Table 21.

Analysis of methods for color determination of amber-colored liquids.

	Methods	Equipment	Sample Preparation	Destructive	Wavelength (nm)	Model Equation	AI-Based Processing	Accuracy	Ref No.
Mineral Oil	Visual Examination	✓	✕	✕	NA	NA	NA	NA	[23]
	Visual Comparator	✓	✕	✕	NA	✕	NA	NA	[25]
		✓	✕	✕	NA	✕	NA	NA	[45]
	UV-Vis Spectroscopy	✓	✕	✕	400–700	✓	✕	RMSE = 0.6274	[62]
		✓	✕	✕	400–700	✓	✕	R2 = 0.99971	[67]
		✓	✓	✕	300–800	✓	✕	RMSEP = 0.18, 0.23	[68]
		✓	✓	✕	300–700	✓	✕	NA	[74]
		✓	✕	✕	590, 840	✓	✕	R2 = 0.9974	[72]
	Image Analysis	✓	✕	✕	NA	✕	✕	NA	[100]
Olive Oil	UV-Vis Spectroscopy	✓	✕	✕	300–800	✕	✕	NA	[77]
		✓	✓	✕	380–770	✕	✕	NA	[75]
		✓	✕	✕	380–770	✓	✕	color diff. = 3.6	[79]
		✓	✕	✕	430–480 and 660–670	✓	✕	R2 = 0.881–0.992	[76]
	Image Analysis	✓	✓	✓	NA	✕	✕	AAE = 3%	[113]
Palm Oil	Visual Colorimeter	✓	✕	✓	NA	✕	✓	MSE = 7.0348 × 10−5	[53]
	UV-Vis Spectroscopy	✓	✓	✓	RGB	✓	✕	R2 = 0.9236	[80]
		✓	✓	✓	380–780	✕	✕	NA	[84]
	Image Analysis	✓	✓	✓	NA	✕	✓	MSE = 0.0011	[81]
Nut Oil	Automatic Colorimeter	✓	✓	✕	NA	✕	✕	NA	[62]
		✓	✓	✕	NA	✕	✕	NA	[63]
		✓	✓	✕	NA	✕	✕	NA	[64]
	UV-Vis Spectroscopy	✓	✓	✕	400–700	✓	✕	R2 = 0.8717, 0.854	[21]
		✓	✓	✕	400–700 Abs–460, 550, 620, 670	✓	✕	R2 = 0.8717 @ 20 °C, R2 = 0.854 @ 40 °C	[87]
		✓	✓	✕	400–700	✕	✕	NA	[86]
Maple Syrup	UV-Vis Spectroscopy	✓	✓	✕	Abs = 560	✕	✕	NA	[94]
		✓	✓	✕	Abs = 560	✕	✕	NA	[20]
		✓	✓	✕	Abs = 560	✕	✕	NA	[95]
	Fluorescence Spectroscopy	✓	✓	✓	230–370	✓	✕	R2 = 0.91 and 0.88	[101]
		✓	✓	✕	Abs = 560	✕	✕	NA	[104]
Honey	Automatic Colorimeter	✓	✕	✕	NA	✕	✕	NA	[22]
	UV-Vis Spectroscopy	✓	✓	✕	380–780	✕	✕	NA	[93]
		✓	✓	✕	450–720	✕	✕	NA	[91]
		✓	✓	✕	ABS = 450, 635, 720	✕	✕	NA	[90]
	Image Analysis	✓	✕	✕	NA	✕	✓	NA	[106]
		✓	✓	✕	NA	✕	✓	Accuracy ≥ 90%	[108]
		✓	✕	✕	NA	✓	✓	R2 = 0.97	[36]
Beer	UV-Vis Spectroscopy	✓	✕	✕	450–800,	✕	✕	NA	[97]
					900–1200
		✓	✓	✕	380–780 Abs = 430	✕	✕	NA	[99]
		✓	✓	✕	430	✓	✕	R2Vlow = 0.9677, R2VHigh = 0.9963	[98]
	Image Analysis	✓	✕	✕	NA	✓	✕	NA	[112]
		✓	✕	✕	NA	✓	✓	100%	[111]

NA = not applicable. ✕ = not needed or not applied, ✓ = needed or applicable.