PCA application

1
PCA application

• Processed cheese
• Ref Ellekjær, Ilseng and Næs (1996). A case
  study of the use of exp. design and mult. anal.
  in product development. Food Quality and Pref. 1,
  29-36.

2
Practical problem

• Processed cheese
• Improvement of texture properties
• Can we increase meltability and decrease
  stickiness, graininess and adhesiveness

3
Designed experiment

• 7 factors
• Melting salt, maturity of cheese, dry matter of
  processed cheese
• pH, addition of dry matter, after creaming,
  cooling of cheese
• Both process and ingredient variables
• Fractional factorial design, 27-2 32
• Three center points for each melting salt
• Three replicates of a reference were added
  (original recipee)
• Resolution IV design
• Main effects and two factors interactions are not
  confounded
• Sensory responses
• Glossiness, ability to retain shape,
  adhesiveness, firmness, graininess, stickiness,
  meltiness, condensation

4
Analysis techniques

• Used averages of sensory variables (over
  assessors)
• Used PCA and ANOVA
• PCA gives an overview and indicates optimal
  samples in the design
• ANOVA is important for determining which
  variables that are important for further study

5
ANOVA results

• Higher order interactions used to test
  significance
• Most important variables were maturity of
  cheese, dry matter of processed cheese and pH
• Only a few interactions were significant

6
Two first PCs
Best candidates are marked with green
Positive attribute green Negative attribute
-red
7
PC components 2 and 3
Best candidates are marked with green
Positive attribute green Negative attribute
-red
8
Conclusions

• Replicates quite close
• Supports reliability of experiment
• We got information about which samples that are
  best
• We got information about which experimental
  factors that are most important