Subsequent Rehydration Research Articles

Rehydration properties of regular and agglomerated milk protein concentrate powders produced using nitrogen gas injection prior to spray drying

This study evaluated the effect of high-pressure nitrogen (N2) gas injection prior to spray drying on the subsequent rehydration properties of regular and agglomerated milk protein concentrate (MPC) powders. Conductivity measurements demonstrated a slower release of ions for powders produced using N2 injection (NI) as they took longer to wet and sink due to their lower density. However, analysis of particle size distribution on reconstitution at both 23 and 50 °C showed an improvement in powder dispersion with NI. Powder solubility, when measured at 23 °C, was higher for the NI powders, while agglomeration negatively impacted solubility. Confocal laser scanning microscopy analysis showed a faster diffusion of dye into MPC powder particles produced using NI. The improvement in powder dissolution with NI was attributed to higher porosity and the presence of air voids which facilitated increased water transfer and accelerated the breakdown of primary powder particles.

The photosynthetic performance of a cultivated Japanese green alga Caulerpa lentillifera in response to three different stressors, temperature, irradiance, and desiccation

The effects of temperature, irradiance, and desiccation on the photosynthesis of a cultivated Japanese green alga Caulerpa lentillifera (Caulerpaceae) were determined by a pulse amplitude modulation (PAM)-chlorophyll fluorometer and dissolved oxygen sensors. The photochemical efficiency in the photosystem II (Fv/Fm and ΔF/Fm') during the 72-h temperature exposures (8, 12, 16, 20, 24, 28, 32, 36, and 40°C) was generally stable at 16–32°C but quickly dropped at lower and higher temperatures. The photosynthesis–temperature curve at 200 μmol photons m−2 s−1 also revealed that the maximum gross photosynthesis (GPmax) occurred at 30.7°C (30.5–30.9, 95% highest density credible intervals). Photosynthesis–irradiance curves at 16, 24, and 32°C quickly saturated, then expressed photoinhibition, and revealed that the maximum net photosynthetic rates (NPmax) and saturation irradiance (Ek) were highest at 32°C and lowest at 16°C. Continuous 6-h exposure to irradiances of 200 (low) and 400 (high) μmol photons m−2 s−1 at 16, 24, and 32°C expressed greater declines in their ΔF/Fm' at 16°C, revealing chronic chilling-light stress. The response to continuous desiccation (~480 min) under 50% humidity at 24°C showed that ΔF/Fm' dropped to zero at 480-min aerial exposure, and the treatments of more than 60-min desiccation did not return to the initial level even after 24-h subsequent rehydration in seawater. Likewise, ΔF/Fm' fell when the absolute water content (AWC) of the frond dropped below AWC of 90% and mostly did not return to the initial level even after 24-h subsequent rehydration in seawater, signifying a low tolerance to desiccation.

Influences of Magnesium Content in Rehydrated Mixed Oxides on Furfural Conversion

In this study, Mg-Fe catalysts with various molar ratio (Mg/Fe 1:1-10:1), prepared by calcination and subsequent rehydration of hydrotalcite structures, were characterized, tested and evaluated as suitable catalysts for the aldol condensation of furfural with acetone. XRD analyses confirmed that the layered structure was completely restored by rehydration in the catalysts with Mg:Fe molar ratio 3:1 and 4:1. TPD-CO2 showed that the catalysts of this molar ratio had the highest basicity. Rehydrated Mg-Fe catalysts were tested in aldol condensation carried out in a glass batch reactor at 60 °C, atmospheric pressure, 2 wt% of catalyst and acetone/furfural molar ratio 10:1. The catalysts with Mg/Fe molar ratio of 3:1 and 4:1 showed total furfural conversion. As high basicity causes a high activity of the catalyst, our results suggest that the rehydrated mixed oxides with molar ratio 3 to 4:1 were promising new catalysts for the aldol condensation of furfural with acetone.

