Response surface methodology-optimized ultrasound-assisted extraction of zeaxanthin and lutein from maize grain and husk, beet tops, and bilberry leaves

Lutein and zeaxanthin are valuable xanthophyll carotenoids with recognized antioxidant activity and important roles in ocular protection. The development of efficient and sustainable extraction methods from underutilized plant materials is therefore of considerable interest for food, nutraceutical, and pharmaceutical applications. In this study, ultrasound-assisted extraction (UAE) was optimized for the recovery of lutein- and zeaxanthin-containing extracts from selected agricultural byproducts, including maize grain and husk fractions, beet tops, and bilberry leaves/berries. Response surface methodology with a central composite design was applied to evaluate the effects of extraction temperature, extraction time, and solid-to-solvent ratio on carotenoid recovery. Conventional solvent extraction was used as a control. The optimized UAE process substantially reduced extraction time from ۳–۴ h to ۳۵–۴۰ min and increased the recovery of target bioactive compounds by approximately ۳۰–۴۲% compared with conventional extraction. The improvement was attributed to ultrasound-enhanced matrix disruption, improved solvent penetration, and intensified mass transfer. Functional and technological characterization showed that ultrasound treatment decreased bulk density and increased water-holding capacity, oil-holding capacity, swelling capacity, and hydration-related properties of the plant powders, indicating improved accessibility of the plant matrix. FTIR spectroscopy confirmed the presence of characteristic functional groups associated with xanthophyll-containing extracts, including O–H, aliphatic C–H, conjugated C=C, and C–O vibrations, without evidence of pronounced structural degradation under the selected extraction conditions. The results demonstrate that UAE is an efficient, rapid, and environmentally favorable approach for producing carotenoid-rich extracts from locally available agro-industrial residues. This method may support the valorization of plant byproducts into functional ingredients for nutraceutical, food, cosmetic, and potential ophthalmological applications.

کلیدواژه ها:

zeaxanthin ، lutein ، ultrasonic-assisted extraction ، plant by-products ، response surface methodology ، Antioxidant activity ، sustainable extraction