Effect of Alginate-Microencapsulated Hydrogels on the Survival of Lactobacillus rhamnosus under Simulated Gastrointestinal Conditions

Enhancing cell viability and GABA production in fermented milk using fruit juice-coated alginate microencapsulated Lactiplantibacillus plantarum B7 during storage

Gamma-aminobutyric acid (GABA) is a non-protein amino acid with diverse health benefits, prompting interest in its incorporation into functional foods. In vitro probiotic characterization of Lactiplantibacillus plantarum B7, selected for its superior GABA production in a previous study, was performed before studying its microencapsulation using alginate coated with apple and pear juices to enhance cell viability and stability during storage in fermented milk. Both apple and pear juice-coated alginate microcapsules (AL-A + B7 and AL-P + B7) showed superior encapsulation, GIT condition tolerance, and release efficiency compared to alginate-only microcapsules. In comparison, free-cell L. plantarum B7 exhibited higher GABA production (2.59 ± 0.03 g/L), cell growth (8.96 ± 0.02 log CFU/mL), and the lowest pH (5.27 ± 0.06) at 48 h of fermentation. Among microencapsulated samples, AL-A + B7 showed the highest cell growth (8.93 ± 0.05 log CFU/g), GABA production (2.45 ± 0.05 g/L), and a lower pH (5.32 ± 0.06). During storage, AL-A + B7 retained higher viable cell counts (8.34 ± 0.13 log CFU/g) and improved GABA levels (3.90 ± 0.25 g/L) after 28 days, while free-cell samples showed a significant decline in cell count (from 8.96 ± 0.05 to 5.51 ± 0.13 log CFU/mL) and no significant improvement in GABA. These results highlight that apple juice-coated alginate (AL-A + B7) enhances the stability and viability of L. plantarum B7 during storage, while also promoting GABA production under storage conditions. These findings suggest its potential application in the development of functional foods with possible health benefits.

Influence of the addition of gum arabic and xanthan gum in the preparation of sodium alginate microcapsules coated with chitosan hydrochloride on the survival of Lacticaseibacillus rhamnosus GG

The microencapsulation of Lactocaseibacillus rhamnosus GG in a matrix of sodium alginate, xanthan gum, gum arabic and chitosan hydrochloride is a promising strategy for protecting this probiotic during passage through the gastrointestinal tract. This study evaluated the influence on the viability of Lactocaseibacillus rhamnosus GG encapsulated with these polymers by external ionic gelation with vibratory extrusion and the microcapsules that showed the best results of capsulation efficiency, viability, size and morphology were analyzed by Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA) and exposure to environmental stress conditions and gastrointestinal simulation. The result revealed encapsulation efficiency values above 95 % for all formulations and survival rate higher than 6 log CFU/mL for most analyzed groups. The lowest viability values after storage at 7 °C were presented by formulations prepared with Arabic Gum and Xanthan, as well as the largest sizes, expansion index, and physical integrity loss of the microcapsules. Sodium alginate microcapsules coated with chitosan hydrochloride demonstrated enhanced viability during storage at 7 °C and 25 °C, alongside superior cell survival rates under environmental stress conditions and simulated gastrointestinal environments indicating that sodium alginate-chitosan hydrochloride microparticles are expected to become an ideal carrier for the actives encapsulation in pharmaceutical and food and industries.

Construction, characterization, and properties of a probiotic delivery system based on oxidized high amylose starch

This study demonstrates the preparation of oxidized high amylose starch (OHAS) and its effect on the survival and release of Lacticaseibacillus rhamnosus GG (LGG) in the gastrointestinal tract when combined with sodium alginate (SA). OHAS with different degrees of oxidation was combined with SA, and through rheological analysis, an SA/OHAS composite with good viscoelasticity, stable structure, and favorable for probiotic colonization was selected as the probiotic carrier. Specifically, SA/OHAS showed a good encapsulation efficiency of 46.21 % and maintained good viability after gastric juice digestion, with a surviving probiotic count of 5.87 × 106 CFU/mL. It exhibits good release efficiency in intestinal fluid, with a release rate reaching 85.67 % within 2 h. In vivo intestinal transit visualization evaluation after feeding mice showed that SA/OHAS could effectively prolong the retention time of probiotics in the intestine. In vitro experiments further proved that SA/OHAS could significantly enhance the resistance of probiotics in gastric juice and provide a targeted release for intestine-specific delivery. These results provide a promising strategy for the delivery system of SA/OHAS encapsulated probiotics in oral food applications.

