An alternative way to encapsulate probiotics within electrospun alginate nanofibers as monitored under simulated gastrointestinal conditions and in kefir

Unveiling the potential of alginate-based nanomaterials in sensing technology and smart delivery applications

Sensors are applied to many fields nowadays because of their high sensitivity, low cost, time-saving, user-friendly, and excellent selectivity. Current biomedical and pharmaceutical science has one focus on developing nanoparticle-based sensors, especially biopolymeric nanoparticles. Alginate is a widely used biopolymer in a variety of applications. The hydrogel-forming characteristic, the chemical structure with hydroxy and carboxylate moieties, biocompatibility, biodegradability, and water solubility of alginate have expanded opportunities in material and biomedical sciences. Recently, research on alginate-based nanoparticles and their applications has begun. These materials are gaining popularity because of their wide usage potential in the biomedical and pharmaceutical fields. Many review papers describe applications of alginate in the drug delivery field. The current study covers the structural and physicochemical properties of alginate-based nanoparticles. The prospective applications of alginate-based nanomaterials in various domains are discussed, including drug delivery and environmental sensing applications for humidity, heavy metals, and hydrogen peroxide. Moreover, biomedical sensing applications of alginate-based nanoparticles regarding various analytes such as glucose, cancer cells, pharmaceutical drugs, and human motion will also be reviewed in this paper. Future research scopes highlight existing challenges and solutions.

The complex world of kefir: Structural insights and symbiotic relationships

Kefir milk, known for its high nutritional value and health benefits, is traditionally produced by fermenting milk with kefir grains. These grains are a complex symbiotic community of lactic acid bacteria, acetic acid bacteria, yeasts, and other microorganisms. However, the intricate coexistence mechanisms within these microbial colonies remain a mystery, posing challenges in predicting their biological and functional traits. This uncertainty often leads to variability in kefir milk's quality and safety. This review delves into the unique structural characteristics of kefir grains, particularly their distinctive hollow structure. We propose hypotheses on their formation, which appears to be influenced by the aggregation behaviors of the community members and their alliances. In kefir milk, a systematic colonization process is driven by metabolite release, orchestrating the spatiotemporal rearrangement of ecological niches. We place special emphasis on the dynamic spatiotemporal changes within the kefir microbial community. Spatially, we observe variations in species morphology and distribution across different locations within the grain structure. Temporally, the review highlights the succession patterns of the microbial community, shedding light on their evolving interactions.Furthermore, we explore the ecological mechanisms underpinning the formation of a stable community composition. The interplay of cooperative and competitive species within these microorganisms ensures a dynamic balance, contributing to the community's richness and stability. In kefir community, competitive species foster diversity and stability, whereas cooperative species bolster mutualistic symbiosis. By deepening our understanding of the behaviors of these complex microbial communities, we can pave the way for future advancements in the development and diversification of starter cultures for food fermentation processes.

Bacteria/Nanozyme Composites: New Therapeutics for Disease Treatment

Bacterial therapy is recognized as a cost-effective treatment for several diseases. However, its development is hindered by limited functionality, weak inherent therapeutic effects, and vulnerability to harsh microenvironmental conditions, leading to suboptimal treatment activity. Enhancing bacterial activity and therapeutic outcomes emerges as a pivotal challenge. Nanozymes have garnered significant attention due to their enzyme-mimic activities and high stability. They enable bacteria to mimic the functions of gene-edited bacteria expressing the same functional enzymes, thereby improving bacterial activity and therapeutic efficacy. This review delineates the therapeutic mechanisms of bacteria and nanozymes, followed by a summary of strategies for preparing bacteria/nanozyme composites. Additionally, the synergistic effects of such composites in biomedical applications such as gastrointestinal diseases and tumors are highlighted. Finally, the challenges of bacteria/nanozyme composites are discussed and propose potential solutions. This study aims to provide valuable insights to offer theoretical guidance for the advancement of nanomaterial-assisted bacterial therapy.

Improvement of Stress Resistance of Microencapsulated Lactobacillus plantarum by Emulsion Electrospinning

Probiotics have become increasingly recognized for their potential health-promoting properties; however, the viability of probiotics can be affected by storage and transportation processes as well as the stressful environment of the human digestive tract, preventing them from achieving effective concentration (107 CFU/mL). In this regard, the embedding technology of probiotics provides an effective protection method. Dextran-based water in water (W/W) emulsion loaded with Lactobacillus plantarum was used as spinning solution to prepare Lactobacillus plantarum-loaded electrospun fibers. The structure of the W/W emulsion and the electrospun fibers was charactered. Lactobacillus plantarum were uniformly embedded in the internal phase of the W/W emulsion and the loading efficiency was 9.70 ± 0.40 log CFU/g. After 240 min digestion in the gastrointestinal tract, and temperature treatment in 65 °C and 72 °C, the loaded probiotics maintained high activity. Even after 5 days of storage in room temperature and 4 °C, the loaded probiotic activity levels remained high, with counts >8 log CFU/g. These results suggest that probiotics encapsulated by emulsion electrospinning could be potentially delivered in a novel food delivery system used in the future food industry.

