Abstract

Complex coacervation is a technique that involves the electrostatic attraction between two biopolymers of opposite charges that surround a compound of interest and can be stabilized by spray drying. This technique has been used to increase the shelf life of functional ingredients, such as essential oils, providing controlled release and allowing an alternative food processing. The aim of this work was to evaluate the effect of essential oil content present in the coacervate, and its effect in the physicochemical characteristics of spray-dried powders of anise essential oil. Complex coacervates between gelatin and chia mucilage were used to encapsulate 5.0 and 7.5% (w/w) of anise essential oil. These coacervates were spray-dried with an inlet air temperature of 160°C and a feeding rate of 5 g/min. Powders were characterized by particle size, moisture content, solid yield, flow properties, and encapsulation efficiency. The powder with 7.5% of anise essential oil had the highest encapsulation efficiency (96.6 0.02%). All physicochemical characteristics of the powders were influenced by the essential oil content in the complex coacervates. Complex coacervation between gelatin and chia mucilage resulted in an effective method to encapsulate anise essential oil stabilized by spray drying with high encapsulation efficiencies.

Keywords: anise essential oil, complex coacervation, spray drying

## 1. Introduction

Essential oils are secondary metabolites of aromatic plants, obtained from different plant materials [1]. Their chemical composition can be influenced by the climate and the soil where the plants are grown, as well as the extraction processes used [2]. These have achieved an increasing interest in the food industry because of their antioxidant and antimicrobial properties that have the potential to eliminate free radicals and inhibit the presence of pathogenic microorganisms in food [3]. However, essential oils are chemically unstable when they are exposed to certain environmental conditions such as light, moisture, oxygen, and elevated temperatures, all of which can cause the loss of their antimicrobial and antioxidant properties [4].

Some research has been conducted to evaluate the formation of complex coacervates encapsulating essential oils, which allows having a better understanding of their behavior [12–14]. The research on this subject is very broad because it is possible to evaluate the formation of complex coacervates of other essential oils using different encapsulating agents or combining encapsulation techniques. This work aims to evaluate the effect of varying the concentration of anise essential oil in the physicochemical characteristics (particle size, moisture content, solid yield, flow properties, and encapsulation efficiency) of complex coacervate powders

Effect of Oil Content in the Physicochemical Characteristics of Spray-Dried Powders of Anise…

Anise essential oil (AEO) was purchased from Laboratorios Hersol (Mexico City, Mexico). To form the complex coacervates, chia seeds (Salvia hispanica L.) were purchased from Verde Limón Trading Company (Mexico City, Mexico), and gelatin (type B) was purchased from Gelco SA (Bogota, Colombia). Tween 80 (Sigma-Aldrich, USA) was used as an emulsifying agent. Other chemicals used (analytical

Chia mucilage was extracted using the modified method described in other studies [15, 16]. Chia seeds were hydrated with distilled water in a ratio of 1:20 (w/v) with constant stirring for 4 h at 35 � 1.0°C. The hydrated seeds were freezedried (Triad™ Labconco, USA), and then the mucilage was mechanically separated

Complex coacervates were prepared with 5.0 and 7.5% (w/w) of AEO using gelatin and chia mucilage as encapsulating agents and Tween 80 as an emulsifying agent. Coacervates were prepared using an ultrasound homogenizer (Cole-Parmer, CP 505, USA) adjusting the pH by adding HCl 0.1 N dropwise, and the system was cooled down to 25°C to allow the wall formation of the coacervate. The coacervate was spray-dried using a mini spray drier (B-290, BÜCHI Labortechnik, Switzerland). To guarantee a better yield, the coacervates were previously dispersed in aqueous maltodextrin (20% w/w) solution. An inlet air temperature of 160°C and a feeding rate of 5.0 g/min were used. The powders of complex coacervates were collected and stored inside an amber flask at 25 � 1.0°C until further use.

Particle size: The granulometric distribution of the powders was determined by a dynamic light scattering particle analyzer (Bluewave, Microtrac Inc., USA), and the instrument was previously calibrated. Span, expressing the polydispersity of the

> Span <sup>¼</sup> <sup>D</sup><sup>90</sup> � <sup>D</sup><sup>10</sup> D<sup>50</sup>

(1)

from the seeds by sieving with a sieve mesh number 35 (500 μm).

2.4 Characterization of spray-dried powders of AEO

powder [17], was calculated using the following equation:

2.3 Microencapsulation of anise essential oil by complex coacervation

grade) were purchased from Hycel (Jalisco, Mexico).

2.2 Extraction of chia mucilage

obtained by spray drying.

DOI: http://dx.doi.org/10.5772/intechopen.90099

2. Methodology

2.1 Materials

85

In order to protect the essential oils from the environmental conditions and the interaction with other components of the food, these can be encapsulated. Encapsulation is a process of building a barrier between the core and wall material to avoid physicochemical reactions and to maintain the biological, functional, and physicochemical properties of the core materials [5]. It is a good resource in the application of essential oils as antimicrobial and antioxidant agents in food because it helps to mask the characteristic strong odor that can alter the sensory characteristics of the food product in which essential oils are used. Other advantages of encapsulation are as follows: it minimizes the interaction of the active compound with the environment by reducing the rate of evaporation or transfer of core components to the outside, and it permits easy handling of the encapsulated substance and allows a controlled release of the active compound [6]. Among the encapsulation methods of essential oils, encapsulation by complex coacervation implies the electrostatic attraction between two polymers of opposite charges, and coacervate formation occurs over a narrow pH range [5]. Complex coacervation consists of four steps: dissolution, emulsification, coacervate formation, and wall formation and drying [5, 7, 8]:


The formation of capsules in complex coacervation is affected by several factors, such as the composition of the emulsion, which includes the mass ratio of the encapsulating agents, the concentration of the encapsulated material, and the quantity of emulsifiers added [9, 10]. On the other hand, a coacervate can be stabilized by spray drying atomizing the liquid substance forming small drops on a stream of hot gas (air), in which the solvent evaporates producing small particles of the encapsulated material [11].

Effect of Oil Content in the Physicochemical Characteristics of Spray-Dried Powders of Anise… DOI: http://dx.doi.org/10.5772/intechopen.90099

Some research has been conducted to evaluate the formation of complex coacervates encapsulating essential oils, which allows having a better understanding of their behavior [12–14]. The research on this subject is very broad because it is possible to evaluate the formation of complex coacervates of other essential oils using different encapsulating agents or combining encapsulation techniques. This work aims to evaluate the effect of varying the concentration of anise essential oil in the physicochemical characteristics (particle size, moisture content, solid yield, flow properties, and encapsulation efficiency) of complex coacervate powders obtained by spray drying.
