# Microencapsulation of Natural Food Antimicrobials: Methods and Applications
###### Abstract  
The global demand for safe and healthy food with minimal synthetic preservatives is continuously increasing. Some natural food antimicrobials with strong antimicrobial activity and low toxicity have been considered as alternatives for current commercial food preservatives. Nonetheless, these natural food antimicrobials are hardly applied directly to food products due to issues such as food flavor or bioavailability. Recent advances in microencapsulation technology have the potential to provide stable systems for these natural antibacterials, which can then be used directly in food matrices. In this review, we focus on the application of encapsulated natural antimicrobial agents, such as essential oils, plant extracts, bacteriocins, etc., as potential food preservatives to extend the shelf-life of food products. The advantages and drawbacks of the mainly used encapsulation methods, such as molecular inclusion, spray drying, coacervation, emulsification, supercritical antisolvent precipitation and liposome and alginate microbeads, are discussed. Meanwhile, the main current applications of encapsulated antimicrobials in various food products, such as meat, dairy and cereal products for controlling microbial growth, are presented. microencapsulation; natural antimicrobial agents; encapsulation methods; food applications +
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with the aim of avoiding undesirable inactivation [3]. Moreover, the direct addition of some bioactive agents can contribute to changes in the flavor, odor and texture of foods and the bioavailability of these compounds might be reduced by the possible interactions with the food ingredients. Consequently, stabilization of these compounds before addition to food products is of great importance in order to obtain products with a prolonged shelf-life without noticeable alterations in their sensory properties, which can be achieved by applying the encapsulation process [4]. Encapsulation is defined as the process in which an active substance (core material) is enveloped into another substance (shell/matrix/wall material) to elaborate particles with a specific geometry at the nanometer (nanoencapsulation), micrometer (microencapsulation) or millimeter scale [4]. The classification of the structure of microcapsules includes the monocore shell, the multicore shell and the matrix type in which the core material is dispersed like small droplets inside the shell material [5]. Natural or synthetic polymers, which form the shell (outer part) of microcapsules, act as a barrier to protect the microparticle core from losing its nutritional value and/or activity and decreasing the undesired interactions with the environment [6]. Internal structure and morphology are the two major parameters for classifying microparticles into microspheres and microcapsules, but often the terms are used synonymously. Microcapsules and microspheres are distinguished by reservoir systems and matrix systems, respectively [7] (Figure 1). Recently, the controlled release of encapsulated bioactive molecules under specific conditions has been well-documented in the literature [8; 9; 10]. However, there are still uncertainties about the selection of appropriate encapsulation techniques and the application of these encapsulated antimicrobials in various foods, which need further exploration. Thus, gaining knowledge about the properties of encapsulated active agents, encapsulation materials used for the formation of microcapsules (shell/matrix/wall material) and suitability of the formed delivery systems for useful applications turns into an important issue. The aim of the current work is to give an overview of the most commonly used microencapsulation methods for natural antimicrobials and the effect of encapsulation processes on the antimicrobial activity of agents. Moreover, the recent applications of microencapsulated antimicrobials in various food products (meat, dairy, cereal products) will be presented.