Drying of shiitake mushrooms in a vacuum dryer and optimization of the process by response surface methodology (RSM)

Optimization of shiitake mushroom vacuum drying process was the objective of this research. In order to produce dried sample with satisfactory shelf life, response surface methodology was used. Vacuum drying used to accomplish the task was previously described by the authors. The samples were dried at 46–74 °C and 20–580 mbar. As quality indicators of dried product, total solids, water activity, total phenolics, IC₅₀ and total color change were used. Response surface methodology resulted in optimal conditions of 57.1 °C and 100 mbar. In order to verify predictions and adequacy of the second-order polynomial models, separate validation experiments were conducted at optimum conditions. The predicted amount of total solids was 85.40 %, while a_w value was 0.615.     

The influence of Mg addition and hydrostatic extrusion HE on the repassivation ability of pure Al,AlMg1 and AlMg3 model alloys in 3.5 wt-% NaCl

ABSTRACT

Commercially pure aluminium and two model aluminium–magnesium alloys were subjected to hydrostatic extrusion (HE). The microstructure of materials was observed using optical microscopy (OM). All materials were subjected to electrochemical corrosion tests in the 3.5?wt-% water solution of sodium chloride. The potentiodynamic polarisation measurements and electrochemical impedance spectroscopy were performed after samples’ immersion in open circuit potential. The surface of samples after corrosion examination was observed with the use of scanning electron microscopy. It was stated that all undeformed materials underwent pitting corrosion and further pits repassivation, while after HE pitting was also observed, but pit repassivation did not occur. This may be related to the microstructural changes caused by deformation, such as grain refinement. What is more, the pits character changed with the addition of a different amount of Mg to Al. Deterioration of corrosion resistance was also observed for all materials after HE.     

Arylpiperazine dopamineric ligands protect neuroblastoma cells from nitric oxide (NO)-induced mitochondrial damage and apoptosis

The protective ability of novel arylpiperazine-based dopaminergic ligands against nitric oxide (NO)-mediated neurotoxicity is investigated. The most potent neuroprotective arylpiperazine identified during the study was N-{4-[2-(4-phenyl-piperazin-1-yl)ethyl]-phenyl}picolinamide, which protected SH-SY5Y human neuron-like cells from the proapoptotic effect of NO donor sodium nitroprusside (SNP) by decreasing oxidative stress, mitochondrial membrane depolarization, caspase activation and subsequent phosphatydilserine externalization/DNA fragmentation. The protective effect was associated with the inhibition of proapoptotic (JNK, ERK, AMPK) and activation of antiapoptotic (Akt) signaling pathways, in the absence of interference with intracellular NO accumulation. The neuroprotective action of arylpiperazines was shown to be independent of dopamine receptor binding, as it was not affected by the high-affinity D?/D? receptor blocker butaclamol. These results reported support the further study of arylpiperazines as potential neuroprotective agents.     

Development of tools to study lacto-N-biosidase: an important enzyme involved in the breakdown of human milk oligosaccharides

Milk and sugar? The elucidation of the catalytic mechanism and the development of the first known inhibitor for lacto-N-biosidases, which are important enzymes involved in the breakdown of human milk oligosaccharides, are described.     

Biodegradable poly(L‐lactic acid)/TiO2 nanocomposites: Thermal properties and degradation

Poly(L ‐lactic acid)‐titanium dioxide nanocomposites (with various loadings of TiO₂: 0.5, 1, 2, 5, and 10 wt %) were produced by solution casting method. The influence of TiO₂ on thermal properties and crystallinity of PLA was investigated by DSC and FTIR spectroscopy. The TiO₂ nano filler has no significant influence on the characteristic temperatures (T_g, T_c, and T_m), but has high impact on the crystallinity of these systems. The degree of crystallinity X_c significantly increases for PLA nanocomposites loaded with up to 5 wt % of TiO₂, while for 10 wt % load of TiO₂ it drops below X_c of the pure resin. The degradation of the prepared composites was evaluated hydrolytically in 1N NaOH, enzymatically in α‐amylase solutions, and under UV irradiation. The catalytic effect of TiO₂ nano particles on the degradation processes under UV light exposure (λ = 365 nm) and hydrolytic degradation was confirmed with the increase of the filler content. The opposite effect was identified in enzymatic degradation experiments. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Adsorptive removal of technetium‐99 using macroporous poly(GMA‐co‐EGDMA) modified with diethylene triamine