Electrospun Fibers Loaded with Probiotics: Fundamentals, Characterization, and Applications

Increasing demand for safe, efficient, and eco-friendly solutions for pharmaceutical and food industries has led researchers to explore new approaches to bacterial storage. Several advantages make electrospinning (ES) a promising technique for food systems, including simple manufacturing equipment, a relatively low spinning cost, a wide variety of spinnable materials, and a mild process that is easily controlled, which allows continuous fabrication of ultrafine polymeric fibers at submicron or nanoscales without high temperatures or high pressures. This review briefly describes recent advances in the development of electrospun fibers for loading probiotics (PRB) by focusing on ES technology, its efficiency for loading PRB into fibers (viability, digestive stability, growth rate, release, thermal stability, and interactions of fibers with PRB), and the application of PRB-loaded fibers as active packaging (spoilage/microbial control, antioxidant effect, shelf life). Based on the literature reviewed, the incorporation of PRB into electrospun fibers is both feasible and functional. However, several studies have been limited to proof-of-principle experiments and the use of model biological products. It is necessary to conduct further research to establish the industrial applicability of PRB-loaded fibers, particularly in the fields of food and medicine.

Core-shell nanofibers based on microalgae proteins/alginate complexes for enhancing survivability of probiotics

In this study, a novel one-step coaxial electrospinning process is employed to fabricate shell-core structure fibers choosing Chlorella pyrenoidosa proteins (CP) as the core material. These nanofibers, serving as the wall material for probiotic encapsulation, aimed to enhance the stability and antioxidant activity of probiotics in food processing, storage, and gastrointestinal environments under sensitive conditions. Morphological analysis was used to explore the beads-on-a-string morphology and core-shell structure of the electrospun fibers. Probiotics were successfully encapsulated within the fibers (7.97 log CFU/g), exhibiting a well-oriented structure along the distributed fibers. Compared to free probiotics and uniaxial fibers loaded with probiotics, encapsulation within microalgae proteins/alginate core-shell structure nanofibers significantly enhanced the probiotic cells' tolerance to simulated gastrointestinal conditions (p < 0.05). Thermal analysis indicated that microalgae proteins/alginate core-shell structure nanofibers displayed superior thermal stability compared to uniaxial fibers. The introduction of CP resulted in a 50 % increase in the antioxidant capacity of probiotics-loaded microalgae proteins/alginate nanofibers compared to uniaxial alginate nanofibers, with minimal loss of viability (0.8 log CFU/g) after 28 days of storage at 4 °C. In summary, this dual-layer carrier holds immense potential in probiotic encapsulation and enhancing their resistance to harsh conditions.

Biological Significance of Probiotic Microorganisms from Kefir and Kombucha: A Review

(1) Background: The human microbiota is essential for maintaining a healthy body. The gut microbiota plays a protective role against pathogenic bacteria. Probiotics are live microorganisms capable of preventing and controlling gastrointestinal and balancing the immune system. They also aid in better nutrients and vitamins absorption. Examples of natural probiotic cultures are kefir and kombucha. (2) Methods: Therefore, the aim of this review was to address the beneficial properties of probiotic kefir and kombucha using a Boxplot analysis to search for scientific data in the online literature up to January 2024: (Latin American and Caribbean Health Sciences (LILACS), PubMed, Medical Literature Analysis (MED-LINE), Science Direct, Google Scholar/Google Academic, Bioline Inter-national and Springer Link). Boxplots showed the summary of a set of data "Index Terms-Keywords" on kefir and kombucha in three languages (English, Portuguese and Spanish). (3) Results: Google Scholar was the database with the highest number of articles found, when the search for the keywords used in the study (containing ~4 × 106-~4 million articles available). This was Followed by the Science Direct database, containing ~3 × 106-~3 million articles available, and the BVS databases-Biblioteca Virtual de Saúde (Virtual Health Library) e Lilacs, both containing a value of ~2 × 106-~2 million articles available. The databases containing the smallest number of articles found were Nutrients and Medline, both containing a value of ≤0.1 × 106-≤100 thousand articles. (4) Conclusions: Scientific studies indicate that kefir and kombucha certainly contain various functional properties, such as antimicrobial, antitumor, anticarcinogenic and immunomodulatory activity, in addition to having a microbiological composition of probiotic bacteria and yeasts. Kefir and kombucha represent key opportunities in the food and clinic/medical fields.

Encapsulation of Probiotics within Double/Multiple Layer Beads/Carriers: A Concise Review

An increased demand for natural products nowadays most specifically probiotics (PROs) is evident since it comes in conjunction with beneficial health effects for consumers. In this regard, it is well known that encapsulation could positively affect the PROs' viability throughout food manufacturing and long-term storage. This paper aims to analyze and review various double/multilayer strategies for encapsulation of PROs. Double-layer encapsulation of PROs by electrohydrodynamic atomization or electrospraying technology has been reported along with layer-by-layer assembly and water-in-oil-in-water (W1/O/W2) double emulsions to produce multilayer PROs-loaded carriers. Finally, their applications in food products are presented. The resistance and viability of loaded PROs to mechanical damage, during gastrointestinal transit and shelf life of these trapping systems, are also described. The PROs encapsulation in double- and multiple-layer coatings combined with other technologies can be examined to increase the opportunities for new functional products with amended functionalities opening a novel horizon in food technology.

