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Actualmente, las enzimas inmovilizadas se utilizan en numerosas aplicaciones de la industria alimentaria. Algunas investigaciones usan parametros cineticos aparentes en sistemas reactores con enzima inmovilizada, los cuales estan limitados a esos casos de estudio. Para mejorar la productividad en un reactor de lecho empacado (RLE), se debe establecer una descripcion clara de todos los mecanismos (cinetico, transporte de masa difusivo intra-particula, transporte de masa convectivo fluido-particula y dispersion axial) que afectan el proceso. El objetivo de este estudio fue modelar la isomerizacion de glucosa en un RLE con perlas de alginato de calcio (PAC), usando un enfoque donde los mecanismos cinetico y difusivo son descritos independientemente. Los coeficientes, convectivo de transferencia de masa (kL) y de dispersion axial (Dz), se calcularon de correlaciones. La validacion se realizo al comparar las predicciones contra datos experimentales (R2 = 0.907) de conversion de glucosa a la salida del reactor, en estado estacionario. En las condiciones de estudio, en contraste con el efecto ejercido por el transporte de masa difusivo sobre la productividad especifica de fructosa, el efecto de la dispersion axial y del transporte de masa convectivo es despreciable. Al analizar diversos parametros de operacion, el tamano de particula tuvo el mayor impacto sobre la bioconversion de glucosa. Al reducir el tamano de las PAC aumenta el area superficial y la conversion. Se recomienda probar nuevos agentes inmovilizadores o disminuir el tamano de las PAC, monitoreando que el agente inmovilizador mantenga su estabilidad y funcionalidad.

Modified atmosphere packaging and refrigeration of fruits and vegetables are used to extend their shelf life. The objective of this research was to evaluate quality variables in avocado (Persea americana Mill.) cv. "Hass" during storage in modified atmosphere packaging (MAP) at 8 °C and contrast them to those obtained during storage at room temperature (RT) and refrigeration (REF). Fruits at physiological maturity were stored in MAP bags with a thickness of 0.20 mm. A completely randomized design was used; factors were: type of storage (RT 21 °C, REF 8 °C, and MAP 8 °C), storage time (8, 16, 24, and 32 days), and ripening time after storage (2, 4, and 6 days). Quality variables were firmness (penetration force), total color difference (ΔE) in exocarp and mesocarp (colorimeter), pH (potentiometry), and total soluble solids (TSS, refractometry). Avocados stored in MAP maintained (p > 0.05) firmness, which was higher compared to REF and RT during the storage period. Firmness retention for avocados at RT, REF, and MAP, at day 16, was 5.7, 32.6, and 87.2%, and at day 32, it was 0 (no reading), 9.5, and 78.2%, respectively. Total color difference in exocarp and mesocarp, pH, and TSS ranged from 3.8 to 25.6, 3.2 to 20.3, 6.7 to 7.1, and 5.3 to 7.7 °Brix, respectively. During the storage period, fruits stored at MAP showed a firmness, ΔEexocarp, and ΔEmesocarp similar to those of fresh fruit. Type of storage showed no effect on pH and TSS during the storage period. The package for modified atmosphere at 8 °C allows to prolong the shelf life of “Hass” avocado for a period twice as long as that at room temperature, based on the fact that changes in firmness and color are reduced, properties that are important quality benchmarks.

Spatial conservation prioritization (SCP) is a planning framework used to identify new conservation areas on the basis of the spatial distribution of species, ecosystems, and their services to human societies. The ongoing accumulation of intraspecific genetic data on a variety of species offers a way to gain knowledge of intraspecific genetic diversity and to estimate several population characteristics useful in conservation, such as dispersal and population size. Here, we review how intraspecific genetic data have been integrated into SCP and highlight their potential for identifying conservation area networks that represent intraspecific genetic diversity comprehensively and that ensure the long-term persistence of biodiversity in the face of global change.

