Drying characteristics and phytochemicals retention of selected clones of Liberica coffee grown in Malaysia

Coffee is one of the world's most well-known and popular beverages, and the trees can be found in many countries, including Malaysia. Coffee beans have been used in a variety of foods and beverages since ancient times due to their unique and tasty flavour. Arabica and Robusta are the two most widely grown clones, with Liberica being the most underutilized. Liberica clones have recently gained popularity in Malaysia due to their distinct flavour profile. In view of this, the current study assessed the drying characteristics of selected clones of Liberica coffees and the influence of drying temperatures on phytochemicals retention was conducted. Coffee beans from selected clones of 211, 213, 222, 224, and MKL7 were harvested at optimum maturity and dried in a convective oven at 50°C, 60°C, and 70°C. The drying periods for all clones were observed at 15 hrs, 8 hrs, and 6.5 hrs when drying at 50°C, 60°C, and 70°C respectively. Clones 211, 213, and 224 showed high antioxidant activity when subjected to oven drying at 60°C with values ranging from 0.997 IC50 (mg/mL) to 1.622 IC50 (mg/mL) for DPPH method and 0.099 µmol/mg to 0.145 µmol/mg for FRAP method respectively. Clone 224 retained the most total phenolics content after drying at 60°C, with a final concentration of 21.94 mg GAE/g. Drying at 50°C and 60°C resulted in the highest retention of total flavonoid content for clones 211, 213, 222, and 224, with concentrations ranging from 5.11 mg RE/g to 10.77 mg/RE, whereas total flavonoid content for clone MKL 7 remained stable at 7.30 mg RE/g, 7.71 mg RE/g, and 8.43 mg RE/g for all drying temperatures. Clone 224 retained the most chlorogenic acid and caffeine content when dried at 60°C. The study demonstrated that drying at 60°C is the recommended temperature for preserving total phenolics, total flavonoids, total antioxidants, chlorogenic acid, and caffeine content in Liberica coffees.