Table 3.

Regression coefficients of response surface models for diffusivity and equilibrium data during solid–liquid extraction of roselle flower (Hibiscus sabdariffa)*

Activity	Response	Parameters*						R 2
		b 0	b 1	b 2	b 12	b 11	b 22
TPC	D × 1011 (m2/s)	0.849	0.246	− 0.604	− 0.114	0.073	0.770	0.99
	ΔXae	36.6	6.38	20.5	4.71	0.54	18.4	0.99
	Κ	0.686	0.149	− 0.071	0.068	0.016	0.530	0.98
TFL	D × 1011 (m2/s)	0.928	0.136	− 0.898	− 0.164	0.109	0.228	0.99
	ΔXbe	77.9	14.5	29.7	8.86	− 1.29	0.30	0.99
	Κ	0.990	0.223	− 0.068	0.047	− 0.006	0.081	0.95
TAC	D × 1011 (m2/s)	3.50	1.44	− 0.339	− 0.659	− 0.031	0.397	0.80
	ΔXce	99.0	39.0	56.4	12.1	6.76	17.4	0.99
	Κ	1.134	0.631	0.156	0.051	0.140	0.294	0.98

*Bold numbers indicate significant parameter estimates (p < 0.05)

TPC total phenolic compounds, TFL total flavonoids, TAC total antioxidant capacity

^ag GAE/kg d.m.

^bg catechin/kg d.m.

^cg trolox/kg d.m.