# Evaluation of Non-Encapsulated and Microencapsulated Lactic Acid Bacteria
## 1 Introduction  
Since 2006, the European Union has banned the addition of antibiotics in animal feed due to the increase in resistance among microorganisms and the accumulation of residues in food products. As an alternative to antibiotics, probiotics contain one or more strains of microorganisms and play a central role in animal feed supplementation [1]. Probiotics are bacteria defined as \"live microorganisms which, when administered in adequate amounts, confer a health benefit to increase the immunity of the host\" [2]. Probiotics are used in both animal and human nutrition as they provide a natural, safe, and effective barrier against pathogens [3; 4; 5]. The most common microorganisms used as probiotics are Gram-positive bacteria such as _Lactobacillus_, _Streptococcus_, _Lactococcus_, _Pediococcus_, _Bifidobacterium_, and _Bacillus_[6; 7]. The supplementation of probiotics in poultry feed has garnered substantial attention due to their benefits on health, modifications on villus intestinal epithelium [8], growth performance, feed conversion ratio, increase of intestinal length, decrease of fat abdomenpercentage [9], and reduction of gastrointestinal disorders such as diarrhea [10]. Ensuring adequate amounts of probiotics at the time of feeding is a real challenge, because several factors during processing and storage can disturb the viability of probiotic bacteria [11]. For example, low acidic conditions, the presence of trypsin, pepsin, and bile salts in the stomach [12], transition through the gastrointestinal tract (GIT), storage conditions (oxygen, high temperature, pH changes, relative humidity) and antimicrobial substances, have all been implicated in the loss of probiotic cells viability [13]. According to the International Dairy Federation (IFD), a good probiotic must present at least \(10^{7}\) CFU/g until used. Therefore, [PERSON] et al. [10] recommended a minimum dose level of probiotic bacteria of at least \(10^{6}\) CFU/g at the time of ingesting to confer beneficial health effects. Similarly, the Canadian Food Inspection Agency (CFIA) [14] affirmed that a probiotic product should contain a minimum of \(1\times 10^{9}\) CFU/g. Microencapsulation is a technique with the ability to protect sensitive microorganisms such as LAB strains against loss of cell viability during GIT passage, through entrapment within a matrix of biopolymeric material [11; 15]. As protection from external damaging factors, in microencapsulation, the semipermeable membrane that surrounds the liquid core is required to preserve cell viability during processing and storage [7; 16]. Spray drying is one of the most popular and appropriate encapsulating techniques, due to its cost-effectiveness, rapidity, and reproducibility [17; 18]. The addition of protectants to the culture medium before drying diminishes the harmful effects of heat treatments. Thermoprotectants like non-fat milk solids, starch, sugars (glucose, lactose, trehalose, inulin, dextrose, maltodextrin, sorbitol, etc.) are involved to stimulate the growth of the organism by improving bacteria viability during drying and storage conditions [19]. Furthermore, microencapsulation coats the active ingredients in the form of solid, liquid, or gaseous substances (the core) with a polymeric material layer (the shell), involving microparticles from the micrometer to the millimeter range. In addition, microencapsulation can modify the physical characteristics by changing liquids into a solid state to enhance its administration property [17] and to protect the probiotics from degradation [14; 18; 20]. The genus _Lactobacillus_ includes Gram-positive, fermentative, facultatively anaerobic, catalase negative, cocc or rod bacteria and non-spore-forming microorganisms [21]. Species from the _Lactobacillus_ group are a large population found in the intestinal tract, and act as an indicator of a healthy microbiota.