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Chemical and physical properties of aloe vera (Aloe barbadensis Miller) gel stored after high hydrostatic pressure processing.

Autores:

Scala, K., Vega-Gálvez, A., Ah-Hen, K., Nuñez-Mancilla, Y., Tabilo-Munizaga, G., Pérez-Won, M., & Giovagnoli, C.

Resumen:

The aim of this study was to evaluate the influence of high hydrostatic pressure (150, 250, 350, 450, and 550 MPa), applied for 5 minutes, on antioxidant capacity, total phenolic content, color, firmness, rehydration ratio, and water holding capacity of aloe vera gel stored for 60 days at 4 °C. The analyzed properties of the pressurized gel showed significant changes after the storage period. The highest value of total phenolic content was found at 550 MPa. However, a decrease in the antioxidant capacity was observed for all pressurized gel samples when compared to the control sample (p < 0.05). The smallest changes in product color were observed at pressure levels between 150 and 250 MP. The application of high hydrostatic pressure resulted in lower gel firmness, and the lowest value was found at 150 MPa (p < 0.05). On the other hand, the untreated sample showed a greater decrease in firmness, indicating that high pressure processing preserves this property. The application of high hydrostatic pressure exhibited modifications in the food matrix, which were evaluated in terms of rehydration ratio and water holding capacity.

Año: 2013

Palabras claves: Antioxidant capacity; total phenolics; quality; aloe vera.

Referencia APA: Scala, K., Vega-Gálvez, A., Ah-Hen, K., Nuñez-Mancilla, Y., Tabilo-Munizaga, G., Pérez-Won, M., & Giovagnoli, C. (2013). Chemical and physical properties of aloe vera (Aloe barbadensis Miller) gel stored after high hydrostatic pressure processing. Food Science And Technology (Campinas), 33(1), 52-59.

Quality Characterization of Waste Olive Cake During Hot Air Drying: Nutritional Aspects and Antioxidant Activity.

Autores:

Uribe, E., Lemus-Mondaca, R., Vega-Gálvez, A., López, L., Pereira, K., & López, J., Ah-Hen, K., Di Scala, K.

Resumen:

Olive cake, a by-product of the olive oil industry, was characterised through a drying process, where the influence of air drying temperature on physicochemical properties and antioxidant activity was investigated. A comparison of fresh and dehydrated olive cake showed that drying led mainly to denaturation of crude protein. Crude fibre content showed a slight increase during drying and may have undergone some alterations in its structure due to Maillard reactions. Fatty acid analysis revealed that olive cake was especially rich in oleic acid and fatty acid composition did not significantly change during drying. Ash content also showed a slight variation but may be considered as practically unchanged. Potassium and sodium were respectively the most and the least abundant minerals found in olive cake. Total phenolic content showed a direct relationship to DPPH radical scavenging activity. Overall antioxidant activity, highest in fresh olive cake, was affected by air drying temperatures being more evident at 90 °C. Vitamin E showed an increasing trend at all drying temperatures. According to this investigation, convective dehydration can lead not only to a dried olive cake that can be used as a material for many processing industries (e.g. food and cosmetic) but also can contribute to minimize the environmental impacts of this agro-industrial waste.

Año: 2013

Palabras claves: Olive cake, Convective dehydration, Phenolic compounds, DPPH, Antioxidant activity, Vitamin E.

Referencia APA: Uribe, E., Lemus-Mondaca, R., Vega-Gálvez, A., López, L., Pereira, K., & López, J., Ah-Hen, K., Di Scala, K. (2013). Quality Characterization of Waste Olive Cake During Hot Air Drying: Nutritional Aspects and Antioxidant Activity. Food Bioprocess Technol, 6(5), 1207-1217.

Effect of Rehydration Temperature on Functional Properties, Antioxidant Capacity and Structural Characteristics of Apple ( Granny Smith ) Slices in Relation to Mass Transfer Kinetics.

