Oleoresin Extraction from Zingiber officinale Using Hot Compressed Water Extraction

Ginger is traditionally processed into two main products: ginger oleoresin and oil using solvent extraction and hydro-distillation, respectively. However, these methods have limitations, including the use of organic solvents, long extraction times, and poor selectivity. In this study, hot compressed water extraction (HCWE) was evaluated as an alternative, and its performance was compared with conventional methods in terms of yield, physical characteristics, and concentration of key bioactive compounds. The HCWE was conducted at a constant pressure of 3.5 MPa and varying temperatures between 130°C and 200°C. The resulting extracts were analyzed using High-Performance Liquid Chromatography (HPLC) to quantify 6-gingerol, 6-shogaol, and 10-gingerol concentration. HCWE process at temperature of 140°C, pressure of 3.5 MPa and 30 minutes extraction time obtains higher extraction yield of 10.37 ± 0.33 % (g/g) in comparison with solvent extraction for 480 minutes at 7.57 ± 0.31 % (g/g). But it resulted in lower concentrations of 6-gingerol at 1957.22 ± 2.55 µg/g and undetectable levels of 6-shogaol. As temperature increased to 170°C, the concentration of 6-gingerol decrease to 851.95 ± 2.34 µg/g and 6-shogaol concentration increase to 1135.23 ± 1.18 µg/g demonstrating HCWE's temperature-driven selectivity. Above 170 °C, both compounds degraded significantly, and the extract quality declined. The HCWE extract resembled ginger oleoresin in texture and aroma, suggesting its suitability for similar applications. In contrast, solvent extraction produced a broader range of compounds but lacked selectivity. In conclusion, this study demonstrates that the HCWE process is a rapid, organic solvent-free extraction method which not only reduces processing time by more than 80 % compared with conventional solvent extraction, but also provides temperature-driven selectivity, underscoring its potential for greener, industrial-scale applications in functional food and phytochemical production. These findings highlight the promise of HCWE as a sustainable approach for phytochemical extraction and functional food development.