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CRANFIELD UNIVERSITY Eleni Anthippi Chatzimichali ...

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Figure 2-1 Mean FTIR spectra for case study 1 in the fingerprint region (1500-1000 cm -1 )<br />

The plot depicts the mean FTIR spectra for each distinct class of shelf life beef fillets (stored in air at<br />

0, 5, 10, 15 and 20°C). The spectral region between 1500 and 1000cm -1 reveals the metabolic<br />

fingerprint of spoilage. Colour representation is used to identify the three classes as determined by the<br />

relevant sensory scores: fresh (red colour), semi-fresh (orange colour) and spoiled (green colour).<br />

2.2.1.4 High Throughput Liquid Chromatography (HPLC)<br />

The analysis was performed using a Jasco (Japan) HPLC equipped with a Model<br />

PU-980 Intelligent pump, a Model LG-980-02 ternary gradient unit pump and a<br />

MD-910 multi-wavelength detector (Argyri, 2010). The software used for the<br />

collection and the processing of the spectra in order to give concentrations of key<br />

metabolites was the Jasco Chrompass Chromatography Data system v1.7.403.1.<br />

Spectral data were collected from 200 to 600nm; however, chromatogram integration<br />

was performed at 210nm and the purity of the peaks was examined through the<br />

software using all spectral ranges. Solutions of oxalic, citric, malic, lactic, acetic,<br />

formic, tartaric, succinic and propionic acids were used as reference substances,<br />

analysed using the same programme, and their spectra were compared with the<br />

samples for the identification of the peaks (Argyri, 2010).<br />

In total, 52 samples were analysed in duplicate. Based on the provided sensory scores,<br />

the HPLC samples consist of 20 fresh (F), 14 semi-fresh (SF) and 18 spoiled (S)<br />

samples.<br />

35

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