If you ever see any of your food coloured a bright blue, there’s a high chance you’re seeing the flower of the butterfly pea (also known as a blue pea) working its magic. Barely having any taste, it is frequently used as natural food colouring in Peranakan, Thai and Malay cuisine, such as in Kueh Salat or Nyonya rice dumplings5.
Image by Shiokman Eddie. Retrieved from: https://www.shiokmanrecipes.com/2016/11/18/kueh-salat-kuih-seri-muka/
Image by Angie Liew.
The butterfly pea flower changes from blue to purple when acid (in lemon) is added, making it visually appealing.
Image by Cynthea Lam.
With blue being such a rare colour in nature, it is not hard to spot the bright blue flowers of the butterfly pea along the streets of Singapore. Being a creeper, they are often found to be growing on wire supports or walls, attached by intertwining their thin, slender legumes4. Even though they are so common here, it may be surprising to note that the butterfly pea may not be native to Singapore. In fact, they are so common across all the continents that it is not definite where they originated from; though they were believed to be from South America and Asia before they spread to India, Europe then finally to tropical Southeast Asia6.
To cultivators, the butterfly pea has value in its culinary uses and medicinal purposes, such as being believed to be able to alleviate inflammation in traditional medicine6. Characteristics such as high growth rates, ability to grow in poor soils and drought tolerance making them easy to grow and maintain2.
From here, some of the seeds were dispersed into the wild, and such hardy characteristics allowed them to thrive equally well in the wild. In some places such as Christmas Island, Hawaii and Queensland, they grew so well that they became invasive – threatening the growth of local, native species1. Despite being an introduced species, they can sometimes be beneficial to the environment. Being able to grow in poor quality soil allows them to survive in disturbed habitats such as coal mines. The butterfly pea was then able to increase the nitrogen level of soil and soil fertility, enhancing further revegetation efforts2.
The next time you see blue in your food, hopefully, it will remind you of the butterfly pea flower!
Written by: Shenny Goh
1 Centre for Agriculture and Bioscience International. Clitoria ternatea (butterfly-pea). Retrieved from: https://www.cabi.org/isc/datasheet/55416#b69c866b-b16e-49de-b720-1dcade921e6f (last accessed 1 March 2019)
2 Cook BG, Pengelly BC, Brown SD, Donnelly JL, Eagles DA, Franco MA, Hanson J, Mullen BF, Partridge IJ, Peters M, Schultze-Kraft R. (2005). Tropical Forages: an interactive selection tool. Retrieved from: http://www.tropicalforages.info/key/forages/Media/Html/entities/clitoria_ternatea.htm
3 Kwek Yan Chong, Hugh T. W. Tan and Richard T. Corlett. (2009). A Checklist of the Total Vascular Plant Flora of Singapore. Raffles Museum of Biodiversity Research National University of Singapore Singapore. Retrieved from: https://lkcnhm.nus.edu.sg/app/uploads/2017/04/flora_of_singapore_tc.pdf
4 NParks Flora & Fauna Web (n.d.) Clitoria ternatea (Pale Blue). Retrieved from: https://florafaunaweb.nparks.gov.sg/Special-Pages/plant-detail.aspx?id=1374 (last accessed 1 March 2019)
5 Quek, E. (2018, February 24). Butterfly pea flower lends a blue hue to foods from tea to pasta. Retrieved from: https://www.straitstimes.com/lifestyle/food/butterfly-pea-flower-lends-a-blue-hue-to-foods-from-tea-to-pasta
6 Singapore Infopedia. (2016). Butterfly pea. Retrieved from: http://eresources.nlb.gov.sg/infopedia/articles/SIP_763_2004-12-20.html
7 The DNA of Singapore. (n.d.) Clitoria ternatea. Retrieved from: https://lkcnhm.nus.edu.sg/dna/organisms/details/522 (last accessed 1 March 2019)