Encapsulated probiotic Lactiplantibacillus strains with promising applications as feed additives for broiler chickens

Lactic acid bacteria (LAB), particularly Lactobacilli strains, represent a widely studied and promising group of probiotics with numerous potential health benefits. In this study, we isolated LAB strains from fecal samples of healthy broiler chickens and characterized their probiotic properties. Out of 62 initial isolates, five strains were selected for further investigations based on their antibacterial activity against pathogenic bacteria. These selected strains were identified as Lactiplantibacillus species. They exhibited desirable probiotic traits, including non-hemolyis, non-cytotoxicity, lack of antibiotic resistance, acid tolerance, auto-aggregation, and antioxidative potential. Encapsulation of these strains in alginate beads enhanced their survival compared to free cells, in stomach (69-87 % vs. 34-47 %) and intestinal (72-100 % vs. 27-51 %) juices, after 120 min exposure. These findings suggest that encapsulated Lactiplantibacillus strains could be used as feed additives for broiler chickens. Nevertheless, further studies are needed to set on their probiotic potential in vivo.

Transforming the Stability, Encapsulation, and Sustained Release Properties of Calcium Alginate Beads through Gel-Confined Coacervation

Calcium alginate (Ca2+/alginate) gel beads find use in diverse applications, ranging from drug delivery and tissue engineering to bioprocessing, food formulation, and agriculture. Unless modified, however, these gels have limited stability in alkaline media (including phosphate buffers), and their high solute permeability limits their ability to efficiently encapsulate and slowly release water-soluble small molecules. Here, we show how these limitations can be addressed by mixing the alginate solutions used in the bead preparation with the nontoxic anionic polymer polyphosphate (PP). Upon complexing Ca2+ ions, PP undergoes complex coacervation (i.e., liquid/liquid phase separation into a Ca2+/PP-rich coacervate phase and a dilute supernatant phase). At lower PP concentrations, the Ca2+/PP coacervate appears to simply remain dispersed within the beads. Though its presence makes the beads more stable in alkaline media (phosphate-buffered saline and seawater), it has little impact on the bead stiffness, morphology, and (at least in the absence of substantial payload/coacervate association) encapsulation and release properties. When the PP concentrations exceed a critical value, however, Ca2+/PP coacervation within the gelling Ca2+/alginate beads collapses the resulting beads into more compact, interpenetrating polymer networks. Besides their enhanced stability to alkaline environments, these hybrid beads exhibit irregular morphologies with wrinkled and dimpled surface structures and macroscopic (closed) internal pores, and their collapse into these polymer-rich networks also makes them significantly stiffer than their PP-free counterparts. Crucially, these beads also exhibit a much lower solute permeability, which enables highly efficient encapsulation and multiday release of water-soluble small molecules (with the beads encapsulating >90% of the added model payload and sustaining its release over 3-5 d). Collectively, these findings provide a mild and simple (single-step) pathway to generating ionically cross-linked alginate beads with significantly enhanced stability, encapsulation efficiency, and sustained release.

Application of biomacromolecules encapsulation systems for the long-term storage of Lactobacillus plantarum F1 and Lactobacillus reuteri 182

The aim of this study was to improve the viability of lactic acid bacteria (LAB) during extended storage of 1 year and mechanical characteristics of the calcium alginate beads with co-encapsulation of prebiotics and chitosan coating and subsequent freeze drying. The results revealed that the addition of trehalose to alginate matrix effectively protects the LAB cells during freeze drying, i.e., the survival rate has increased up to more than 92.5 %. Chitosan coating reinforced Ca-alginate beads, therefore the sphericity and mechanical strength of the beads improved. The findings also showed that bacteria encapsulation with the prebiotics resulted in more cells stability during the prolonged storage of 1 year and were 4.82 ± 0.06 log CFU g-1 in the lyophilized alginate-trehalose beads for Lactobacillus plantarum and 5.64 ± 0.08 log CFU g-1 in the lyophilized alginate-trehalose-inulin beads for Lactobacillus reuteri. No survival, however, was noted for the LAB cells in wet capsules after the same period. This study demonstrated that prebiotics had a significant impact on the viability of cells during freeze drying and storage. What is more, physical properties of the alginate beads were enhanced by coating beads with the chitosan.

Antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. against cariogenic Streptococcus mutans in vitro and viability when added to chewing gum during storage

