Evaluating the effect of drying techniques on extract yield and functional group profiles in Citrus hystrix using FTIR

Citrus hystrix (Kaffir lime) is widely recognized for its aromatic leaves and essential oils (EOs), which possess various biological and functional properties. This study aims to evaluate the effect of two drying techniques— air-drying and microwave-drying—on the yield and functional group profiles of C. hystrix leaf extracts using Fourier Transform Infrared (FTIR) spectroscopy. The dried leaf samples were extracted, and the resulting crude extracts were analyzed with FTIR to identify the presence of key functional groups. Characteristic absorption bands were observed, including O–H stretching (3625–3025 cm⁻¹), C–H stretching (2939–2834 cm⁻¹), C=O stretching (1721–1719 cm⁻¹), and C=C stretching (1624–1622 cm⁻¹). The findings indicate that the type of drying method influences both the extract yield and the integrity of functional groups. For future work, the application of ultrasound-assisted extraction (UAE) is recommended as a greener and more time-efficient method to enhance extraction quality.