When and Why does the color of “TURMERIC” change?

Turmeric is known by several names (Hindi: Haldi, Nepali: Besar, Spanish: Curcuma, Japanese: Ukon). Used worldwide, India is the largest producer producing nearly 80% of the world’s turmeric (1). India again is the largest consumer of the Turmeric.

However, today we will look at an interesting property of turmeric. That is its color-changing property. Turmeric changes its color and is known as a natural indicator while Phenolphthalein and methyl orange are common synthetic indicators.

But, “WHEN AND WHY DOES THE COLOR OF TURMERIC CHANGE ?“

In-depth knowledge of it is cool to show off in science projects or just curiosity about science brings you here. In any case, You may have eaten a spicy Indian curry that led to a yellow stain on your clothes. Washing the cloth with soap or detergent changed the color of the yellow stain to red stain instead of removing it.

Well, the culprit is the curcumin pigment present in the turmeric. It is a compound that is insoluble in water. Naturally, the turmeric is slightly acidic (Measured pH: 6.92). However, when the pH of the solution containing turmeric changes (like washing with soap), the color of the curcumin changes from yellow to red in the basic solution.

Naturally, when we see turmeric, its color is yellow and remains yellow in food as most of the cooked food that we eat is acidic. However, when alkaline/basic condition is made with any basic substance like soda, detergent, soap, or caustic, Turmeric changes color from yellow to red.

Now, it is known that the turmeric changes its color and this is due to the presence of curcumin pigment in the turmeric, which is also used in food coloring.

Now, let’s see the exact point of pH when the change occurs. For this, we have conducted a simple experiment.

Materials: Water, Turmeric, Lemon, Detergent, pH meter

Process:

• The pH of the water was measured and kept in two glasses
• 1.5 grams of turmeric was dissolved in water and pH was measured
• The detergent solution is dropped which changed color from yellow to red (pH was measured)
• Lemon juice was added, which again changed color from red to original yellow (pH was measured)

Measured pH of the solutions:

• Initial Water :- pH: 7.30
• Turmeric Water :- pH: 6.92
• Lemon Juice :- pH: 2.13
• Detergent Water :- pH: 9.60

The pH of the transition of color was found as:

Initial Turmeric (pH: 7.30) >>>> with Detergent (pH: 8.71) >>>> with Lemon (pH: 6.46)

“The VIDEO below shows the Turmeric Color Experiment”