The aim of the work was to evaluate antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. in vitro against cariogenic Streptococcus mutans UA 159 and viability in chewing gum, during storage. Antagonistic activity was evaluated in vitro by the "spot on the lawn" test. Two bacteria were chosen and subjected to lyophilization and microencapsulation using the atomization method, containing polyvinylpyrrolidone polymer and lactose as encapsulating agents. For application in food matrices, four treatments were elaborated: chewing gum containing lyophilized B. lactis B94 (BLL), microencapsulated B. lactis B94 (BLE), lyophilized L. brevis (LBL), and microencapsulated L. brevis (LBE). Both microorganisms demonstrated a high capacity for inhibition against S. mutans, when compared to oral antiseptic chlorhexidine 0.2% in vitro, and according to the test of sensitivity profile to proteolytic enzymes, all the bacteria tested are producers of antimicrobial peptides, resulting in the inhibitory activity of the cariogenic bacterium. Furthermore, the viability of B. lactis B94 and L. brevis was maintained after microencapsulation, indicating that the process was efficient, with no significant difference (p < 0.05) between the results. And, in the chewing gum containing the bacteria during the storage period (33 days), it was found that cell immobilization did not significantly influence (p < 0.05) the counts of L. brevis but benefited the viability of B. lactis B94. Therefore, both probiotic bacteria are producers of antimicrobial substances with the ability to inhibit S. mutans, in vitro. The microencapsulation was considered efficient since it influenced the viability of B. lactis B94 (> 8 log CFU/g); however, the microencapsulation did not influence the viability of L. brevis since in both lyophilized and encapsulated form; the concentration of the bacteria remained above 8 log CFU/g during the storage period of the chewing gum.

Probiotic-loaded calcium alginate/fucoidan hydrogels for promoting oral ulcer healing

Probiotics are beneficial bacteria located in the oral cavity which exhibit antimicrobial properties and contribute to the regulation of immune function and the modulation of tissue repair. Fucoidan (FD), a marine prebiotic, may further enhance the ability of probiotics to promote ulcer healing. However, neither FD nor probiotics are attached to the oral cavity and neither are well-suited for oral ulcer healing owing to the wet and highly dynamic environment. In this study, probiotic-loaded calcium alginate/fucoidan composite hydrogels were developed for use as bioactive oral ulcer patches. The well-shaped hydrogels exhibited remarkable wet-tissue adhesion, suitable swelling and mechanical properties, sustained probiotic release, and excellent storage durability. Moreover, in vitro biological assays demonstrated that the composite hydrogel exhibited excellent cyto/hemocompatibility and antimicrobial effects. Importantly, compared to commercial oral ulcer patches, bioactive hydrogels show superior therapeutic capability for promoting ulcer healing in vivo by enhancing cell migration, inducing epithelial formation and orderly collagen fiber deposition, as well as facilitating neovascularization. These results demonstrate that this novel composite hydrogel patch demonstrates great potential for the treatment of oral ulcerations.

Screening and Identification of Goat-Milk-Derived Lactic Acid Bacteria with Bacteriocin-like Activity and Probiotic Potentials

In the current study, we screened 46 isolates of lactic acid bacteria (LAB) derived from goat milk for bacteriocin producers that can inhibit common foodborne pathogens (Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus). The following three strains that showed antimicrobial activity against all indicators were identified: Enterococcus faecalis DH9003 and DH9012, and Lactococcus lactis DH9011. Their antimicrobial products exhibited typical bacteriocin characteristics, such as heat stability and proteinase nature. The bacteriostatic activity of concentrated bacteriocins produced by these LAB was observed at low concentrations (half-minimum inhibitory concentration [MIC50] and 4MIC50), whereas complete inhibition activity against Listeria monocytogenes was detected at high concentrations (16MIC50) of the two Enterococcus faecalis strains (DH9003 and DH9012). Furthermore, the probiotic potentials of the three strains were investigated and described. The results revealed that none of the strains had hemolytic activity, whereas all: were sensitive to ampicillin (50 mg/mL) and streptomycin sulfate (100 mg/mL); were resistant to bile, artificial simulated intestinal tract, and gastric juice at different pH levels (2.5, 3.0, 3.5); and had β-galactosidase activity. Furthermore, all strains exhibited an auto-aggregating phenotype, with self-aggregation ranging from 30% to 55%. DH9003 and DH9012 co-aggregated well with Listeria monocytogenes and Escherichia coli (52.6% and 63.2%, 68.5% and 57.6%, respectively), whereas DH9011 co-aggregated poorly with Listeria monocytogenes (15.6%) and did not co-aggregate with Escherichia coli. Furthermore, our results showed that all three isolates exhibited strong antibacterial activity, tolerance to bile and simulated gastrointestinal environments, adhesion capability, and safety. Finally, DH9003 was selected and used for gavage in rats. By observing the pathological characteristics of rat intestinal and liver tissue sections, DH9003 showed no harmful effects on the intestine and liver of rats, but rather resulted in a denser and longer intestinal mucosa, as well as improving the intestinal mucosa of rats. Considering their substantial prospective applications, we concluded that these three isolates are potential probiotic candidates.

