Independent variable Intensity of green color Force (gf)   Coefficients Pr>t Coefficients Pr>t b0 5.37 x10-1   <0.0001 7.44x103 <0.0001   b1 1.59x10-2   0.0001 -5.92x102 <0.0001   b2 1.85 x10-2  0.0579 -2.21x102 0.2420   b3 -1.44x10-2   <0.0001 -2.70x102 <0.0001   b12 -1.61x10-3 <0.0001 38.3 <0.0001   b22 -1.13x10-3 0.6689 -21.9 0.6724   b32 4.35x10-4 0.0178 13.7 0.0003   b12 -1.31x10-3 0.0644 12.4 0.3637 6.24 0.0923 b13 -6.43x10-5 0.7286 15.7 0. 1397   b23 -7.58x10-4 0.1617       Significance level was defined as P< 0.05; the values in bold indicate the significance

Table 2: Regression coefficients of second-order polynomials for response variables (intensity of green color and hardness).