An article in European Food Research and Technology [Factorial Design Optimisation of Grape (Vitis vinifera) Seed Polyphenol

An article in European Food Research and Technology [€œFactorial Design Optimisation of Grape (Vitis vinifera) Seed Polyphenol Extraction€ (2009, Vol. 229(5), pp. 731€“742)] used a central composite design to study the effects of basic factors (time, ethanol, and pH) on the extractability of polyphenolic phytochemicals from grape seeds. Total ployphenol (TP in mg gallic acid equivalents/100 g dry weight) from three types of grape seeds (Savatiano, Moschofilero, and Agiorgitiko) were recorded. The data follow.

(a) Build a second-order model for each seed type and compare the models.

(b) Comment on the importance of any interaction terms or second-order terms in the models from part (a).

(c) Analyze the residuals from each model.

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Ethanol (%) Time (H) Run pH TP Moschofilero Savatiano Agiorgitiko 13,320 1 40 2 1 13,127 8,673 13,596 8,925 40 2 5 4,370 3 40 1 10,714 12,047 8,049 4 40 5 10,730 11,299 5,315 2 12,149 9,700 9,384 2 10,910 7,107 8,290 1 11,620 8,755 7,905 9,757 8. 60 5 9,792 9,347 9,748 9. 40 13,593 7,253 10 60 4. 3 13,459 8,727 8,390 11,980 7,164 7,611 11 50 12 50 6. 3 10,338 5,928 7,292 13 50 13,992 12,200 8,305 14 50 13,450 10,552 8,380 8,792 15 50 3 11,745 9,284 16 50 4 3 12,267 9,084 8,302