A red light-controlled probiotic bio-system for in-situ gut-brain axis regulation

Microbes regulate brain function through the gut-brain axis, deriving the technology to modulate the gut-brain axis in situ by engineered probiotics. Optogenetics offers precise and flexible strategies for controlling the functions of probiotics in situ. However, the poor penetration of most frequently used short wavelength light has limited the application of optogenetic probiotics in the gut. Herein, a red-light optogenetic gut probiotic was applied for drug production and delivery and regulation of the host behaviors. Firstly, a Red-light Optogenetic E. coli Nissle 1917 strain (ROEN) that could respond to red light and release drug product by light-controlled lysis was constructed. The remaining optical power of red light after 3 cm tissue was still able to initiate gene expression of ROEN and produce about approximately 3-fold induction efficiency. To give full play to the in vivo potential of ROEN, its responsive ability of the penetrated red light was tested, and its encapsulation was realized by PH-sensitive alginate microcapsules for further oral administration. The function of ROEN for gut-brain regulation was realized by releasing Exendin-4 fused with anti-neonatal Fc receptor affibody. Neuroprotection and behavioral regulation effects were evaluated in the Parkinson's disease mouse model, after orally administration of ROEN delivering Exendin-4 under optogenetic control in the murine gut. The red-light optogenetic probiotic might be a perspective platform for in situ drug delivery and gut-brain axis regulation.

Enzymatic Crosslinked Hydrogels of Gelatin and Poly (Vinyl Alcohol) Loaded with Probiotic Bacteria as Oral Delivery System

Probiotic bacteria are widely used to prepare pharmaceutical products and functional foods because they promote and sustain health. Nonetheless, probiotic viability is prone to decrease under gastrointestinal conditions. In this investigation, Lactiplantibacillus plantarum spp. CM-CNRG TB98 was entrapped in a gelatin−poly (vinyl alcohol) (Gel−PVA) hydrogel which was prepared by a “green” route using microbial transglutaminase (mTGase), which acts as a crosslinking agent. The hydrogel was fully characterized and its ability to entrap and protect L. plantarum from the lyophilization process and under simulated gastric and intestine conditions was explored. The Gel−PVA hydrogel showed a high probiotic loading efficiency (>90%) and survivability from the lyophilization process (91%) of the total bacteria entrapped. Under gastric conditions, no disintegration of the hydrogel was observed, keeping L. plantarum protected with a survival rate of >94%. While in the intestinal fluid the hydrogel is completely dissolved, helping to release probiotics. A Gel−PVA hydrogel is suitable for a probiotic oral administration system due to its physicochemical properties, lack of cytotoxicity, and the protection it offers L. plantarum under gastric conditions.

Preparation and Characteristics of Alginate Microparticles for Food, Pharmaceutical and Cosmetic Applications

Alginates are the most widely used natural polymers in the pharmaceutical, food and cosmetic industries. Usually, they are applied as a thickening, gel-forming and stabilizing agent. Moreover, the alginate-based formulations such as matrices, membranes, nanospheres or microcapsules are often used as delivery systems. Alginate microparticles (AMP) are biocompatible, biodegradable and nontoxic carriers, applied to encapsulate hydrophilic active substances, including probiotics. Here, we report the methods most frequently used for AMP production and encapsulation of different actives. The technological parameters important in the process of AMP preparation, such as alginate concentration, the type and concentration of other reagents (cross-linking agents, oils, emulsifiers and pH regulators), agitation speed or cross-linking time, are reviewed. Furthermore, the advantages and disadvantages of alginate microparticles as delivery systems are discussed, and an overview of the active ingredients enclosed in the alginate carriers are presented.

Materials Used for the Microencapsulation of Probiotic Bacteria in the Food Industry

Probiotics and probiotic therapy have been rapidly developing in recent years due to an increasing number of people suffering from digestive system disorders and diseases related to intestinal dysbiosis. Owing to their activity in the intestines, including the production of short-chain fatty acids, probiotic strains of lactic acid bacteria can have a significant therapeutic effect. The activity of probiotic strains is likely reduced by their loss of viability during gastrointestinal transit. To overcome this drawback, researchers have proposed the process of microencapsulation, which increases the resistance of bacterial cells to external conditions. Various types of coatings have been used for microencapsulation, but the most popular ones are carbohydrate and protein microcapsules. Microencapsulating probiotics with vegetable proteins is an innovative approach that can increase the health value of the final product. This review describes the different types of envelope materials that have been used so far for encapsulating bacterial biomass and improving the survival of bacterial cells. The use of a microenvelope has initiated the controlled release of bacterial cells and an increase in their activity in the large intestine, which is the target site of probiotic strains.

Novel Developments on Stimuli-Responsive Probiotic Encapsulates: From Smart Hydrogels to Nanostructured Platforms

Biomaterials engineering and biotechnology have advanced significantly towards probiotic encapsulation with encouraging results in assuring sufficient bioactivity. However, some major challenges remain to be addressed, and these include maintaining stability in different compartments of the gastrointestinal tract (GIT), favoring adhesion only at the site of action, and increasing residence times. An alternative to addressing such challenges is to manufacture encapsulates with stimuli-responsive polymers, such that controlled release is achievable by incorporating moieties that respond to chemical and physical stimuli present along the GIT. This review highlights, therefore, such emerging delivery matrices going from a comprehensive description of addressable stimuli in each GIT compartment to novel synthesis and functionalization techniques to currently employed materials used for probiotic’s encapsulation and achieving multi-modal delivery and multi-stimuli responses. Next, we explored the routes for encapsulates design to enhance their performance in terms of degradation kinetics, adsorption, and mucus and gut microbiome interactions. Finally, we present the clinical perspectives of implementing novel probiotics and the challenges to assure scalability and cost-effectiveness, prerequisites for an eventual niche market penetration.

