Hygroscopic behaviour of spray dried soursop pulp powder

Abstract Powdered products are characterized by their convenience and long shelf life; however, powdered fruit pulps are highly hygroscopic and tend to agglomerate due to their hydrophilic nature. The stability of fruit pulp powders can be studied by means of hygroscopic equilibrium isotherms. On the other hand, soursop pulp presents great economic and industrial potential and stands out from other pulps due to its excellent sensory attributes. This study aimed to evaluate the physicochemical and hygroscopic characteristics of the powdered soursop pulp processed by spray drying, and evaluate its hygroscopic behaviour by analysing the adsorption isotherms by fitting the experimental data to the GAB, BET, Henderson and Oswin mathematical models at 25 °C, 30 °C, 35 °C and 40 °C. The results demonstrated that the soursop pulp powder was a good source of ascorbic acid, slightly hygroscopic and showed a lot of caking. The GAB model presented the best fit to the adsorption isotherms, with a coefficient of determination (R2) above 0.99 and mean errors (E) below 5%, presenting Type III behaviour, characteristic of sugar rich foods, and revealing that care should be taken when storing this product in environments with a relative humidity above 60%.