Advances in the preparation, applications, challenges, and future trends of polysaccharide-based gels as food-grade delivery systems for probiotics: A review

Probiotics are highly regarded for their multiple functions, such as regulating gut health, enhancing the immune system, and preventing chronic diseases. However, their stability in harsh environments and targeted release remain significant challenges. Therefore, exploring effective protection and delivery strategies to ensure targeted release of probiotics is critically important. Polysaccharides, known for their non-toxicity, excellent biocompatibility, and superior biodegradability, show broad prospects in probiotic delivery by forming physical barriers to protect the probiotics. Particularly, polysaccharide-based gels (PBGs), with their unique "spider-web" like structure, capture and ensure the targeted release of probiotics, significantly enhancing their efficacy. This review discusses common polysaccharides used in PBG preparation, their classification and synthesis in food applications, and the advantages of PBGs as probiotic delivery systems. Despite their potential, challenges such as inconsistent gel properties and the need for improved stability remain. Future research should focus on developing novel PBG materials with higher biodegradability and mechanical strength, optimizing the physicochemical properties and cross-linking methods, as well as designing multilayered structures for more precise release control. Additionally, exploring the co-delivery of probiotics with prebiotics, active ingredients, or multi-strain systems could further enhance the efficacy of probiotic delivery.

Debranched Lentil Starch-Sodium Alginate-Based Encapsulated Particles of Lacticaseibacillus rhamnosus GG: Morphology, Structural Characterization, In Vitro Release Behavior, and Storage Stability

Starches with different degrees of debranching (DBS30, DBS60, and DBS90) and sodium alginate were used as the wall material for encapsulating particles of Lacticaseibacillus rhamnosus GG (LGG). The structural characteristics of these encapsulated particles were examined, along with the impact of varying levels of debranching on the encapsulation efficiency, the in vitro release of LGG under the simulated gastrointestinal environment, and the storage stability of the encapsulated particles. The results revealed a transformation in the crystalline polymorph from C- to B+V-type following debranching and retrogradation. This process also resulted in a significant decrease in molecular weight and polydispersity index, accompanied by an increase in amylose and resistant starch levels along with the relative crystallinity of the debranched lentil starch. Comparatively, DBS60-LGG and DBS90-LGG exhibited higher encapsulation efficiency and encapsulation yield than UDBS-LGG and DBS30-LGG. Furthermore, these encapsulated particles provided enhanced protection for LGG in both the simulated gastrointestinal environment and the storage process. It can be inferred that a superior encapsulation performance of the debranched lentil starch-sodium alginate-based encapsulated LGG particles was associated with higher debranching levels, a more uniform molecular weight distribution, and a more ordered multi-scale structure of the debranched lentil starch.

Stability of probiotics through encapsulation: Comparative analysis of current methods and solutions

Probiotics have awakened a great interest in the scientific community for their potential beneficial effects on health. Although only allowed by the European Food Safety Agency as a nutrition declaration associated with the improvement of lactose digestion, recent in vitro and in vivo studies have demonstrated their varied beneficial effect for the improvement of certain pathologies. However, probiotics face stability and viability challenges, which make their delivery difficult in sufficient quantities for these effects to be observed. Thus, there is a dire need for the development and implantation of innovative technological protection procedures. In this sense, encapsulation rises as a widely applied technique, offering additional advantages. In the present study, a systematic review was conducted for the evaluation of the main encapsulation technologies applied in literature, considering operating conditions, probiotics, and encapsulation efficacy. For this purpose, several conditions are evaluated: a) the characteristics, storage conditions and viability of probiotics; b) evaluation and comparison of the probiotic stabilization for the main encapsulation methods; and c) co-encapsulation with potential bioactive molecules as a new alternative for improving cell viability. This evaluation revealed the efficacy of seven encapsulation techniques on the improvement of the stability and viability of probiotics.