Survival of Microencapsulated Lactococcus lactis Subsp. lactis R7 Applied in Different Food Matrices

Survival of Lactococcus lactis subsp. lactis R7, microencapsulated with whey and inulin, was analyzed when added to blueberry juice, milk, and cream. For 28 days, cell viability was evaluated for storage (4 °C), simulated gastrointestinal tract (GIT), and thermal resistance. All matrices demonstrated high cell concentration when submitted to GIT (11.74 and 12 log CFU mL^-1), except for the blueberry juice. The thermal resistance analysis proved the need for microencapsulation, regardless of the food matrix. The results indicate that L. lactis R7 microcapsules have potential for application in different matrices and development of new probiotic products by thermal processing.

Viability of Lactobacillus delbrueckii in chocolates during storage and in-vitro bioaccessibility of polyphenols and SCFAs

This study evaluated the viability of encapsulated Lactobacillus delbrueckii subsp. bulgaricus in chocolate during storage and in-vitro gastrointestinal transit. Flavonoid contents and short chain fatty acids (SCFAs) production during gastrointestinal transit were also assessed. Encapsulated L. delbrueckii subsp. bulgaricus survived well in chocolates >7 logs both after 120 days of storage at 4 °C and 25 °C, and during in-vitro gastrointestinal transit. The release of SCFAs through in-vitro gastrointestinal digestion and colonic fermentation revealed that probiotic-chocolates could be an excellent source of nutrients for the gut microbiota. Encapsulated probiotic in chocolates with 70% cocoa produced significantly (P < 0.05) more acetic, propionic, isobutyric, butyric and isovaleric acids than that with 45% cocoa. The bioconversion results of a specific polyphenol by L. delbrueckii subsp. bulgaricus exhibited that chocolate polyphenols could be utilized by probiotics for their metabolism. These findings confirmed that chocolate could be successfully fortified with L. delbrueckii subsp. bulgaricus encapsulation to improve health promoting properties of chocolates.

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Chocolates enhance the biosynthesis of SCFAs and Vit B₁₂ in colonic fermentation.

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Chocolates served as a prebiotic source for gut microbiota proliferation.

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Chocolate with probiotics would favor the bioconversion of a specific polyphenols.

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Chocolates nutritional value can be enhanced via fortification with probiotics.

Nanoencapsulation for Probiotic Delivery

Gut microbiota dynamically participate in diverse physiological activities with direct impact on the host's health. A range of factors associated with the highly complex intestinal flora ecosystem poses challenges in regulating the homeostasis of microbiota. The consumption of live probiotic bacteria, in principle, can address these challenges and confer health benefits. In this context, one of the major problems is ensuring the survival of probiotic cells when faced with physical and chemical assaults during their intake and subsequent gastrointestinal passage to the gut. Advances in the field have focused on improving conventional encapsulation techniques in the microscale to achieve high cell viability, gastric and temperature resistance, and longer shelf lives. However, these microencapsulation approaches are known to have limitations with possible difficulties in clinical translation. In this Perspective, we present a brief overview of the current progress of different probiotic encapsulation methods and highlight the contemporary and emerging single-cell encapsulation strategies using nanocoatings for individual probiotic cells. Finally, we discuss the relative advantages of various nanoencapsulation approaches and the future trend toward developing coated probiotics with advanced features and health benefits.

Encapsulation and dispersion of Lactobacillus acidophilus in a chocolate coating as a strategy for maintaining cell viability in cereal bars

Flour from Pereskia aculeata leaf and green banana were used as ingredients in the formulation of a cereal bar with added Lactobacillus acidophilus LA02-ID-1688. Encapsulation in a calcium-alginate hydrogel reinforced with magnesium hydroxide was used as a strategy to protect the probiotic cells under gastrointestinal conditions and to prolong shelf-life. The results are relevant especially for maintaining cell viability during shelf-life; a challenge for the food industry in relation to dry probiotic products. Encapsulation promoted the protection of probiotic cells in simulated gastric and intestinal conditions, allowing the maintenance of high viable cell counts (> 10 log CFU, colony forming unit). Encapsulation also contributed to cellular protection under extreme temperature conditions, with reductions of cell viability of < 1 logarithmic cycle when the capsules were subjected to 55ºC/10 min. Even at 75ºC/10 min, encapsulation protected the probiotic cells 3-times greater than the free-cells. The food bar proved to be rich in dietary fiber (19 g 100 g-1), lipids (12.63 g 100 g-1) and showed an appreciable protein content (5.44 g 100 g-1). A high viable probiotic cell count on storage over 120 days (12.54 log CFU) was observed, maintaining a probiotic survival rate > 90% and viability levels sufficient to promote health benefits.