The possibility of sorption of technetium‐99 in the form of pertechnetate anion (TcO₄^?) and the sorption kinetics for removing TcO₄^? from aqueous solution by chelating polymers based on glycidyl methacrylate (GMA) were investigated. Two samples of macroporous crosslinked poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME), with different amount of the crosslinker (ethylene glycol dimethacrylate, EGDMA), were synthesized by suspension copolymerization and functionalized with diethylene triamine (deta). We propose that nonspecific sorption of pertechnetate anion via electrostatic interactions takes place at the protonated amino groups of macroporous crosslinked copolymer. The results of batch experiments performed at pH 1–14 showed fast sorption kinetics for removing TcO₄^? by amino‐functionalized PGME‐deta in a wide range of pH, that is, from 1.0 to 9.0. Almost complete removal of TcO₄^? (91–98%) was reached within 180 min in the stated pH range (1.0–9.0), with the sorption half‐times of under 25 min. The partitioning coefficients of linear adsorption isotherms, with 180‐min equilibrium time, reach the high values of 2130 mL g^?1 and 1698 mL g^?1 for the two samples of synthesized PGME‐deta. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Modeling of kinetics of pertechnetate removal by amino-functionalized glycidyl methacrylate copolymer

Technetium-99 comprises a significant health risk, since edible plants can bioaccumulate and convert it to more lipophilic species that cannot be excreted through urine. Batch kinetics of pertechnetate removal from aqueous solutions by two samples of crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) functionalized with diethylene triamine (PGME-deta) was investigated at the optimum pH value of 3.0, and the initial solution activity of 325 MBq dm⁻³. PGME-deta was characterized by elemental analysis, mercury intrusion porosimetry, and scanning electron microscopy. Five kinetic models (pseudo-first, pseudo-second order, Elovich, Bangham, and intraparticle diffusion) were used to determine the best-fit equation for pertechnetate sorption. After 24 h, PGME-deta samples sorbed more than 98% of pertechnetate present, with maximum sorption capacity of 25.5 MBq g⁻¹, showing good potential for remediation of slightly contaminated groundwater.     

Rheological and Breadmaking Properties of Wheat Flours Supplemented with Octenyl Succinic Anhydride-Modified Waxy Maize Starches

The feasibility of emulsifying starches as bread improvers was investigated by incorporating starch sodium octenyl succinate (OSA-st), pre-gelatinized OSA-st and hydrolysed spray-dried OSA-st at 2.5, 5 and 10 % into wheat flour. Dough rheological properties (creep and recovery measurements; Mixolab, Alveograph) and bread quality parameters (specific loaf volume, crust and crumb colour, crumb moisture, crumb grain features, texture) were evaluated. The substituted flours, except hydrolysed OSA-st, significantly increased water absorption measured by Mixolab. The study on the rheological behaviour of doughs containing emulsifying starches, performed using a rheometer and an Alveograph, showed that OSA-st incorporation yielded strengthened dough, whereas pre-gelatinized and hydrolysed OSA-st addition led to more extensible dough. With regard to the thermal behaviour, investigated in water-limited systems by Mixolab, doughs prepared from pre-gelatinized OSA-st and hydrolysed OSA-st exhibited lower maximum peak torque, whilst all three examined starches increased cooking stability and decreased the setback value. Specific volumes of loaves baked from the substituted flours increased, and the highest effect was observed with pre-gelatinized OSA-st, which consequently produced bread crumbs with the largest mean gas cell area. The bread crumbs baked with octenyl succinate starches were whiter and softer. Although upon 1 day of storage no significant moisture retention capacity of emulsifying starches was noticed, the firmness values of OSA-st and pre-gelatinized OSA-st-supplemented bread crumbs, after 24 h of storage, were similar to or significantly lower than those of the control determined 2 h after baking. The obtained results indicate a requirement for further optimization of the octenyl succinate starch-supplemented doughs in terms of the combination of different types and levels of modified starches in order to obtain maximum bread quality.