Microencapsulation of Lactobacillus reuteri by Emulsion Technique and Evaluation of Microparticle Properties and Bacterial Viability Under Storage, Processing, and Digestive System Conditions

In this research, the emulsification method was used to encapsulate Lactobacillus reuteri in microparticles of whey protein concentrate (WPC) at different levels (1%, 2%, and 4%) and gum Arabic (GA) at three levels (0/5%, 1%, and 1/5%) and a constant level of sunflower oil (5%). The results showed that emulsions with higher quantities of wall materials exhibited better encapsulation efficiency (67%/57%) and preservation ability at different temperatures, different pH, and presence of 1% bile salt. During the storage time, the droplet size of the emulsion increased more than two times (from 2.2 to 4.6 μm) and the absolute zeta potential of the optimal emulsion decreased (from -19/63 to -16/76 mV). Encapsulating Lactobacillus reuteri in the stabilized emulsion with the highest concentration of wall material improved the cells' protection during storage. The study also observed a decline in the number of primary encapsulated live cells in the gastrointestinal tract (from 4/32 to 3/58 Log CFU/mL) after 90 days of storage. In the case of the nonencapsulated sample, the initial live population decreased from 2.8 to 1 Log CFU/mL after 90 days of storage. The electron microscope images showed that the emulsions became unstable after 30, 60, and 90 days of storage, but the microbial cells were still visible in the continuous phase. Overall, encapsulating Lactobacillus reuteri using emulsification technique can preserve the probiotics during storage and "in vitro" gastrointestinal digestion.

Co-Encapsulation of Coffee and Coffee By-Product Extracts with Probiotic Kluyveromyces lactis

Coffee and coffee by-products contain several chemical compounds of great relevance, such as chlorogenic acid (CGA), trigonelline, and caffeine. Furthermore, yeasts have been the target of studies for their use as probiotics because of their interesting biochemical characteristics. The combined administration of probiotic microorganisms with components that provide health benefits mediated by alginate encapsulation is an alternative that ensures the stability of cells and chemical compounds. In this context, the aim of this work was to co-encapsulate the probiotic yeast Kluyveromyces lactis B10 and extracts of green coffee beans, coffee silverskin, and PVA (black, green or immature, and sour coffee beans). The bioactive composition, antioxidant and antimicrobial activities of the extracts, microcapsule morphological characteristics and encapsulation efficiency, ability of the encapsulation to protect the yeast cells subjected to gastrointestinal conditions, and antioxidant activity of the microcapsules were evaluated. All the evaluated extracts showed antioxidant activity, of which PVA showed 75.7% and 77.0%, green coffee bean showed 66.4% and 45.7%, and coffee silverskin showed 67.7% and 37.4% inhibition of DPPH and ABTS•+ radicals, respectively, and antimicrobial activity against the pathogenic bacteria E. coli, Salmonella, and S. aureus, with high activity for the PVA extract. The microcapsules presented diameters of between 1451.46 and 1581.12 μm. The encapsulation efficiencies referring to the yeast retention in the microcapsules were 98.05%, 96.51%, and 96.32% for green coffee bean, coffee silverskin, and PVA, respectively. Scanning electron microscopy (SEM) showed that the microcapsules of the three extracts presented small deformations and irregularities on the surface. The K. lactis cells encapsulated in all treatments with the extracts showed viability higher than 8.59 log CFU/mL, as recommended for probiotic food products. The addition of green coffee bean, coffee silverskin, and PVA extracts did not reduce the encapsulation efficiency of the alginate microcapsules, enabling a safe interaction between the extracts and the K. lactis cells.