The efficacy of three double-microencapsulation methods for preservation of probiotic bacteria

Lactic acid bacteria (LAB) are used as a probiotic alternative to antibiotics in livestock production. Microencapsulation technology is widely used for probiotic preservation. A variety of microencapsulation protocols have been proposed and compared based on chemicals and mechanical procedures. This study aimed to develop a double-encapsulated coating from alginate (1.5%) and chitosan (0.5%) by extrusion, emulsion, and spray drying methods using the LAB strains Lactobacillus plantarum strains 31F, 25F, 22F, Pediococcus pentosaceus 77F, and P. acidilactici 72N, and to monitor the basic probiotic properties of the encapsulated prototypes. The final products from each microencapsulation protocol were analysed for their appearance, probiotic properties and viable cell count. Using the spray drying method, particles smaller than 15 μm in diameter with a regular spherical shape were obtained, whereas the other methods produced larger (1.4–52 mm) and irregularly shaped microcapsules. After storage for 6 months at room temperature, the LAB viability of the spray-dried particles was the highest among the three methods. In all the LAB strains examined, the encapsulated LAB retained their probiotic properties in relation to acid-bile tolerance and antibacterial activity. This study highlights the efficacy of double-coating microencapsulation for preserving LAB properties and survival rate, and demonstrates its potential for probiotic application in livestock farms.

Characterization of potential probiotic strain, L. reuteri B2, and its microencapsulation using alginate-based biopolymers

In this study, Lactobacillus reuteri B2 was isolated from the feces of C57BL/6 mice and assessed on probiotic activity. L. reuteri B2 was identified by 16S rDNA sequencing, which the cell viability in acidic conditions at pH 2.0 was 64% after 2 h, and in the presents of 0.30% of the bile salts, after 6 h, was 37%. Antimicrobial assay with L. reuteri B2 showed maximum diameters against Klebsiela oxytoca J7 (12.5 ± 0.71 mm). We further hypothesized if L. reuteri B2 strain in the free form can survive all conditions in the gastrointestinal tract (GIT) then the utilization of the appropriate biomaterials would ameliorate its stability and viability in GIT. L. reuteri B2 was microencapsulated into sodium alginate-(Na-alg) and different content of Na-alg and sodium maleate (SM) beads. Characterization materials enveloped their thermal characteristics (TGA/DTA analysis) and structure using: scanning electron microscopy (SEM), FTIR, and particle size distribution. The high survival rate of L. reuteri B2 at low pH from 2.0 to 4.0 and in the presence of the bile salts, at concentrations up to 0.30%, was obtained. L. reuteri B2 showed strong antimicrobial activity and the best protection microencapsulated with Na-alg + SM in simulated gastric juices (SGJ).

Modulatory Effects of Probiotics During Pathogenic Infections With Emphasis on Immune Regulation

In order to inhibit pathogenic complications and to enhance animal and poultry growth, antibiotics have been extensively used for many years. Antibiotics applications not only affect target pathogens but also intestinal beneficially microbes, inducing long-lasting changes in intestinal microbiota associated with diseases. The application of antibiotics also has many other side effects like, intestinal barrier dysfunction, antibiotics residues in foodstuffs, nephropathy, allergy, bone marrow toxicity, mutagenicity, reproductive disorders, hepatotoxicity carcinogenicity, and antibiotic-resistant bacteria, which greatly compromise the efficacy of antibiotics. Thus, the development of new antibiotics is necessary, while the search for antibiotic alternatives continues. Probiotics are considered the ideal antibiotic substitute; in recent years, probiotic research concerning their application during pathogenic infections in humans, aquaculture, poultry, and livestock industry, with emphasis on modulating the immune system of the host, has been attracting considerable interest. Hence, the adverse effects of antibiotics and remedial effects of probiotics during infectious diseases have become central points of focus among researchers. Probiotics are live microorganisms, and when given in adequate quantities, confer good health effects to the host through different mechanisms. Among them, the regulation of host immune response during pathogenic infections is one of the most important mechanisms. A number of studies have investigated different aspects of probiotics. In this review, we mainly summarize recent discoveries and discuss two important aspects: (1) the application of probiotics during pathogenic infections; and (2) their modulatory effects on the immune response of the host during infectious and non-infectious diseases.

Impact of encapsulating a probiotic (Pediococcus pentosaceus Li05) within gastro-responsive microgels on Clostridium difficile infections

Antibiotic treatment is often followed by Clostridium difficile infection (CDI), which causes severe diarrhea and other health issues. Oral administration of Pediococcus pentosaceus Li05 (Li05) has been shown to have great potential in preventing CDI. However, the viability of Li05 is greatly reduced during storage and passage through the gastrointestinal (GI) tract, which limits its biological activity. In this study, a gastro-responsive microgel was designed to encapsulate and protect Li05 to enhance its efficacy against CDI. The viability of Li05 encapsulated within the microgels was significantly enhanced during long-term storage and after exposure to simulated GI fluids. Moreover, this gastro-responsive microgel led to greater sustained release of the probiotic. In a mouse CDI model, we found that encapsulated Li05 was better at inhibiting C. difficile infection than nonencapsulated Li05, as demonstrated through analysis of the probiotic survival rate, spleen weight, colonic histology, and inflammatory cytokine levels. Moreover, the gut microbial diversity was enriched by treatment with encapsulated Li05. These results suggest that encapsulating Li05 within biopolymer microgels may enhance its ability to prevent and treat CDI using functional foods, supplements, or pharmaceuticals.