Sampling was conducted under the collection permit numbers SGPA/DGVS/02485/13 and SGPA/DGVS/05052/15.; International audience; How environmental and anthropogenic factors influence genetic variation and local adaptation is a central issue in evolutionary biology. The Mexican golden trout (Oncorhynchus chrysogaster), one of the southernmost native salmonid species in the world, is susceptible to climate change, habitat perturbations and the competition and hybridization with exotic rainbow trout (O. mykiss). The present study aimed for the first time to use genotyping-by-sequencing to explore the effect of genetic hybridization with O. mykiss and of riverscape and climatic variables on the genetic variation among O. chrysogaster populations. Genotyping-by-sequencing (GBS) was applied to generate 9767 single nucleotide polymorphisms (SNPs), genotyping 272 O. chrysogaster and O. mykiss. Population genomics analyses were combined with landscape ecology approaches into a riverine context (riverscape genetics). The clustering analyses detected seven different genetic groups (six for O. chryso-gater and one for aquaculture O. mykiss) and a small amount of admixture between aquaculture and native trout with only two native genetic clusters showing exotic introgression. Latitude and precipitation of the driest month had a significant negative effect on genetic diversity and evidence of isolation by river resistance was detected, suggesting that the landscape heterogeneity was preventing trout dispersal, both for native and exotic individuals. Moreover, several outlier SNPs were identified as potentially implicated in local adaptation to local hydroclimatic variables. Overall, this study suggests that O. chrysogater may require conservation planning given (i) exotic introgression from O. mykiss locally threatening O. chryso-gater genetic integrity, and (ii) putative local adaptation but low genetic diversity and hence probably reduced evolutionary potential especially in a climate change context.

The objective of this work was to model the mass transfer in corn tortilla baking using different approaches for effective diffusivity based on the Fick's law of diffusion and to evaluate the impact of the process on quality parameters. The 1st one assumes constant effective diffusivity (method of slopes by subperiods and method of successive approximations) and the 2nd one considers variable effective diffusivity (quadratic function of time and Weibull distribution). In addition, the Weibull distribution was applied to fracturability. The effective moisture diffusivity inside the tortilla during baking is not constant and the estimations generated when considering variable diffusivity with quadratic time and Weibull distribution showed better fits (both, R2= 0.999) to the average moisture content. Quality parameter fracturability was affected by the baking process and the Weibull model adequately described (R2= 0.996) the fracturability behavior. This work will allow an adequate estimation of the concentration profiles and histories for mass transfer operations in products that can be represented as an infinite plate. The obtained analytical solutions with variable diffusivity will help to estimate the optimal conditions of the baking process to achieve the required final moisture content for baked corn tortilla shells. The analytical solutions of the Fick's law of diffusion for the moisture content in products that can be represented as an infinite plate, considering variable diffusivity, can be useful in studies when accurate estimations of effective diffusivity and concentration are needed.

Carbohydrate polymers based on fructose from Agave tequilana Weber var. azul, known as fructans, have a great potential as carriers of drugs due to their chemical structure, which makes them non degradable in the upper digestive tract, but enzymatically degradable in the colon. However, esterification is necessary to obtain hydrophobic compounds capable to preserve drugs at stomach conditions. We esterified fructans with acetyl, lauroyl and palmitoyl moieties for encapsulating ibuprofen as a model drug. Esterification of fructan was confirmed using attenuated total reflectance infrared spectroscopy (ATR-FTIR), while the degree of substitution (DS) was quantified by proton nuclear magnetic resonance (1H-NMR).

Pacific trout Oncorhynchus spp. in western North America are strongly valued in ecological, socioeconomic, and cultural views, and have been the subject of substantial research and conservation efforts. Despite this, the understanding of their evolutionary histories, overall diversity, and challenges to their conservation is incomplete. We review the state of knowledge on these important issues, focusing on Pacific trout in the genus Oncorhynchus. Although most research on salmonid fishes emphasizes Pacific salmon, we focus on Pacific trout because they share a common evolutionary history, and many taxa in western North America have not been formally described, particularly in the southern extent of their ranges. Research in recent decades has led to the revision of many hypotheses concerning the origin and diversification of Pacific trout throughout their range. Although there has been significant success at addressing past threats to Pacific trout, contemporary and future threats represented by nonnativ...

How environmental and anthropogenic factors influence genetic variation and local adaptation is a central issue in evolutionary biology. The Mexican golden trout (Oncorhynchus chrysogaster), one of the southernmost native salmonid species in the world, is susceptible to climate change, habitat perturbations and the competition and hybridization with exotic rainbow trout (O. mykiss). The present study aimed for the first time to use genotyping-by-sequencing to explore the effect of genetic hybridization withO. mykissand of riverscape and climatic variables on the genetic variation amongO. chrysogasterpopulations. Genotyping-by-sequencing (GBS) was applied to generate 9767 single nucleotide polymorphisms (SNPs), genotyping 272O. chrysogasterandO. mykiss. Population genomics analyses were combined with landscape ecology approaches into a riverine context (riverscape genetics). The clustering analyses detected seven different genetic groups (six forO. chrysogaterand one for aquacultureO. mykiss) and a small amount of admixture between aquaculture and native trout with only two native genetic clusters showing exotic introgression. Latitude and precipitation of the driest month had a significant negative effect on genetic diversity and evidence of isolation by river resistance was detected, suggesting that the landscape heterogeneity was preventing trout dispersal, both for native and exotic individuals. Moreover, several outlier SNPs were identified as potentially implicated in local adaptation to local hydroclimatic variables. Overall, this study suggests thatO. chrysogatermay require conservation planning given i) exotic introgression fromO. mykisslocally threateningO. chrysogatergenetic integrity, and ii) putative local adaptation but low genetic diversity and hence probably reduced evolutionary potential especially in a climate change context.

