Picrocrocin – Saffron’s taste

C. sativus is a species of the genus Crocus in the family Iridaceae that is primarily cultivated in Iran, Greece, India, Spain and less commonly in France and Switzerland. The orange to crimson red stigma and styles of C. sativus are collected, dried and powdered to make the spice saffron which is mainly used as a seasoning and colouring agent in food

Figure 1: Crocus sativus plants (left) and saffron threads soaking in water to yield the yellowish to orange colour that saffron is famous for.

Saffron is one of the first spices children in Germany learn about with the popular children’s rhyme «Backe, backe Kuchen, der Bäcker hat gerufen. Wer will guten Kuchen backen, der muss haben sieben Sachen, Eier und Schmalz, Zucker und Salz, Milch und Mehl, Safran macht den Kuchen gehl! Schieb, schieb in’n Ofen ’rein”. The yellow colouring effect of saffron that the lyrics refer to (“Safran macht den Kuchen gehl”), is attributed to the carotenoids and apocarotenoids (degradation products of carotenoids) such as α-crocin and crocetin. During the cleavage of carotenoids to apocarotenoids, picrocrocin (CAS 138-55-6) is formed as another degradation product.

Figure 2: Saffron flower with the dominant orange to crimson red tubes used to make the spice (left) and the molecular structure of picrocrocin (right).

Saffron contains between 2.7 and 12.9% picrocrocin, a monoterpene glycoside that is not found in any other plants of the Crocus family. During storage, the odorless picrocrocin is transformed to safranal by cleavage of the glucose group. The volatile aldehyde safranal is mainly responsible for the aroma of saffron.

Picrocrocin and it’s degradation products are also those phytochemicals supposedly responsible for the toxic effects of saffron. However, the LD50 (mice) is rather high with 20g/kg bodyweight and humans can consume up to 1.5 g of saffron per day without any undesirable effects. Symptoms of saffron intoxication are vomiting and diarrhoea, dizziness, swelling of lips, lids or joints. If taken up in high doses, saffron can induce miscarriage in pregnant women. Nevertheless, saffron extracts have also been shown to have positive effects such as high antioxidant and free radical scavenging activity or cytotoxicity towards cancer cells in animal tests.

SMILES: CC1=C(C(C[C@@H](C1)O[C@H]2[C@@H]([C@H]([C@@H]([C@H](O2)CO)O)O)O)(C)C)C=O

References:
Teuscher, E.; Lindequist, U. (2010) Biogene Gifte: Biologie-Chemie-Pharmakologie-Toxikologie. Wissenschaftliche Verlagsgesellschaft GmbH, Stuttgart, 3 Auflage. (in german)

CSID:115678, http://www.chemspider.com/Chemical-Structure.115678.html (accessed 10:48, Feb 20, 2020)

Pictures:

https://upload.wikimedia.org/wikipedia/commons/1/17/Saffron8.jpg

https://upload.wikimedia.org/wikipedia/commons/2/2c/860808-Saffronfarm-01-IMG_7707-2.jpg

https://upload.wikimedia.org/wikipedia/commons/9/97/Saffron_soak.jpg