ULTRASOUND-ASSISTED EXTRACTION OF PECTIN FROM COCOA POD HUSK

The cocoa (Theobroma cacao L.) production chain generates large volumes of pod husk, which can account for up to 70% of the fruit mass and is often underutilized, creating an environmental liability. Because it is rich in pectin, a polysaccharide widely used as a gelling agent and stabilizer in foods, cocoa pod husk is a promising raw material for the circular economy. Ultrasound-assisted extraction (UAE) has emerged as an alternative to conventional methods based on strong acids and prolonged heating, since acoustic cavitation disrupts the cell wall in less time and with milder organic acids. This study aimed to extract pectin from cocoa pod husk by UAE with citric acid and to determine its yield. Flour was obtained from husks collected from small-scale farmers in Barrolândia, Tocantins, Brazil, which were washed, dried (48 h at 60 °C), ground, and sieved through a 100-mesh screen. Extraction was performed in triplicate, using approximately 5 g of flour per experimental unit. A 700 mL citric acid solution at 0.086% (pH 2–3) was prepared, of which 200 mL was allocated to each sample. First, 50 mL of the solution was used to hydrate the flour under stirring for 10 min on a hot plate; then, 150 mL was added, reaching a solid:liquid ratio of approximately 1:40. The samples were sonicated in an ultrasonic bath at 40 kHz and 600 W for 30 min, with a set temperature of 50 °C, which reached approximately 55 °C by the end due to cavitation. Each extract was then filtered through filter paper, and the pectin was precipitated with 95% ethanol (1:2, v/v), kept under refrigeration for 12 h, recovered, and dried. Yield was determined gravimetrically as the ratio of dry pectin mass to initial flour mass. The mean pectin yield was 5.38 ± 0.28% (w/w). The process used a low-concentration organic acid and only 30 min of sonication, which is advantageous from both environmental and energy standpoints. It is concluded that UAE with citric acid is a viable alternative for recovering pectin from cocoa pod husk. Next steps include optimizing extraction parameters, such as time, temperature, pH, ultrasonic power, and solid:liquid ratio, by response surface methodology, and characterizing the pectin obtained. The authors thank CAPES (Finance Code 001) and FINEP for financial support.