Improved automatic steam distillation combined with oscillation-type densimetry for determining alcoholic strength in spirits and liqueurs

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Table 1 Regression coefficients in coded values for the optimisation of steam distillation on different instruments

Regression coefficient	Experiment 1 A-Steam power B-Distillation time C-Sample volume		Experiment 2 A-Steam power B-Coolant flow	Experiment 3 A-Sample volume B-Receiver volume C-Pipette/flask
Device	Vapodest 30	Vapodest 200	Vapodest 200	Vapodest 200
Matrix	Liquorice liqueur		Cream liqueur	Cream liqueur
Intercept	16.89	19.96	16.77	16.63
A	1.92**	1.39	0.03	0.43**
B	3.26***	4.41***	0.02*	−0.25*
C	−0.20	−0.70	–	−0.35**
A²	−0.82	−0.33	−0.04	−0.084
B²	−2.34***	−2.87***	no effect	–
C²	−0.21	−0.09	–	–
AB	−1.57*	−1.45	−0.02	0.30*
AC	−0.85	−1.10	–	0.31*
BC	0.36	−0.18	–	0.14
r²	0.947**	0.949***	0.605*	0.842**