Lacticaseibacillus paracasei AD22 Stress Response in Brined White Cheese Matrix: In Vitro Probiotic Profiles and Molecular Characterization

Functionalizing foods involve discovering and integrating new candidate health-promoting bacteria into the food matrix. This study aimed (i) to reveal the probiotic potential of autochthonous Lacticaseibacillus paracasei AD22 by a series of in vitro tests and molecular characterization and (ii) to evaluate its application to the matrix of brined white cheese, which is the most common cheese in Türkiye, in terms of survival and stress response. To evaluate in vitro probiotic characteristics, L. paracasei AD22 was exposed to functional, technological, and safety tests. Pilot scale production was conducted to integrate L. paracasei AD22 into the brined white cheese matrix. The expression levels of stress-related genes (dnaK, groES, ftsH, argH, and hsp20) were detected by reverse-transcriptase polymerase chain reaction to determine the transcriptional stress response during ripening. The presence of genes encoding stress-related proteins was determined by whole-genome sequence analysis using a subsystem approach; the presence of antibiotic resistance and virulence genes was determined by ResFinder4.1 and VirulenceFinder 2.0 databases. The BAGEL4 database determined the presence of bacteriocin clusters. L. paracasei AD22 was found to survive in pH 2 and medium with 12% NaCl and did not cause hemolysis. Adhesion of the strain to Caco2 cells was 76.26 ± 4.81% and it had coaggregation/autoaggregation properties. It was determined that L. paracasei AD22 exceeded 7 log cfu/g in the cheese matrix at the end of the ripening period. Total mesophilic aerobes decreased in the cheese inoculated with L. paracasei AD22 after the 45th day of ripening. While hsp20 and groES genes were downregulated during ripening, argH was upregulated. Both downregulation and upregulation were observed in dnaK and ftsH. Fold changes indicating the expression levels of dnaK, groES, ftsH, argH, and hsp20 genes were not statistically significant during ripening (p > 0.05). Whole-genome sequence profiles revealed that the strain did not contain antibiotic and virulence genes but bacteriocin clusters encoding Enterolysin A (Class III bacteriocin), Carnosine CP52 (class II bacteriocin), Enterocin X beta chain (Class IIc bacteriocin), and the LanT region. Subsystems approach manifested that the most functional part of the genomic distribution belonged to metabolism, protein processing, and stress response functions. The study findings highlight that L. paracasei AD22 will provide biotechnological innovation as a probiotic adjunct because it contains tolerance factors and probiotic characteristics to produce new functional foods.

Emerging Multiscale Biofabrication Approaches for Bacteriotherapy

Bacteriotherapy is emerging as a strategic and effective approach to treat infections by providing putatively harmless bacteria (i.e., probiotics) as antagonists to pathogens. Proper delivery of probiotics or their metabolites (i.e., post-biotics) can facilitate their availing of biomaterial encapsulation via innovative manufacturing technologies. This review paper aims to provide the most recent biomaterial-assisted strategies proposed to treat infections or dysbiosis using bacteriotherapy. We revised the encapsulation processes across multiscale biomaterial approaches, which could be ideal for targeting different tissues and suit diverse therapeutic opportunities. Hydrogels, and specifically polysaccharides, are the focus of this review, as they have been reported to better sustain the vitality of the live cells incorporated. Specifically, the approaches used for fabricating hydrogel-based devices with increasing dimensionality (D)-namely, 0D (i.e., particles), 1D (i.e., fibers), 2D (i.e., fiber meshes), and 3D (i.e., scaffolds)-endowed with probiotics, were detailed by describing their advantages and challenges, along with a future overlook in the field. Electrospinning, electrospray, and 3D bioprinting were investigated as new biofabrication methods for probiotic encapsulation within multidimensional matrices. Finally, examples of biomaterial-based systems for cell and possibly post-biotic release were reported.

A comprehensive review on the utilization of biopolymer hydrogels to encapsulate and protect probiotics in foods

Probiotics must survive in foods and passage through the human mouth, stomach, and small intestine to reach the colon in a viable state and exhibit their beneficial health effects. Probiotic viability can be improved by encapsulating them inside hydrogel-based delivery systems. These systems typically comprise a 3D network of cross-linked polymers that retain large amounts of water within their pores. This study discussed the stability of probiotics and morphology of hydrogel beads after encapsulation, encapsulation efficiency, utilization of natural polymers, and encapsulation mechanisms. Examples of the application of these hydrogel-based delivery systems are then given. These studies show that encapsulation of probiotics in hydrogels can improve their viability, provide favorable conditions in the food matrix, and control their release for efficient colonization in the large intestine. Finally, we highlight areas where future research is required, such as the large-scale production of encapsulated probiotics and the in vivo testing of their efficacy using animal and human studies.

Alginate biopolymeric structures: Versatile carriers for bioactive compounds in functional foods and nutraceutical formulations: A review

Alginate-based biopolymer products have gained attention for protecting and delivering bioactive components in nutraceuticals and functional foods. These naturally abundant anionic, unbranched, and linear copolymers are also produced commercially by microorganisms. Alone or in combination with other copolymers, they efficiently transport bioactive molecules in food and nutraceutical products. This review aims to provide an in-depth understanding of alginate-based products and structures, emphasizing their role in delivering functional molecules in various formulations and delivery systems. These include edible coatings/films, gels/emulsions, beads/droplets, microspheres/particles, and engineered nanostructures where alginates have been used potentially. By exploring these applications, readers gain insights into the benefits of these products. Because, alginate-based biopolymer products have shown promise in delivering bioactive compounds like vitamin C, vitamin D3, curcumin, β-carotene, resveratrol, folic acid, gliadins, caffeic acid, betanin, limonoids, quercetin, several polyphenols and essential oils, etc., which are chief contributors to treating specific/overall nutritional and chronic metabolic disorders. So, this review summarizes the potential of alginate-based structures/products in various forms for delivering a wide range of functional food ingredients and nutraceutical components that offer promising perspectives for future investigations.

