Ultrasound-Assisted Extraction of Phenolic Compounds from Moroccan Lavandula stoechas L.: Optimization Using Response Surface Methodology

Table 4

Estimated regression coefficients for the yield response and their level of significance value.

Term	Coefficient	Estimation	Standard deviation	‐value
Constant	b0	21.62	1.075	<0.0001
Extraction time	b1	0.899	0.658	0.23
Solvent-to-material ratio	b2	4.421	0.658	0.001
Ethanol (%)	b3	−2.138	0.658	0.023
Extraction time  solvent-to-material ratio	b12	2.758	0.931	0.031
Extraction time  ethanol (%)	b13	−0.24	0.931	0.806
Solvent-to-material ratio  ethanol (%)	b23	−3.285	0.931	0.017
Extraction time  extraction time	b11	−3.709	0.969	0.012
Solvent-to-material ratio  solvent-to-material ratio	b22	−3.989	0.969	0.009
Ethanol (%)  ethanol (%)	b33	3.449	0.969	0.016

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