Microencapsulation of Probiotics: History
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Probiotics are defined by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) as “living microorganisms which, when ingested in certain amounts, provide health benefits to the host”.

  • biopolymers
  • coatings
  • microencapsulation
  • probiotic
  • processing technologies

1. Introduction

The consumption of probiotics has been associated with a wide range of health benefits for consumers. Products containing probiotics need to have effective delivery of the microorganisms for their consumption to translate into benefits to the consumer. In the last few years, the microencapsulation of probiotic microorganisms has gained interest as a method to improve the delivery of probiotics in the host as well as extending the shelf life of probiotic-containing products. The microencapsulation of probiotics presents several aspects to be considered, such as the type of probiotic microorganisms, the methods of encapsulation, and the coating materials.

2. Data

Probiotics are defined by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) as “living microorganisms which, when ingested in certain amounts, provide health benefits to the host” [1]. The consumption of probiotics positively influences the growth of targeted microorganisms in the host gastrointestinal tract, eliminates harmful bacteria or fungi, and boosts the naturally occurring defence actions of the host’s immune system. Additionally, it also helps in the treatment for irritable bowel syndrome (IBS), gastrointestinal dysbiosis, as for other intestinal disorders [2,3,4]. Most of the known probiotics are Generally Recognized As Safe (GRAS), including Lactobacillus and Bifidobacterium species, and certain yeast strains such as Saccharomyces boulardii, S. cerevisiae CNCM I-3856, and Lipomyces starkeyi VIT-MN03 [3,4,5,6]. Several mechanisms are proposed on how these microorganisms are beneficial to the host wellbeing. Some examples are: by the production of antimicrobial or antifungal peptides; by stimulating changes in the intestinal environment which make it unfavourable for other microorganisms, including pathogens; as well as by competing for nutrients and for attachment to intestinal epithelial cells [7,8,9]. Probiotic microorganisms are also required to have certain features, such as: genetic stability; resistance to the gastric environment (acid and bile tolerance); adhesion capability to a mucosal surface; good in vitro/in vivo growth properties; maintaining high viability at processing; survival during storage, among others. These features ensure the survivor of a large number of these beneficial microorganisms for the successful colonization of the host’s colon. Strict safety criteria are also compulsory, such as origin, the lack of pathogenicity and infectivity, or presence of virulence factors (toxicity, metabolic activity, and intrinsic properties, i.e., antibiotic resistance) [10,11].

Microencapsulation with edible coatings is often used to carrying a wide variety of products, such as: probiotics, flavours, fragrances, enzymes, antioxidants, antimicrobials, lipids, minerals, edible pigments, nucleic acids, etc. [12,13]. During the last decades, the microencapsulation has arisen as a trendy method for enhancing the survival of probiotic microorganisms. Probiotic microcapsules, when ingested, should result in more efficient probiotic delivery to the host gastrointestinal tract [14,15]. The term “microencapsulation” is defined as a process in which tiny particles or droplets of liquid or solid material are surrounded by a coating, or embedded in a homogeneous or heterogeneous film of polymeric matrix, to give small capsules with many useful properties [16,17]. According to the size, the capsules can be classified as: macro- (>5000 μm), micro- (0.2 to 5000μm), and nano-capsules (<0.2 μm) [18].

The protection efficiency provided by microencapsulation depends on many parameters, such as the probiotic microorganism strain, the method of microencapsulation, the coating material, among others. Microencapsulation has proven to reduce probiotic cell damage and enhance survival in simulated gastrointestinal fluid (SGIF) models. [14]. Coating material gives protection to the microorganism through the control of stress response mechanisms against gastric environment, which involve: moisture, solute migration, gas exchange, oxidative reaction rates, etc. It also offers protection from adverse external conditions as UV light and heat. Many technical approaches based on several physical and chemical principles have been explored for the microencapsulation of probiotic microorganism. Successful methods of microencapsulation include: spray drying; spray chilling; spray freeze drying; extrusion; electrospraying; layer-by-layer; fluidised bed drying; and other physicochemical techniques such as emulsification and coacervation. Furthermore, most of the coating materials currently used in the microencapsulation of probiotics mainly comprises proteins, polysaccharides, and lipids. These naturally occurring polymers, or their chemically modified versions, are often used alone or in blends to form the structural coatings [19]. A successful probiotic microencapsulation mainly depends on the compatibility of all the components, namely the type of microorganism, the method of microencapsulation and the coating material. Little changes in the composition of coating and/or core material, as well as in the physical and/or chemical treatments that the capsules are subjected to, make great differences in the final properties of the microcapsule [20].

This entry is adapted from the peer-reviewed paper 10.3390/coatings10030197

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