Acoplamento de técnicas espectrométricas com métodos quimiométricos de classificação e calibração multivariada em alimentos / Coupling spectrometric techniques with chemometric methods for classification and multivariate calibration in food

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

06/05/2011

RESUMO

This research work describes three studies of chemometric methods employed for the classification and characterization of edible oils and its quality parameters through Fourier Transform mid infrared spectroscopy and near infrared spectroscopy, and for the monitoring the oxidative stability and quality of yogurt using fluorescence spectroscopy . The first and second studies aimed the classification and characterization of edible oil and its quality parameters using Fourier Transform mid infrared spectroscopy (FT-MIR) and near infrared spectroscopy (NIR) measurements, respectively. Kennard-Stone algorithm was used for selecting the training set, after a principal component analysis (PCA) was applied. The discrimination of canola oils from sunflower, corn and soybean was investigated using SVM-DA, SIMCA and PLS-DA. The quality parameters refraction index and relative density of edible oil was investigated using partial least squares (PLS), iPLS, LS- SVM multivariate calibration of FT-MIR and NIR data were evaluated. Several preprocessing alternatives (first derivative, multiplicative scatter correction, mean centering, orthogonal signal correction and standard normal variate) were investigated by using the root mean square error of validation cross validation (RMSECV) and prediction (RMSEP), as control parameters. In fact, the methodology developed is proposed for direct relative density and refraction index in edible oils and their classification, requiring a few minutes per sample without any previous treatment. The third study aimed to evaluate the oxidative stability and quality of yogurt stored at 40C with light or dark using the combined parallel factor (PARAFAC) analysis and fluorescence spectroscopy. PARAFAC analysis of the fluorescence landscapes exhibited three fluorophores present in the yogurt, where, at least one of them was strongly related to the storage conditions. The fluorescence signal was resolved into excitation and emission profiles of the pure fluorescent compounds, which are suggested to be vitamin A, tryptophan and riboflavin. Regression model based on PARAFAC scores for riboflavin were built using the scores obtained in the first day as dependent variable and the scores obtained during the storage as independent variable. It was clear demonstrated that the slope of the analytical curve has become smaller throughout the experiment. Therefore, riboflavin level could be considered a good indicator for the yogurt stability. Thus, it is concluded that fluorescence spectroscopy in combination with chemometrics has a potential as a fast method for monitoring the oxidative stability and quality of yogurt

ASSUNTO(S)

calibração multivariada de primeira ordem tecnologia quimica infravermelho próximo (nir) infravermelho médio com transformada de fourier (ft-mir) análise discriminatória óleos comestíveis vegetais iogurte first-order multivariate calibration methods near infrared spectroscopy fourier transform mid infrared spectroscopy classification chemometric methods yogurt edible oils

ACESSO AO ARTIGO

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