Design expert software version 9

Two design factors—water and oat β-glucan content—were chosen as quantitative independent factors to analyse their influence on cooking yield, texture, colour, specific volume, β-glucan content and overall acceptance. The independent factors were tested at the following levels: − 1, 0, + 1, between the ranges 0.5–3% for oat β-glucan (OBG) and 30–90% for water. Those levels were established based on literature research and preliminary study where maximum and minimum doses of water and oat β-glucan were checked to see if creation of a dough structure is still possible. Using the Design Expert software version 9 (Stat-Ease, Inc., USA), 13 runs (Table 1) were calculated and the quadratic equation was chosen to describe the relations among factors and responses. The central point of the model was replicated five times. The last step was the optimisation of the formula and the experimental verification of calculated values of responses.Table 1

Experimental design: amounts of oat β-glucan and water needed to be analyzed in each elaboration

Run	OBG (%)	W (%)
1	3	60
2C*	1.75	60
3C	1.75	60
4	2.63	38.79
5	1.75	90
6	1.75	30
7C	1.75	60
8	0.87	81.21
9	2.63	81.21
10	0.5	60
11C	1.75	60
12C	1.75	60
13	0.87	38.79

^*C central points, OBG oat β-glucan, W water

The effect of independent variables on the responses was analyzed using Design Expert software version 9 (Stat-Ease, Inc., Minneapolis, USA). The polynomial equation was generated after omitting the insignificant coefficients at 95% confidence level using Pareto chart. The values of effects of coefficients were interpreted with the help of bar graph of coefficients obtained between the Bonferroni line and t-limit line. The generated polynomial equation for response parameter was used for validation of design. The 3D response surface graphs were used to analyze the influence of different levels of the variables on the response parameter (%  CDR_8 h).