# Encapsulating volatiles by spray drying: The choice of dextrose equivalent influences d-limonene retention via skin formation and particle morphology

## TL;DR

This paper shows that the structure of dried particles, not just how fast they form a skin, affects how well volatile oils like d-limonene are retained during spray drying.

## Contribution

The study reveals that particle morphology, rather than skin formation rate, is the key factor in volatile retention during spray drying.

## Key findings

- Higher DE maltodextrin values increase d-limonene retention by improving particle structure.
- Lower DE values lead to unstable oil droplets and more volatile loss due to cavity formation.
- Particle morphology controls volatile retention more than skin formation rate.

## Abstract

Maltodextrin is extensively used as a wall material for volatile encapsulation via spray drying. The dextrose equivalent (DE) is hypothesized to influence the retention of volatiles by affecting the rate of skin formation. However, the DE is also known to affect final particle morphology, and it is not known whether skin formation rate or particle morphology has the most significant influence on retention. This study investigates the encapsulation of d-limonene (diluted in sunflower oil) by emulsification and subsequent spray drying. It focused on understanding the impact of the DE value of maltodextrin on the d-limonene retention after spray drying by evaluating the resulting powder properties and particle morphology. Four formulations were prepared by varying the DE value of maltodextrin (DE6, 12, 21, and 38) using the same drying conditions and having a similar concentration of oil (6 wt%), pea protein isolate (0.9 wt%), and solids (20 wt%). Results showed that the DE value influences d-limonene retention due to differences in the formation of surface oil that is affected by the morphology of the particle formed during drying. The powder containing DE6 resulted in the highest surface oil percentage (6.6 ± 0.8 %) with the lowest d-limonene retention (57.6 ± 2.4 %). These results were attributed mainly to the formation of holes and large cavities in the particle as the droplet skin formed and dehydrated. This phenomenon created additional surface area that allowed for increased d-limonene losses, thereby challenging the initial hypothesis that lower-DE maltodextrin induces rapid skin formation and thereby improves volatile retention. Instead, the findings of this study emphasize that controlling the morphology and structural integrity of spray-dried emulsions is crucial for improving the retention of volatile compounds like d-limonene.

Image 1

•Volatiles are released more from encapsulated oil than from surface oil.•The particle morphology during drying influences the volatile retention.•Higher maltodextrin DE values result in increased volatile retention.•Lower maltodextrin DE values lead to reduced oil droplet stability during drying.•There is a trade-off between rapid skin development and cavity formation.

Volatiles are released more from encapsulated oil than from surface oil.

The particle morphology during drying influences the volatile retention.

Higher maltodextrin DE values result in increased volatile retention.

Lower maltodextrin DE values lead to reduced oil droplet stability during drying.

There is a trade-off between rapid skin development and cavity formation.