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CRANFIELD UNIVERSITY Eleni Anthippi Chatzimichali ...

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5.3 Results and Discussion<br />

5.3.1 Case study 2<br />

In case study 2 (“Shelf life of minced beef stored in air, MAP, and in active<br />

packaging at 0, 5, 10 and 15°C”), data have been acquired from two main<br />

experimental techniques: FTIR spectroscopy and high performance liquid<br />

chromatography (HPLC). The data intersection approach presented in Section 2.3.1<br />

extracted a total of 75 common samples along with their respective sensory scores,<br />

which were inserted in the analysis pipeline; these samples consist of 25 fresh (F), 12<br />

semi-fresh (SF) and 38 spoiled (S) samples. In this instance, the spoiled samples<br />

constitute the majority class, whereas the semi-fresh samples the minority class.<br />

Initially, PCA was applied on standalone pre-processed data for dimensionality<br />

reduction purposes in addition to investigating any underlying patterns in the data.<br />

The percentages of variance and cumulative variance for each experimental technique<br />

are presented in Table 8. In the case of FTIR, the first two PCs account for 99% of the<br />

variance. On the contrary, the HPLC data accumulate only 53.23% of the variance for<br />

the first three PCs, while at least five PCs are required to capture approximately 70%<br />

of the total variance. It is apparent that the percentages of variance and cumulative<br />

variance present a similar trend to the datasets of case study 1 (See Table 2)<br />

FTIR<br />

HPLC<br />

PCs %Var %Cum Var %Var %Cum Var<br />

PC1 98.26 98.26 25.89 25.89<br />

PC2 0.83 99.09 14.12 40.01<br />

PC3 0.33 99.42 13.22 53.23<br />

PC4 0.21 99.63 9.22 62.45<br />

PC5 0.16 99.79 7.87 70.32<br />

Table 8 PCA proportion and cumulative variance captured for the datasets of case study 2<br />

121

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