1,720,993 research outputs found
Chemical profile changes during myrtle (Myrtus communis L.) fruit development and ripening
No full textThe chemical composition of fruit belonging to ‘Barbara’ and ‘Daniela’ myrtle cultivars was monitored
during development from fruit-set to an over-ripe stage (July–January), with the aim to identify a reliable
maturity index. Acidity, pH, reducing and total sugars, phenols, tannins, anthocyans, carbon dioxide and
ethylene production rates were monitored over two different year seasons. Titratable acidity decreased
during maturation, with significant differences due to cultivar and year of observation. Reducing sugars
increased in both cultivars approximately sevenfold from fruit set to complete maturation. Total sugar
content increased similarly ranging from 1.43% and 1.41% at fruit set to 8.28% and 7.56% at maturation
for ‘Barbara’ and ‘Daniela’, respectively. Total phenols and tannins occurred at high levels after fruit set
and declined during development. Anthocyans levels increased, in both cultivars, according to a sigmoid
curve. The pattern of respiration rate showed a gradual decline in both cultivars ranging from 365.81
and 396.42mgkg−1 h−1 to 79.98 and 52.27mgkg−1 h−1, respectively for ‘Barbara’ and ‘Daniela’ in 2006. A
peak of variable size was observed in October–November period. Small increases in ethylene production
have been detected during fruit development ranging from 130.57 and 269.14Lkg−1 h−1 measured at
the onset of development to 13.04 and 19.36Lkg−1 h−1 measured at harvest for ‘Barbara’ and ‘Daniela’,
respectively
Effect of maturation and cold storage on the organic acid composition of myrtle fruits
No full textBACKGROUND: The effect of maturation and senescence on the chemical composition of two myrtle cultivars was studied in mature, overripe and cold-stored fruits in order to find the most appropriate harvesting period and best storage technology for industrial purposes.
RESULTS: After cold storage at 10 °C for 15 days, berry weight loss ranged from 12.5 to 18.4%, with the highest losses in less mature fruits. Titratable acidity decreased during maturation and cold storage in both cultivars. Reducing and total sugars increased during maturation. Anthocyanin concentration increased during maturation but decreased in overripe berries. The major organic acids in myrtle fruits were quinic, malic and gluconic acids. In fresh and cold-stored fruits, malic acid rose to 3 g kg−1 and decreased thereafter. Quinic acid peaked at 90 or 120 days after bloom and decreased thereafter to reach low concentrations in mature fruits.
CONCLUSION: Cold storage for 15 days at 10 °C does not affect myrtle fruit quality for liqueur production. Anthocyanin concentration is the best indicator of harvest time for industrial purposes. Gluconic acid concentration is high in mature, overripe and cold-stored berries. This parameter can be used as a marker of the onset of fruit senescence
Genetic Diversity and Population Structure of Sardinian Myrtle (Myrtus communis L.) Selections as Obtained by AFLP Markers
No full textMyrtle is an aromatic plant typical of the Mediterranean maquis. It is widely
exploited in pharmaceutical, cosmetic, and food industries, whereas in Italy, it is mainly
used for the production of the typical liqueur. Amplified fragment length polymorphism
(AFLP) markers were used to evaluate the genetic variability of some Sardinian Myrtus
communis L. candidate cultivars. The AFLP selective amplification produced 138
reproducible AFLP fragments, 96% of which were polymorphic. STRUCTURE analysis
divided the myrtle accessions into two main genetic groups (K = 2). The two clusters
showed different numbers of individuals. Most of the individuals belonged to Cluster B,
whereas only eight genotypes were attributed toCluster A. Unweighted pair groupmethod
with Arithmetic Mean (UPGMA) dendrogram segregated all the myrtle cultivars into five
main groups, displaying a partial congruence with the division observed by STRUCTURE
analysis. The analysis of the genetic diversity distribution in a candidate cultivar selection
displayed a geographical gradient of myrtle from north to south, which reflects the
Sardinian shape, and fromwest to east, which reflects the Sardinianmountain distribution
Determination of free radical scavenging activity of plant extracts through DPPH assay: an EPR and UV-VIS study