The effect of long-term dehydration and subsequent rehydration on markers of inflammation, oxidative stress and apoptosis in the camel kidney

BackgroundDehydration has deleterious effects in many species, but camels tolerate long periods of water deprivation without serious health compromise. The kidney plays crucial role in water conservation, however, some reports point to elevated kidney function tests in dehydrated camels. In this work, we investigated the effects of dehydration and rehydration on kidney cortex and medulla with respect to pro-inflammatory markers, oxidative stress and apoptosis along with corresponding gene expression.ResultsThe cytokines IL-1β and IL-18 levels were significantly elevated in the kidney cortex of dehydrated camel, possibly expressed by tubular epithelium, podocytes and/or mesangial cells. Elevation of IL-18 persisted after rehydration. Dehydration induced oxidative stress in kidney cortex evident by significant increases in MDA and GSH, but significant decreases in SOD and CAT. In the medulla, CAT decreased significantly, but MDA, GSH and SOD levels were not affected. Rehydration abolished the oxidative stress. In parallel with the increased levels of MDA, we observed increased levels of PTGS1 mRNA, in MDA synthesis pathway. GCLC mRNA expression level, involved in GSH synthesis, was upregulated in kidney cortex by rehydration. However, both SOD1 and SOD3 mRNA levels dropped, in parallel with SOD activity, in the cortex by dehydration. There were significant increases in caspases 3 and 9, p53 and PARP1, indicating apoptosis was triggered by intrinsic pathway. Expression of BCL2l1 mRNA levels, encoding for BCL-xL, was down regulated by dehydration in cortex. CASP3 expression level increased significantly in medulla by dehydration and continued after rehydration whereas TP53 expression increased in cortex by rehydration. Changes in caspase 8 and TNF-α were negligible to instigate extrinsic apoptotic trail. Generally, apoptotic markers were extremely variable after rehydration indicating that animals did not fully recover within three days.ConclusionsDehydration causes oxidative stress in kidney cortex and apoptosis in cortex and medulla. Kidney cortex and medulla were not homogeneous in all parameters investigated indicating different response to dehydration/rehydration. Some changes in tested parameters directly correlate with alteration in steady-state mRNA levels.

Comparative Quantitative Proteomics Reveals the Desiccation Stress Responses of the Intertidal Seaweed NEOPORPHYRA haitanensis.

Neoporphyra haitanensis is an economically important red seaweed that inhabits upper intertidal zones. The thallus tolerates extreme fluctuating environmental stresses (e.g., surviving more than 80% water loss during low tides). To elucidate the global molecular responses relevant to this outstanding desiccation tolerance, a quantitative proteomics analysis of N.haitanensis under different desiccation treatments as well as rehydration was performed. According to the clustering of expression patterns and the functional interpretation of the 483 significantly differentially expressed proteins, a three-stage cellular response to desiccation stress and subsequent rehydration was proposed. Stage I: at the beginning of water loss, multiple signal transduction pathways were triggered including lipid signaling, protein phosphorylation cascades, and histone acetylation controlling acetate biosynthesis to further modulate downstream hormone signaling. Protein protection by peptidyl-prolyl isomerase and ROS scavenging systems were also immediately switched on. Stage II: with the aggravation of stress, increases in antioxidant systems, the accumulation of LEA proteins, and the temporary biosynthesis of branched starch were observed. Multiple enzymes involved in redox homeostasis, including peroxiredoxin, thioredoxin, ascorbate peroxidase, superoxide dismutase, glutathione peroxidase, and glutathione reductase, were hypothesized to function in specific cellular compartments. Stage III: when the desiccated thalli had rehydrated for 30mins, photosynthesis and carbon fixation were recovered, and antioxidant activities and protein structure protection were maintained at a high level. This work increases the understanding of the molecular responses to environmental stresses via a proteomic approach in red seaweeds and paves the way for further functional studies and genetic engineering.

