Caffeine, Chlorogenic Acid and Antioxidant Properties in Different Clones of Green and Roasted Liberica Coffee Bean Extracts

Abstract

Background: Liberica coffee (Coffea liberica), one of the lesser-known coffee species, is commonly grown and consumed in most Southeast Asia countries, especially in Malaysia. Despite its growing relevance, limited information exists on the influence of clone and roasting on its bioactive compounds and antioxidant activity. Aims: The study aimed to evaluate and compare caffeine, chlorogenic acid and antioxidant properties of three newly developed Liberica clones; MKL 8, MKL 9 and MKL 10, with the goal of identifying the best clone for potential use in high quality coffee production and functional food or nutraceutical applications. Study Design: The study was conducted using a Completely Randomized Design (CRD) involving the three Liberica coffee clones, where both green (unroasted) and medium-roasted bean samples were independently analyzed. Place and Duration of Study: The study was conducted at the Malaysian Agricultural Research and Development Institute (MARDI), with samples collected from the Industrial Crops Research Centre, MARDI Research Station, Kluang, Johor, between March and September 2022. Methodology: Green coffee beans were dried under a hot air oven at 60°C and medium-roasted prior to extraction with 70% ethanol using ultrasonication-assisted extraction method. Both green and medium-roasted bean extracts were analyzed for phytochemical and antioxidant properties using spectroscopic and non-enzymatic antioxidant methods. Results: Green bean extracts showed significantly (p<0.05) higher antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC) compared to roasted beans. Among the clones, MKL 10 showed the strongest antioxidant activity (DPPH, IC₅₀ = 0.582 mg/mL; FRAP = 9.636 mM) and MKL 8 recorded the highest TPC (148.708 mg CGAE/g). HPLC analysis revealed that chlorogenic acid (CGA) levels were significantly (p<0.05) higher in green bean extracts (3.345 to 7.172 mg/g), while roasted beans showed significantly (p<0.05) higher caffeine content (11.712 to 13.691 mg/g). After roasting, MKL 8 retained the highest antioxidant activity, TPC and TFC, while MKL 10 maintained the highest CGA content (6.21%). Conclusion: Both clone and roasting significantly influence the phytochemical and antioxidant properties of Liberica coffee. MKL 8 and 10 stand out as the most promising clones, exhibiting the highest antioxidant and phytochemical properties. These findings suggest their strong potential as a high performing Liberica clones for quality enhancement and future product development.