The objective of this workshop is to show the possibility of explaining and understanding the concept of pH through a natural product such as, in our case, red cabbage.

The objective of this workshop is to show the possibility of explaining and understanding the concept of pH through a natural product such as, in our case, red cabbage. Red cabbage contains pigments called anthocyanins that change colour when in contact with acids and bases. For this reason, red cabbage extract is used as a natural indicator, since it turns pink or red in an acidic medium and blue, green or yellow in a basic medium. Acid-base indicators or pH indicators are weak organic acids or bases; their undissociated form is different from that of their corresponding conjugate acid or base. The colour change that occurs is due to a structural change in the indicator substance induced by protonation or deprotonation of the product. Chemists use pH to accurately indicate the acidity or basicity of a substance. Normally, pH ranges from 0 (most acidic) to 14 (most basic).

Some vegetables, such as red cabbage, strawberries or red onions, have a group of substances (anthocyanins) that are very sensitive to changes in pH, so they can be used as natural indicators. Anthocyanins are a group of water-soluble pigments responsible for the red, blue or violet coloration of many flowers, fruits, vegetables, etc. Therefore, with a simple red cabbage we can qualitatively determine the pH of many everyday products at home, including certain foods and cleaning products.

Coordinated by: Natalia Muñoz Padial

Date and time:
September 29, 2022, from 10 am to 14 pm and from 16.30 pm to 20 pm

Place: Dock shed number 2 of the Valencia port.