Secado solar de berenjenas impregnadas con Ca y Zn

La berenjena (Solanum melongena L.) posee componentes bioactivos beneficiosos para la salud. El objetivo del trabajo fue obtener berenjenas deshidratadas con alto valor nutricional y excelente capacidad de rehidratación. Las berenjenas se cortaron en rodajas de 5 mm, se deshidrataron en un secadero solar, algunas de ellas se sometieron a un pretratamiento de deshidratación osmótica/impregnación (DO/I) para fortificarlas con calcio y zinc y otras no para poder comparar posteriormente su calidad estructural y nutricional. La solución deshidratante consistió en 40% m/m sacarosa, 5% m/m cloruro de calcio, 5% m/m ácido ascórbico y 1% m/m ácido cítrico (55° Brix) a una temperatura de 40°C. Se empleó una relación masa de solución a masa de berenjenas de 4 y un nivel de agitación de 120 rpm.Durante el secado se tomaron muestras para determinar el contenido de calcio y zinc por espectrofotometría de absorción atómica, la humedad, la pérdida de peso y, el color. Asimismo, se modeló la cinetica de secado y la posterior rehidratación.Luego del secado solar por 6 h, las berenjenas sin DO/I alcanzaron una concentración de 600 mg Ca/kg mientras que las pretratadas, un valor de 18000mg Ca/kg. Las berenjenas frescas presentan un rango de humedad de 91-94% en base húmeda, luego de un pretratamiento por (DO/I) de 1h se alcanza un valor de 64-67% (bh) y el posterior secado solar por 7h logra un valor de 30-21%. Con secado solar sin pretratamiento de 7h, se obtuvo una humedad 66- 63% (bh). El producto pretratado presentó menor luminosidad L*: 49,7 ± 0,7 respecto del sin pretratar L*: 71,7 ± 3,1, valores de a* superiores con una diferencia del 50% y valores de b* bastante similares. Para modelar la cinetica de secado se usó el modelo Page y Crank, Los parámetros del modelo de Page obtenidos fueron: C: 1±0,25; K: 0,078±0,004 y n: 1,7±0,3 para un ajuste (R2: 0,995), para las muestras que se sometieron a pretratamiento por deshidratación osmótica y C: 2,65±0,50; K: 0,0047±0,00024, n: 2,75±0,48 (R2: 0.998) para las restantes. El coeficiente de difusión efectivo obtenido por el modelo de Crank fue de 2,44 ± 0,33. 10 -10 m2 /s y de 1,87 ± 0,25. 10 -10 m2 /s para las muestras con y sin pretratamiento por deshidratación osmótica, respectivamente. La rehidratación fue mejor en la berenjena pretratada. Al cabo de 4h de rehidratación a 20°C, se alcanzó una humedad de 89% (b.h). Este fenómeno evidenció que la deshidratación osmótica/impregnación logra preservar la estructura del alimento.

Rehydration on high temperature-mortars based on recycled glass as aggregate

The incorporation of waste of different nature as components of mortars and cement concretes is a scientifically valid option that allows us to obtain a positive environmental balance in the manufacturing process of these construction materials.Considering the capacity of improvement of the thermal properties provided by glass, this work approaches the recovery by forced rehydration of mortars based on recycled glass after undergoing a process of heating at high temperature. Its mineralogical by XRD, structural evolution by SEM, X-ray computed tomography and DTA/TGA along with its physical-mechanical properties has been analyzed.Results have shown that, although the initial influence of glass can lead to inconsistent results according to the dosage and alteration process suffered, the favourable effect of the crushed glass after a thermal degradation and the subsequent rehydration treatment is observed. The rehydrated material based on recycled glass develops a capacity of mechanical recovery 6.2 times higher than the conventional mortar. This is due to the thermal an alkaline activation of amorphous silica, which favours the new formation of hydrated silicates as manifested the variation of the eccentricity coefficient of the pores: 0.5707 for conventional mortar and 0.6627 for glass based one.

