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Abstract(s)
Spectroscopic methods have been widely used in the quality assessment of different matrices, among
which food products [1,2,3]. The advantage of these analytical techniques is related to the minimal or
no sample preparation, quickness of the procedure and potential to run multiple tests with only one
sample. However, different methodologies may be applied, emphasizing the importance of identifying
the most accurate method and equipment.
The aim of this work was to compare the performance of Near-infrared spectroscopy (NIR) and Fourier
Transform infrared spectroscopic method with Attenuated Total Reflectance (FTIR-ATR) for the
multivariate characterization of honey’s chemical composition. In the first approach, the analysed
parameters were: protein content (%), ascertainedby the Kjeldahl method; and apparent sucrose
content (%), evaluated according to the regulatory standards of International Honey Commission.
Partial least squares (PLS) regression was used to build the calibration model for these parameters, in
comparison to the data obtained with the reference methods.
For the 150 Lavandula honey samples two different methodologies were tested: i) a calibration with
cross validation followed by ii) a cross validation (70% of the samples) with a test set (remaining 30%
of the samples).
The obtained models of suitable accuracy for protein content presented an r2 ranging from 96.7% to
81.8% (RPD = 5.5 to 2.4) for FTIR-ATR and between 89.4% and 77.6% (RPD = 3.1 to 2.1) for NIR.
Concerning sucrose content, r2 was between 96.9% and 70.0% (RPD = 5.7 to 1.9) for FTIR-ATR, and
between 88.5% and 64.4% (RPD = 3.0 to 1.9) for NIR. The root means square error of cross validation
and prediction was lower using FTIR-ATR.
The precision achieved using these two parameters suggests that the infrared spectroscopy is a suitable
technique for the characterization of honey samples. However, in general, FTIR-ATR appeared to be
the most accurate method. Different models are in development for other chemical parameters
comparing these two techniques.
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Citation
Anjos, Ofélia; Pereira, Ana Paula; Santos, António J.A.; Estevinho, Letícia M. (2016). Comparison between FTIR-ATR and NIR spectroscopy for Lavandula honey characterization. In Gomes, Helder; Ferreira, Olga ; Barreira, João C.M.; Amaral, J.S. (Ed.) XXII Encontro Luso-Galego de Química: livro de resumos. Bragança: Sociedade Portuguesa de Química. ISBN 978-989-8124-17-3