Physical Evaluation and Hygroscopic Behavior of Dragon Fruit (Hylocereus undatus) Lyophilized Pulp Powder

Abstract

Relations between moisture content and water activity of foodstuff can be estimated by determining moisture sorption isotherms. This work aimed at investigating the hygroscopic behavior of dragon fruit powder through sorption isotherms, encapsulated with maltodextrin, and analyzing hygroscopicity, density, and caking degree of samples stored in polyethylene wrappings and laminated coverings at 25°C. Dragon fruit powder showed good results regarding hygroscopicity, density, and caking degree for laminated coverings. In order to describe balance of sorption isotherms, the BET model was the most recommended.

Keywords:

• Food drying
• Fruit powders
• Hylocereus undatus
• Isotherms

Notes

^a a _w  = water activity; X _m  = moisture content in the molecular (g H₂O · g⁻¹ dry basis); X _eq  = equilibrium moisture (g H₂O · g⁻¹ dry basis); C = constant related to heat of sorption of the molecular layer; a, b, e K = adjusting parameters.

^a R ²: determination coefficient; E%: relative average error; X _m : moisture content in the monolayer (g H₂O · g⁻¹ dry basis); C: constant related to the heat of sorption in the molecular layer; K: GAB constant related to multi-layers; n: BET constant related to multi-layers; a & b: adjusting parameters of the Henderson and Oswin models.

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