Fabrication and Characterization of PVA-WPI Based Nanofiber Mats for Improved Viability of Lactobacillus rhamnosus GG

In the current study, whey protein-based nanofibers were fabricated to encapsulate Lactobacillus rhamnosus. Purposely, different ratios of PVA (polyvinyl alcohol) and WPI (whey protein isolate) were blended to fabricate nanofibers. Nanofiber mats were characterized in terms of particle size, diameter, tensile strength, elongation at break, and loading efficiency. Morphological and molecular characterizations were carried out using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). Moreover, in vitro viability under simulated gastrointestinal (GI) conditions and thermal stability were also assessed. The results reveal that by increasing the PVA concentration, the conductivity increased while the viscosity decreased. SEM micrographs showed that probiotics were successfully loaded within the nanofiber. The FTIR spectra show strong bonding between the encapsulating materials with the addition of probiotics. In vitro and thermal analyses revealed that the survival of encapsulated probiotics significantly (p < 0.05) improved. In a nutshell, PVA-WPI composite nanofibers have promising potential when used to enhance the viability and stability of probiotics under adverse conditions.

A novel material for the microbiological, oxidative, and color stability of salmon and chicken meat samples: Nanofibers obtained from sesame oil

Sesame oil nanofibers (diameter min: 286 max: 656nm), starting thermal degradation at 60 °C, were successfully obtained using the electrospinning technique in Türkiye. The distance, high voltage, and flow rate in electrospinning parameters were defined as 10 cm, 25 kV, and 0.065 mL/min. Mesophilic, psychrophilic bacteria, and yeast & molds counts of control group samples were higher (up to 1.21 log CFU/g) than those of salmon and chicken meat samples treated with sesame oil nanofibers. Thiobarbituric acid (TBA) value in control salmon meat samples stored for 8 days was defined between 0.56 and 1.48 MDA/kg (increase: 146%). However, the rise in TBA for salmon samples treated with sesame oil nanofibers was 21%. Also, nanofiber application for chicken samples limited the rapid oxidation up to 51.51% compared to control samples on the 8th day (p < 0.05). b* value (decline: 15.23 %) associated with rapid oxidation of the control group in salmon samples was more rapidly decreased than that of fish samples treated with sesame-nanofibers (b*: 12.01%) (p < 0.05). Chicken fillets b* values were more stable compared to control chicken meat samples for 8 days. Sesame oil-nanofiber application did not adversely affect the L* value color stability of all meat samples.

Biomaterials and Encapsulation Techniques for Probiotics: Current Status and Future Prospects in Biomedical Applications

Probiotics have garnered significant attention in recent years due to their potential advantages in diverse biomedical applications, such as acting as antimicrobial agents, aiding in tissue repair, and treating diseases. These live bacteria must exist in appropriate quantities and precise locations to exert beneficial effects. However, their viability and activity can be significantly impacted by the surrounding tissue, posing a challenge to maintain their stability in the target location for an extended duration. To counter this, researchers have formulated various strategies that enhance the activity and stability of probiotics by encapsulating them within biomaterials. This approach enables site-specific release, overcoming technical impediments encountered during the processing and application of probiotics. A range of materials can be utilized for encapsulating probiotics, and several methods can be employed for this encapsulation process. This article reviews the recent advancements in probiotics encapsulated within biomaterials, examining the materials, methods, and effects of encapsulation. It also provides an overview of the hurdles faced by currently available biomaterial-based probiotic capsules and suggests potential future research directions in this field. Despite the progress achieved to date, numerous challenges persist, such as the necessity for developing efficient, reproducible encapsulation methods that maintain the viability and activity of probiotics. Furthermore, there is a need to design more robust and targeted delivery vehicles.

Enhanced viability of probiotics encapsulated within synthetic/natural biopolymers by the addition of gum arabic via electrohydrodynamic processing

To enhance the probiotics' viability, novel vehicles consisting of synthetic/natural biopolymers, i.e., polyvinyl alcohol (PVOH), polyvinylpyrrolidone, whey protein concentrate and maltodextrin, encapsulated with L. plantarum KLDS 1.0328 and gum arabic (GA) as a prebiotic were fabricated by electrohydrodynamic techniques. Inclusion of cells into composites caused an increase in conductivity and viscosity. Morphological analysis showed that cells were distributed along the electrospun nanofibres or distributed randomly in the electrosprayed microcapsules. Both intramolecular and intermolecular hydrogen bond interactions exist between biopolymers and cells. Thermal analysis revealed that the degradation temperatures (>300 °C) of various encapsulation systems have potential applications in heat-treatment foods. Additionally, cells especially immobilized in PVOH/GA electrospun nanofibres showed the highest viability compared with free cells after exposure to simulated gastrointestinal stress. Furthermore, cells retained their antimicrobial ability after rehydration of the composite matrices. Therefore, electrohydrodynamic techniques have great potential in encapsulating probiotics.