Vegetative desiccation tolerance in Eragrostiella brachyphylla: biochemical and physiological responses

Eragrostiella brachyphylla is an angiosperm desiccation-tolerant resurrection plant, which can survive during desiccation in the air-dry state and recover completely on availability of water. The present study was conducted to understand the vegetative desiccation tolerance of Eragrostiella brachyphylla by evaluating its ability to recover the physiological, biochemical and morphological functions post desiccation. In order to understand the responses of Eragrostiella brachyphylla to desiccation and subsequent rehydration experiments were conducted in the hydrated state (HS), desiccated state (DS) and rehydrated state (RS). Scanning electron microscopy revealed significant changes between the three stages in the internal ultra-structures of leaves and stems. Compared to the other states, photosynthetic parameters such as chlorophyll a, chlorophyll b, total chlorophylland total carotenoid contents decreased significantly in the desiccated state. Superoxide radical (O2•−) content also increased, resulting in an oxidative burst during desiccation. Consequently, antioxidant enzymes such as catalase (CAT) superoxide dismutase (SOD) peroxidase (APX) and glutathione reductase (GR) activities were found to be significantly elevated in the desiccated state to avoid oxidative damage. Increased malondialdehyde (MDA) content and relative electrolyte leakage (REL) during desiccation provide evidence for membrane damage and loss of cell-wall integrity. During desiccation, the contents of osmolytes represented by sucrose and proline were found to increase to maintain cell structure integrity. After rehydration, all physiological, biochemical and morphological properties remain unchanged or slightly changed when compared to the hydrated state. Hence, we believe that these unique adaptations contribute to the remarkable desiccation-tolerance property of this plant.

Reduction in Resources and Cost for Gastroenteritis Through Implementation of Dehydration Pathway.

Management decisions for patients with gastroenteritis affect resource use within pediatric emergency departments (EDs), and algorithmic care using evidence-based guidelines (EBGs) has become widespread. We aimed to determine if the implementation of a dehydration EBG in a pediatric ED resulted in a reduction in intravenous (IV) fluid administration and the cost of care. In a single-center quality improvement initiative between 2010 and 2016, investigators aimed to decrease the percentage of patients with gastroenteritis who were rehydrated with IV fluids. The EBG assigned the patient a dehydration score with subsequent rehydration strategy on the basis of presenting signs and symptoms. The primary outcome was proportion of patients receiving IV fluid, which was analyzed using statistical process control methods. The secondary outcome was cost of the episode of care. Balancing measures included ED length of stay, admission rate, and return visit rate within 72 hours. A total of 7145 patients met inclusion criteria with a median age of 17 months. Use of IV fluid decreased from a mean of 15% to 9% postimplementation. Average episode of care-related health care costs decreased from $599 to $410. For our balancing measures, there were improvements in ED length of stay, rate of admission, and rate of return visits. Implementation of an EBG for patients with gastroenteritis led to a decrease in frequency of IV administration, shorter lengths of stay, and lower health care costs.

Fractal and Topological Analyses and Antioxidant Defense Systems of Alfalfa (Medicago sativa L.) Root System under Drought and Rehydration Regimes