Autores:

Zura-Bravo, L., Ah-Hen, K., Vega-Gálvez, A., García-Segovia, P., & Lemus-Mondaca, R.

Resumen:

Apple slices dried at 60C were rehydrated at 20, 40 and 60C to analyze the influence of processing temperature on quality attributes and rehydration kinetics. Diffusion coefficient increased with process temperature from 1.36 to 2.37 × 10−9 m2/s. The Weibull model obtained the best fit quality for the experimental data based on statistical test, chi square. Color was not recovered during rehydration and the results indicated that the use of low temperatures is more adequate. Water-holding capacity decreased, while rehydration ratio increased with increasing rehydration temperature, indicating structural modifications. Increasing rehydration temperatures led to a reduction in the glass transition temperature and hardness values of samples. The radical-scavenging activity showed higher antioxidant activity at higher rehydration temperatures rather than at lower temperatures. It was found that rehydration temperature modifies the cell structure and antioxidant capacity of final product.

Año: 2013

Palabras claves:

Referencia APA: Zura-Bravo, L., Ah-Hen, K., Vega-Gálvez, A., García-Segovia, P., & Lemus-Mondaca, R. (2013). Effect of Rehydration Temperature on Functional Properties, Antioxidant Capacity and Structural Characteristics of Apple (Granny Smith) Slices in Relation to Mass Transfer Kinetics. Journal Of Food Process Engineering, n/a-n/a.

Combined Infrared-Convective Drying of Murta ( Ugni molinae Turcz) Berries: Kinetic Modeling and Quality Assessment.

Autores:

Puente-Díaz, L., Ah-Hen, K., Vega-Gálvez, A., Lemus-Mondaca, R., & Scala, K.

Resumen:

Murta (Ugni molinae Turcz) berries were dried under convective and combined convective-infrared conditions at 40, 50 and 60°C and 400–800 W in order to determine the drying characteristics and to compare the dried product's quality. To model the drying kinetics, seven mathematical equations were fitted to experimental data. According to statistical tests performed, the Midilli-Kuçuk model best fitted experimental data and was closely followed by the logarithmic model. Effective moisture diffusivity also showed dependency on drying conditions and varied between 7.59 × 10−10 to 44.18 × 10−10 m2/s and 11.34 × 10−10 to 85.41 × 10−10 m2/s for air-convective drying and combined infrared-convective drying. As to quality attributes of the berries, total surface color difference (ΔE) and total phenolic content (TPC) were determined. It was found that chromaticity coefficients a* and b* changed significantly, showing ΔE to be dependent on the mode of heat supply. TPC under all drying conditions decreased and was significantly different from the initial value in fresh samples. However, at a constant drying temperature, an increase in infrared power enhanced retention of TPC in samples. In particular, working at 40°C/800 W resulted in dried samples with the highest TPC.

Año: 2013

Palabras claves: Drying kinetics modeling, Infrared drying, Murta berries, Quality of dried fruit.

Referencia APA: Puente-Díaz, L., Ah-Hen, K., Vega-Gálvez, A., Lemus-Mondaca, R., & Scala, K. (2013). Combined Infrared-Convective Drying of Murta (Ugni molinae Turcz) Berries: Kinetic Modeling and Quality Assessment. Drying Technology, 31(3), 329-338.

Morphogenesis by mass movements in western Andes (Chile).

Autores:

Novoa Jerez, J.

Resumen:

Numerous examples of mass movements on slopes of western Andes and related landforms are analyzed. Regionalization of the country is fulfilled, taking into account climatic and hydrologic factors. 9 regions were distinguished with more or less similar physical-geographical conditions for mass movements’ development. Recommendations are suggested concerning future investigations in the field of mass movements risk under the rising anthropogenic impact.

Año: 2013

Palabras claves: ground mass movements, slope, morphogenesis, the Andes, zoning, risk, danger, anthropogenic impact.

