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,

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

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, = 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

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

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

Best candidates are marked with green ”Positive” attribute – green ”Negative” attribute -red Two first PC’s

PC components 2 and 3 Best candidates are marked with green ”Positive” attribute – green ”Negative” attribute -red

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