Table 2.

Mathematical models for conjugated diene content, total polar material content, polymer triglyceride content, viscosity and color values of oil samples taken after 50th frying

Models	Equationsa	P values		Adequate precision	Determination coefficient (R2)
		Model	Lack of fit
Model 1	CD (%) = −0.67 + 6.72 × 10−3A − 0.29B + 0.48C + 1.97 × 10−3AB – 1.1 × 10−3AC − 0.02BC -0.03C2	< 0.0001*	0.1666	16.369	0.9331
Model 2	TPM (%) = 8.11 − 0.03A − 7.24B − 1.38C + 0.05AB + 7.5 × 10−3AC − 0.68B2 + 0.13C2	0.0005*	0.9593	13.061	0.8451
Model 3	Polymer TAG (%) =  −54.53 + 0.61A − 1.97B − 0.07C + 0.01AB + 9.77 × 10−3AC − 1.58 × 10−3A2 − 0.16C2	< 0.0001*	0.7303	17.363	0.9196
Model 4	Viscosity (cP) =  + 27.00 + 0.12A − 3.86B + 3.56C + 0.03AB − 0.016AC−0.21BC	< 0.0001*	0.6105	19.656	0.9199
Model 5	L* = -134.32 + 2.26A + 5.65B – 1.59C – 0.03AB -0.25BC −6.55 × 10−3A2 + 0.20C2	0.0001*	0.9537	18.273	0.9276
Model 6	a* =  + 182.46 − 2.24A − 0.52B −1.76C − 7.09 × 10−3AB + 0.02AC + 6.67*10−3A2 + 0.65B2 − 0.12C2	< 0.0001*	0.2227	19.749	0.9654
Model 7	b* =  + 65.00 − 0.59A − 3.30B + 0.88C + 0.30BC + 2.34 × 10−3A2	< 0.0001*	0.4874	21.611	0.9076

*Statistically significant at a significant level (α) of 0.05

^aLetters A, B, C indicate frying temperature (°C), dough salt content (%) and frying time (min), respectively

CD, conjugated diene value, TPM, total polar material, TAG, triglyceride