Referencia APA: Novoa Jerez, J. (2013). Morphogenesis by mass movements in western Andes (Chile). Geomorfologiâ (Mosk.), (2), 81

Use of 222 radon as a simple tool for surface water-groundwater connectivity assessment: a case study in the arid Limarí basin, north-central Chile.

Autores:

Oyarzún, R., Jofré, E., Maturana, H., Oyarzún, J., & Aguirre, E.

Resumen:

We report the results from a pilot study on the use of 222Rn (222radon) for river–aquifer interaction assessment in the Limarí watershed, north-central Chile. Previous studies on this tool for such applications are not abundant at international level, and no records exist for Chile. The lowest 222Rn levels (less than 1000 Bq/m3) were found in water reservoirs, thus indicating that this isotope is easily lost (and therefore usually absent) in surface waters. Conversely, the highest levels of 222Rn were found in groundwater, with maxima activities around 20 000 Bq/m3. This remarkable contrast allowed clear identification of zones of surface water–groundwater connectivity in the searched watershed domain.

Año: 2013

Palabras claves: Environmental tracer; radioactive isotope; watershed hydrology.

Referencia APA: Oyarzún, R., Jofré, E., Maturana, H., Oyarzún, J., & Aguirre, E. (2013). Use of 222 radon as a simple tool for surface water-groundwater connectivity assessment: a case study in the arid Limarí basin, north-central Chile. Water And Environment Journal, n/a-n/a.

Influence of Pacific Ocean multidecadal variability on the distributional properties of hydrological variables in north-central Chile.

Autores:

Núñez, J., Rivera, D., Oyarzún, R., & Arumí, J.

Resumen:

This paper addresses the relationship between multitemporal variability and regime shifts in the Pacific Decadal Oscillation and El Niño Southern Oscillation, with precipitation and streamflows in Andean watersheds of the north-central region of Chile. In addition, an analysis of the effect of a regime shift displayed by annual streamflow records on their distributional properties is performed. By applying empirical fluctuation processes to monthly standardized PDO, Niño 3.4, precipitation and streamflow time series, the occurrence of a regime shift in the streamflow series, consistent with that for PDO, but highly dependent on the latitude of particular watersheds, is shown. No regime shift is detected for the precipitation time series. Using the ensemble Empirical Mode Decomposition procedure on all series, a relationship between climatic indices and hydrological variables in two main modes is determined: the former associated with a mean period of quasi 1.5–3 years related to interannual variability, and the latter with a mean period of quasi 30–35 years, related to decadal low frequency variability. Using the regional frequency analysis based on the L-moments procedure, it is found that the distributional properties of streamflow records are influenced by the phases of the PDO, with changes that affect the mean, L-CV, L-skewness and L-kurtosis in three identified homogeneous regions. The importance of incorporating low-frequency climate variability for distributional analysis and the implications of these results for water resources management and planning in north-central Chile and similar areas is discussed.

Año: 2013

Palabras claves: Climate variability; Distributional analysis; L-moments; Pacific Decadal Oscillation; Empirical Mode Decomposition.

Referencia APA: Núñez, J., Rivera, D., Oyarzún, R., & Arumí, J. (2013). Influence of Pacific Ocean multidecadal variability on the distributional properties of hydrological variables in north-central Chile. Journal Of Hydrology, 501, 227-240.

Long-term monitoring of mammals in the face of biotic and abiotic influences at a semiarid site in north-central Chile.

Autores:

Kelt, D., Meserve, P., Gutiérrez, J., Milstead, W., & Previtali, M.

Resumen:

The data set covers a 16-year period (1989–2005) of monthly small-mammal surveys and associated habitat and environmental data. Small mammals are trapped every month on all experimental plots, and both ephemeral and perennial plant cover and soil seed bank composition are measured at regular intervals. Rainfall is recorded and compiled annually (through 1998) or monthly; information on captured small mammals and on all vegetative and rainfall data is contained in associated files. These data have been applied to diverse population- and community-level analyses and remain useful for investigations of population dynamics, species interactions, and the relative influence of biotic and abiotic factors. Sampling is ongoing, and data will be added over time.

