Analysis of total flavonoid and antioxidant activity of coconut shell liquid smoke (Cocos nucifera L.) as an antibacterial

Abstract

Background: Coconut shell is often used for cooking or treated as waste. Liquid smoke is a by-product of coconut shell processing, which results from condensation of combustion steam. It is divided into grades one, two, and three based on the characteristics and utilisation. It contains phenolic, carbonyl acids and other compounds which act as antioxidants, antibacterials, and antifungals. Objective: To determine the total content of flavonoids, antioxidants and antibacterial activity in liquid smoke. Method: Liquid smoke was produced by a pyrolysator and distilled to produce grades one, two and three. It was then tested for antibacterial activity using the minimal inhibitory concentration (MIC) method against S. aureus and E. coli. The AlCl3 reagent and DPPH method were used to determine the total flavonoid and antioxidant levels, respectively. Results: The MIC of grade one, two, and three coconut shell liquid smoke was 10%; 10%; 5% against S. aureus; and 10%, 5%, and 5% against E. coli. The total flavonoid yields from grades one, two and three were 0.0041, 0.0174, and 0.2741 mg QE/ml, respectively. Test results for antioxidant grades with IC50 values were 142.82, 121.64, and 90.80 µg/mL. Conclusion: Coconut shell liquid smoke has antibacterial activity, contains a certain amount of flavonoids, and also possesses antioxidant activity.