Flavor Investigator: Turmeric

According to the Campbell’s Culinary Trendscape of 2018 it is expected that earthy flavours will dominate the beverage sector. Campbell’s has observed that recently the top searches in the beverage category are ginger, matcha and turmeric with ginger seeing a 32% growth year over year. Previously on the flavour investigator we have explored the flavour of ginger however we have yet to put a spotlight on turmeric, the rhizome cousin to ginger.  Today we are going to change that.

Turmeric (Curcuma longa) is a rhizomatous herbaceous perennial plant and belongs to the genus Curcuma. A rhizome is an underground plant stem used to store starches for a plant. Turmeric originates from India and was originally used a food additive to improve the palatability, storage and preservation of food.  It is estimated that 80% of the world’s supply of turmeric grows in India. This spice is also grown in countries such as Pakistan, Malaysia, Myanmar, the Caribbean Islands and Central America.

Overall, the characteristic flavour of turmeric is spicy, warm, earthy, fresh, slightly bitter, mustard-like, orange, ginger and galangal (sharp, citrusy and piney).

The Colour of Turmeric

One of the most characteristic properties of turmeric is it’s rich yellow-orange colour.  Most Indian curries are golden because of the spices dyes the dish color orange. The compound responsible for the rich colour in turmeric is curcumin.  Curcumin is a curcuminoid and a natural colour. The reason why curcumin has such as rich colour is because of the structure of the molecule.  This compound is made up a of large system of double and single bonds also known as a conjugated system.

Many pigments make use of a conjugated electron systems to absorb visible light.  This absorption leads to strong colour like we see in turmeric. Other compound which have long conjugated hydrocarbon chains include beta-carotene (give carrots an orange colour) and carmine (a natural red dye). Therefore, conjugated systems are what give many natural colours their rich colour.

Flavour Compounds in Turmeric

Ar-turmerone and α- and β-turmerone have been identified as the two major compounds responsible for the aroma of turmeric.  These aromatic compounds are commonly used in Asian medicines because it is believed that they have the ability to reduce blood sugar. Unfortunately, I was unable to find the exact flavour descriptors for this compound but it is likely you can associate it with characteristic turmeric flavor.

Other major compounds which have been found in rhizome oil are borneol, zingiberene and α-phellandrene. Borneol is a bicyclic organic compound is a common tradition Chinese herbal formula used to stimulate the production of gastric juices.  In regards flavour, borneol is described as being camphoreous, minty, herbal, earthy and woody.

Zingiberene is the terpene responsible for the slight spiciness found in turmeric. It is also the compound that gives ginger it’s characteristic spice. Finally, α-phellandrene is an organic compound characteristically known for being having terpenic, citrus, lime and green notes.