Alfalfa (Medicago sativa L.) is a nutritious forage plant in dryland regions with strong drought tolerance and broad adaptability. To understand the architectural characters and physiological functions of the root systems in response to different drought stress and rehydration, two experiments were conducted in a glasshouse. Experiment 1 used three alfalfa cultivars and four soil moisture treatments in a split-plot design with four replicates to investigate the response of root systems of different alfalfa cultivars to drought stress and subsequent rehydration. Experiment 2 used one alfalfa cultivar and four soil moisture treatments in a randomized complete block (RCB) design with three replicates to measure reactive oxidant species and antioxidant defense systems of alfalfa root. The soil moisture treatments included (1) 75–80% of the water-holding capacity (CK); (2) 60–65% of the water-holding capacity and subsequent rehydration to 75–80% of the water-holding capacity; (3) 45–50% of the water-holding capacity and subsequent rehydration to 60–65% and 75–80% of the water-holding capacity; and (4) 30–35% of the water-holding capacity and subsequent rehydration to 45–50%, 60–65% and 75–80% of the water-holding capacity. Our results demonstrated that plants had higher root biomasses (mean = 0.77 g), fractal dimensions (1.47), fractal abundances (3.84), and branching ratios (0.39) under severe water deficit and rehydration than under less stressful soil moisture conditions. Plant root systems tended to exhibit herringbone branching (Topological Index = 0.63) when soil moisture was at 60–65% water-holding capacity with the soil being then rehydrated, whereas they tended to have a smaller lateral root length, root surface area, root volume, and branching ratio and larger root diameter under more favorable soil moisture conditions for less stressful soil moisture treatments. Severe water stress and subsequent considerably improved superoxide (O2−) generation rate, the content of hydrogen peroxide (H2O2) and Malondialdehyde (MDA), and non-enzyme antioxidant glutathione (GSH), and reduced the content of ascorbate (AsA) and activity of catalase (CAT), ascorbate peroxidase (APX), and glutathione peroxidase (GPX). It is concluded that Medicago sativa L. cv Zhaodong (ZD) and cv Aohan (AH) exhibited higher drought resistances than cv Golden empress (GE) using topological and fractal analyses. This could be a key contributor to altering optimum soil moisture conditions and screening alfalfa cultivars based on root system architecture and antioxidant defense systems. The molecular functions warrant further investigation which could help explain the observed root phenotypes after drought conditions and rehydration.

O/W emulsions stabilised by solid lipid particles: Understanding how the particles’ Pickering functionality can be retained post their dehydration and subsequent rehydration

Pickering particles have been extensively shown to hold an immense potential as emulsion stabilisers. Lipid-based particles in particular, are increasingly studied as edible Pickering structures. The aim of this work was to investigate whether specific formulation parameters that are key for the fabrication of lipid particles with a Pickering functionality can also impact upon the ability of these structures to withstand drying and subsequent rehydration events, without loss to their original capacity to provide stable o/w emulsions. The formulation parameters studied here included the type of the lipid source, type and concentration of the surface active species and type and concentration of cryoprotectants used. Freeze-drying was used as the process for the dehydration of the fabricated lipid particles, while two methods for the subsequent rehydration of these structures were tested. It is demonstrated that lipid particles fabricated using sodium caseinate during the melt-emulsification step can maintain their original Pickering functionality even following lyophilisation; i.e., once reconstituted, they provide stable o/w emulsions with the same droplet sizes as those produced by their precursors (lipid particles that haven’t undergone the freezing and desiccation stages). In contrast, a typical small molecular weight surfactant (Tween 80) does not exhibit the same functionality as the protein, and lipid particle agglomeration following drying and reconstitution was unavoidable, even in the presence of traditional drying aids (cryoprotectants) in the formulation. Parameters relating to the drying and rehydration stages (drying kinetics, final moisture content and storage conditions) were also studied, but their impact upon the Pickering functionality of the reconstituted lipid particles was deemed secondary to the effects brought upon by changes to formulation elements.Overall, the present work advances the current limited understanding on formulation approaches that enable the conservation of the Pickering functionality of the lipid particles following their drying and rehydration, in particular offering insight into the contribution of the specific emulsifier employed during particle fabrication.

MaCDSP32 From Mulberry Enhances Resilience Post-drought by Regulating Antioxidant Activity and the Osmotic Content in Transgenic Tobacco.

