Green extraction of Quercus infectoria gall with supercritical CO₂ and methanol co-solvent

Green extraction of supercritical liquid CO₂ (SCFE-CO₂) using co-solvent methanol can produce a more complete phenolic acid composition and a higher quantity when compared to those without using co-solvent. The extract was devoid of toxicity. SCFE-CO₂ is carried out by putting 100 g of Quercus infectoria gall of size 0.3 mm into extraction tube at temperature of 60 °C and the pressure of 20 MPa with a CO₂ flow rate of 25 ml/min using co-solvent methanol with variation of flow speed 0.05, 0.5, 1.5, 3, and 6 for 60 min. The extract is analyzed using LC–MS/MS, the total phenolic content is determined using the Folin-Ceocateu method, and the toxicity value is determined using the Vero cell. According to the results, the green method of extracting SCFE-CO₂ with methanol co-solvent can produce a peak and identify about 27 phenolic compounds, and increasing the rate of flow of methane co-solvent will greatly affect the outcome of the extraction to a flow rate of 0.5 ml/min, while adding a co-solvent with a flow speed above 0.5 does not affect the result. Repeated extraction of some of the largest phenolic peaks provide phenol content with minimal extract variability (div. sd. 0.1%), and the addition of soluble methanol will also increase the TPC concentration but does not increase the IC₅₀ toxicity value above 1000.