Microstructural modification of papaya tissue during calcium diffusion: Effects on macrostructure level.

The microstructural changes in papaya tissue during calcium diffusion, the effect on drying kinetics and texture parameters were investigated. Calcium pretreatment was applied to papaya samples for 3 h, at a solution concentration of 1.5 g Ca(OH)2/100 mL H2O, and a solution temperature of 25 °C; subsequently, the samples were convectively dried at 70 °C, air flow of 1.5 m/s, and a relative humidity of 5 ± 2%. Calcium content was determined using the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) technique, the microstructure of the samples was analyzed by High-Resolution Scanning Electron Microscopy (HR-SEM), and the elementary analysis was performed by Energy-Dispersive X-ray Spectroscopy (EDS). Effective diffusivity of calcium (DefCa) and moisture (Defw) were calculated during pretreatment and drying, respectively and texture parameters were determined by double compression using a texturometer. The transport mechanism determined during calcium pretreatment was diffusion with a DefCa = 3.10 × 10-10 m2/s. Also, branched calcium microstructures in the cell walls of tissue were observed due to the calcium effect, it was supported by elemental analysis, which showed an increase of calcium in section restructured compared to non-restructured. During drying, Defw = 1.86 × 10-9 m2/s was higher in pretreated compared to non-pretreated samples with Defw = 1.17 × 10-9 m2/s, indicating a higher drying rate and moisture loss. The texture values changed significantly (α ≤ 0.05) due to calcium pretreatment and drying; the calcium microstructures caused higher cohesiveness, springiness, gumminess, and chewiness. Calcium modifies the microstructure and composition of papaya tissue; therefore, drying kinetics and texture parameters depend on this modification.

Techno-functional properties and antioxidant capacity of the concentrate and protein fractions of Leucaena spp. seeds / Propiedades tecno-funcionales y capacidad antioxidante del concentrado y fracciones proteicas de semillas de Leucaena spp

Introduction: The use of vegetable proteins as ingredients in food systems is based on their functional properties. The water and oil holding capacity, foaming, and emulsifying capacity/stability, and antioxidant assay of the protein fractions - albumins, globulins 7S/11S, glutelins and prolamins - isolated from Leucaena seed were evaluated. Objective: The objective of this study was to evaluate the functional properties and antioxidant capacity of the concentrate and protein fractions of ripe Leucaena spp. seeds. Materials and methods: Ripe Leucaena seeds were collected and evaluated in Oaxaca, Mexico (16°59'21''N 96°43'26''O) during the months of February-April 2021.The protein concentrate was isolated by isoelectric precipitation (pH=9, pH=4). The albumins, globulins, glutelins and prolamins were isolated based on their solubility properties in different extracting solutions. Results: Glutelins constituted the main protein fraction (75.88%). Prolamins were not found. The glutelins fractions showed the highest oil holding capacity (0.93±0.08 mL g-1). The albumins fraction had the highest water holding capacity (2.53±0.15 mL g-1), foaming capacity and foam stability (71.83±1.26 % and 70.00±0.00%, respectively) and antioxidant capacity (18.09±0.88%). The globulins exhibited the highest emulsifying capacity and emulsion stability (56.83±1.76% and 55.67±1.20%, respectively). Conclusions: The concentrate and protein fraction of Leucaena seeds showed different techno-functional and antioxidant properties of interest for the food industry, like those showed by other commercial vegetable proteins(AU)

Introducción: El uso de proteínas vegetales como ingredientes en sistemas alimentarios se basa en sus propiedades funcionales. Se evaluó la capacidad de retención de agua y aceite, la capacidad/estabilidad espumante y emulsionante y el ensayo antioxidante de las fracciones proteicas -albúminas, globulinas 7S/11S, glutelinas y prolaminas- aisladas de las semillas de Leucaena. Objetivo: El objetivo de este estudio fue evaluar las propiedades funcionales y la capacidad antioxidante del concentrado y las fracciones proteicas de las semillas maduras de Leucaena spp. Materiales y métodos: Las semillas maduras de Leucaena fueron recolectadas y evaluadas en Oaxaca, México (16°59'21''N 96°43'26''O) durante los meses de febrero-abril del año 2021. Se usó harina de Leucaena desgrasada para la preparación de las fracciones proteicas. El concentrado proteico se aisló por precipitación isoeléctrica (pH=9, pH=4). Las albúminas, globulinas, glutelinas y prolaminas se aislaron en función de sus propiedades de solubilidad en diferentes soluciones de extracción. Resultados: Las glutelinas constituyeron la principal fracción proteica (75,88%). No se encontraron prolaminas. La fracción de glutelinas mostró la mayor capacidad de retención de aceite (0.93±0,08 mL g-1). La fracción de albúminas presentó la mayor capacidad de retención de agua (2,53±0,15 mL g-1), capacidad espumante y estabilidad de la espuma (71,83±1,26% y 70,00±0,00%, respectivamente) y capacidad antioxidante (18,09±0,88%). Las globulinas mostraron la mayor capacidad emulsionante y estabilidad de la emulsión (56,83±1,76 y 55,67±1,20%, respectivamente). Conclusiones: El concentrado y las fracciones proteicas de las semillas de Leucaena mostraron diferentes propiedades tecno-funcionales y antioxidantes de interés para la industria alimentaria, similares a los reportados por diversas proteínas vegetales comerciales(AU)

Influence of osmotic pretreatments on the quality properties of deep-fat fried green plantain.