Probiotic Encapsulation: Bead Design Improves Bacterial Performance during In Vitro Digestion (Part 2: Operational Conditions of Vibrational Technology)

The development of functional foods is a viable alternative for the prevention of numerous diseases. However, the food industry faces significant challenges in producing functional foods based on probiotics due to their high sensitivity to various processing and gastrointestinal tract conditions. This study aimed to evaluate the effect of the operational conditions during the extrusion encapsulation process using vibrating technology on the viability of Lactobacillus fermentum K73, a lactic acid bacterium with hypocholesterolemia probiotic potential. An optimal experimental design approach was employed to produce sweet whey-sodium alginate (SW-SA) beads with high bacterial content and good morphological characteristics. In this study, the effects of frequency, voltage, and pumping rate were optimized for a 300 μm nozzle. The microspheres were characterized using RAMAN spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy. The optimal conditions for bead production were found: 70 Hz, 250 V, and 20 mL/min with a final cell count of 8.43 Log10 (CFU/mL). The mean particle diameter was 620 ± 5.3 µm, and the experimental encapsulation yield was 94.3 ± 0.8%. The INFOGEST model was used to evaluate the survival of probiotic beads under gastrointestinal tract conditions. Upon exposure to in vitro conditions of oral, gastric, and intestinal phases, the encapsulated viability of L. fermentum was 7.6 Log10 (CFU/mL) using the optimal encapsulation parameters, which significantly improved the survival of probiotic bacteria during both the encapsulation process and under gastrointestinal conditions compared to free cells.

Physiological and Technological Properties of Probiotic Lacticaseibacillus rhamnosus GG Encapsulated with Alginate-Chitosan Mixture and Its Incorporation in Whole Milk

This study developed and evaluated chitosan-sodium alginate capsules containing the probiotic Lacticaseibacillus rhamnosus GG using extrusion and emulsification techniques. The encapsulated L. rhamnosus GG cells were also evaluated for technological and probiotic-related physiological functionalities, as well as when incorporated in UHT and powdered milk. Extrusion (86.01 ± 1.26%) and emulsification (74.43 ± 1.41%) encapsulation techniques showed high encapsulation efficiency and high survival rates of L. rhamnosus GG during 28 days of refrigeration and room temperature storage, especially emulsification capsules (> 81%). The encapsulated L. rhamnosus GG cells showed high survival rates during exposure to simulated gastrointestinal conditions (72.65 ± 1.09-114.15 ± 0.44%). L. rhamnosus GG encapsulated by extrusion and emulsification performed satisfactorily in probiotic-related physiological (pH and bile salts tolerance) and technological properties (positive proteolytic activity, diacetyl and exopolysaccharides production, high NaCl tolerance (> 91%), besides having high heat tolerance (> 76%)). L. rhamnosus GG in extrusion and emulsification capsules had high survival rates (> 89%) and did not significantly affect physicochemical parameters in Ultra-High Temperature (UHT) and powdered milk during storage. The results demonstrate that L. rhamnosus GG can be successfully encapsulated with alginate-chitosan as a protective material through extrusion and emulsification techniques. UHT and powdered milk could serve as appropriate delivery systems to increase the intake of this encapsulated probiotic by consumers.

Optimizing conditions of mycelial inoculum immobilized in Ca-alginate beads: a case study in ectomycorrhizal fungus Astraeus odoratus

Ectomycorrhizal inoculum has emerged as a critical tool for forest restoration, especially under challenging climate change conditions. The inoculation of selective ectomycorrhizal fungi can enhance seedling survival and subsequent growth in the field. This study optimized the liquid media for mycelial growth of Astraeus odoratus strain K1 and the sodium alginate solution composition for enhanced mycelial viability after entrapment. Using Modified Melin-Norkrans as the optimal media for mycelial cultivation and 2% sodium alginate supplemented with Czapek medium, 0.25% activated charcoal, 5% sucrose, and 5% sorbitol in the alginate solution yielded the highest viability of A. odoratus mycelia. Preservation in distilled water and 10% glycerol at 25 °C for 60 days proved to be the most effective storage condition for the alginate beads. Both fresh and preserved alginate beads were tested for colonizing on Hopea odorata Roxb. seedlings, showing successful colonization and ectomycorrhizal root formation, with over 49% colonization. This study fills a crucial gap in biotechnology and ectomycorrhizal inoculum, paving the way for more effective and sustainable forest restoration practices.

