Preliminary study on the antibacterial activity of liquid smoke from cacao pod shells (Theobroma cacao L)

Abstract

Cacao pod shells (Theobroma cacao L) form biomass waste that can be used as raw material for liquid smoke because this biomass contains lignin, cellulose, and hemicellulose. This research studied the antimicrobial activity of liquid smoke from cacao pod shells on several common food-borne pathogens, such as Salmonella choleraesuis, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. The liquid smoke used was obtained from cacao pod shells that were pyrolyzed at 300 °C (T1), 340 °C (T2), and 380 °C (T3). Liquid smoke concentration varied from 1% to 5%. The antbacterial activity test was conducted using the Kirby–Bauer method. The results showed that liquid smoke produced from T1 and T2 (and at liquid smoke concentrations of 4% and 5%) could inhibit the growth of all the tested bacteria. At T3 and 1–5% of liquid smoke, only E. coli was consistently inhibited (inhibition zone = 6–7.05 mm), while the growth of S. choleraesuis and S. aureus was inhibited at 3–5% liquid smoke with the inhibition zone ranging from 6 mm to 7.2 mm. B. subtilis was inhibited by a 2–5% liquid smoke concentration. All the tested bacteria showed sensitivity to liquid smoke, but E. coli was the stronger resistant compared to others. The results of this study show that liquid smoke from cacao pod shells could be used as a preservative agent to inhibit microorganisms in food.