Thermal and chemical treatments to control polygalacturonase activity in passion fruit albedo

Abstract

The objective of this work was to evaluate the use of thermal and chemical treatments with Ca²⁺, in order to control the activity of polygalacturonase and its effects on extraction yield and degree of pectin esterification from albedo of yellow passion fruit (Passiflora edulis) rind. Rinds of fruit with light‑green peel were washed, sanitized, grind, and left to stand in water for albedo suspension. Albedo was collected and subjected to a temperature of 90^oC for 30, 60, and 120 min, or to calcium levels of 0.01 and 1% during 1 hour of stirring, at 400 rpm, at ambient temperature. Thermal treatment of the crude enzymatic extract obtained from the albedo at 65, 75, and 85^oC was also performed. The thermal treatment of the albedo at 90^oC did not inactivate polygalacturonase after 120 min. The inactivation of the enzyme extracted from the albedo occurred after incubation at 65, 75, and 85^oC for 30, 20, and 10 min, respectively. The treatment with calcium ion solution at 1% promoted enzymatic inactivation and a decrease in the content of free carboxylic acids (FCA) of pectin. The treatment of passion fruit albedo with calcium Ca²⁺ solution at 1% for 1 hour inhibits the polygalacturonase activity and decreases the content of FCA.