Año: 2013

Palabras claves: Biotic vs. abiotic interactions; climate; competition; ENSO; ephemeral plant cover; LTREB data; predation; semiarid ecosystem; shrub cover; small mammals.

Referencia APA: Kelt, D., Meserve, P., Gutiérrez, J., Milstead, W., & Previtali, M. (2013). Long-term monitoring of mammals in the face of biotic and abiotic influences at a semiarid site in north-central Chile. Ecology, 94(4), 977-977.

Osmotic dehydration under high hydrostatic pressure: Effects on antioxidant activity, total phenolics compounds, vitamin C and colour of strawberry (Fragaria vesca).

Autores:

Nuñez-Mancilla, Y., Pérez-Won, M., Uribe, E., Vega-Gálvez, A., & Di Scala, K.

Resumen:

Simultaneous application of osmotic dehydration under high hydrostatic pressure conditions of strawberries was studied with the purpose of analyzing the effect of the combined process on the antioxidant capacity, phenolic compounds, colour and vitamin C of strawberries during refrigerated storage. The osmotic solution was prepared using commercial sugar at 40 °Brix. Samples were pressurized between 100 and 500 MPa for 10 min. The radical scavenging activity showed higher antioxidant activity at 400 MPa rather than at low pressure (100, 200 and 300 MPa). The total phenolic content increased with pressure presenting a maximum at 400 MPa. Pressurized samples retained vitamin C content. Based on these results, working at 400 MPa for 10 min ensures physicochemical and high levels of nutritional parameters in osmo-dried strawberries.

Año: 2013

Palabras claves: Osmotic dehydration; High hydrostatic pressure; Antioxidant capacity; Total phenolic content; Colour; Vitamin C; Strawberry

Referencia APA: Nuñez-Mancilla, Y., Pérez-Won, M., Uribe, E., Vega-Gálvez, A., & Di Scala, K. (2013). Osmotic dehydration under high hydrostatic pressure: Effects on antioxidant activity, total phenolics compounds, vitamin C and colour of strawberry (Fragaria vesca). LWT - Food Science And Technology, 52(2), 151-156.

The ecology, distribution and conservation status of Myrcianthes coquimbensis : a globally endangered endemic shrub of the Chilean Coastal Desert

Autores:

García-Guzman, P., Loayza, A., Carvajal, D., Letelier, L., & Squeo, F.

Resumen:

The current distribution of M. coquimbensis extends along 82.8 km of the Chilean coast, where the species is mainly threatened by habitat loss. Only 13% of the individuals flowered during 2010, and 66% of these plants lost their entire flower crop due to desiccation. Few seeds (7.5%) were lost to post-dispersal seed predation. The populations are composed mainly of adult plants (70% of the individuals), and little to no recruitment was observed.

Año: 2012

Palabras claves: Atacama Desert, Chile, conservation biology, habitat loss, Myrtaceae, restricted-range species,

Referencia APA: García-Guzman, P., Loayza, A., Carvajal, D., Letelier, L., & Squeo, F. (2012). The ecology, distribution and conservation status of Myrcianthes coquimbensis: a globally endangered endemic shrub of the Chilean Coastal Desert. Plant Ecology & Diversity, 5(2), 197-204.

Progress in creating a joint research agenda that allows networked long-term socio-ecological research in southern South America: Addressing crucial technological and human capacity gaps limiting its application in Chile and Argentina.

Autores:

Anderson, C., Celis-Diez, J., Bond, B., Martínez Pastur, G., Little, C., & Armesto, J., Ghersa, C., Austin, A., Schlichter, T., Lara, A., Carmona, M., Chaneton, E.J., Gutierrez, J.R.,et al.

