Table 4.

Results of statistical analysis a regression model of central composite design on extraction yield from the model system for Maesil wine

Source	Yield
Linear	0.005*
X1	<0.001*
X2	<0.001*
X3	0.193
X4	0.672
Quadratic	0.002*
X1X2	0.596
X1X3	0.143
X1X4	0.568
X2X3	0.690
X2X4	0.003*
X3X4	0.013*
X12	0.005*
X22	0.035*
X32	<0.001*
X42	0.001*
Residual
Lack of fit	0.577
Fitness of model (R2)	0.920

Statistically significant at *P<0.05.