# Encapsulated Probiotics: Potential Techniques and Coating Materials for Non-Dairy Food Applications
## 1 Introduction
In recent years, non-dairy matrices, such as fruits [10; 11; 12], fruit and vegetable juices [7; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26], fermented rice beverages [27], tea [28; 29], jelly-like desserts [30], bakery products [31; 32; 33], cereal bars [34], sauces [35], gum products [36], and powdered functional drink [37] have been explored as vehicles to deliver probiotics. Although non-dairy food matrices are more versatile (absent of lactose, dairy allergens, and cholesterol) than dairy food matrices, the delivery of probiotics using non-dairy food matrices is more challenging. As an example of a dairy food matrix, milk, which is rich in proteins and fats, could effectively act as a protective matrix to protect the probiotics throughout the digestive tract [38]. In contrast, non-dairy food matrices, such as fruit and vegetable juices, have considerable amounts of organic acids, dissolved oxygen, and inherently low pH values that could negatively affect the viability of inoculated probiotics [9]. Dairy food matrices are usually stored at refrigerated temperature (4 \({}^{\circ}\)C), and therefore, the viability of probiotics can be well-maintained throughout the product's shelf life. In contrast to dairy food matrices, non-dairy food matrices are often stored at ambient temperature, which could adversely affect the viability of probiotics [2]. The sensory qualities of non-dairy food matrices could also be enhanced or deteriorated by the metabolic compounds produced through the interaction between the probiotics and food matrices [2; 9]. To address these challenges, encapsulation techniques have been implemented to preserve the viability of probiotics. Encapsulation can be defined as \"a process in which small solid particles, liquid droplets, or gases are entrapped by a coating layer, or incorporated into a homogeneous or heterogeneous matrix, yielding small capsules with useful properties in immobilization, protection, controlled release, structuration, and functionalization\" [39]. In other words, encapsulation is a technique of retaining a substance (core material, such as probiotics) within another (wall material). When applied successfully,the encapsulation technique may improve the resistance of probiotics to the harsh gastric environment and hence, facilitate the controlled release and successful delivery of probiotics to the site of action. By restricting the probiotics from being directly in contact with food components, encapsulation could maintain the viability of probiotics during the food manufacturing process and long-term storage. Through encapsulation techniques, probiotic cultures can be transformed into concentrated dry powder form, which is more stable and easier to incorporate into many food matrices [1; 40; 41; 42]. This article aims to review and analyze the effectiveness of encapsulation techniques and supplementation of coating materials on the viability of probiotics in non-dairy food and beverage products during storage, as well as while transiting through our gastrointestinal tract.