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Novel dry state co-milling encapsulation of olive leaf extract
Full text linkMicro-encapsulation or nano-encapsulation is nowadays representing an interesting strategy to enhance the functionality of bioactives and other biomolecules, serving several purposes such as solubility enhancement, increased gastrointestinal absorption or targeted delivery of bioactive compounds (Li et al., 2015).
High energy ball milling is used in the pharmaceutical industry to produce fine dispersions or “molecular alloys” of the active ingredient in a carrier/matrix to enhance solubility and bioavailability (Bandarkar and Vavia, 2011), to produce similar solid dispersion obtained with freeze-dying or spray drying (Willart et al., 2006). Modified starch by ball milling has been applied to encapsulate β-carotene (Roa et al., 2016), but no co-milling in the dry state to encapsulate food bioactives has been implemented yet. Olive leaves phenolic compounds have been widely studied for their health promoting properties (Martín-Peláez et al., 2013) In this work, olive leaf extract (OLE) was co-milled with maltodextrin/maltodextrin-trehalose as carrier, at different ratios and milling treatment time, using a planetary ball-mill. A milling time of 60 min resulted in maximized encapsulation efficiency (95-97%). When a higher ratio of OLE to matrix was applied, encapsulation efficiency was slightly lower compared to lower ratio up to 60 min treatment, but was maximized upon longer treatment. Microstructural analysis of the highly encapsulated OLE dispersions (60-180min) using CLSM microscopy showed fine and homogeneously distributed dispersion of OLE in the internal surface of the maltodextrin/maltodextrin-trehalose matrix. Also in these samples, OLE seemed to be protected from environmental moisture/solvent compared to low encapsulated samples (0-30min) as observed during microscopy analysis. Colour analysis of powder dispersions highlights that co-milling resulted in lighter yellowish homogeneous powders as compared to non-milled, thereby masking the brownish-yellowish colour of OLE. Further experiments are needed to confirm the encapsulation and stabilization of OLE by co-milling with a carrier in order to produce stable ingredients with nutritional and health promoting potential.
References
BANDARKAR, F. S. & VAVIA, P. R. 2011. An optimized commercially feasible milling technique for molecular encapsulation of meloxicam in beta-cyclodextrin. Drug Dev Ind Pharm, 37, 1318-28.
MARTÍN-PELÁEZ, S., COVAS, M. I., FITÓ, M., KUŠAR, A. & PRAVST, I. 2013. Health effects of olive oil polyphenols: Recent advances and possibilities for the use of health claims. Molecular Nutrition & Food Research, 57, 760-771.
ROA, D. F., BUERA, M. P., TOLABA, M. P. & SANTAGAPITA, P. R. 2016. Encapsulation and Stabilization of β-Carotene in Amaranth Matrices Obtained by Dry and Wet Assisted Ball Milling. Food and Bioprocess Technology, 10, 512-521.
WILLART, J. F., DESCAMPS, N., CARON, V., CAPET, F., DANÈDE, F. & DESCAMPS, M. 2006. Formation of lactose-mannitol molecular alloys by solid state vitrification. Solid State Communications, 138, 194-199
Dietary Fibers Effects on Physical, Thermal, and Sensory Properties of Low-Fat Ice Cream
No full textThis study investigated the effect of incorporating dietary fibers, inulin, acacia, oat, and apple, in a low-fat vanilla ice cream. A significant increase in the ice cream mixture viscosity was observed with the addition of dietary fibers. Significant differences (p<0.05) were observed in the crystallization temperature when apple and oat fibers were used. Additionally, low-fat dietary fiber ice creams displayed statistically lower (p<0.05) glass transition and melting temperatures than full-fat ones, with the most pronounced reductions observed for samples enriched with acacia and apple fibers. Dietary fibers affected (p<0.05) the sensory profile of low-fat ice cream. However, inulin and acacia fibers samples showed a sensory profile comparable to the full-fat ice cream for nearly all attributes. These findings suggest that utilizing inulin and acacia fibers in low-fat ice cream yields characteristics of full-fat, underscoring the potential for crafting high-quality, reduced-fat ice cream products
Liposome encapsulation of a oleuropein-rich olive leaf extract and study of the effect of oleuropein on model lipid membrane
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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
Development of encapsulated olive leaf extracts as innovative natural and functional food ingredients
Full text linkThe increasing consumer concern and demand in the last decades for foods with natural ingredients and enhanced nutritional and health-promoting properties has pushed the research in the fields of nutrition and food technology in order to find, characterize, formulate and incorporate bioactive compounds into common foods or nutraceuticals. Some of the most used food bioactives are plant phytochemicals like polyphenols present in most plants as secondary metabolites. Olive biophenols, present in most parts of the plant and found in high concentrations in the leaves, are widely recognized for their bioactive properties. Thus, olive leaves, traditionally considered as a by-product, are an abundant source of olive phenolic compounds that can be recovered and further exploited as functional ingredients in food and nutraceuticals.
