Navegando por Assunto "Quimiometria"

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Acesso aberto (Open Access)
Farinha de mandioca (Manihot esculenta) e tucupi: uma abordagem analítica utilizando espectroscopia no unfravermelho próximo (NIRS) e ferramentas quimiométricas
(Universidade Federal do Pará, 2022-04-25) POMPEU, Darly Rodrigues; SOUZA, Jesus Nazareno Silva de; http://lattes.cnpq.br/3640438725903079; PENA, Rosinelson da Silva; http://lattes.cnpq.br/3452623210043423
The near infrared spectroscopy (NIRS) coupled to chemometrics has been used as an alternative tool for quick and reliable solutions. Cassava flour (CF) can be classified as fermented and non-fermented types. Tucupi is a yellow broth, acidic, mostly aromatic and widely used in Regional dishes in Para state. This thesis proposed to apply for the first time the NIRS associated with chemometrics to predict quality parameters from CF and tucupi, as well as to discriminate fermented and non-fermented CF. One hundred six samples of CF was investigated and nine physicochemical parameters of CF were evaluated. Calibration equations with independent validation were developed to predict all parameters using the partial least square regression method. The performance of models was evaluated by the root mean standard error of calibration (RMSEC) and validation (RMSEV), and R2 values. The aW (RMSEC = RMSEV = 0.05), moisture content (RMSEC = 0.35%; RMSEV = 0.45%) and pH (RMSEC = 0.16; RMSEV = 0.18) could be predicted (R2 > 0.727) by NIRS coupled to multivariate analysis. NIRS coupled to Principal Component Analysis–Linear Discriminant Analysis (PCA-LDA) was also used to investigate the classification of fermented and unfermented CF. The use of NIRS spectra allows to obtain better performance parameters (training accuracy: 86.3–93.8%; validation accuracy: 84.6–96.2%) to discriminate fermented and unfermented CF than the use of the physicochemical properties (training accuracy: 80%; validation accuracy: 84.6%). NIRS was also used to predict nine quality physicochemical properties of tucupi Sixty-five samples of tucupi were used in this study. The performance of models was evaluated by the R2, RMSEC, root mean standard error of cross-validation (RMSECV) and RMSEV values. The total soluble solids contents could be predicted (R2 > 0.727; RMSEC = 0.184%; RMSECV = 0.411%; RMSEV = 0.338%) by NIRS coupled to multivariate analysis. NIRS and chemometrics proved to be a powerful tool to predict quality parameters in CF and tucupi as well as to discriminate fermented and non-fermented CF.
Acesso aberto (Open Access)
Parâmetros da qualidade das amêndoas de cacau (theobroma cacao L.) de regiões produtoras no estado do Pará e aplicação de NIR associado a ferramentas quimiométricas para sua classificação.
(Universidade Federal do Pará, 2021-10-11) SILVA, Niara Maria de Jesus; SOUZA, Jesus Nazareno Silva de; http://lattes.cnpq.br/3640438725903079; https://orcid.org/0000-0002-0288-2321; LIMA, Consuelo Lúcia Sousa de; http://lattes.cnpq.br/2971385954203459; https://orcid.org/0000-0001-9432-8637
Cocoa (Theobroma cacao L.) is a native fruit of tropical forests and plays an important role in the economy of producing regions, however, due to the lack of infrastructure and inadequate processing practices, they generate almonds with low potential for application in the food industry. In order to value cocoa beans, this research aimed to evaluate the quality of cocoa beans from regions of Pará (Lower Tocantins, Northeast, West, Southeast and Trans-Amazon) by physical, physicochemical and chromatographic evaluation and near infrared datroscopy combined with chemometric tools. A questionnaire was informed with the producers about fermentation and drying practices, followed by physical, physical-active, antioxidant capacity, quantification of total polyphenols and bioactive compounds, in addition to using NIR as an analytical tool. According to the physical evaluation, as it presents an acceptable commercial standard, however, the cutting test results showed the lack of standardization in the preprocessing of the seeds. Among the physicochemical parameters (proteins, lipids, moisture, ash, pH, acidity and water activity), moisture within the limit tolerated by legislation and only relevant dissipation lipids. As for the antioxidant capacity, total polyphenols and bioactive compounds, only the bioactive compounds differences differences, with the Lower Tocantins region these values higher for all studied compounds. The grouping of the functions of physicalchemical composition variations was evidenced by the Principal Components Analysis that there was a cluster formation for a region of Baixo Tocantins.
Acesso aberto (Open Access)
Rosetas e concrescências cristalinas silicificadas em Piper (Piperaceae): registros inéditos de macropadrões
(Instituto Nacional de Pesquisas da Amazônia, 2014-12) SILVA, Rolf Junior Ferreira; DIAS, Ana Cristina Andrade de Aguiar; MENDONÇA, Maria Sílvia de
Piper L. (Piperaceae) is monophyletic, with species of difficult taxonomic distinction, and thus tools that facilitate interspecific identification are needed. The aims of this study were to describe the macropatterns and characterize in situ the chemical composition of leaf and stem crystals of Piper arboreum Aubl. var. arboreum, P. callosum Ruiz & Pav. and P. tuberculatum Jacq., in order to evaluate the use of the crystals on interspecific distinction. Samples were submitted to analyses under light and scanning electron microscopies, energy-dispersive x-ray spectroscopic microanalyses, and histochemical tests. We observed cuneiform, tabular, cubic, and bipiramidal prismatic crystals; raphides; styloids; blocky crystal druses; styloid crystal rosettes; and crystal concretions. We described 15 crystal macropatterns, which were distributed along three categories. The crystals were chemically classified as: pure calcium oxalate; and mixtures of oxalates and sulfates, and of oxalates, sulfates and silica. Crystal rosettes, silicified crystal concretions, and 14 out of the 15 macropatterns described are unpublished reports on biomineral inclusions in Piper and Piperaceae. The stem and leaf crystal macropatterns observed are constitutive and useful for interspecific separation of the studied species. Moreover, the crystals present relevant functions for the autecology of the analyzed taxa from Piper.