Acta Scientiarum Polonorum Technologia Alimentaria

Background. Conventional pectin extraction requires high temperatures, long extraction times, and mineral acids, leading to significant environmental impact. This study explored the extraction of pectin from rough lemon peel (Citrus jambhiri) using a combined ultrasound–microwave assisted method (UMAE) with citric acid as a green solvent.
Materials and methods. The effects of temperature (60–65°C), microwave power (500–600 W), and ultra­sonic amplitude (50–55%) on pectin yield, degree of esterification (DE), methoxyl (MeO) content, anhydro­uronic acid (AUA), water retention capacity (WRC), oil retention capacity (ORC), emulsification capacity (EC), and emulsion stability (ES) were evaluated using a 2³ factorial design.
Results. Optimal extraction (60°C, 500 W, 50% amplitude) yielded 47.37% pectin with an equivalent weight of 616 g/mol, MeO of 9.07%, DE of 73.27%, and AUA of 80.08%, classifying it as high-methoxyl and high-purity pectin. The extracted pectin exhibited high water retention (10.85 g water/g), oil retention (5.45 g of oil/g), and strong emulsifying properties (EC: 46.65%; ES: 76.25%), demonstrating its potential as a stabi­liser and emulsifier in food applications.
Conclusion. UMAE with citric acid is an efficient, environmentally friendly approach for producing high-quality pectin from citrus waste, offering excellent physicochemical, techno-functional, and emulsifying properties suitable for food matrices.