Saffron

The quality of saffron is dependent on coloring strength (crocin concentration), odor (safranal) and taste (picrocrocin). Besides in commercial evaluations content of flora waste and extraneous matter is important.
An international standard for saffron is available: ISO 3632-1:1993.
Saffron in filaments is classified into four categories (or in another word four grades) based on the content of flora waste and extraneous matter.
The chemistry of saffron has been investigated in detail. The major pigment, a water soluble carotenoid giving saffron its value as a dye, is crocin, a yellow-red pigment found at levels of up to 2%. Picrocrocin (less than 4%) is a bitter-tasting principle that hydrolyses to glucose and safranal (less than 4%), on drying.