Chitosan coated alginate beads for the survival of microencapsulated Lactobacillus plantarum in pomegranate juice

Applications of chitosan in the agri-food sector: A review

Chitosan is a natural and renewable polysaccharide that can form biopolymers. It is derived from the deacetylation of chitin mainly from crustaceans' shells, but also from fungi and insects. Thanks to unique characteristics such as antimicrobial effects, antioxidant properties or film forming capacities, it has triggered an important amount of research in the last decade about possible applications in industrial fields. The main application field of chitosan is the food industry where it can be used for preservation purposes and shelf-life improvement for fresh food products such as fruits or meat. For beverages, it is used for clarification and fining as well as elimination of spoilage flora in beverages like fruit juices or wine. And in agriculture, it can be used as a plant protection product through different mechanisms like the elicitation of plant defences. The mechanisms of action of chitosan on microorganisms are multiple and complex but revolve mostly around the disturbance of microorganisms' membranes and cell walls resulting in the leakage of cell material. The use of chitosan is still minor but is promising in finding environmentally friendly alternatives to synthetic chemicals and plastics. Therefore, its characterization is primordial for the future of sustainable production and preservation processes.

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.

Improving the survival of Lactobacillus plantarum FZU3013 by phase separated caseinate/alginate gel beads

The phase separation behavior of mixed solution of caseinate (Cas) and alginate (Alg) was investigated. Lactobacillus plantarum FZU3013 was encapsulated using 4 % Cas/1 % Alg gel beads with a phase-separated structure. The bacteria were predominantly distributed in the Alg-rich continuous phase. The use of 4 % Cas/1 % Alg beads resulted in higher encapsulation efficiency for L. plantarum FZU3013 compared to 1 % Alg beads. After 5 weeks of storage at 4 °C, the viable count in 4 % Cas/1 % Alg beads was 8.3 log CFU/g, which was 1.1 log CFU/g higher than that of the 1 % Alg beads. When 1 % Alg beads of the smallest size were subjected to in vitro digestion, no viable bacteria could be detected at the end of the digestion, whereas the 4 % Cas/1 % Alg beads of the smallest size had a viable count of 3.9 log CFU/g. When the size of the 4 % Cas/1 % Alg beads was increased to 1000 μm, the viable count was 7.0 log CFU/g after digestion. The results of infrared spectroscopy and zeta potential indicated that hydrogen bonding and electrostatic interactions between caseinate and alginate reinforced the structure of the gel beads and improved the protection for L. plantarum FZU 3013.

A chitosan-coated lentinan-loaded calcium alginate hydrogel induces broad-spectrum resistance to plant viruses by activating Nicotiana benthamiana calmodulin-like (CML) protein 3

Control of plant virus diseases largely depends on the induced plant defence achieved by the external application of synthetic chemical inducers with the ability to modify defence-signalling pathways. However, most of the molecular mechanisms underlying these chemical inducers remain unknown. Here, we developed a chitosan-coated lentinan-loaded hydrogel and discovered how it protects plants from different virus infections. The hydrogel was synthesized by coating chitosan on the surface of the calcium alginate-lentinan (LNT) hydrogel (SL-gel) to form a CSL-gel. CSL-gels exhibit the capacity to prolong the stable release of lentinan and promote Ca2+ release. Application of CSL-gels on the root of plants induces broad-spectrum resistance against plant viruses (TMV, TRV, PVX and TuMV). RNA-seq analysis identified that Nicotiana benthamiana calmodulin-like protein gene 3 (NbCML3) is upregulated by the sustained release of Ca2+ from the CSL-gel, and silencing and overexpression of NbCML alter the susceptibility and resistance of tobacco to TMV. Our findings provide evidence that this novel and synthetic CSL-gel strongly inhibits the infection of plant viruses by the sustainable release of LNT and Ca2+ . This study uncovers a novel mode of action by which CSL-gels trigger NbCML3 expression through the stable and sustained release of Ca2+ .

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.

Microencapsulation of Piscirickettsia salmonis Antigens for Fish Oral Immunization: Optimization and Stability Studies

The development of fish oral vaccines is of great interest to the aquaculture industry due to the possibility of rapid vaccination of a large number of animals at reduced cost. In a previous study, we evaluated the effect of alginate-encapsulated Piscirickettsia salmonis antigens (AEPSA) incorporated in feed, effectively enhancing the immune response in Atlantic salmon (Salmo salar). In this study, we seek to characterize AEPSA produced by ionic gelation using an aerodynamically assisted jetting (AAJ) system, to optimize microencapsulation efficiency (EE%), to assess microparticle stability against environmental (pH, salinity and temperature) and gastrointestinal conditions, and to evaluate microparticle incorporation in fish feed pellets through micro-CT-scanning. The AAJ system was effective in obtaining small microparticles (d < 20 μm) with a high EE% (97.92%). Environmental conditions (pH, salinity and temperature) generated instability in the microparticles, triggering protein release. 62.42% of the protein content was delivered at the intestinal level after in vitro digestion. Finally, micro-CT-scanning images confirmed microparticle incorporation in fish feed pellets. In conclusion, the AAJ system is effective at encapsulating P. salmonis antigens in alginate with a high EE% and a size small enough to be incorporated in fish feed and produce an oral vaccine.