Advances in polysaccharides for probiotic delivery: Properties, methods, and applications

Probiotics are essential to improve the health of the host, whereas maintaining the viability of probiotics in harsh environments remains a challenge. Polysaccharides have non-toxicity, excellent biocompatibility, and outstanding biodegradability, which can protect probiotics by forming a physical barrier and show a promising prospect for probiotic delivery. In this review, we summarize polysaccharides commonly used for probiotic microencapsulation and introduce the microencapsulation technologies, including extrusion, emulsion, spray drying, freeze drying, and electrohydrodynamics. We discuss strategies for better protection of probiotics and introduce the applications of polysaccharides-encapsulated probiotics in functional food, oral formulation, and animal feed. Finally, we propose the challenges of polysaccharides-based delivery systems in industrial production and application. This review will help provide insight into the advances and challenges of polysaccharides in probiotic delivery.

Evaluation of immobilized microspheres of Clonostachys rosea on Botrytis cinerea and tomato seedlings

Tomato (Solanum lycopersicum L.) is a popular vegetable crop which is widely cultivated around the world. However, the production of tomatoes is threatened by several phytopathogenic agents, including gray mold (Botrytis cinerea Pers.). Biological control using fungal agents such as Clonostachys rosea plays a pivotal role in managing gray mold. However, these biological agents can negatively be influenced by environmental factors. However, immobilization is a promising approach to tackle this issue. In this research, we used a nontoxic chemical material, sodium alginate as a carrier to immobilize C. rosea. For this, sodium alginate microspheres were prepared using sodium alginate prior to embedding C. rosea. The results showed that C. rosea was successfully embedded in sodium alginate microspheres, and immobilization enhanced the stability of the fungi. The embedded C. rosea was able to suppress the growth of gray mold efficiently. In addition, the activity of stress related enzymes, peroxidase superoxidase dismutase and polyphenol oxidation was promoted in tomatoes treated with the embedded C. rosea. By measuring photosynthetic efficiency, it was noted that the embedded C. rosea has positive impacts on tomato plants. Taken together, these results indicate that immobilization of C. rosea improved its stability without detrimentally affecting its efficiency on gray mold suppression and tomato growth. The results of this research can be used as a basis for research and development of new immobilized biocontrol agents.

Development of probiotic loaded multilayer microcapsules incorporated into dissolving microneedles for potential improvement treatment of vulvovaginal candidiasis: A proof of concept study

Vulvovaginal candidiasis (VVC) is a vaginal infection caused by abnormal growth of Candida sp., especially Candida albicans, in the vaginal mucosa. A shift in vaginal microbiota is prominent in VVC. The presence of Lactobacillus plays a vital role in maintaining vaginal health. However, several studies have reported resistance of Candida sp. against azoles drugs, which is recommended as VVC treatment. The use of L. plantarum as a probiotic would be an alternative to treat VVC. In order to exert their therapeutic activity, the probiotics needed to remain viable. Multilayer double emulsion was formulated to obtain L. plantarum loaded microcapsules (MCs), thus improving its viability. Furthermore, a vaginal drug delivery system using dissolving microneedles (DMNs) for VVC treatment was developed for the first time. These DMNs showed sufficient mechanical and insertion properties, dissolved rapidly upon insertion, facilitating probiotic release. All formulations proved non-irritating, non-toxic, and safe to apply on the vaginal mucosa. Essentially, the DMNs could inhibit the growth of Candida albicans up to 3-fold than hydrogel and patch dosage forms in ex vivo infection model. Therefore, this study successfully developed the formulation of L. plantarum-loaded MCs with multilayer double emulsion and its combination in DMNs for vaginal delivery to treat VVC.

