Rehydration Capacity of Chilean Papaya (Vasconcellea pubescens): Effect of Process Temperature on Kinetic Parameters and Functional Properties

Slabs of Chilean papaya hot air-dried at 60 °C were rehydrated at 20, 40, 60, and 80 °C to study the influence of process temperature on mass transfer kinetics during rehydration. Diffusive and empirical models were selected to simulate the experimental rehydration curves. All models parameters showed dependence with temperature, thus activation energy could be estimated according to an Arrhenius-type equation. Among the applied models, Weibull provided the best fit for each rehydration curve based on the statistical tests RMSE, SSE, and chi-square. According to these results, this model could be used to estimate the rehydration time of Chilean papaya. In addition, rehydration ratio and water-holding capacity were analyzed. Both indices showed a decrease with increasing rehydration temperature indicating modification of the papaya cell structure due to thermal treatment which resulted in a reduction of the rehydration ability, in particular at high rehydration temperatures.     

Studies on polymeric conservation treatments of ceramic tiles with Paraloid B‐72 and two alkoxysilanes

The aim of this study was to evaluate the effect of different polymeric protections applied on ceramic tiles on their mechanical and water absorption properties. Three conservation products were used: the acrylic polymer Paraloid B‐72 and two alkoxysilane‐based formulations (tetraethoxysilane (TEOS) and IN2210, a polidimetilsiloxane‐based formulation). The coatings were applied onto handmade tiles manufactured according to a 18th century procedure. Different application procedures (immersion, brushing, and spraying) were tested. The protection effectiveness was assessed through capillary water absorption and four point bending tests. The mineralogical characterization of tiles was undertaken by XRD. The best protective properties of the tiles were achieved by immersion treatments with Paraloid B‐72 based on the protocols followed by the museums restoration departments. Nevertheless, the results of the present work show that the second immersion in Paraloid B‐72 solution, commonly made, can be eliminated, as it does not provide any significant increase in the hydrophobic or mechanical properties of the tiles. As a result, there are obvious economical benefits, as the coating process became less time‐consuming and more environmental friendly, as the amount of organic compounds is reduced. On the other hand, the use of small volumes of Paraloid B‐72 solution applied by brush, or IN2210 sprayed can provide good results, if the only purpose of the treatment is the increase of the hydrophobic properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Changes in maize starch water sorption isotherms caused by high pressure

The effect of high pressure (300 MPa, for up to 60‐min duration) on water sorption (adsorption and desorption) properties of maize starch suspensions was studied. Increase in the pressurisation time (5–60 min) augmented linearly the water‐holding capacity of starch by 2.7‐fold. Adsorption and desorption isotherms moved to higher moisture contents with the increment of pressurisation time. These movements caused the hysteresis effect extent to decrease/increase with the pressurisation time for lower/higher water activity values. While no particular tendency was found for the effect of pressurisation time on energy‐related constants, Cb (BET) and Cg (GAB), the K value decreases linearly, being always higher for sorption. The monolayer value obtained using the BET model was lower compared with the GAB model, increasing linearly in both cases with the pressurisation time. The results obtained in this study are of possible technological importance for food products containing starch.     

Morphological characterization of the growing front of Rhizopus oligosporus in solid media

Rhizopus oligosporus is used to prepare tempeh and is formed by hyphae which grow as a complex branched structure with irregular borders. The objective of this research was to characterize the macro and micro structural development of R. oligosporus colonies growing on solid media in Petri dishes through image processing and fractal dimension. Stereomicroscope images of the colony were used to detecting the zone in which the fractal dimension (FDE) of the edge (growing front) of the colony represented 97% of the maximum FDE for the 80% of the image of the border. Evaluated characteristics were: radial growth, number of tips in the growing front and the average length of hypha. Two simultaneous events of different and oscillating magnitude were detected in the growing front: branching and increase of the average hypha length. Biomass had a good correlation with radius of the colony, fractal dimension of texture (FDT) and number of tips in the border.     