Recent advances in the structure, synthesis, and applications of natural polymeric hydrogels

Hydrogels, polymeric network materials, are capable of swelling and holding the bulk of water in their three-dimensional structures upon swelling. In recent years, hydrogels have witnessed increased attention in food and biomedical applications. In this paper, the available literature related to the design concepts, types, functionalities, and applications of hydrogels with special emphasis on food applications was reviewed. Hydrogels from natural polymers are preferred over synthetic hydrogels. They are predominantly used in diverse food applications for example in encapsulation, drug delivery, packaging, and more recently for the fabrication of structured foods. Natural polymeric hydrogels offer immense benefits due to their extraordinary biocompatible nature. Hydrogels based on natural/edible polymers, for example, those from polysaccharides and proteins, can serve as prospective alternatives to synthetic polymer-based hydrogels. The utilization of hydrogels has so far been limited, despite their prospects to address various issues in the food industries. More research is needed to develop biomimetic hydrogels, which can imitate the biological characteristics in addition to the physicochemical properties of natural materials for different food applications.

Effective microencapsulation of Enterococcus faecium in biopolymeric matrices using spray drying

The objective of this work was to evaluate the potential of whey protein concentrate (WPC), native agave fructans (NAF), and their mixture (WPC-NAF, 1:1 w/w) as wall materials and evaluate the physicochemical properties and stability of encapsulated Enterococcus faecium during the spray drying, storage, and passage through the simulated gastrointestinal tests. The encapsulated microorganisms with WPC-NAF by spray drying showed greater viability (9.26 log CFU/g) and a higher microencapsulation yield (88.43%). They also had a smaller reduction in the cell count (0.61 log cycles), while the microcapsules produced with NAF had the greatest reduction in viability during the simulated gastrointestinal tests. Similarly, probiotics encapsulated with WPC-NAF revealed a higher survival rate (> 8 log CFU/g) when stored at a water activity of 0.328. The thermal analysis showed that the addition of NAF to the WPC produced a slight shift in the Tg towards temperatures higher than that shown by NAF. Therefore, this study provides evidence that the spray drying process was appropriate to encapsulate the probiotic strain Enterococcus faecium and that the mixture WPC-NAF protected it from adverse drying conditions and improved the viability of Enterococcus faecium during storage and simulated gastrointestinal tests, demonstrating that the combination of NAF and WPC as encapsulating material is adequate in the production of more stable microcapsules with potential application in various foods.Key Points• E. faecium was successfully encapsulated in WPC and NAF.• WPC-NAF offered protection to E. faecium in the gastrointestinal tests and during storage.• Aw around 0.328 positively influenced the viability of the microorganism during storage. Graphical abstract.

Microencapsulation Delivery System in Food Industry—Challenge and the Way Forward

Microencapsulation is a promising technique, which provides core materials with protective barrier, good stability, controlled release, and targeting delivery. Compared with the pharmaceutical, cosmetic, and textile industries, food processing has higher requirements for safety and hygiene and calls for quality and nutrition maintenance. This paper reviews the widely used polymers as microcapsule wall materials and the application in different food products, including plant-derived food, animal-derived food, and additives. Also, common preparation technologies (emphasizing advantages and disadvantages), including spray-drying, emulsification, freeze-drying, coacervation, layer-by-layer, extrusion, supercritical, fluidized bed coating, electrospray, solvent evaporation, nanocapsule preparation, and their correlation with selected wall materials in recent 10 years are presented. Personalized design and cheap, efficient, and eco-friendly preparation of microcapsules are urgently required to meet the needs of different processing or storage environments. Moreover, this review may provide a reference for the microencapsulation research interests and development on future exploration.

The Effect of Encapsulation on The Stability of Probiotic Bacteria in Ice Cream and Simulated Gastrointestinal Conditions

The objective of this work was to explore the effect of two encapsulating polysaccharides (sodium alginate and carrageenan) on the viability of probiotic bacteria (L. acidophilus) in ice cream and under simulated gastrointestinal (GIT) conditions. For the purpose, probiotic cells were encapsulated in sodium alginate and carrageenan by an encapsulator using standard operating conditions. Ice cream was manufactured by adding free and microencapsulated probiotics. The survival of free and encapsulated probiotics was monitored over a period of 120 days at - 20 °C. Furthermore, the survival of free and encapsulated probiotic bacteria under the simulated GIT conditions was investigated. The results of the study showed that encapsulation significantly (p < 0.05) improved the cell survival of probiotics in ice cream compared to free cells (non-encapsulated). The viable cell count of probiotic bacteria in the free-state in ice cream was 9.97 log cfu/ml at 0 day that decreased to 6.12 log cfu/ml after 120 days. However, encapsulation improved the viability of the probiotics in the prepared ice cream and GIT. The cell count of probiotics encapsulated with sodium alginate and carrageenan was 9.91 log cfu/ml and 9.89 log cfu/ml respectively at 0 day that decreased to 8.74 log cfu/ml and 8.39 log cfu/ml respectively after 120 days. Similarly, during simulated gastrointestinal assay, the survival rate of encapsulated probiotic bacteria in simulated gastric solution and intestinal solutions was higher than that of free cells. In the case of encapsulated bacteria, only three log while for free cells seven log reduction was recorded. Sodium alginate microcapsules exhibited better release profile than carrageenan. Conclusively, the incorporation of encapsulated probiotics had a significant effect on quality parameters and sensorial characteristics of ice cream.