Microencapsulation of Probiotic Streptococcus salivarius LAB813

Probiotics are living microorganisms that confer a health benefit on the host when administered in adequate amounts. Streptococcus salivarius, a commensal bacterium found in the oral cavity, has been shown to secrete antimicrobial peptides and can be used as probiotics. This study aimed to develop a delivery system for the probiotic LAB813, a novel S. salivarius strain first identified in the laboratory. Probiotics can be delivered and protected through the encapsulation of biomaterials such as polysaccharides. Their biocompatibility, biodegradability, user-friendliness, and ease of access make polysaccharides useful for encapsulating probiotics. Alginate (Alg) and chitosan (Ch) are naturally obtained polysaccharides and, hence, tested for LAB813 encapsulation. An extrusion method of encapsulation was performed to form Alg microcapsules (Alg-LAB813), some of which were coated with Ch (Alg-LAB813-Ch) to provide dual-layered protection. Inhibitory assays of the Alg-LAB813 and Alg-LAB813-Ch microcapsules were assayed against an indicator strain. Alg-LAB813-Ch microcapsules showed superior antibacterial properties compared to Alg-LAB813 microcapsules over 24 h and when subject to temperatures ranging from 4 to 68 °C. In addition, Alg-LAB813-Ch microcapsules retained antibacterial activity for up to 28 days of storage at 4 °C. The strong and sustained inhibitory activities of Ch-coated Alg encapsulated LAB813 signify the potential for their use to improve oral health.

The Impact of Yeast Encapsulation in Wort Fermentation and Beer Flavor Profile

The food and beverage industry is constantly evolving, and consumers are increasingly searching for premium products that not only offer health benefits but a pleasant taste. A viable strategy to accomplish this is through the altering of sensory profiles through encapsulation of compounds with unique flavors. We used this approach here to examine how brewing in the presence of yeast cells encapsulated in alginate affected the sensory profile of beer wort. Initial tests were conducted for various combinations of sodium alginate and calcium chloride concentrations. Mechanical properties (i.e., breaking force and elasticity) and stability of the encapsulates were then considered to select the most reliable encapsulating formulation to conduct the corresponding alcoholic fermentations. Yeast cells were then encapsulated using 3% (w/v) alginate and 0.1 M calcium chloride as a reticulating agent. Fourteen-day fermentations with this encapsulating formulation involved a Pilsen malt-based wort and four S. cerevisiae strains, three commercially available and one locally isolated. The obtained beer was aged in an amber glass container for two weeks at 4 °C. The color, turbidity, taste, and flavor profile were measured and compared to similar commercially available products. Cell growth was monitored concurrently with fermentation, and the concentrations of ethanol, sugars, and organic acids in the samples were determined via high-performance liquid chromatography (HPLC). It was observed that encapsulation caused significant differences in the sensory profile between strains, as evidenced by marked changes in the astringency, geraniol, and capric acid aroma production. Three repeated batch experiments under the same conditions revealed that cell viability and mechanical properties decreased substantially, which might limit the reusability of encapsulates. In terms of ethanol production and substrate consumption, it was also observed that encapsulation improved the performance of the locally isolated strain.

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

Polysaccharides for Medical Technology: Properties and Applications

Over the past decade, the use of polysaccharides has gained tremendous attention in the field of medical technology. They have been applied in various sectors such as tissue engineering, drug delivery system, face mask, and bio-sensing. This review article provides an overview and background of polysaccharides for biomedical uses. Different types of polysaccharides, for example, cellulose and its derivatives, chitin and chitosan, hyaluronic acid, alginate, and pectin are presented. They are fabricated in various forms such as hydrogels, nanoparticles, membranes, and as porous mediums. Successful development and improvement of polysaccharide-based materials will effectively help users to enhance their quality of personal health, decrease cost, and eventually increase the quality of life with respect to sustainability.

Stability and Survivability of Alginate Gum-Coated Lactobacillus rhamnosus GG in Simulated Gastrointestinal Conditions and Probiotic Juice Development

