1,720,954 research outputs found
Optimización de la extracción de polifenoles de vaina de tara y su estabilización por microencapsulación para el desarrollo de un ingrediente antioxidante natural
Full text linkMagíster en Ciencias de los AlimentosMemoria para optar al título de Ingeniero en AlimentosActualmente, existe una gran demanda de alimentos naturales con ingredientes que
además de aportar nutrientes, ayuden a mejorar la salud. En esta investigación se
utilizó la Tara, Caesalpinia spinosa, árbol de leguminosas nativo de América del Sur
que posee polifenoles, los cuales una vez que se extraen, son altamente
susceptibles a degradación frente a condiciones del medioambiente. Así, la
tecnología de microencapsulación permite estabilizarlos para ser agregados en un
alimento. El objetivo de esta investigación fue estudiar la encapsulación de un
extracto de vaina de tara con maltodextrina e inulina por secado por atomización y
evaluar su estabilidad durante el almacenamiento. La optimización de la extracción
de polifenoles en el polvo de vaina de tara (PVT) se realizó aplicando un diseño
estadístico Box-Behnken. Las condiciones óptimas de temperatura (24ºC),
proporción de etanol (100%) y relación sólido:solvente (1:18), entregaron un
extracto de vaina de tara (EVT) con contenido de polifenoles totales de 600,3 ± 0,6
mg EAG/g PVT, ORAC 17,4 ± 0,9 mmol ET/100 g PVT, sólidos totales 25,6 ± 0,1
ºBrix y pH 5,01 ± 0,01.
La optimización de la encapsulación del EVT por secado por atomización se realizó
aplicando un diseño Compuesto Central. Las condiciones óptimas fueron
temperatura del aire de entrada al secador y relación EVT:AE de 187ºC y 1:1,25,
respectivamente para MD; 169ºC y 1:1,25, respectivamente para In. La EE alcanzó
valores sobre 97% para ambos sistemas (EVT-MD y EVT-In), lo cual se atribuye a
la interacción polifenoles-polímero por puentes de hidrógeno. EVT-MD y EVT-In
mostraron valores de humedad de 6,3 ± 0,08% y 6,0 ± 0,05%, respectivamente, y
actividad de agua de 0,3 ± 0,001 y 0,22 ± 0,001, respectivamente, asegurando así
la estabilidad microbiológica de las micropartículas. La higroscopicidad para EVTMD
y EVT-In fue de 25 ± 0,9 y 17 ± 0,6 g/100 g, respectivamente; mostrando que la
higroscopicidad es específica de cada polímero. Las microfotografías (SEM)
mostraron micropartículas esféricas con algunas abolladuras sobre la superficie. La
estabilidad de los polifenoles encapsulados de los sistemas EVT-MD y EVT-In, no mostraron degradación de los polifenoles durante las 19 semanas de
almacenamiento a 60ºC. Los resultados permitieron desarrollar micropartículas de
polifenoles de vaina de tara utilizando MD e In como recubrimiento, para su
potencial aplicación como un ingrediente saludableCurrently, there is a great demand for foods with natural ingredients, since it provides
nutrients, and improves the health. In this research, Tara (Caesalpinia spinosa),
leguminous tree native to South America was studied as source of polyphenols.
However, when polyphenols are extracted, they are highly susceptible to
degradation against environmental conditions. Thus, the use of encapsulated
polyphenols as food ingredient, should allow the protection of polyphenols until they
are added to food vehicle. The aim of this research was to study the encapsulation
from Tara pod extract by spray drying, using maltodextrin (MD) and inulin (In) as
encapsulating agents and evaluate its stability during storage. The optimization of
the extraction of the polyphenols from Tara pod powder (TPP) was performed using
a Box-Behnken statistical design. The optimal conditions of temperature (24ºC),
ethanol percentage (100%) and solid:solvent ratio (1:18), giving Tara pod extract
(TPE) with total polyphenol content of 600.3 ± 0.6 mg EGA/g TPP, ORAC 17.4 ± 0.9
mmol ET/100g TPP, total solids 25.6 ± 0.1 ºBrix and pH 5.01 ± 0.01. The optimization
of the encapsulation of TPE by spray drying was performed applying a Central
Composite design. The optimal conditions were inlet air temperature and TPE:EA
ratio of 187 ºC and 1:1.25, respectively for MD; 169 ºC and 1:1.25, respectively for
In. The EE reached values over 97% for both systems (TPE-MD and TPE-In), which
could be attributed to polyphenol-polymer interaction by hydrogen bonds. TPE-MD
and TPE-In microparticles showed moisture values of 6.3 ± 0.08% and 6.0 ± 0.05%,
respectively, and water activity of 0.3 ± 0.001 y 0.22 ± 0.001, respectively), ensuring
microbiological quality of the microparticles. The hygroscopicity for EVT-MD and
EVT-In was 25±0.9 y 17±0.6 g/100g, respectively; showing that the hygroscopicity
is polymer-specific. The microphotographs (SEM) showed spherical microparticles
with some dents on the surface. Polyphenols stability in TPE-MD and TPE-In, did
not show polyphenols degradation during 19 weeks of storage at 60 ºC. The Tara
pod polyphenol microparticles were developed using MD and In as coating, for their
potential application as a healthy ingredien
Sustainable recovery of phlorotannins from Durvillaea incurvata: Integrated extraction and purification with advanced characterization
No full textThis article belongs to the Special Issue Antioxidants from Food and Food Wastes for Nutraceutical, Pharmaceutical and Cosmetic Fields.The rising demand for bioactive compounds from marine resources highlights the need for sustainable separation technologies. This study introduces an integrated process combining ultrasound-assisted extraction (USAE) and resin purification (RP) to isolate phlorotannins from Durvillaea incurvata, a brown seaweed with significant biomedical potential. Using a 32.5% ethanol–water solvent system for USAE followed by RP on Diaion HP-20 resin, phlorotannins were enriched 2.4-fold, with simultaneous removal of interfering compounds such as mannitol (~100%), which was demonstrated by FTIR and HPLC-IR analysis. Advanced characterization using UHPLC-QToF-MS/MS identified five novel phlorotannins with polymerization degrees of 3 to 8 phloroglucinol units in both USAE extracts and post-RP. Mass balance based on spectrophotometric measurements indicated a purification factor of ~2, confirming process effectiveness. RP streams showed distinct phlorotannin profiles, with one phlorotannin exceeding 70% relative abundance. However, MS/MS results showed significantly lower recoveries than spectrophotometric data, revealing a novel insight into RP purification. These findings highlight the critical role of comprehensive chemical characterization in optimizing sustainable phlorotannin extraction from seaweed. They propose a framework for scalable, eco-efficient technologies for achieving high-purity phlorotannin recovery. This approach facilitates the development of phlorotannin-based applications in the nutraceutical and pharmaceutical industries.Financial support was received from FONDECYT Regular projects number 1220097 and 1230115, and FOVI project number 240263.Peer reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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