However, the intrinsic chemical characteristics of these and other phytochemicals compounds makes its direct use in foods very challenging. In this context, food microencapsulation has been progressively implemented to partially or totally tackle these technological and sensorial issues associated to their incorporation into foods. The large variety of bioactives (pure compounds, phenolic-rich extracts) and carriers, the specific objective of the encapsulation and the large complexity of food matrices are the reasons for the wide research and development approaches in this field. Due to the different nature of the encapsulation techniques, specific investigations on their related critical parameters and optimization of the encapsulation process and performance are needed.
The investigations carried out in this work aimed to better understand the use of phenolic extracts from olive leaves by studying its chemical stability and developing encapsulated ingredients with encapsulation techniques of different nature with the potential to be used in real food matrices.
Firstly, a phenolic extract from olive leaves rich in oleuropein, a well defined compound with significant health-promoting properties, was characterised in terms of thermal stability at varying pH conditions of the phenolic content, profile and radical scavenging properties, by implementing a kinetic model and also structural characterization using flurescence spectroscopy.The thermal degradation of the major component, oleuropein, followed first-order kinetics and was high at lowest pH values (pH = 2), while verbascoside appeared to be more labile at pH 6. Oleuropein hydrolysis products resulted in an increasing hydroxytyrosol concentration, that followed zero-order kinetics. These changes were also detected by fluorescence spectroscopy. On the other hand, no remarkable changes in total phenolic content and radical scavenging activity were observed.
Freeze-drying was studied as a method to encapsulate olive leaf bioactives in amorphous dry carbohydrate matrices. The effect of the carrier formulation and ratio bioactive:carrier on the encapsulation efficiency, the thermal, physical and structural properties of freeze-dried microencapsulated powders was assessed by using a response surface modellig approach. Also, the impact of these factors on the chemical stability of bioactive compounds was studied. Maltodextrin and trehalose were chosen as encapsulating materials as representatives of high and low molecular weight carbohydrates with good glass forming properties for encapsulation purposes. The increasing concentration of maltodextrin enhanced the encapsulation of both total phenolics and oleuropein up to an almost total retention when maltodextrin was used alone, which could be directly observed thanks to fluorescence imaging. Color and thermal properties of the microencapsulated powders depended on the maltodextrin-trehalose ratio and a plasticizing effect of olive leaf extract was also observed, especially in the glassy powders containing maltodextrin. The storage study of unencapsulated and microencapsulated olive leaf extract powders under different physical states revealed that at least for 7 weeks, the chemical stability and antioxidant properties of the bioactives were not affected.
Liposomal encapsulation of olive bioactives was investigated, first in model phospholipid membranes by evaluating the effects of oleuropein on membrane thermotropic behavior (differential scanning calorimetry) and ordering and fluidity (fluorescence polarization) in systems with passively encapsulated oleuropein (i.e., added after formation of liposomes) compared to actively encapsulated oleuropein (i.e., encapsulated during formation of liposomes). Also, the antioxidant capacity of oleuropein to inhibit lipid peroxidation. was evaluated under two types of oxidation induction. A potential food ingredient was developed by encapsulating the olive leaf extract in commercial soy phosphatidylcholine, and characterized for its morphological, physical and functional properties in model and real systems (commercial soft drink). Oleuropein and verbascoside were encapsulated with a mean efficiency of 34% and 75%, which indicated that optimization this process can be further investigated to improve the encapsulation. However, liposome encapsulation was effective for a delay of oleuropein degradation at low pH (i.e., pH 2.0), and for the maintenance of oleuropein stability over long periods at refrigeration temperatures and at different pHs. This thus shows that this lipid encapsulation indeed provides a suitable carrier in food systems, such as beverages.
Finally, the antioxidant performance of olive leaf extract and other standard and plant extracts was assessed in more challenging and real food processing conditions like those commonly employed during melt-extrusion processing/encapsulation, as opposed to classical liquid antioxidant assays. A simple and novel approach has been proposed to estimate the antioxidant performance under controlled conditions using a lab-scale extruder by implementing a solid-state adaption of the crocin-bleaching liquid assay, based on the bleaching of saffron crocins
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
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