Quality Characterization of Celery (Apium graveolens L.) by Plant Zones and Two Harvest Dates

Abstract: The aim of this study was to characterize the quality of celery petioles (Apium graveolens L. cv Golden Clause) from the external, middle, and internal zones of each plant. Harvest dates were 93 (HD1) and 124 (HD2) days after transplantation. Total weight (TW), total length (TL), total leaves number (LN), and petiole length of leaves (PL) for the 3 zones were measured. Physicochemical (color, b* and h; texture; total soluble solids, TSS; titratable acidity, TA; water content, WC), nutraceutical (ascorbic acid, AA; total quinones, TQ; browning potential, BP), and sensorial analysis (flavor, fibrosity, crunchiness) were done at harvest on petioles of each zone. No differences between harvesting dates were found in TW, TL, LN, and PL. Middle leaves had the highest PL. Harvest dates were not different in b*, h, TA, AA, and WC. Texture, TSS, BP, and TQ resulted higher in petioles of HD2 than in HD1. Similar TSS and TA were found in leaves of different plant zones. The yellow color of both external and internal zones was significantly higher than in the middle zone. The texture and BP was similar between the external and middle zones but the WC was lower in the external zone. Similarly, the AA content as well as the TQ was also lower than in the middle zone. Harvest delay improved the nutraceutical value in terms of BP and TQ, even though it also resulted in pithiness and fibrosity of the leaves. This study therefore suggests that the petioles of the middle zone when harvested at HD1 are the most suitable for consumption. Practical Application: Celery is a vegetable reduced in calories, has a high nutritional value and its fresh petioles are mainly consumed in salads. The texture and flavor are the most important attributes that define consumers’ acceptability. As nutritional value, texture, and flavor may change with plant age and different zones of the plant, harvest date plays an important role on quality. Results indicate that harvest delay improved the nutraceutical value even though it also resulted in pithiness and fibrosity of the stalks. Petioles of the middle zone, when harvested at 93 d after transplanting, are the most suitable for consumers’ consumption.     

Investigation of the composition-dependent properties of BaTi1−xZrxO3 ceramics prepared by the modified Pechini method

Single phase and dense BaTi_1?xZr_xO₃ (BTZ) ceramics (x = 0.10, 0.15 and 0.20) were obtained from nanopowders synthesised by the modified Pechini method. The evolution of both Raman spectra and low-field dielectric properties against temperature indicated the occurrence of diffuse ferroelectric–paraelectric phase transitions for all the BTZ compositions under investigation. The evolution of first-order reversal curves (FORC) diagrams emphasised the crossover from the ferroelectric towards the relaxor state as the Zr content increased. Lower values of the Curie temperatures than those usually reported earlier in the literature were obtained for all the BTZ samples analysed here. The high-field tunability data completed the low-field and Raman results, showing that by increasing Zr addition, multiple polarisation components with various weights are responsible for the dielectric and ferroelectric properties.     

Attenuated effects of chitosan-capped gold nanoparticles on LPS-induced toxicity in laboratory rats

The impact of nanoparticles in medicine and biology has increased rapidly in recent years. Gold nanoparticles (AuNP) have advantageous properties such as chemical stability, high electron density and affinity to biomolecules. However, the effects of AuNP on human body after repeated administration are still unclear. Therefore, the purpose of the present study was to evaluate the effects of gold-11.68 nm (AuNP1, 9.8 μg) and gold-22.22 nm (AuNP2, 19.7 μg) nanoparticles capped with chitosan on brain and liver tissue reactivity in male Wistar rats exposed to lipopolysaccharide (LPS from Escherichia coli serotype 0111:B4, 250 μg) upon 8 daily sessions of intraperitoneal administration. Our results suggest that the smaller size of chitosan-capped AuNP shows the protective effects against LPS-induced toxicity, suggesting a very high potential for biomedical applications.     

Experiences in a Modeling Laboratory: Didactic Exhibit curated by the Istituto Statale d’Arte di Monza in collaboration with the Liceo Artistico di Busto Arsizio

The model-building laboratory, more than just a place for building models, is a place of study, research, thought processes, and ideation; the place where the acquisition and transmission of knowledge constitutes a fundamental method for growth both for the students as well as the instructors; the place where disciplines are not always considered akin can meet and be compared. Architecture and mathematics come together in this exhibit for Nexus 2000 at the Museum of Architecture (MusArc) in Ferrara, Italy.