Hygroscopic trend of lyophilized 'mangaba' pulp powder

Mangaba is a widely-consumed fruit in the Northeast of Brazil, which is usually exploited through extractivism. This fruit is rich in various nutrients, especially in vitamin C, with pleasant taste and aroma. The lyophilization process transforms these fruits into amorphous powders, which must be analyzed regarding their properties and hygroscopic trend. Thus, the objective of this study was to characterize and evaluate the physico-chemical properties of adsorption isotherms of the lyophilized 'mangaba' pulp powder, with addition of maltodextrin (DE 20). The pH, titratable acidity, soluble solids, ascorbic acid and water activity were analyzed. Regarding the isotherms, the mathematical models of GAB, BET, Oswin, and Henderson were used at temperatures of 25, 30, 35 and 40 degrees C. The obtained powder presented pH of 3.14, titratable acidity of 1.95 mg of citric acid 100g(-1) of powder, soluble solid contents of 99 degrees Brix, ascorbic acid content of 55.97 mg 100g(-1) and water activity of 0.16. Henderson was the mathematical model that best fitted the data of the adsorption isotherms at the four evaluated temperatures, with average errors ranging from 5.76 to 9.70% and R-2 from 0.9974 to 0.9995.