Modification of the surface properties of materials is a promising approach to reduce the uptake of oils during frying. In this work, the quality characteristics of plantain chips subjected to a pretreatment consisting of osmotic drying in sugar solutions (29 and 45° Brix; 40 and 80 °C) were evaluated. True density, apparent density, porosity and moisture content were measured in pretreated samples (PS) before frying. Image ESEM was used to evaluate microstructural changes on the surface and in cross-sections at different depths. Global oil absorption (GOA) and fatty acid profile were monitored in surface and deep cross-sections (DCS). The color parameters of chips (L*, a*, b*, ΔE), browning index, crispness, crunchiness and hardness were evaluated during frying. Oil absorption in the crust was lower in samples subjected to pretreatments with a higher temperature. PS showed high gelatinization in both the surface and DCS, thus changing crust physical properties, total oil uptake and fatty acid profile. An exponential correlation between porosity (ε) and GOA was found, while a second order correlation was found between ε and the fatty acid profile. The characteristics of texture and color, as desired by the consumer, were reached more quickly in the PS at 29° Brix and 40 °C.

Solute Transfer in Osmotic Dehydration of Vegetable Foods: A Review.

While various mechanisms have been proposed for the water transfer during osmotic dehydration (OD), little progress has been made to understand the mechanisms of solute transfer during osmotic dehydration. The transfer of solutes has been often described only by the diffusion mechanism; however, numerous evidences suggest the participation of a variety of mechanisms. This review deals with the main issues of solute transfer in the OD of vegetables. In this context, several studies suggest that during OD of fruits and vegetables, the migration of solutes is not influenced by diffusion. Thus, new theories that may explain the solute transport are analyzed, considering the influence of the plant microstructure and its interaction with the physicochemical properties of osmotic liquid media. In particular, the surface adhesion phenomenon is analyzed and discussed, as a possible mechanism present during the transfer of solutes in OD.

Convective drying kinetics of strawberry (Fragaria ananassa): Effects on antioxidant activity, anthocyanins and total phenolic content.

The thermal drying effects on strawberries were investigated in terms of the kinetics of antioxidant activity (AA), anthocyanins (A) and total phenolic compound content (TPC), as well as the final colour. The evaluated drying temperatures were 50 and 60°C with an air rate of 1.5m/s. The 2,2-diphenyl-2-picryl-hydrazyl, pH differential and Folin-Ciocalteu methods were used to assess the antioxidant properties. The kinetics of TPC and AA showed an initial and final period of degradation attributed to inhibition of enzymes. A plateau between these two periods suggests that under certain conditions of temperature and water content, no degradation reactions occurred. Final losses of up to 74, 45 and 78% were found for AA, A and TPC, respectively. The total colour change (ΔE) was lesser degree at 60 than 50°C. Thermal degradation of the antioxidant compounds followed a first-order reaction kinetics and the degradation rate constants (k) were calculated.

Regulatory T Cells: Molecular Actions on Effector Cells in Immune Regulation.

T regulatory cells play a key role in the control of the immune response, both in health and during illness. While the mechanisms through which T regulatory cells exert their function have been extensively described, their molecular effects on effector cells have received little attention. Thus, this revision is aimed at summarizing our current knowledge on those regulation mechanisms on the target cells from a molecular perspective.

True Density Prediction of Garlic Slices Dehydrated by Convection.

Physiochemical parameters with constant values are employed for the mass-heat transfer modeling of the air drying process. However, structural properties are not constant under drying conditions. Empirical, semi-theoretical, and theoretical models have been proposed to describe true density (ρp). These models only consider the ideal behavior and assume a linear relationship between ρp and moisture content (X); nevertheless, some materials exhibit a nonlinear behavior of ρp as a function of X with a tendency toward being concave-down. This comportment, which can be observed in garlic and carrots, has been difficult to model mathematically. This work proposes a semi-theoretical model for predicting ρp values, taking into account the concave-down comportment that occurs at the end of the drying process. The model includes the ρs dependency on external conditions (air drying temperature (Ta)), the inside temperature of the garlic slices (Ti ), and the moisture content (X) obtained from experimental data on the drying process. Calculations show that the dry solid density (ρs ) is not a linear function of Ta, X, and Ti . An empirical correlation for ρs is proposed as a function of Ti and X. The adjustment equation for Ti is proposed as a function of Ta and X. The proposed model for ρp was validated using experimental data on the sliced garlic and was compared with theoretical and empirical models that are available in the scientific literature. Deviation between the experimental and predicted data was determined. An explanation of the nonlinear behavior of ρs and ρp in the function of X, taking into account second-order phase changes, are then presented.

Ideación suicida y grupo de iguales: análisis en una muestra de adolescentes venezolanos / Suicide Ideation and Peers Group: Analysis of a Venezuelan Adolescents Sample

El objetivo de este estudio fue determinar un modelo de relaciones para predecir la ideación suicida de adolescentes escolarizados. Se propuso un modelo basado en la conducta suicida de los iguales, el apoyo del padre y de la madre, la violencia familiar y la depresión. La muestra estuvo conformada por 912 sujetos. Los resultados obtenidos mediante un path analysis indican que los adolescentes con síntomas de depresión optan por amigos con conductas suicidas y estos, además, aumentan directamente la probabilidad de ideación suicida.

The goal of this study was to determine a model of relationship in order to predict school-age adolescents suicide ideation. A model based on peers' suicidal behavior, father and mother's support, family violence and depression was proposed. A sample of 912 subjects was used. The results through path analysis suggest that teenagers with depression symptoms prefer relating with friends who show suicidal behavior.