Amplitude–time effects in NADES-UAE extraction of turmeric (Curcuma longa L.) polyphenols: Recovery efficiency, bioactivity evaluation, mass balance, and economic assessment

Turmeric (Curcuma longa L.) is an important natural source of polyphenols with strong antioxidant and antimicrobial activity, widely needed for functional foods and nutraceuticals applications. This study investigates amplitude–time interaction effects in natural deep eutectic solvent (NADES)–based ultrasound-assisted extraction (UAE) of turmeric polyphenols within a unified mass–economic framework. Turmeric powder was extracted using a citric acid–glucose NADES- UAE, where ultrasound amplitude (50–70%) and extraction time (15–45 min) were evaluated using a randomized block design. A closed mass balance and economic evaluation were conducted to assess process efficiency and economic feasibility of scaling-up turmeric polyphenol extraction. Amplitude–time interaction significantly affected yield, total polyphenol content/TPC, and bioactivity. The best treatment (A2B3; 60% amplitude, 45 min) achieved 28.28% yield, 86.73 µg GAE/g TPC, 62.60 µg AAE/g antioxidant activity, and strong antimicrobial activity against Escherichia coli (38.28 mm) and Bacillus cereus (23.83 mm). Closed mass balance indicated enhanced polyphenol recovery at moderate amplitude with extended extraction time. Economic estimation indicated at a 6.00 USD/kg selling price, the process achieved a 43.36% IRR and a 2.73-year payback. Product price and electricity consumption played as key profitability drivers, supporting scalable and sustainable implementation.