4. Conclusions

3.3 Solid yield

For spray drying processes, the yield is highly influenced by the control of the powder formation, avoiding wet quenching or material losses due to the stickiness or adhesiveness of the material to the equipment walls. To reduce wet quenching, it is recommended to operate with a high solid content of the feed solutions, in order to reduce the quantity of water that must be evaporated during the process, which also increases the operation costs [27]. In our study, the solid yield was influenced by the essential oil content in the complex coacervates, being the 5.0% of AEO sample, the one with the highest solid yield value (Table 1). The lower oil content in the feeding sample reduces the stickiness of the powder during the drying process, which contributed to recover more solids at the end of the process.

Other authors [19, 25, 28] have reported solid yields in a range of 51.8–62.04% for the encapsulation of essential oils by spray drying; these values are lower to the ones obtained in this study. It can be stated that the process conditions used for this study, as well as the formulations of the samples, were adequate for this encapsula-

Bulk density obtained for both powders agrees with the values reported in the

and 7.5% of oil content in the coacervates, respectively; due to the high repeatability of the method, small standard deviation was obtained, and significant difference

The tapped density is an important factor related to the packaging, transport, and commercialization of powders. The optimization of this value can be used in terms of quality of material inside a container [31]. The values obtained for both powders agree with that reported in the literature for encapsulation of rosemary essential oil by atomization (0.41 g/mL) [32]. Similar to bulk density, a significant difference (P < 0.05) was found between the samples, due to the high repeatability

It was observed that the sample with 5.0% of AEO had the biggest values of bulk density and tapped density compared to the sample with 7.5% of AEO, which is related to the particle size distribution and moisture content. With more moisture content, the particle size increases, and the bulk density and tapped density increase as well [33]. Besides, the heterogeneous particle size distribution of the coacervate powder with 5.0% of AEO provides a better reorganization of the particles when the powder is tapped, decreasing the volume occupied by the powder and, therefore,

However, the determined flow properties of the powders, the compressibility index, and the Hausner ratio did not demonstrate significant differences (P > 0.05) between the samples (Table 1). With a compressibility index of 50%, both powders were classified as materials with very bad flowability [34], and according to the Hausner ratio obtained for both powders (2.00), the cohesiveness of the samples is

The coacervates with 7.5% of AEO had the highest encapsulation efficiency (EE) in this study (96.6 0.02%) with significant differences (P < 0.05) between the

) [30]. The values obtained were 0.233 and 0.227 g/cm<sup>3</sup> for 5.0

for the encapsulation of rosemary essential oil using gum arabic as wall material

) [29], as well as

tion technique, resulting viable for practical application.

Technology, Science and Culture - A Global Vision, Volume II

literature for encapsulation of soy milk powder (0.21–0.22 g/cm3

3.4 Flow properties of powders

(P < 0.05) was found between the samples.

(0.25–0.36 g/cm3

of the test (Table 1).

increasing the tapped density.

3.5 Encapsulation efficiency

considered high [35].

88

Complex coacervation between gelatin and chia mucilage resulted in an effective method to encapsulate anise essential oil after being spray-dried. All physicochemical characteristics obtained in the powders (particle size, moisture content, solid yield, flow properties, and encapsulation efficiency) were affected by the oil content in the complex coacervates. The coacervate with 7.5% of AEO had a moisture content adequate for food powders and the highest encapsulation efficiency. Further research is needed to study the practical applications of this complex coacervate system and explore other sensitive ingredients needed to be protected by encapsulation techniques.

## Acknowledgements

This work was supported by the Universidad de las Américas Puebla (UDLAP) and Consejo Nacional de Ciencia y Tecnología (CONACYT). Authors, Hernández-Nava and Ruíz-González, acknowledge the financial support for their PhD studies in food science given by the UDLAP and CONACYT.