Survival and stability of free and encapsulated probiotic bacteria under simulated gastrointestinal conditions and in ice cream

The aim of the present study was to evaluate the upshot of microencapsulation on the stability and viability of probiotics in carrier food (ice cream) and simulated gastrointestinal (GIT) conditions. Purposely, Lactobacillus casei was encapsulated with two different hydrocolloids, that is, calcium alginate (Ca-ALG) and whey protein concentrate (WPC) by using encapsulator. The obtained microbeads were characterized in terms of encapsulation efficiency and morphological features. Afterward, the probiotics in free and encapsulated form were incorporated into ice cream. The product was subjected for physicochemical, microbiological, and sensory attributes over a storage period of 80 days. Microencapsulation with both hydrogels significantly (p < .05) improved the viability of probiotics in both carrier food and simulated GIT conditions.The initial viable count of probiotics encapsulated with Ca-ALG and WPC was 9.54 and 9.52 log CFU/ml, respectively, that declined to 8.59 and 8.39 log CFU/ml, respectively, over period of 80 days of storage. While nonencapsulated/free cells declined from 9.44 to 6.41 log CFU/ml during same storage period. Likewise, during in vitro GIT assay, encapsulated probiotic with Ca-ALG and WPC showed 0.95 and 1.13 log reduction, respectively. On other hand, free probiotics showed significant 3.03 log reduction. Overall, microencapsulated probiotic exhibited better survival as compared to free cells. Moreover, the amalgamation of encapsulated and free probiotics affected the physicochemical (decrease in pH and increase in viscosity) was and sensory parameters of ice cream during storage.

Functional exploration of free and encapsulated probiotic bacteria in yogurt and simulated gastrointestinal conditions

The core objective of the current study was to evaluate the effect of microencapsulation on the viability and stability of probiotic bacteria in yogurt and simulated gastrointestinal conditions. For this purpose, probiotic bacteria were encapsulated with sodium alginate and carrageenan by encapsulator. Yogurt was prepared with the incorporation of free and encapsulated probiotic bacteria and was analyzed for physicochemical, microbiological, and sensorial attributes. Encapsulation and storage exhibited a significant (p < .05) effect on different parameters of yogurt. An increasing trend in syneresis and acidity while a decreasing trend in viscosity, pH, viability, and stability were observed. The value of syneresis increased from 2.27 ± 0.17 to 2.9 ± 0.14 and acidity from 0.48 ± 0.04 to 0.64 ± 0.01 during 4 weeks of storage. The value of viscosity decreased from 3.68 ± 0.21 to 2.42 ± 0.09 and pH from 4.88 ± 0.31to 4.43 ± 0.36 during 28 days of storage. Unencapsulated (free) cells exhibited poor survival. The viable cell count of probiotic bacteria in the free-state in yogurt was 9.97 logs CFU/ml at zero-day that decreased to 6.12 log CFU/ml after 28 days. However, encapsulation improved the viability of the probiotics in the prepared yogurt and GIT. The cell count of probiotics encapsulated with sodium alginate and carrageenan was 9.91 logs CFU/ml and 9.89 logs CFU/ml, respectively, at zero-day that decreased to 8.74 logs CFU/ml and 8.39 log CFU/ml, respectively. Free cells (unencapsulated) showed very poor survival. Similarly, during in vitro gastrointestinal assay, the survival rate of encapsulated probiotic bacteria in simulated gastric solution and intestinal solutions was higher than that of free cells. In the case of encapsulated bacteria, only 3 logs while for free cells, 7 log reduction was recorded. Sodium alginate microcapsules exhibited better release profile than carrageenan. Conclusively, microencapsulation improved the survival of probiotic bacteria in carrier food as well as in simulated gastrointestinal condition.