Nanocoating of lactic acid bacteria: properties, protection mechanisms, and future trends

Lactic acid bacteria (LAB) is a type of probiotic that may benefit intestinal health. Recent advances in nanoencapsulation provide an effective strategy to protect them from harsh conditions via surface functionalization coating techniques. Herein, the categories and features of applicable encapsulation methods are compared to highlight the significant role of nanoencapsulation. Commonly used food-grade biopolymers (polysaccharides and protein) and nanomaterials (nanocellulose and starch nanoparticles) are summarized along with their characteristics and advances to demonstrate enhanced combination effects in LAB co-encapsulation. Nanocoating for LAB provides an integrity dense or smooth layer attributed to the cross-linking and assembly of the protectant. The synergism of multiple chemical forces allows for the formation of subtle coatings, including electrostatic attractions, hydrophobic interactions, π-π, and metallic bonds. Multilayer shells have stable physical transition properties that could increase the space between the probiotic cells and the outer environment, thus delaying the microcapsules burst time in the gut. Probiotic delivery stability can be promoted by enhancing the thickness of the encapsulated layer and nanoparticle binding. Maintenance of benefits and minimization of nanotoxicity are desirable, and green synthesized nanoparticles are emerging. Future trends include optimized formulation, especially using biocompatible materials, protein or plant-based materials, and material modification.

Fabrication of whey protein/pectin double layer microcapsules for improving survival of Lacticaseibacillus rhamnosus ZFM231

To improve the viability of Lacticaseibacillus rhamnosus ZFM231 strain in the gastrointestinal tract and exhibit better probiotic effect, an internal emulsification/gelation technique was employed to encapsulate this strain using whey protein and pectin as wall materials to fabricate the double layer microcapsules. Four key factors affecting the encapsulation process were optimized using single factor analysis and response surface methodology. Encapsulation efficiency of L. rhamnosus ZFM231 reached 89.46 ± 0.82 %, the microcapsules possessed a particle size of 172 ± 1.80 μm and ζ-potential of -18.36 mV. The characters of the microcapsules were assessed using optical microscope, SEM, FT-IR and XRD analysis. It was found that after exposure to simulated gastric fluid, the bacterial count (log (CFU g^-1)) of the microcapsules only lost 1.96 units, the bacteria were released readily in simulated intestinal fluid, reaching 86.56 % after 90 min. After stored at 4 °C for 28 days and 25 °C for 14 days, bacterial count of the dry microcapsules decreased from 10.59 to 9.02 and 10.49 to 8.70 log (CFU g^-1), respectively. The double layered microcapsules could significantly increase the storage and thermal abilities of bacteria. Such L. rhamnosus ZFM231 microcapsules could find applications as ingredient of the functional foods and the dairy products.

Electrospinning and Electrospraying: Emerging Techniques for Probiotic Stabilization and Application

Probiotics are beneficial for human health. However, they are vulnerable to adverse effects during processing, storage, and passage through the gastrointestinal tract, thus reducing their viability. The exploration of strategies for probiotic stabilization is essential for application and function. Electrospinning and electrospraying, two electrohydrodynamic techniques with simple, mild, and versatile characteristics, have recently attracted increased interest for encapsulating and immobilizing probiotics to improve their survivability under harsh conditions and promoting high-viability delivery in the gastrointestinal tract. This review begins with a more detailed classification of electrospinning and electrospraying, especially dry electrospraying and wet electrospraying. The feasibility of electrospinning and electrospraying in the construction of probiotic carriers, as well as the efficacy of various formulations on the stabilization and colonic delivery of probiotics, are then discussed. Meanwhile, the current application of electrospun and electrosprayed probiotic formulations is introduced. Finally, the existing limitations and future opportunities for electrohydrodynamic techniques in probiotic stabilization are proposed and analyzed. This work comprehensively explains how electrospinning and electrospraying are used to stabilize probiotics, which may aid in their development in probiotic therapy and nutrition.

Polysaccharides, proteins, and their complex as microencapsulation carriers for delivery of probiotics: A review on carrier types and encapsulation techniques

Probiotics provide several benefits for humans, including restoring the balance of gut bacteria, boosting the immune system, and aiding in the management of certain conditions such as irritable bowel syndrome and lactose intolerance. However, the viability of probiotics may undergo a significant reduction during food storage and gastrointestinal transit, potentially hindering the realization of their health benefits. Microencapsulation techniques have been recognized as an effective way to improve the stability of probiotics during processing and storage and allow for their localization and slow release in intestine. Although, numerous techniques have been employed for the encapsulation of probiotics, the encapsulation techniques itself and carrier types are the main factors affecting the encapsulate effect. This work summarizes the applications of commonly used polysaccharides (alginate, starch, and chitosan), proteins (whey protein isolate, soy protein isolate, and zein) and its complex as the probiotics encapsulation materials; evaluates the evolutions in microencapsulation technologies and coating materials for probiotics, discusses their benefits and limitations, and provides directions for future research to improve targeted release of beneficial additives as well as microencapsulation techniques. This study provides a comprehensive reference for current knowledge pertaining to microencapsulation in probiotics processing and suggestions for best practices gleaned from the literature.

Encapsulation of Lactobacillus plantarum ELB90 by electrospraying in a double emulsion (W1/O/W2) loaded alginate beads to improve the gastrointestinal survival and thermal stability

BACKGROUND

In the present study, the Lactobacillus plantarum ELB90 was encapsulated in double emulsion (W1/O/W2) loaded alginate beads (emulbeads) by electrospraying and compared with emulsion-free control beads. The viability of encapsulated and free cells was assessed by exposing them to thermal processing (65 °C for 30 min and 72 °C for 3 min) and simulated gastrointestinal conditions. The beads were characterized by optical, scanning electron, fluorescence, and confocal laser scanning microscopy, as well as Fourier transform infrared and gel strength analysis.