The objective of this work was to simulate heat transfer during blanching (90 °C) and hydrocooling (5 °C) of broccoli florets (Brassica oleracea L. Italica) and to evaluate the impact of these processes on the physicochemical and nutrimental quality properties. Thermophysical properties (thermal conductivity [line heat source], specific heat capacity [differential scanning calorimetry], and bulk density [volume displacement]) of stem and inflorescence were measured as a function of temperature (5, 10, 20, 40, 60, and 80 °C). The activation energy and the frequency factor (Arrhenius model) of these thermophysical properties were calculated. A 3-dimensional finite element model was developed to predict the temperature history at different points inside the product. Comparison of the theoretical and experimental temperature histories was carried out. Quality parameters (firmness, total color difference, and vitamin C content) and peroxidase activity were measured. The satisfactory validation of the finite element model allows the prediction of temperature histories and profiles under different process conditions, which could lead to an eventual optimization aimed to minimize the nutritional and sensorial losses in broccoli florets.

The objective of this work was to model the mass transfer in corn tortilla baking using different approaches for effective diffusivity based on the Fick's law of diffusion and to evaluate the impact of the process on quality parameters. The 1st one assumes constant effective diffusivity (method of slopes by subperiods and method of successive approximations) and the 2nd one considers variable effective diffusivity (quadratic function of time and Weibull distribution). In addition, the Weibull distribution was applied to fracturability. The effective moisture diffusivity inside the tortilla during baking is not constant and the estimations generated when considering variable diffusivity with quadratic time and Weibull distribution showed better fits (both, RThe analytical solutions of the Fick's law of diffusion for the moisture content in products that can be represented as an infinite plate, considering variable diffusivity, can be useful in studies when accurate estimations of effective diffusivity and concentration are needed.

International audience; Aim: We explored the factors between riverscape features and exotic introgression of cultured rainbow trout (Oncorhynchus mykiss) that drive the current genetic structure in the endemic Mexican golden trout (Oncorhynchus chrysogaster) using a riverscape genetics simulator. Location: Sierra Madre Occidental, Northwest Mexico, North America. Methods: We created a system model for Mexican golden trout to test various scenarios for the effect of riverscape resistance and rainbow trout introgression on the native genetic structure of the Mexican golden trout. Individual genotypes were used to initialize the model and were based upon empirical allele frequencies from three genetically and spatially distinct groups in the study area. The geographical location of the simulated populations was defined using a species distribution model. We included hypotheses for movement of riverine distance and riverscape resistance. We evaluated model performance by conducting population and landscape genetics analyses on the simulation outputs. Results: The most plausible scenario included riverscape resistance without introgression, which presented a spatial genetic structure matching the observed riverscape genetic structure and fitting expected general life-history patterns for high elevation trout streams. In addition, temperature, precipitation, hydrology and topography were the most important variables influencing species occurrence and dispersal. Main conclusion: This work presents one of the first empirically derived simulation studies of introgression. It highlights the importance of considering riverscape resistance (i.e. hydroclimatic and topographical gradient effects) in models of spatial genetic structure and introgression. Moreover, our modelling suggests that what we characterize as riverscape resistance is acting as a boundary against exotic introgression. The results of this study could help to develop management strategies that preserve native gene pools.

The Mexican native trout complex is the group of salmonids that naturally has the southernmost distribution in the world. Despite its unique status and evidence of more than 13 distinct lineages, there are only two described species (Oncorhynchus mykiss nelsoni and O. chrysogaster). These fishes are threatened by environmental and anthropogenic factors, most notably the introduction of the exotic species O. mykiss (rainbow trout) for aquaculture. Here we applied population genetics analysis in 1,017 wild and cultured trout to understand the extent of genetic introgression of rainbow trout in Mexican native trout. Present results indicate a high degree of introgression and genetic admixture among introduced rainbow trout and some populations of Mexican native trout, exposing them to loss of genetic diversity. Thus, introduction of exotic trout for aquaculture purposes must be strictly regulated or avoided and we advise the use of native trout for aquaculture.

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