Navegando por Orientadores "SOUZA, Jesus Nazareno Silva de"

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Acesso aberto (Open Access)
Discriminação de espécies de peixes da costa amazônica e predição da composição centesimal usando um espectrofotômetro NIR portátil
(Universidade Federal do Pará, 2014-03-28) FERREIRA, Fabielle Negrão; SILVA, Evaldo Martins da; http://lattes.cnpq.br/6649371901290988; SOUZA, Jesus Nazareno Silva de; http://lattes.cnpq.br/3640438725903079
Vibrational spectroscopy in the near infrared (NIR) has many applications in industry, particularly in quality control, discrimination and determination of the chemical composition of different foods because of the speed and ease of application in routine analysis when compared to traditional physical and chemical methods. This work aims to use this technique to discriminate five fish species from the Amazonian coast (Genyatremus luteus , Lutjanus purpureus , Macrodon ancylodon , Cynoscion acoupa, Micropogonias furnieri) and predict major components (water content, lipids and proteins). A portable low-resolution spectrometer (1600-2400 nm) was used for obtaining spectral measures of fish samples (intact, crushed and lyophilized muscle tissue). The spectra were preprocessed by means of derivatives using the Savitzky-Golay algorithm for smoothing of spectral noises, when constructing both prediction and discrimination models. The PCA and SIMCA models were applied for species discrimination, while PCR and PLS were used in the prediction of the major components. Using PCA, it was observed the formation of well-defined groups of the species G. luteus and L. purpureus in intact and lyophilized samples. With SIMCA, it was observed the formation of groups of the five species, which were confirmed by the distance between groups in the range from 4.16 to 13.31 and 2.90 to 57.05 for intact and lyophilized samples, respectively. The PLS regression model showed a small positive variation values for r2 and R2 , and the lyophilized samples showed better results for the three studied parameters: water content ( r2: 0.58 , RMSEPcv: 1.11 and RDP: 1.40 ), lipids (r2 : 0.96 , RMSEPcv : RDP 1.09 and 4.82 ), and crude protein (r2: 0.86 , RMSEPcv : RDP and 1.96 : 2.60). A good correlation between proximate composition data and those predicted by PLS regression was obtained.
Acesso aberto (Open Access)
Estudo comparativo do efeito da clivagem ácida (escalas analítica e piloto) de proantocianidinas presentes em extratos de matrizes vegetais da Amazônia
(Universidade Federal do Pará, 2014-09-30) SATO, Suenne Taynah Abe; SOUZA, Jesus Nazareno Silva de; http://lattes.cnpq.br/3640438725903079
The Amazon Region presents a great source of species rich in bioactive compounds, such as Euterpe oleracea (açaizeiro), Byrsonima crassifolia (murucizeiro) and Inga edulis (ingazeiro). From these matrices, purified extracts rich in phenolic content have been produced containing compounds such as flavonoids and tannins. It is known that tannins, more specifically condensed tannins (proanthocyanidins) are polymers of simple phenolic compounds, and when present in foods, are involved in the sensation of astringency due to its complexation with saliva protein, thus acting as an anti-nutrition agent. Methods have been developed aiming the depolymerization of these compounds, such as acid cleavage, because apart from promoting the reduction of astringency, studies have shown that they also contribute to increased antioxidant capacity and to promote the absorption of these compounds. It is noteworthy that, with the growing interest in monomeric phenolic compounds, tests on a pilot scale, to produce them in larger quantities, are necessary. Therefore, the aim of this study was to verify the effects of the acid cleavage of proanthocyanidins, on a pilot scale, present in the extracts of Amazonic plants, thus evaluating the phenolic content, the astringent and antioxidant capacity. In order to achieve that, the purified aqueous extracts of each plant were characterized by spectrophotometric analysis (total phenolic content, total flavonols and total flavanols, total anthocyanidins, proanthocyanidins and antioxidant capacity (DPPH)), astringency analysis and identification of the main compounds by on High Pressure Liquid Chromatography. Subsequently the samples underwent an acid cleavage with a reaction medium of 60% Ethanol, HCl 3N, in a temperature of 88 °C for 165 minutes. The purified aqueous extracts of muruci, ingá and açaí showed a high concentration of polyphenols (761.83, 493.59 and 531.55 mg GAE/g MS, respectively), as well as high concentrations of total flavanols, total flavonols, and proanthocyanidins. The process of acid cleavage promoted an increase in the content of total polyphenols and was effective in hydrolyzing the proanthocyanidins, in reducing the astringency, in increasing the antioxidant capacity as well as in obtaining subclass of compounds of anthocyanins for the three extracts. The scaling-up process resulted in no significant difference (p>0.05) regarding the cleavage held in analytical scale, for all extracts. Besides the depolymerization of proanthocyanidins, the acid treatment provides the deglycosylation of flavonoids as glycosylated quercetins (Byrsonima crassifolia and Inga edulis), glycosylated miricetins (Inga edulis) and glycosylated cianidins (Euterpe oleracea). Thus, the increase in scale of the process made possible the production of extracts rich in compounds with high antioxidant capacity which provided good indication to the possible use of these extracts as antioxidants agents in food and pharmaceutical products.