RESULTS

After the intestinal stage of digestion, the survival rate of free bacteria was 38% [3.70 log colony-forming units (CFU) g^-1 ], only increased to 43% and 53% for bare and chitosan-coated control beads, and it elevated the survival rate to 75% and 84% (8.70 log CFU g^-1 ) for bare and chitosan-coated emulbeads, respectively. The presence of inulin increased gastrointestinal viability only in uncoated emulbeads. The bacteria loaded in emulbeads retained greater viability (5.90-6.90 log CFU g^-1 ) against thermal treatment, compared to control beads (2.07-4.10 log CFU g^-1 ) and free bacteria (2.57-3.11 log CFU mL^-1 ). Encapsulation of L. plantarum ELB90 only in emulsion-free beads may not be appropriate for providing thermal stability. Inulin addition and chitosan-coating of the beads increased the size, and emulbeads presented smoother surfaces compared to emulsion-free beads.

CONCLUSION

The contribution of a double emulsion into the gel matrix of electrosprayed alginate beads exhibited enhanced protection for probiotic bacteria that could be useful for the development of functional foods. © 2023 Society of Chemical Industry.

Electrospinning Living Bacteria: A Review of Applications from Agriculture to Health Care

Living bacteria are used in biotechnologies that lead to improvements in health care, agriculture, and energy. Encapsulating bacteria into flexible and modular electrospun polymer fabrics that maintain their viability will further enable their use. This review will first provide a brief overview of electrospinning before examining the impact of electrospinning parameters, such as precursor composition, applied voltage, and environment on the viability of encapsulated bacteria. Currently, the use of nanofiber scaffolds to deliver live probiotics into the gut is the most researched application space; however, several additional applications, including skin probiotics (wound bandages) and menstruation products have also been explored and will be discussed. The use of bacteria-loaded nanofibers as seed coatings that promote plant growth, for the remediation of contaminated wastewaters, and in energy-generating microbial fuel cells are also covered in this review. In summary, electrospinning is an effective method for encapsulating living microorganisms into dry polymer nanofibers. While these living composite scaffolds hold potential for use across many applications, before their use in commercial products can be realized, numerous challenges and further investigations remain.

Development of engineered probiotics with tailored functional properties and their application in food science

The potential health benefits of probiotics may not be cognized because of the substantial curtailment in their viability during food storage and passage through the gastrointestinal system. Intestinal flora composition, and resistance against pathogens are among the health benefits associated with probiotic consumption. In the gastric environment, pH 2.0, probiotics dramatically lose their viability during the transit through the gastrointestinal system. The challenge remains to maintain cell viability until it reaches the large intestine. In extreme conditions, such as a decrease in pH or an increase in temperature, encapsulation technology can enhance the viability of probiotics. Probiotic bacterial strains can be encapsulated in a variety of ways. The methods are broadly systematized into two categories, liquid and solid delivery systems. This review emphasizes the technology used in the research and commercial sectors to encapsulate probiotic cells while keeping them alive and the food matrix used to deliver these cells to consumers.

Graphical abstract

Micro-/bio-/nano-/syn-encapsulations and co-treatments of bioactive microbial feed supplementation in augmenting finfish health and aquaculture nutrition: a review

Finfish and fish products are globally the most acknowledged health-promoting foods. The rising incidence of pathogenic and disease outbreaks have had a sizeable impact on aquaculture. Microbial supplementation of food in the form of probiotics, prebiotics, and their controlled release combinations (=co-encapsulations) as 'synbiotics' is noted for its significant biotherapeutic and health benefits. Supplementation of probiotic microbial feed additives in the fish diet claims to improve fish health by modulation of resident intestinal microbiota and by introducing healthy microbiota procured from an exogenous source, capable of combating pathogens, improving nutrient uptake, assimilation, growth as well as survival. Prebiotics are selectively digestible substrates beneficially used by host gut microbes to enhance probiotic effects. Formulating a fish diet with augmented probiotics and prebiotic microbial bio-supplements can ensure a sustainable alternative for establishing fish health in a naturally susceptible aquaculture scenario. Micro-encapsulation, co-encapsulation, and nano-encapsulation are novel strategies of biotechnical interventions in functional feeds for finfish. These aim to improve probiotic persistence, survivability, and efficacy in commercial formulations during probiotic transit through the host-gut environment. This review discusses the importance of co-treatment and encapsulation strategies for improving probiotic and prebiotic potential in aquafeed formulations, reliably improving finfish health and nutritional returns from aquaculture, and, consequently, for consumers.

Fabrication of electrospun gum Arabic-polyvinyl alcohol blend nanofibers for improved viability of the probiotic

In the current study, the probiotic (Lactobacillus acidophilus) was encapsulated using Gum Arabic and polyvinyl alcohol blended nanofibers by electrospinning. Obtained nanofibers were characterized in terms of particle size, diameter, mechanical strength, and encapsulation efficiency. The molecular and internal structure characterization was carried out using Fourier transform infrared spectroscopy and X-ray diffraction respectively. Thermo Gravimetric (TGA) analysis was conducted to determine the thermal features of PVA/GA/probiotics nanofibers. Free and encapsulated probiotics were also subjected to in vitro assay under different detrimental conditions. Images obtained using SEM indicated that probiotics were successfully encapsulated in blends by a nano-spider. FTIR and XRD spectra showed bonding interactions between the wall and core materials. In-vitro assay indicated that probiotics with encapsulated showed significantly (P < 0.05) viability compared to free cells. Free cells lost their viability under simulated gastrointestinal conditions while encapsulated cells retained viability count above the therapeutic number (107 cfu).

