5,856 research outputs found
Potencial forrageiro da Brachiaria humidicola cv. Llanero (ex. B. dictyoneura) para a recria de equinos.
bitstream/item/132420/1/COT-56.pdf.pd
Application of quality-by-design approach in the analytical method development for quantification of sugars in sugarcane honey by reversed-phase liquid chromatography
Produced in Madeira Island from regional sugarcane cultivars through a traditional manufacturing and storage process, sugarcane
honey (SCH) is a black syrup recognized by its excellent quality. Its economic value has led to the emergence of adulterated SCH,
whereby the identification of molecular markers became an essential task in order to overcome the fraudulent activities, protect its
authenticity, and guarantee the consumer safety. In the present study, an analytical strategy based on ultrasound-assisted liquid liquid extraction (USA-LLE) followed by reversed-phase liquid chromatography with a refractive index detector (LC-RI) was
developed for the determination of sugars (glucose, fructose, sucrose, xylose, and mannose) in SCH samples from certified
producers, supported on analytical quality-by-design (AQbD) approach, as a useful tool to establish its typicality. The application
of AQbD was based on analytical risk assessment, multivariate statistics and quality control procedures for definition of the
Method Operable Design Region (MODR). The optimal conditions into MODR were accomplished using BEH Amide column
operating at a temperature of 80 °C and a flow rate of 300 μL min−1
, with a mobile phase composed by acetone and water (85:15,
v v−1
) at a flow rate of 1.0 mL min−1
. The robustness was determined by Monte Carlo simulation and capability analysis. The
concentration-response function for all sugars was described by polynomial models. Accuracy was presented by recovery values
between 98.2 and 119.5%. The analytical figures of merit validated the utility of AQbD in the systematic design of a LC-RI
method with fine sensitivity for sugar analysis in SCH.info:eu-repo/semantics/publishedVersio
Ocorrência de fotossensibilização em equinos mantidos em pastagem de Brachiaria humidicola.
bitstream/item/138780/1/COT-40.pdfCNPGC
Matrix Assisted Formation of Ferrihydrite Nanoparticles in a Siloxane/Poly(Oxyethylene) Nanohybrid
Matrix-assisted formation of ferrihydrite, an iron oxide hydroxide analogue
of the protein ferritin-core, in a sol-gel derived organic-inorganic hybrid is
reported. The hybrid network (named di-ureasil) is composed of
poly(oxyethylene) chains of different average polymer molecular weights grafted
to siloxane domains by means of urea cross-linkages and accommodates
ferrihydrite nanoparticles. Magnetic measurements, Fourier transform infrared
and nuclear magnetic resonance spectroscopy reveal that the controlled
modification of the polymer molecular weight allows the fine-tuning of the
ability of the hybrid matrix to assist and promote iron coordination at the
organic-inorganic interface and subsequent nucleation and growth of the
ferrihydrite nanoparticles whose core size (2-4 nm) is tuned by the amount of
iron incorporated. The polymer chain length, its arrangement and crystallinity,
are key factors on the anchoring and formation of the ferrihydrite particles.Comment: 7 pages, 6 figures. To be published in J. Mater. Che
Chemical Differentiation of Sugarcane Cultivars Based on Volatile Profile and Chemometric Analysis
Sugarcane (SC) is a perennial grass widely cultivated in tropical and subtropical regions. However, its cultivation in
Europe is residual, where Madeira Island, Portugal, is the only region where SC continues to be extensively cultivated. For the first
time, the volatile profiles of regional cultivars were established by solid-phase microextraction combined with gas chromatography−
mass spectrometry. Different volatile profiles for each cultivar were recognized, identifying 260 volatile organic compounds
belonging to 15 chemical classes, such as aldehydes, alcohols, ketones, hydrocarbons, esters, and terpenes. Chemometric analysis
procedure, namely, one-way ANOVA with Tukey’s test, principal component analysis, partial least-square analysis, linear
discriminant analysis, and hierarchical clustering analysis, allowed the differentiation between all regional cultivars. This study
represents an important contribution for the maintenance of biodiversity and subsistence of the SC industry in Europe. Furthermore,
it is also a valuable contribution to establish the typicality of traditional SC-based products, such as SC honey.info:eu-repo/semantics/publishedVersio
A Predictive Strategy Based on Volatile Profile and Chemometric Analysis for Traceability and Authenticity of Sugarcane Honey on the Global Market
Sugarcane honey (SCH) is a syrup produced on Madeira Island and recognized by its
unique aroma, a complex attribute of quality with an important influence on the final consumer’s
acceptance of the product, and determined by a complex mixture of a large number of volatile organic
compounds (VOCs) generated during its traditional making process and storage. Therefore, the
purpose of this study was to establish the volatile profile of genuine SCH produced by a regional
certified producer for seven years and compare it with syrups from non-certified regional producers
and with producers from different geographical regions (Spain, Egypt, Brazil and Australia), as
a powerful strategy to define the volatomic fingerprint of SCH. Different volatile profiles were
recognized for all samples, with 166 VOCs being identified belonging to different chemical classes,
including furans, ketones, carboxylic acids, aldehydes and alcohols. Chemometric analysis allowed
(i) the differentiation between all syrups, being more pronounced between SCH and other syrups;
and (ii) the identification of 32 VOCs as potential markers for the traceability and authenticity of
SCH on the global market.info:eu-repo/semantics/publishedVersio
Effect of processing and storage on the volatile profile of sugarcane honey: A four-year study
Sugarcane honey (SCH) is a syrup from Madeira Island recognized by its unique and excellent aroma, associated
to volatile organic compounds (VOCs) generated during the well-defined five stages of its traditional making
process. The establishment of volatile profile throughout all SCH-making stages during four years, allowed the
evaluation of the influence of each stage in the typical characterisitcs of SCH. One hundred eighthy seven VOCs
were identified, being associated to several origins and formation pathways. VOCs formed during stage 1 and 2
were originate from raw material, and its oxidation (i.e. enzymatic browning) and thermal degradation (i.e. lipid
oxidation, Maillard reactions, Strecker degradation). In stage 3 and 4, the caramelization and melanoidin
degradation also occurred, while in stage 5, the thermal degradation continues, followed by microbial activity.
Chemometric analysis allowed to identify 35 VOCs as potential markers for processing control by the producers
and as guarantee of the typicality and authenticity of SCH. Based on the obtained results, we propose for the first
time an innovative schematic diagram explaining the potential reactions and pathways for VOCs formation
during the different steps of the SCH production.info:eu-repo/semantics/publishedVersio
Avaliacao de gramineas forrageiras para equinos.
bitstream/item/137594/1/PESQ-EM-ANDAMENTO-45.pdfCNPGC
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