In the last years the fraudulent practices have proliferated in saffron spice. It is due to the high price of the spice and to the lack of technological methodologies available to detect them.
The term adulteration refers to the addition of mineral substances, oils or molasses for increasing weight on the one hand, and on the other, it refers to the addition of various dye material in order to improve its image.
According to ISO / TS 3632:2003, saffron is considered to be pure when the samples fulfill the requirements defined in the technical specification section 1 and when no other substance is added to the natural product.
The most common saffron adulterations are mentioned in the table of the document attached.
Techniques of adulteration determination
Three different methods are used for detecting adulterations: Thin layer chromatography (TLC), high pressure liquid chromatography (HPLC) and microscopic analysis.
Thin Layer Chromatographic (TLC)
The thin layer chromatographic method allows the detection of artificial water-soluble dye acid substances. It applies to saffron threads as well as to saffron powder. The detected dye substances are as follows: cynoline yellow, S – napthol yellow, tartrazine, amaranth, A – cochineal red, azorubine, orange II, erythrocine and rocceline.
High pressure Liquid Chromatography (HPLC)
The HPLC method is used for the determination of three different elements:
• Identification of dye substances responsible for saffron couloring intensity (crocines),
• Identification through artificial dye substances, water-soluble acid, pursuant to the ISO/TS 3632, 2003,
• Identification through fat-soluble dye substances.
This method is applied on saffron threads or saffron powder in order to determine whether the sample consists solemnly of Crocus sativus L. stigmas or if other flower residue and foreign material are also present.
The preparations for microscopic analysis are performed according to ISO 3632, section 6. The elements that should be found in order to verify the sole existence of Crocus sativus L. stigmas are as follows:
• Upper end stigma residue with epitheliums
• Epidermal stigma residue
• Epidermal column residue
• Pollen granules with a 80 – 100 μm diameter
• Transport container debris
• Stamens residue
• Starch granules
• Inorganic material
• Foreign material cellular residue
• Cells with content that remains colored