concentration voire le fractionnement des composés aromatiques à partir de ce type d'extraits naturels. Réalisé en milieu hydroalcoolique, il confirme que la présence d'éthanol influence la sélectivité et les performances de la séparation. La compréhension des phénomènes mis en jeu reste à approfondir afin d'être capable de proposer des solutions fiables pour la production d'un extrait concentré de qualité, à moindre coût, avec un impact environnemental limité.