The encapsulation strategy to improve the survival of probiotics for food application: From rough multicellular to single-cell surface engineering and microbial mediation

The application of probiotics is limited by the loss of survival due to food processing, storage, and gastrointestinal tract. Encapsulation is a key technology for overcoming these challenges. The review focuses on the latest progress in probiotic encapsulation since 2020, especially precision engineering on microbial surfaces and microbial-mediated role. Currently, the encapsulation materials include polysaccharides and proteins, followed by lipids, which is a traditional mainstream trend, while novel plant extracts and polyphenols are on the rise. Other natural materials and processing by-products are also involved. The encapsulation types are divided into rough multicellular encapsulation, precise single-cell encapsulation, and microbial-mediated encapsulation. Recent emerging techniques include cryomilling, 3D printing, spray-drying with a three-fluid coaxial nozzle, and microfluidic. Encapsulated probiotics applied in food is an upward trend in which "classic probiotic foods" (yogurt, cheese, butter, chocolate, etc.) are dominated, supplemented by "novel probiotic foods" (tea, peanut butter, and various dry-based foods). Future efforts mainly include the effect of novel encapsulation materials on probiotics in the gut, encapsulation strategy oriented by microbial enthusiasm and precise encapsulation, development of novel techniques that consider both cost and efficiency, and co-encapsulation of multiple strains. In conclusion, encapsulation provides a strong impetus for the food application of probiotics.

Characteristics of Probiotic Preparations and Their Applications

The probiotics market is one of the fastest growing segments of the food industry as there is growing scientific evidence of the positive health effects of probiotics on consumers. Currently, there are various forms of probiotic products and they can be categorized according to dosage form and the site of action. To increase the effectiveness of probiotic preparations, they need to be specifically designed so they can target different sites, such as the oral, upper respiratory or gastrointestinal tracts. Here we review the characteristics of different dosage forms of probiotics and discuss methods to improve their bioavailability in detail, in the hope that this article will provide a reference for the development of probiotic products.

Alginate-based nanocarriers for the delivery and controlled-release of bioactive compounds

Alginate-based nanocarriers are propitious vehicles used for the delivery of bioactive compounds (bioactives). In this area, calcium alginate and sodium alginate are the most promising wall materials because they are nontoxic, comparatively cheap, simple in production, biocompatible and biodegradable. In this review, we have highlighted different alginate-based nanocarriers such as nanoparticles, nanofibers, nanoemulsions, nanocomplexes, and nanohydrogels; also entrapment of different bioactives within alginate nanocarriers and their bioavailability in the gastric environment has been comprehensively discussed. Being biopolymers, alginates can be exploited as emulsifiers/ encapsulants for entrapment and delivery of different bioactives such as vitamins, minerals, essential fatty acids, peptides, essential oils, bioactive oils, polyphenols and carotenoids. Furthermore, the use of alginate-based nanocarriers in combination with other polysaccharides/ emulsifiers was recognized as the most effective and favorable approach for the protection, delivery and sustained release of bioactives.

Novel nano-encapsulated probiotic agents: Encapsulate materials, delivery, and encapsulation systems

Gut microbes are closely associated with most human health. When ingested orally, probiotics can effectively regulate the composition and quantity of human intestinal microorganisms, which is beneficial to human health. However, probiotics will be affected by the harsh environment of the digestive tract during the in vivo transportation process, and ensuring the viability of probiotics is a great challenge. Probiotic encapsulating technology provides an effective solution to this problem. The introduction of extreme temperatures, large probiotic microcapsule sizes and the difficulty in controlling probiotic microcapsule particle sizes mean that traditional microcapsule encapsulation methods have some limitations. From traditional microcapsule technology to the bulk encapsulation of probiotics with nanofibers and nanoparticles to the recent ability to wear nano "armor" for a single probiotic through biofilm, biological membrane and nanocoating. Emerging probiotic nanoagents provides a new conceptual and development direction for the field of probiotic encapsulation. In this review, we presented the characteristics of encapsulated probiotic carrier materials and digestive tract transport systems, we focused on the encapsulation systems of probiotic nanoagents, we analyzed the shortcomings and advantages of the current agent encapsulation systems, and we stated the developmental direction and challenges for these agents for the future.

Microencapsulating Alginate-Based Polymers for Probiotics Delivery Systems and Their Application

Probiotics exhibit many health benefits and a great potential for broad applications in pharmaceutical fields, such as prevention and treatment of gastrointestinal tract diseases (irritable bowel syndrome), prevention and therapy of allergies, certain anticancer effects, and immunomodulation. However, their applications are limited by the low viability and metabolic activity of the probiotics during processing, storage, and delivery in the digestive tract. To overcome the mentioned limitations, probiotic delivery systems have attracted much attention. This review focuses on alginate as a preferred polymer and presents recent advances in alginate-based polymers for probiotic delivery systems. We highlight several alginate-based delivery systems containing various types of probiotics and the physical and chemical modifications with chitosan, cellulose, starch, protein, fish gel, and many other materials to enhance their performance, of which the viability and protective mechanisms are discussed. Withal, various challenges in alginate-based polymers for probiotics delivery systems are traced out, and future directions, specifically on the use of nanomaterials as well as prebiotics, are delineated to further facilitate subsequent researchers in selecting more favorable materials and technology for probiotic delivery.

