Statistical Optimization of Process Parameters for Lipase-Catalyzed Synthesis of Triethanolamine-Based Esterquats Using Response Surface Methodology in 2-Liter Bioreactor

Table 1

Variables and their levels employed in the central composite design.

Variables	Units	Coded level of variables
		−1.75	−1	0	1	1.75
𝑋1: Enzyme amount	w/w%	1.5	3	5	7	8.5
𝑋2: Reaction time	h	2	8	16	24	30
𝑋3: Reaction temperature	°C	51.25	55	60	65	68.75
𝑋4: Molar ratio of substrates	OA : TEA (mole : mole)	0.25 : 1	1 : 1	2 : 1	3 : 1	3.75 : 1
𝑋5: Agitation speed	r.p.m.	137.5	250	400	550	662.5