Desiccation tolerance is a complex phenomenon that depends on the regulated expression of numerous genes during dehydration and subsequent rehydration. Our previous study identified a chloroplast drought-induced stress protein (MaCDSP32) in mulberry, a thioredoxin (Trx) that is upregulated under drought conditions and is likely to confer drought tolerance to transgenic plants. Mulberry (Morus spp.) is an ecologically and economically important perennial woody plant that is widely used in forest management to combat desertification. However, its stress tolerance physiology is not well understood. In this study, the functions of MaCDSP32 gene were investigated. The expression of MaCDSP32 exhibited a circadian rhythm and was induced by mild and severe water deficits. Under abiotic stress, MaCDSP32-overexpressing plants exhibited increased stress sensitivity with lower water retention capacity and more severe lipid peroxidation than the wild-type (WT) plants. Furthermore, the activity of superoxide dismutase (SOD), the contents of proline and soluble sugars and the expression of stress-related transcription factors were lower in the MaCDSP32-overexpressing plants than in the WT plants. However, the MaCDSP32-overexpressing lines exhibited stronger recovery capability after rewatering post-drought. Moreover, the SOD enzyme activity, proline content, and soluble sugar content were higher in the transgenic plants after rewatering than in the WT plants. The production of the reactive oxygen species (ROS) H2O2 and O2– was significantly lower in the transgenic plants than in the WT plants. In addition, under abiotic stress, the MaCDSP32-overexpressing lines exhibited improved seed germination and seedling growth, these effects were regulated by a positive redox reaction involving MaCDSP32 and one of its targets. In summary, this study indicated that MaCDSP32 from mulberry regulates plant drought tolerance and ROS homeostasis mainly by controlling SOD enzyme activity and proline and soluble sugar concentrations and that this control might trigger the stress response during seed germination and plant growth. Overall, MaCDSP32 exerts pleiotropic effects on the stress response and stress recovery in plants.

High temperature induced structural changes of apo-lactoferrin and interactions with β-lactoglobulin and α-lactalbumin for potential encapsulation strategies

There has been increasing interest in lactoferrin as a bioactive compound from milk, as it functions as an antimicrobial and also in delivering iron. Despite the potential as a food ingredient, the low bioavailability of lactoferrin has limited opportunities for commercialisation. Therefore, protective encapsulation of lactoferrin has been explored as a means of enhancing its bioavailability. In this study, a novel in silico approach was adopted to explore the possibility of employing whey protein components to encapsulate lactoferrin. The most unstable form of the protein, apo-lactoferrin has been studied, particularly interactions with the whey proteins β-lactoglobulin and α-lactalbumin. Temperature conditions that might be encountered during spray drying (95 and 180 °C) have been modelled in order to provide an in-depth understanding of the interactions at the molecular level. The findings indicate that β-lactoglobulin and α-lactalbumin are able to preserve the two antibacterial regions within the apo-lactoferrin structure (lactoferricin and lactoferampin). Intra-molecular residue contact analyses within apo-lactoferrin illustrate the tendency for agglomeration under these temperature conditions, indicating that it is most likely to be readily dispersible during subsequent rehydration. Furthermore, free energy calculations found electrostatic attractions to be the primary mode of interaction between apo-lactoferrin, β-lactoglobulin, and α-lactalbumin. This data is confirmed by a network analysis that demonstrates how interactions amongst apo-lactoferrin, β-lactoglobulin, and α-lactalbumin are predominantly a result of the acidic and basic amino acid residues of the proteins. Overall, this study provides molecular insights in understanding the interactions between lactoferrin with β-lactoglobulin and α-lactalbumin for potential encapsulation strategies via spray drying.