Survivability of probiotics is severely affected by harsh gastrointestinal conditions. In the present study, microbeads of Lactobacillus rhamnosus GG were formulated using alginate (1.5% w/v) and combination of alginate (1.5% w/v) with xanthan gum (0.5% w/v) through an emulsion technique to improve bacterial viability in low pH orange juice and in gastrointestinal conditions. The microbeads were tested for encapsulation efficiency, survivability in bile salt, SGF (simulated gastric juice), SIF (simulated intestinal fluid), and storage stability. Probiotic orange juice was formulated and tested for physicochemical parameters (pH, titratable acidity, and total sugars) and sensorial properties during storage. Gum-coated alginate microbeads (T3) showed higher encapsulation efficiency, i.e., 95.2% compared to alginate microbeads (T2), i.e., 86.85%. Similarly, T3 showed the highest resistance against bile salt (8.50 log CFU/g), SGF (7.95 log CFU/g), and SIF (8.0 log CFU/g) during 80 min exposure compared to T2 and free cells. The viability of gum-coated alginate beads (T3) remained above 107 CFU/g in gastrointestinal conditions and at the end of 21 days storage (8.3 log CFU/mL). All physicochemical parameters of probiotic juice were significantly ( $p\le 0.05$ ) decreased with respect to storage except acidity. In addition, minimal changes in physicochemical parameters were observed in T3 compared to other treatments. Treatment had no significant impact on the sensory characteristics of juice, but storage had a significant effect ( $p\le 0.05$ ) on the sensory characteristics of juice. The alginate gum microbeads improve the survivability of probiotics for targeted delivery. Hence, encapsulated probiotics can be used for functional beverage development to take advantage of their therapeutic benefits.

Enhanced quorum sensing capacity via regulating microenvironment to facilitate stress resistance of probiotic in alginate-based microcapsules

Alginate-based microcapsule has becoming a promising carrier for probiotic encapsulation due to the improved stress resistant ability. Besides the physical protection of microcapsules, bacterial quorum sensing (QS) is another prominent factor affecting microbial stress resistance in microcapsules. In the present study, Vibrio harveyi cells were entrapped and proliferated into cell aggregates in alginate-based microcapsules. The microenvironment composed of cells and biomacromolecules was regulated by the diameter, alginate concentration and core state of microcapsule. Then the effect of microenvironment on bacterial QS capacity was investigated, including bioluminescence, autoinducers (AIs) production and QS related genes expression. The highest diameter of 1200 μm and highest alginate concentration of 2.0 % w/v under the investigation range presented strongest QS capacity, and the maintenance of hydrogel core could enhance bacterial QS. Moreover, the mechanism analysis revealed that the formed biofilm on the surface of cell aggregates hampered the outward transfer of AIs, and the local AIs inside the cell aggregates induced stronger bacteria QS by close-range interaction. As a whole, these findings are helpful to guide the technological development and optimization of microencapsulated probiotics with stronger stress resistance, and the potential application in food, dairy, wastewater treatment and biosensor.

Role of wound microbiome, strategies of microbiota delivery system and clinical management

Delayed wound healing is one of the most global public health threats affecting nearly 100 million people each year, particularly the chronic wounds. Many confounding factors such as aging, diabetic disease, medication, peripheral neuropathy, immunocompromises or arterial and venous insufficiency hyperglycaemia are considered to inhibit wound healing. Therapeutic approaches for slow wound healing include anti-infection, debridement and the use of various wound dressings. However, the current clinical outcomes are still unsatisfied. In this review, we discuss the role of skin and wound commensal microbiota in the different healing stages, including inflammation, cell proliferation, re-epithelialization and remodelling phase, followed by multiple immune cell responses to commensal microbiota. Current clinical management in treating surgical wounds and chronic wounds was also reviewed together with potential controlled delivery systems which may be utilized in the future for the topical administration of probiotics and microbiomes. This review aims to introduce advances, novel strategies, and pioneer ideas in regulating the wound microbiome and the design of controlled delivery systems.

Development and characterization of probiotic (co)encapsulates in biopolymeric matrices and evaluation of survival in a millet yogurt formulation