Encapsulation of Lacticaseibacillus rhamnosus GG: Probiotic Survival, In Vitro Digestion and Viability in Apple Juice and Yogurt

This study was aimed to prepare and characterize capsules loaded with Lacticaseibacillus rhamnosus GG (LGG), evaluating cell viability under gastrointestinal in vitro conditions and during storage in yogurt and apple juice, an alternative to traditional probiotic foods for people who are lactose intolerant. The capsules were prepared by ionic gelation, with an emulsification process as pretreatment. Cell viability of encapsulated LGG was evaluated after two different homogenization processes: magnetic stirring (AM) and Ultraturrax® homogenizer (UT). The system with the best relationship between viability and morphology was UT, which produced a viability of 85.80%. During in vitro evaluation, the capsules provided higher protection than free cells, up to 100% of cell viability. The morphology of capsules of both systems displayed a continuous and homogeneous surface. The cell viability of the encapsulated probiotics added in apple juice stored for 22 days at 4 °C was 86.16% for AM and 100% for UT, while the viability of free cells was 80.50%. In natural yogurt, the cell viability of the probiotics encapsulated stored 30 days at 4 °C was 100% for AM, 100% for UT, and 92.68% for free cells. This study suggests an alternative to preserve probiotic bacteria in a potential functional food.

Microencapsulation of Lactobacillus plantarum by spray drying: Protective effects during simulated food processing, gastrointestinal conditions, and in kefir

Probiotics are incorporated into food products because of numerous favorable effects on human health. The viability of probiotics is often affected by unfavorable interference during processing. The encapsulation can provide protection to probiotics during mechanical processing, storage, and gastrointestinal digestion. This study aimed to evaluate the protective effect of whey protein isolate (WPI) and dextran (DX) conjugates for Lactobacillus plantarum. The WPI-DX conjugate was prepared by Maillard-based glycation and confirmed by gel electrophoresis. Extending the heating time from 1 to 5 h decreased the content of tryptophan residues and increased the amide I and amide II bands. The enhanced protective ability of Maillard reaction products (MRPs) for L. plantarum was observed under conditions of stress (pH, heat, and salt) and in vitro digestion. In situ viability tests showed that encapsulation improved the survival of bacteria in kefir during 15 days of storage at 4 °C. Overall, our results provide valuable information for the development of functional probiotic food products.

Emerging Technologies and Coating Materials for Improved Probiotication in Food Products: a Review

From the past few decades, consumers' demand for probiotic-based functional and healthy food products is rising exponentially. Encapsulation is an emerging field to protect probiotics from unfavorable conditions and to deliver probiotics at the target place while maintaining the controlled release in the colon. Probiotics have been encapsulated for decades using different encapsulation methods to maintain their viability during processing, storage, and digestion and to give health benefits. This review focuses on novel microencapsulation techniques of probiotic bacteria including vacuum drying, microwave drying, spray freeze drying, fluidized bed drying, impinging aerosol technology, hybridization system, ultrasonication with their recent advancement, and characteristics of the commonly used polymers have been briefly discussed. Other than novel techniques, characterization of microcapsules along with their mechanism of release and stability have shown great interest recently in developing novel functional food products with synergetic effects, especially in COVID-19 outbreak. A thorough discussion of novel processing technologies and applications in food products with the incorporation of recent research works is the novelty and highlight of this review paper.

Latest developments in food-grade delivery systems for probiotics: A systematic review

Tremendous progress in the inseparable relationships between probiotics and human health has enabled advances in probiotic functional foods. To ensure the vitality of sensitive probiotics against multiple harsh conditions, rising food-grade delivery systems for probiotics have been developed. This review gives a summary of recently reported delivery vehicles for probiotics, analyzes their respective merits and drawbacks and makes comparisons among them. Subsequently, the applications and future prospects are discussed. According to the types of encapsulating probiotics, food-grade delivery systems for probiotics can be classified into "silkworm cocoons" and "spider webs", which are put forward in this paper. The former, which surrounds the inner probiotics with the outer protective layers, includes particles, emulsions, beads, hybrid electrospun nanofibers and microcapsules. While hydrogels and bigels belong to the latter, which protects probiotics with the aid of network structures. The future prospects include preferable viability and stability of probiotics, co-delivery systems, targeted gut release of probiotics, delivery of multiple strains, more scientific experimental verification and more diversified food products, which will enlighten further studies on delivering probiotics for human health. Taken together, delivery vehicles for probiotics are-or will soon be-in the field of food science, with further applications under development.

Decorating Bacteria with a Therapeutic Nanocoating for Synergistically Enhanced Biotherapy

Disorders in the gut microbiota have been implicated in various diseases, such as inflammatory bowel diseases, diabetes, and cancers. Oral microecologics are of great importance due to their ability to directly intervene the gut microbiome as well as their noninvasiveness and low side effects, while have suffered from low bioavailability and a single therapeutic effect. Here, probiotics are coated with a therapeutic nanocoating for synergistically enhanced biotherapy, a method inspired by the robust protective and therapeutic effectiveness of silkworm cocoon. With its transition from a random coil to β-sheet conformation, silk fibroin can self-assemble onto the surface of bacteria. By a simple layer-by-layer procedure, an entire nanocoating can be formed along with a near quantitative coating ratio and almost uninfluenced bacterial viability. Thanks to its protective barrier role and innate pharmaceutical activity, silk fibroin nanocoating endows the coated bacteria with a markedly improved survival against gastric insults and a synergistically enhanced therapeutic effect in a murine model of intestinal mucositis. This work demonstrates how therapeutic elements can be combined with probiotics via a simple coating strategy and proposes an alternative to enhance bioavailability and treatment efficacy of oral microecologics.