Novel mango bars using gellan gum as gelling agent: rheological and microstructural studies

This work aimed the development of mango bars, made with fresh mango puree and gellan gum. The influence of gellan concentration as well as the ratio of LA (low-acyl) and HA (high-acyl) gellan on the rheological and microstructural properties of the mango bars was studied. Rheological outcomes showed that both LA and HA, and in mixtures, were able to produce jellified products, within a rather low maturation time. Furthermore, a synergistic effect was observed at different ratios of LA/HA, enabling the production of mango bars with intermediate viscoelastic properties. Higher values of the dynamic moduli were perceived as the LA content increased. Confocal microscopy is in agreement with the rheological results, revealing a weakening of the gel structure with the increasing percentage of HA. Results suggest that 1 g of LA/HA 50/50 per 100 g of puree produces structures with suitable mechanical properties. However, the results need to be correlated to texture and sensory analysis, before proceeding to the next steps of product developmentinfo:eu-repo/semantics/publishedVersio

A Riboswitch-Based Inducible Gene Expression System for Mycobacteria

Research on the human pathogen Mycobacterium tuberculosis (Mtb) would benefit from novel tools for regulated gene expression. Here we describe the characterization and application of a synthetic riboswitch-based system, which comprises a mycobacterial promoter for transcriptional control and a riboswitch for translational control. The system was used to induce and repress heterologous protein overexpression reversibly, to create a conditional gene knockdown, and to control gene expression in a macrophage infection model. Unlike existing systems for controlling gene expression in Mtb, the riboswitch does not require the co-expression of any accessory proteins: all of the regulatory machinery is encoded by a short DNA segment directly upstream of the target gene. The inducible riboswitch platform has the potential to be a powerful general strategy for creating customized gene regulation systems in Mtb

Protecting Group and Solvent Control of Stereo- and Chemoselectivity in Glucal 3-Carbamate Amidoglycosylation

In the Rh2(OAc)4-catalyzed amidoglycosylation of glucal 3-carbamates, anomeric stereoselectivity and the extent of competing C3−H oxidation depend on the 4O and 6O protecting groups. Acyclic protection permits high α-anomer selectivity with further improvement in less polar solvents, while electron-withdrawing protecting groups limit C3-oxidized byproducts. Stereocontrol and bifurcation between alkene insertion and C3−H oxidation reflect an interplay of conformational, stereoelectronic, and inductive factors

The effect of ultrasound pretreatment on quality attributes of freeze-dried quince slices: Physical properties and bioactive compounds

The study was conducted to examine the effect of ultrasound (US) pretreatment on physical and chemical/nutritional attributes of freeze-dried quince slices. The quince fruits were washed, hand-peeled and cut with a dimension of 1 cm (L) × 0.2 (W) cm × 1 cm (H). The quince samples were treated in an ultrasonic bath in three different times which were 10, 20, and 30 min. Untreated and ultrasonically pretreated quince samples were dried in a freeze dryer. Freeze-dried samples were analyzed in terms of physical properties such as shrinkage, rehydration, color, water activity, and hardness and bioactive compounds including total phenols, ascorbic acid, and antioxidant capacity. A significant difference was observed among untreated and ultrasonically pretreated quince samples. The freeze-dried quince slices treated with a US (especially 20 min—treatment) showed a higher preservation of bioactive compounds in addition to improved physical properties compared to the untreated quince samples. In overall, US pretreatment is a promising process as demonstrated in current research by its capability to better retain freeze-dried quince quality in terms of physical and chemical properties. Practical Applications: The freeze drying of quince fruit with the aid of US pretreatment was investigated. A significant development in the quality preservation of freeze-dried of quince slices with an US-pretreatment was accomplished. This research will contribute a useful technique to produce freeze-dried quinces with a significantly enhanced product quality. Drying of quince samples with a freeze drying in addition to US-pretreatment might be applied to get a high-quality fruit with an improved bioactive compounds and physical property. © 2019 Wiley Periodicals, Inc