Modelling of Rehydration Kinetics of Desert Truffles (Terfezia spp.) Dried by Microwave Oven

It is very important to develop a new way of treatment for foodstuffs to provide consumers more chances to choose their foods. In the present study, we aimed to investigate the effect of microwave drying conditions on the rehydration process of Algerian truffles. Previously dried truffles, at different microwave power output (350, 500 and 650 Watt) and weights (100 and 150 g) have been utilized to analyses and to model the rehydration kinetics. Among the six used empirical models, Weibull model has been the most fitted model to all the treated samples. Microwave power output and sample weight were found to have an effect on truffles during drying, and consequently on their rehydration capacity. The high samples amount has decreased the effects of microwave drying by decreasing the density of treatment, also, the high-power output has probably reduced the time of evaporation, and thus more preservation to the dried truffles. These results can be taken into consideration for more industrial applications of microwave drying and subsequent rehydration of truffles.

The Influence of Composition and Manufacturing Approach on the Physical and Rehydration Properties of Milk Protein Concentrate Powders.

This study investigated the physical and rehydration properties of milk protein concentrate (MPC) powders with five different protein contents (i.e., 38.9, 53.7, 63.6, 74.1, and 84.7%, w/w) prepared by recombining the ultrafiltration (UF) retentate and UF permeate of skim milk. Powder density and flowability increased, while the powder particle size decreased with decreasing powder protein content. The amount of non-wetting MPC powder decreased with decreasing protein content, demonstrating greater wettability for lower protein powders. At protein contents >65% (w/w), the dispersibility and solubility of the powders decreased significantly, likely due to the greater hydrophobic interactions between casein proteins and a lower concentration of lactose. Therefore, as the protein content of the MPC powders was decreased, their rehydration properties improved. The results obtained in this study provide novel insights into the relationship between the composition of recombined UF retentate and UF permeate streams on the subsequent powder particle size, density, and rehydration properties, and demonstrate that such powders possess similar properties to those prepared using conventional direct membrane filtration.

Impact of Drying on Meso- and Nanoscale Structures of Citrus Fiber: A Study by SFG, ATR-IR, XRD, and DLS

Citrus fibers are a sidestream of the pectin extraction process from citrus peel. This sidestream can be converted into a functional ingredient through a shear-induced homogenization process. One technical challenge with this material is that dehydration and subsequent rehydration result in reduction of viscosity compared to the original product. In this study, various drying methods were compared with never-dried fibers to investigate the structural changes underlying the viscosity loss. Infrared and X-ray diffraction analyses confirmed no changes in chemical composition and crystalline structure of citrus fibers. The dynamic light scattering and sum frequency generation analyses of citrus fiber suspension showed that the rehydration process could not fully disperse aggregated fibers, which appears to be the main cause for the viscosity loss.

Osmotic Dehydration and Assessment of Quality Attributes of Seasonal Vegetable Crops: Carrot and Beetroot Cubes

Fulfilling the food demand of a growing population is the biggest challenge as lot of food globally got wasted due to improper storage and processing. Osmotic dehydration offers high-quality preservation and maintenance of the integrity of fruits & vegetables. Response surface methodology was performed to estimate the main effect of osmotic dehydration process on quality attributes of carrot and beetroot cubes. Higher values of the osmotic solution of salt and sucrose at sample to solution ratio of 1:5 had provoked higher flows of water and solutes through the carrot and beetroot cubes. The range of NaCl concentration varies from 4-12 % w/v in carrot and 12-16 % w/v in beetroot for 2, 4 and 6 hour. However, sucrose concentration varies from 40-60º Brix in both carrot and beetroot. Quality attribute of carrot and beetroot including ascorbic acid, carotenoid, total phenol etc. didn’t changed on recommended process variables 50º Brix of sucrose + 8 % w/v sodium chloride for carrot and 50º Brix of sucrose + 14 % w/v NaCl for beetroot under osmotic dehydration for 4 hours. It was considered to get maximum water loss, weight reduction, subsequent rehydration ratio, overall acceptability and minimum solute gain of rehydrated product. Keywords: Osmotic dehydration; Carrot; Beetroot; Preservation; Response Surface Methodology

