Annex White book.pdf

Picture 5. UV-Vis absorption spectrum characteristic for saffronaqueous solutionOn the other hand, the absorption is determined in three wavelengths(λmax): at 257 nm where picrocrocine demonstrates its maximumabsorption level, at 330 nm where safranol demonstrates its maximumabsorption level and at 440 nm for coloring power determination.The three wavelengths are calculated according to following formulawhere D is the absorption value for each wavelength, m is the saffronmass in gram and H is the sample humidity and volatile substancescontent in percentage %. The minimum value coloring power (440 nm)in category I is 190. The minimum absorption at 257 nm ( 257 nm) forcategory I is 70, while absorption at 300 nm ( 300 nm) varies between20 (min) and 50 (max).This test shows two significant points regarding coloring power ofsaffron: the smaller the particles are after grinding, the higher is theobtained value of the coloring power. For this reason, saffron shouldbe grinded so that 95 % of the powder can pass through the 500 μm“sieve”. This is a quality norm for saffron powder that should be fulfilled.In other cases the sample fraction should be grinded until such particlesize is reached.The other important point is the agitation speed for the extractionof the saffron’s dye substances: the higher the speed the greater theextracted amount. According to ISO 1000 rounds per minute shouldbe used even if the magnetic agitators do not allow the verification ofsuch speed. We can assume that this speed is reached when the createdsolution vortex reaches the round bottom of the bottle.153