Resumen:

Since 1980, more than 40 countries have implemented long-term ecological research (LTER) programs, which have shown their power to affect advances in basic science to understand the natural world at meaningful temporal and spatial scales and also help link research with socially relevant outcomes. Recently, a disciplinary paradigmatic shift has integrated the human dimensions of ecosystems, leading to a long-term socio-ecological research (LTSER) framework to address the world's current environmental challenges. A global gap in LTER/LTSER only exists in the latitudinal range of 40–60°S, corresponding to Argentina and Chile's temperate/sub-Antarctic biome. A team of Chilean, Argentine and US researchers has participated in an ongoing dialogue to define not only conceptual, but also practical barriers limiting LTER/LTSER in southern South America. We have found a number of existing long-term research sites and platforms throughout the region, but at the same time it has been concluded an agenda is needed to create and implement further training courses for students, postdoctoral fellows and young scientists, particularly in the areas of data and information management systems. Since LTER/LTSER efforts in Chile and Argentina are incipient, instituting such courses now will enhance human and technical capacity of the natural science and resource community to improve the collection, storage, analysis and dissemination of information in emerging LTER/LTSER platforms. In turn, having this capacity, as well as the ongoing formalization of LTER/LTSER programs at national levels, will allow the enhancement of crucial collaborations and comparisons between long-term research programs within the region and between hemispheres and continents. For Spanish version of the entire article, see Online Supporting Information (Appendix S1).

Año: 2012

Palabras claves: environmental monitoring; information management; long-term ecological research; LTER; LTSER; science policy; socio-ecology

Referencia APA: Anderson, C., Celis-Diez, J., Bond, B., Martínez Pastur, G., Little, C., & Armesto, J., Ghersa, C., Austin, A., Schlichter, T., Lara, A., Carmona, M., Chaneton, E.J., Gutierrez, J.R., et al. (2012). Progress in creating a joint research agenda that allows networked long-term socio-ecological research in southern South America: Addressing crucial technological and human capacity gaps limiting its application in Chile and Argentina. Austral Ecology, 37(5), 529-536.

Leaf morphological and genetic divergence in populations of Drimys (Winteraceae) in Chile.

Autores:

Jara-Arancio, P., Carmona, M., Correa, C., Squeo, F., & Arancio, G.

Resumen:

The genus Drimys is distributed in Chile from semiarid zones to sub-Antarctic forests; there are three species of this tree, D. andina, D. confertifolia and D. winteri, the latter with varieties chilensis and winteri. Northern populations are found in small disjunct natural refuges, specifically mountain cloud forests and the bottom of ravines. The size and continuity of populations are greater in the south, where wetter conditions prevail. Morphological differences between populations have been observed, particularly between the northern populations of Fray Jorge and Talinay. This observation, led to the following questions: a) what is the level of morphological and genetic divergence among the populations of Drimys in Chile? and b) do the populations from Fray Jorge/Talinay, currently classified as D. winteri var. chilensis, differ genetically from the other populations of this variety? To answer these questions, we collected leaf samples from 37 populations of all Chilean Drimys, performed leaf morphology analysis and estimated genetic divergence using RAPD markers. We found a high degree of leaf morphological and genetic divergence between the populations of Fray Jorge/Talinay and the other Chilean species of Drimys. The morphological and genetic divergence among varieties of D. winteri was greater than that among the species of Drimys, which may indicate problems with their taxonomic classification.

Año: 2012

Palabras claves: Drimys; RAPD; Fray Jorge/Talinay; Divergence

Referencia APA: Jara-Arancio, P., Carmona, M., Correa, C., Squeo, F., & Arancio, G. (2012). Leaf morphological and genetic divergence in populations of Drimys (Winteraceae) in Chile. Genetics And Molecular Research, 11(1), 229-243.