No full textSeveral methods have been developed to assess the radical scavenging activity. Among them, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) spectrophotometric method is one of the most widely applied and is appreciated for its reliability. In this study, a comparison of two spectroscopic methods (electron paramagnetic resonance (EPR) and ultraviolet-visible (UV-Vis) spectroscopy) was performed analysing the spectroscopic features of DPPH in mixed ethanol/water solution and the free radical scavenging properties of myrtle leaves extracts and citrus juices. When DPPH was dissolved in mixed solvents, EPR enabled to identify the aggregation phenomena that occur when high amounts of water were employed. On the contrary, UV-Vis revealed only small differences in the absorption maximum among solutions with increasing water contents, without detecting aggregation. EC 50 values of myrtle leaf extracts and citrus juices calculated from UV-Vis data were lower than those calculated with EPR. In myrtle extracts, the DPPH depletion measured by UV-Vis was not concentration dependent, revealing the interference in the analysis of the decomposition products of the antioxidants, which absorb at 517 nm. EPR spectroscopy was proven to be most reliable with all types of matrix since it is not dependent on the chemical composition of the extract
Behavior of the potential antitumor VIVO complexes formed by flavonoid ligands. 3. Antioxidant properties and radical production capability
No full textThe radical production capability and the antioxidant properties of some VIVO complexes formed by flavonoid ligands were examined. In particular, the bis-chelated species of quercetin (que), [VO(que)2]2 -, and morin (mor), [VO(mor)2], were evaluated for their capability to reduce the stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and produce the hydroxyl radical •OH by Fenton-like reactions, where the reducing agent is VIVO2 +. The results were compared with those displayed by other VIVO complexes, such as [VO(H2O)5]2+, [VO(acac)2] (acac = acetylacetonate) and [VO(cat)2]2 - (cat = catecholate). The capability of the VIVO flavonoids complexes to reduce DPPH is much larger than that of the VIVO species formed by non-antioxidant ligands and it is due mainly to the flavonoid molecule. Through the 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trapping assay of the hydroxyl radical it was possible to demonstrate that in acidic solution VIVO2+ has an effectiveness in producing •OH radicals comparable to that of Fe2+. When VIVO complexes of flavonoids were taken into account, the amount of hydroxyl radicals produced in Fenton-like reactions depends on the specific structure of the ligand and on their capability to reduce H2O2 to give •OH. Both the formation of reactive oxygen species (ROS) under physiological conditions by VIVO complexes of flavonoid ligands and their radical scavenging capability can be put in relationship with their antitumor effectiveness and it could be possible to modulate these actions by changing the features of the flavonoid coordinated to the VIVO2+ ion, such as the entity, nature and position of the substituents and the number of phenolic groups
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
Suitability for ready-to-eat processing and preservation of six green and red baby ceaves cultivars and evaluation of their antioxidant value during storage and after the expiration date
No full textThe physiological and chemical traits of three red (MS151, Copacabana and Excellent) and three green (Ortis 398, Summerbell and Babybell) baby leaf lettuce cultivars were evaluated during postharvest cold storage. In addition, their potential use as a source of antioxidants, after the expiration date, was also investigated. Red cultivars showed the best performance in terms of nutritional and physiological parameters. In particular, the antioxidant activity was 11-fold higher in red than in green baby leaf lettuces. Moreover, Ortis 398, MS151 and Copacabana, showing the lowest values for respiration rate, ammonium accumulation and electrolyte leakage, were selected as suitable for ready-to-eat processing and preservation. Finally, the cultivars Ortis 398, MS151 and Excellent were found to be of interest for the extraction of antioxidants due to their high phenol content. Practical Applications: The selection of the most appropriate cultivars for ready-to-eat (RTE) salads is of primary importance in order to have good quality, to reduce storage losses and to have, after the expiration date, a produce still exploitable for the extraction of phytochemicals. Ortis 398, MS151 and Copacabana were selected, among the studied new baby leaves cultivars, for their particular aptitude for RTE processing. In addition, because RTE lettuce remains often unsold due to the loss of its fresh appearance, our results suggest the possibility to re-utilize the waste (after the expiration date) as a source of antioxidants. This could represent a practical application opportunity for the food industry. With this aim, the cultivars Ortis 398, MS151 and Excellent were selected for their high content in total polyphenols even after the expiration date
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