The Effect of Citric Acid on Antioxidant and Antibacterial Activities of Butterfly Flower Extract (Clitoria ternatea L.)

Abstrak

Telang (Clitoria ternatea L.) is an herbaceous plant with blue flower that has been used as a natural dye in beverages because of its potential as antioxidant source. When it is consumed, orange or lime juice is added to butterfly flower infusion to give it a taste. This study is aimed to analyze the effect of citric acid on the antioxidant and antibacterial activity of butterfly flower extract. This study starts with the extraction of butterfly flower powder at three conditions, which are without addition of acid, pH 2 and pH 4 with addition of citric acid. Phytochemical screening, inhibition and antioxidant activity were carried out on all extracts. Phytochemical assay showed the presence of tannin, saponin, terpenoid, flavonoid, alkaloid, and anthocyanins in extract from all treatments. The inhibition test resulted the highest antibacterial activity at pH 2 extract with an inhibition zone diameter of 39 ± 0.153 mm in Staphylococcus aureus and 28 ± 0.100 mm in Escherichia coli, which were classified as very strong activity. This extract also had the highest antioxidant activity with IC₅₀ 136 ppm which was categorized as moderate activity. This study presents that butterfly flower extraction at pH 2 using citric acid is potential to increase the antioxidant and antibacterial activity of this extract which can be used in the development of functional food.

Keyword: antibacterial, antioxidant, butterfly flower extract, pH