Probiotics, mechanisms of action, and clinical perspectives for diarrhea management in children

Infectious diarrhea is the second most common cause of morbidity and mortality in children under 5 years of age in the underdeveloped areas of the world. Conventional treatment consists of rehydration, which may be coupled with antimicrobial agents in more severe bacterial infections or with antiprotozoal agents. In the last few decades, research on the use of probiotic strains, such as Lactobacillus rhamnosus GG ATCC 53013 (LGG), Lactobacillus reuteri DSM 17938 and Saccharomyces boulardii, has gained much attention to prevent and treat diarrheal diseases. However, they are rarely used in the clinical routine, perhaps because there are still gaps in the knowledge about the effective benefit to the patient in terms of the reduction of the duration of diarrhea and its prevention. Furthermore, only a few probiotic strains are safely indicated for usage in pediatric practice. This review summarizes the current knowledge on the antimicrobial mechanisms of probiotics on distinct enteropathogens and their role in stimulating host defense mechanisms against intestinal infections. In addition, we highlight the potential of probiotics for the treatment and prevention of diarrhea in children. We conclude that the use of probiotics is beneficial for both the treatment and prevention of diarrhea in children and that the identification of other candidate probiotics might represent an important advance to a greater reduction in hospital stays and to prevent infectious diarrhea in a larger portion of this population.

Multifunctional Hierarchically-Assembled Hydrogel Particles with Pollen Grains via Pickering Suspension Polymerization

Hierarchical assembly of heterogeneous particles is of great importance to interface and colloid science. In this work, a facile but powerful approach for the large-scale production of multifunctional hydrogel particles armored with biological colloidal species is developed by combining Pickering stabilization and photopolymerization. Biocompatible hollow pollen grains extracted from naturally occurring pollen species with an average diameter of ∼32 μm serve as universal solid emulsifiers dispersed in an oil phase and are self-assembled at the interface between an oil phase and a photo-cross-linkable hydrogel to make water-in-oil (W/O) emulsion droplets. While droplets are solidified into hydrogel particles by UV-induced free-radical polymerization, self-assembled hollow pollen grains are transformed to a robust shell on hydrogel particles with supracolloidal structures. The physically adsorbed hollow pollen grains on the hydrogel core can be released by a hydration-induced swelling of hollow pollen grains, leading to a transient floating behavior of core-shell particles. The size of the resultant core-shell particles is easily controlled by tailoring the process parameters such as a liquid volume or a loading mass of hollow pollen grains. The incorporation of magnetic or upconverting luminescent nanoparticles into a hydrogel core successfully expands the functionality of core-shell particles that can provide new design opportunities for floating drug delivery or ecofriendly proppants.

Immobilization of Bifidobacterium infantis Cells in Selected Hydrogels as a Method of Increasing Their Survival in Fermented Milkless Beverages

The aim of the study was to examine whether immobilization of Bifidobacterium infantis inside hydrogels could prolong their survival in fermented milkless beverages. The starter culture Streptococcus thermophilus was used to obtain fermented nonmilk beverages: oat, oat-banana, and oat-peach. The biota of beverages were supplemented with Bifidobacterium infantis cells, free and immobilized, in three types of spherical hydrogel particles: microcapsules with a liquid and gelled core, microbeads of 0.5 mm diameter, and beads of 2.5 mm diameter. As a carrier material, low-methoxylated pectin and alginate were used. Microbeads and microcapsules were obtained using extrusion techniques: vibrating and electrostatic method, and beads were obtained using manual method with a syringe. A significantly lower decrease in the count of cells immobilized in hydrogels compared to free cells was observed during storage of fermented beverages at 4°C. Microcapsules were more effective compared to microbeads in terms of bacterial cells protection. The observed effect was better for higher biopolymer concentration. The highest survival of the strain was noted in cells immobilized in low-methoxylated pectin beads of 2.5 mm diameter. Supplementing the biota of fermented beverages with microencapsulated bacteria did not negatively affect the overall sensory quality of beverages during the entire storage period.

Designing biopolymer microgels to encapsulate, protect and deliver bioactive components: Physicochemical aspects

Biopolymer microgels have considerable potential for their ability to encapsulate, protect, and release bioactive components. Biopolymer microgels are small particles (typically 100nm to 1000μm) whose interior consists of a three-dimensional network of cross-linked biopolymer molecules that traps a considerable amount of solvent. This type of particle is also sometimes referred to as a nanogel, hydrogel bead, biopolymer particles, or microsphere. Biopolymer microgels are typically prepared using a two-step process involving particle formation and particle gelation. This article reviews the major constituents and fabrication methods that can be used to prepare microgels, highlighting their advantages and disadvantages. It then provides an overview of the most important characteristics of microgel particles (such as size, shape, structure, composition, and electrical properties), and describes how these parameters can be manipulated to control the physicochemical properties and functional attributes of microgel suspensions (such as appearance, stability, rheology, and release profiles). Finally, recent examples of the utilization of biopolymer microgels to encapsulate, protect, or release bioactive agents, such as pharmaceuticals, nutraceuticals, enzymes, flavors, and probiotics is given.

Microencapsulated cells of Lactobacillus paracasei subsp. paracasei in biopolymer complex coacervates and their function in a yogurt matrix

L. paracasei subsp. paracasei E6 cells were encapsulated by complex coacervation using whey protein isolate (WPI) and gum arabic and introduced in stirred yogurts. The encapsulated cells showed improved survival during product cold storage and on exposure to simulated gastric juice.