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Chocolate Science and Technology 7100
Hardness (g.force)
6600 R 2 = 82.74
6100 5600 5100 4600 4100
6.1
6.5
6.9
7.3
7.7
8.1
8.5
8.9
Melting index Fig. 7.33 Relationship between hardness and melting index in chocolate (Afoakwa et al ., 2008f). Data points (squares); linear regression (inner solid line); 95% minimum and maximum tolerance intervals (both outer lines); hardness = −4396.97 + 1318.07 × melting index. With kind permission from Springer Science and Business Media, Afoakwa et al . (2008f).
were closely related with loadings for PSD, fat and lecithin content as influencing factors. Fat and lecithin content had polar influences on principal component 1 (PC1) (69.67% variance) score, while PS had marginal influence on PC2 (12.71% variance) score. Afoakwa et al. (2008a) established that PSD had multiple discrete components – specific surface area, largest PS (D90 ), smallest PS (D10 ), mean PS (D50 ) and Sauter mean diameter (D[3,2]) – together influencing rheological properties of dark chocolates. A small number of linear combinations of the nine variables accounted for most of variability (98.7%). In this case, three components were extracted, since 1888 components had eigenvalues 1 or more. The PCA (Fig. 7.34) product space for rheological properties (apparent viscosity and yield stress),
2.6
Component 2 (12.71%)
B
Fat
A
1.6
Melting index 0.6
Lecithin
Hardness Firmness Yield stress Apparent viscosity Index of viscosity
-0.4 -1.4 -2.4
Particle size
-3.4 -9
-6
-3
0
3
6
Component 1 (69.67%) Fig. 7.34 Principal component analysis of rheological, textural and melting properties of dark chocolates (A) as affected by PSD, fat and lecithin content (B) (Afoakwa et al ., 2008f). With kind permission from Springer Science and Business Media, Afoakwa et al . (2008f).