The formulation of probiotics-enriched products still remains a challenge for the food industry due to the loss of viability, mainly occurring upon consumption and during storage. To tackle this challenge, the current study investigated the potential of using sodium alginate and inulin (SIN) in combination with various encapsulating materials such as skim milk (SKIM), whey protein concentrate (WPC), soy protein concentrate (SPC), and flaxseed oil (FS) to increase the viability of Lactobacillus casei upon freeze-drying, under simulated gastrointestinal conditions, during 28 days of storage at 4°C, and in a formulation of millet yogurt. Microstructural properties of microcapsules and co-microcapsules by SEM, oxidative stability of flaxseed oil in co-microcapsules, and physicochemical and sensory analysis of the product were performed. The produced microcapsules (SIN-PRO-SKIM, SIN-PRO-WP, and SIN-PRO-SP) and co-microcapsules (SIN-PRO-FS-SKIM, SIN-PRO-FS-WP, and SIN-PRO-FS-SP) had a high encapsulation rate >90%. Moreover, encapsulated and co-encapsulated strains exhibited a high in vitro viability accounting for 9.24 log10 CFU/g (SIN-PRO-SKIM), 8.96 log10 CFU/g (SIN-PRO-WP), and 8.74 log10 CFU/g (SIN-PRO-SP) for encapsulated and 10.08 log10 CFU/g (SIN-PRO-FS-SKIM), 10.03 log10 CFU/g (SIN-PRO-FS-WP), and 10.14 log10 CFU/g (SIN-PRO-FS-SP) for co-encapsulated. Moreover, encapsulated and co-encapsulated cells showed higher survival upon storage than free cells. Also, the SEM analysis showed spherical particles of 77.92-230.13 µm in size. The physicochemical and sensory analysis revealed an interesting nutritional content in the millet yogurt. The results indicate that the SIN matrix has significant promise as probiotic encapsulating material as it may provide efficient cell protection while also providing considerable physicochemical and nutritional benefits in functional foods.

Hydrogel Derived from Glucomannan-Chitosan to Improve the Survival of Lactobacillus acidophilus FNCC 0051 in Simulated Gastrointestinal Fluid

The probiotic encapsulating hydrogel derived from porang (Amorphophallus oncophyllus) glucomannan and chitosan was investigated with regard to its encapsulation efficiency, physical properties, prebiotic activity, and survival under simulated gastrointestinal conditions. The hydrogel's encapsulation efficiency was improved by varying the number of the Lactobacillus acidophilus FNCC 0051, which also served to increase the diameter (2-3 mm), polydispersity index (1.23-1.65), positive zeta potential, whiteness, and brightness of the hydrogel. Moreover, the hydrogel's prebiotic activity score was higher than that of inulin after 24 h of incubation, reflecting its role as a cell encapsulant, particularly when it comes to maintaining cells during exposure to simulated gastrointestinal fluid. The cell viability increased from 86% to 100% when immersed in intestinal juice, which is comparable to the increase achieved using alginate and konjac glucomannan hydrogels. Future animal studies are required to determine the cell viability in actual gastrointestinal conditions and assess the health effects of the hydrogel.

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.

A Mild Method for Encapsulation of Citral in Monodispersed Alginate Microcapsules

Citral is a typical UV-irritation and acid-sensitive active and here we develop a mild method for the encapsulation of citral in calcium alginate microcapsules, in which UV irritation or acetic acid is avoided. Monodispersed oil-in-water-in-oil (O/W/O) emulsions are generated in a capillary microfluidic device as precursors. The middle aqueous phase of O/W/O emulsions contains sodium alginate, calcium-ethylenediaminetetraacetic acid (EDTA-Ca) complex as the calcium source, and D-(+)-Gluconic acid δ-lactone (GDL) as the acidifier. Hydrolysis of GDL will decrease the pH value of the middle aqueous solution, which will trigger the calcium ions released from the EDTA-Ca complex to cross-link with alginate molecules. After the gelling process, the O/W/O emulsions will convert to alginate microcapsules with a uniform structure and monodispersed size. The preparation conditions for alginate microcapsules are optimized, including the constituent concentration in the middle aqueous phase of O/W/O emulsions and the mixing manner of GDL with the alginate-contained aqueous solution. Citral-containing alginate microcapsules are successfully prepared by this mild method and the sustained-release characteristic of citral from alginate microcapsules is analyzed. Furthermore, a typical application of citral-containing alginate microcapsules to delay the oxidation of oil is also demonstrated. The mild gelling method provides us a chance to encapsulate sensitive hydrophobic actives with alginate, which takes many potential applications in pharmaceutical, food, and cosmetic areas.

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.