This study aims to optimize ultrasonic-assisted natural deep eutectic solvents (NADES) based extraction from C. longa. Choline chloride-lactic acid (CCLA-H₂O = 1:1, b/v) was used to investigate the impact of various process parameters such as solvent’s water content, solid loading, temperature, and extraction time. The optimal yield of 79.635 mg/g of C. longa was achieved from extraction in 20% water content NADES with a 4% solid loading in 35 °C temperature for 1 h. Peleg’s model was used to describe the kinetics of the optimized ultrasonic-assisted extraction (UAE) method, and the results were found to be compatible with experimental data. The optimum conditions obtained from C. longa extraction were then used for the extraction of C. xanthorriza and C. mangga, which give yields of 2.056 and 31.322 mg/g, respectively. Furthermore, n-hexane was utilized as an anti-solvent in the separation process of curcuminoids extract from C. longa, C. xanthorriza, and C. mangga, which gave curcuminoid recovery of 39%, 0.74%, and 27%, respectively. Solidification of curcuminoids was also carried out using the crystallization method with n-hexane and isopropanol. However, the solution of CCLA and curcuminoids formed a homogeneous mixture with isopropanol. Hence, the curcuminoids could not be solidified due to the presence of NADES in the extract solution.

Background/Objectives: Solvent-intensive methods are traditionally required to extract curcumin, a potent bioactive compound from Curcuma longa, raising environmental and safety concerns. Methods: This study introduces an efficient and scalable extraction approach using microwave–ultrasound-assisted extraction (MUAE) combined with a natural deep eutectic solvent (NADES) composed of choline chloride and lactic acid. Process parameters, including solvent water content (20–30% v/v) and solid loading (4–8% w/v), were optimized using response surface methodology (RSM) to enhance curcumin yield. Results: Under optimal conditions (20% water content and 8% solid loading), the MUAE method achieved a curcumin content of 40.72 ± 1.21 mg/g, representing a 14.36% improvement over conventional ultrasound-assisted extraction (UAE), while reducing solvent usage by 50%. The quadratic model demonstrated excellent predictive capability, with an R² value of 0.98. In addition, anti-solvent precipitation using water increased curcuminoid purity from 0.31% to 20.54%, with a recovery rate of 21.49%. Conclusions: Mechanistic analysis revealed that microwave-induced cell disruption, ultrasound cavitation, and the modulation of NADES viscosity contributed synergistically to the enhanced extraction performance. This study is the first to combine MUAE with NADES for optimized curcumin extraction, delivering both high yield and reduced solvent consumption. The proposed method offers a sustainable and industrially relevant alternative for curcumin recovery in the food, nutraceutical, and pharmaceutical sectors.

Lignocellulosic biomass has great potential as a low-cost source of fermentable sugar for the production of biofuels and high value organic acids. One potential biomass is oil palm empty fruit bunch, since it has high cellulose and hemicellulose content. However, its lignin content can hinder the access of cellulose and hemicellulose during the hydrolysis process. Therefore, an effective pretreatment for the delignification of lignocellulose biomass should be considered to reduce the lignin content. In this study, delignification of oil palm empty fruit bunch using peracetic acid and alkaline peroxide solution combined with the ultrasound method is investigated as a novel combination method of biomass pretreatment. The effect of pretreatment time was observed by using a peracetic acid solution for 1, 3, 5, 7 and 9 hours, followed by an alkaline peroxide solution for 4, 6, 8 and 10 hours. Based on the results, the best delignification was achieved by pretreatment using peracetic acid pretreatment for 3 hours, followed by alkaline peroxide pretreatment for 10 hours. Both pretreatments were assisted by the ultrasound method. The results show hemicellulose, cellulose and lignin content of 14.13%, 77.27% and 8.6% respectively. The lignin content was reduced by 68.73% and the cellulose content increased by 121.85%, relative to the untreated EFB. This result was considered as the best pretreatment, since the pretreatment time was shorter and high cellulose content together with low lignin content was achieved, which will improve the hydrolysis process.