Aldol Condensation of Cyclohexanone and Furfural in Fixed-Bed Reactor

Aldol condensation reaction is usually catalysed using homogeneous catalysts. However, the heterogeneous catalysis offers interesting advantages and the possibility of cleaner biofuels production. Nowadays, one of the most used kinds of heterogeneous catalysts are hydrotalcites, which belong to a group of layered double hydroxides. This paper describes the aldol condensation of cyclohexanone (CH) and furfural (F) using Mg/Al mixed oxides and rehydrated mixed oxides in order to compare the catalyst activity after calcination and rehydration, as well as the possibility of its regeneration. The catalysts were synthesized by calcination and subsequent rehydration of the laboratory-prepared and commercial hydrotalcites, with Mg:Al molar ratio of 3:1. Their structural and chemical properties were determined by several analytical methods (inductively coupled plasma analysis (ICP), X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), specific surface area (BET), thermogravimetric analysis (TGA), temperature programmed desorption (TPD)). F-CH aldol condensation was performed in a continuous fixed-bed reactor at 80 °C, CH:F = 5:1, WHSV 2 h−1. The rehydrated laboratory-prepared catalysts showed a 100% furfural conversion for more than 55 h, in contrast to the calcined ones (only 24 h). The yield of condensation products FCH and F2CH was up to 68% and 10%, respectively. Obtained results suggest that Mg/Al mixed oxides-based heterogeneous catalyst is suitable for use in the aldol condensation reaction of furfural and cyclohexanone in a fixed-bed reactor, which is an interesting alternative way to obtain biofuels from renewable sources.

Influence of osmolarity and hydration on the tear resistance of the human amniotic membrane

The amnion is considered to be the load-bearing part of the fetal membranes. We investigated the influence of osmolarity of the testing medium and hydration on its fracture toughness. Mode I fracture tests revealed that physiological variations in the bath osmolarity do not influence the tear resistance of amnion, while larger changes, i.e. from physiological saline solution to distilled water, lead to a significant reduction of the fracture toughness. Uniaxial tensile tests on collagen hydrogels confirmed the reduction in toughness, suggesting that lower bath osmolarity triggers changes in the failure properties of single collagen fibers. Prenatal surgeries, in particular fetoscopic procedures with partial amniotic carbon dioxide insufflation, might result in dehydration of the amnion. Dehydration induced a brittle behavior; however, subsequent rehydration for 15 min resulted in a similar tear resistance as for the fresh tissue.

How do coffee trees deal with severe natural droughts? An analysis of hydraulic, diffusive and biochemical components at the leaf level

We analysed field-grown coffee trees that faced the most severe drought event in the last 28 years in Brazil. Vulnerability curves indicated that water potentials were low enough to decrease leaf hydraulic conductance and carbohydrate content under drought. However, individual tree mortality was not observed indicating a great resilience of coffee to drought stress. Drought affects leaf photosynthesis by acting on hydraulic, diffusive and/or biochemical components. Here, we analysed two field-grown coffee (Coffea arabica L.) cultivars (Catuai and Catimor) subjected to a severe natural drought (the most severe drought event in the last 28 years in Brazil) followed by a subsequent rehydration. We estimated leaf hydraulic vulnerability and found that the leaf water potential under drought reached values that were low enough to cause drastic decreases (up to 90%) in leaf hydraulic conductance (Kleaf) in both cultivars. Such Kleaf loss was associated with a reduced stomatal conductance (gs) under drought (c. 70%) and likely limited gas-exchange recovery upon rainfall as abscisic acid levels and gs were not correlated. Net photosynthesis rates (An) were largely limited by diffusive constraints, with gs explaining c. 90% of the variation in An. Rubisco carboxylation capacity and soluble protein content remained unaltered, in contrast to starch content which was drastically reduced by drought. Soluble sugars were less affected, with hexoses having an apparent role as osmolytes. Even though hydraulics, gas-exchange traits and non-structural carbohydrate pools were negatively affected, coffee trees did not present individual mortality, demonstrating a great resilience to drought events.