Second- order response surface method: factorıal experiments an alternative method in the field of agronomy

Abstract

The main purpose in all experimental designs is to take into account the factors that are considered likely tohave an effect on the response variable emphasized, and to minimize the error of experiment in this way.Bread, which is the staple human food, c annot have any negative effect on human beings as long as it isproduced by using suitable materials under appropriate conditions . However, when inappropriate amounts ofraw materials are used (e.g. non-optimal amounts of bran, yeast or other additives), bread threatens health. Inthis study, Box -BehnkenDesign (BBD) and Central Composite Design (CCD), the two different designs of theresponse surface method, were applied to a single dataset. Two designs were evaluated in terms of the resultsobtained. The purpose in the second-order factorial experiments is to identify the optimum levels ofindependent variables for the dependent variable. In this study, the implementation of second-order responsesurface model and interpretation of the results were based on 2 k CCD (Central Composite Design) and BBD(Box -Behnken Design) with one replicate. In the CCD, the amount of bran added, flour type , the ratio of yeastadded, furnace temperature, the duration of remaining in the furnace, and fermentation time were accepted tobe significant factors that affected volume yield. In addition, R 2 = 80.7 % shows that the regression equationexplains variables by 80.7 % . In the BBD, the ratio of bran added, the type of flour, the ratio of yeast added,furnace temperature (only in quadratic form ), the duration of remaining in the furnace (only in quadraticform), and fermentation time (only in quadratic form) were accepted to be significant factors that affectedvolume yield. Furthermore, R2 = 89.64 % shows that the regressio n equation explains variables by %89.64 .This method provides savings in terms of time and the amount of material by limiting the area at particularlevels. Researcher may use the results of either CCD or BBD (whichever s/he deems suitable) according to thevolume s/he wants to obtain.