Intensification of curcuminoid extraction from aeroponic Curcuma longa L. raw material using a combined ultrasonic method

Optimization of curcuminoid extraction methods from plant material remains a relevant task in food biotechnology, since these compounds possess high biological activity, but their recovery from the plant matrix is hindered by their hydrophobic nature and instability. A comparative analysis of the efficiency of aqueous, alcoho-lic, ultrasonic, combined (ultrasound followed by thermostating) and Soxhlet extraction was carried out. The object of the study was turmeric rhizomes grown in an aeroponic system, which ensured standardization of raw materials and the absence of soil conta-minants. The efficiency was evaluated by dry residue yield, total curcuminoid content high-performance liquid chromatography (HPLC) and refractive index. It was found that the highest dry residue yield (4.56 g/100 ml) and maximum curcuminoid concentration (7.72 mg/g) are achieved using the combined method with 70% ethanol, ultrasonic treatment for 20 minutes at 30–35 °C and subsequent thermostating at 50 °C for 30 minutes. This method provides 92–95 % curcuminoid recovery compared to Soxhlet extraction, while reducing the process time from 4–8 hours to 50 minutes. The qualitative composition of curcuminoids (curcumin : demethoxycurcumin : bisdemethoxycurcumin ratio ≈ 6.2:3.3:1.0) is independent of the extraction method. A high correlation between the refractive index and the dry residue content (r=0.98) was revealed, justifying the use of refractometry for rapid quality control of extracts without time-consuming gravimetric analysis. The combined ultrasonic method is consistent with the principles of green chemistry, is scalable and promising for the industrial production of standardized curcuminoid extracts from aeroponic raw materials.