STUDY OF ENCAPSULATION OF DEFECTIVE COFFEE EXTRACT BY IONIC GELATION

Coffee is produced on a large scale worldwide and has in its chain by-products such as defective coffee, which has an interesting profile of bioactive compounds. Phenolic compounds have antioxidant, antimutagenic and anticancer properties, and can prevent cardiovascular diseases. In green and defective coffee can find chlorogenic acid, catechin, epicatechin and epicatechin galactopossum. Many of these compounds are sensitive to heat and oxidation, in addition to altering flavor, so microencapsulation is a strategy to face these challenges and include phenolic compounds in food products. The aim of this work was to evaluate the encapsulation of defective coffee extract by ionic gelation. The hydroalcoholic extract used was previously extracted from defective (85%) and green (15%) coffee. Ionic gelation by atomization was performed using an atomizer with a 0.7 mm nozzle of the Spray Dryer B-290 Büchi, with a pressure of 0.25 bar and a feed rate of 25 to 32%. The crosslinking solution was 2% calcium chloride with pH 3. Two tests were performed, simple encapsulation pectin : extract (94 : 6) - test A, and double emulsions (W/O/W) with pectin : (oil : extract) (80 : 14 : 6) - test B. The oily part was added with 4% PGPR and the pectin used had a 2% concentration. The mean diameter and size distribution of the particles were analyzed by Laser Light Scattering Analyzer LA-950V2 Horiba Instruments. The mean diameter was calculated by De Brouckere diameter – D[4.3]. The encapsulation efficiency and release of phenolics in 30 and 180 minutes were analyzed. The total phenolic content estimated according to the spectrophotometric method of Folin Ciocalteau. The morphology was analyzed with an optical microscope with incident and reflected light. The coffee extract presented 195,16 μg GAE/mg. Test A showed smaller diameter than test B (166.6; 376,8, respectively), which may be related to the viscosity of the solution before the gelation process. The sample with emulsion (B) showed lower release of total phenolic compounds to the environment, with a 15% increase, while the particles without emulsion showed a 45% increase in phenolic compounds as 180 minutes pass. With microscopy it was possible to observe the emulsion of the extract and oil trapped inside the pectin matrix. The presence of emulsion influenced the gel structure and reduced the release of phenolic compounds from the particles of coffee extract.