Probiotics encapsulated gastroprotective cross-linked microgels: Enhanced viability under stressed conditions with dried apple carrier

In the current study, Lactobacillus acidophilus was encapsulated in sodium alginate and whey protein isolate, with the addition of antacids CaCO₃ or Mg(OH)₂. The obtained microgels were observed by scanning electron microscopy. Encapsulated and free probiotics were subjected to vitality assay under stressed conditions. Furthermore, dried apple snack was evaluated as a carrier for probiotics for 28 days. A significant (p ≤ .05) effect of antacid with an encapsulating agent was observed under different stressed conditions. During exposure to simulated gastrointestinal conditions, there were observations of 1.24 log CFU and 2.17 log CFU, with corresponding 0.93 log CFU and 2.63 log CFU decrease in the case of SA + CaCO₃ and WPI + CaCO₃ respectively. Likewise, high viability was observed under thermal and refrigerated conditions for probiotics encapsulated with SA + CaCO₃. In conclusion, the results indicated that alginate microgels with CaCO₃ are effective in prolonging the viability of probiotics under stressed conditions.

Effect of water-in-oil-in-water (W/O/W) double emulsions to encapsulate nisin on the quality and storage stability of fresh noodles

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Ultrasonic and microwave treatment improved the extraction rate of rock bean protein.

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Rock bean protein has a high content of 7S and 11S globulin components.

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The prepared W/O/W microcapsules can keep the noodles fresh.

Rock-bean protein (RP) was extracted from wild rock beans by ultrasonic treatment and microwave extraction. The RP has a high content of 7S and 11S globulin components and good heat stability. Subsequently, water-oil-water double emulsions were prepared using a water core containing nisin, momordica charantia extract (MCE), and Lactobacillus plantarum as functional additives, corn oil as the intermediate wall, and RP/gum arabic (GA) as the outer wall material. For a ratio of corn oil to water of 5:1, the maximum encapsulation efficiency was 28.22%, and RP/GA had good dispersion characteristics, where the smallest average particle size was achieved for a 1:1 ratio. Finally, the microcapsules were used to study the effect of its addition to noodles. The addition of 2 wt% of the microcapsules to low-gluten flour resulted in a dough with suitable rheology, and can extend the shelf life of the fresh noodles prepared using this dough.

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

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

Recent insights into polysaccharide-based hydrogels and their potential applications in food sector: A review

Hydrogels are ideal for various food applications because of their softness, elasticity, absorbent nature, flexibility, and hygroscopic nature. Polysaccharide hydrogels are particularly suitable because of the hydrophilic nature, their food compatibility, and their non-immunogenic character. Such hydrogels offer a wide range of successful applications such as food preservation, pharmaceuticals, agriculture, and food packaging. Additionally, polysaccharide hydrogels have proven to play a significant role in the formulation of food flavor carrier systems, thus diversifying the horizons of newer developments in food processing sector. Polysaccharide hydrogels are comprised of natural polymers such as alginate, chitosan, starch, pectin and hyaluronic acid when crosslinked physically or chemically. Hydrogels with interchangeable, antimicrobial and barrier properties are referred to as smart hydrogels. This review brings together the recent and relevant polysaccharide research in these polysaccharide hydrogel applications areas and seeks to point the way forward for future research and interventions. Applications in carrying out the process of flavor carrier system directly through their incorporation in food matrices, broadening the domain for food application innovations. The classification and important features of polysaccharide-based hydrogels in food processing are the topics of the current review study.

Probiotics in anthocyanin-rich fruit beverages: research and development for novel synbiotic products

Anthocyanin-rich fruit beverages are of special interest as functional products due to their antioxidant activity, antimicrobial properties against pathogens, and, more recently, evidence of prebiotic potential. The stability and bioactivity of anthocyanins, probiotics, prebiotics, and synbiotics have been extensively documented in beverage models and reviewed separately. This review summarizes the most recent works and methodologies used for the development of probiotic and synbiotic beverages based on anthocyanin-rich fruits with a synergistic perspective. Emphasis is made on key optimization factors and strategies that have allowed probiotic cultures to reach the minimum recommended doses to obtain health benefits at the end of the shelf life. The development of these beverages is limited by the high acidity and high content of phenolic compounds in anthocyanin-rich fruits. However, a proper selection of probiotic strains and strategies for their media adaptation may improve their viability in the beverages. Fermentation increases the viability of the probiotic cultures, improves the safety and stability of the product, and may increase its antioxidant capacity. Moreover, fermentation metabolites may synergistically enhance probiotic health benefits. On the other hand, the inoculation of probiotics without fermentation allows for synbiotic beverages with milder changes in terms of physicochemical and sensory attributes.

In vitro digestion of sodium alginate/pectin co-encapsulated Lactobacillus bulgaricus and its application in yogurt bilayer beads

The purpose of this study was to prepare sodium alginate (SA)/pectin (PE) hydrogel microspheres using the extrusion method to encapsulate Lactobacillus bulgaricus. Microscopic observation showed that the beads were spherical with a smooth and uniform surface. For microspheres with a diameter range of 140-156 μm, the encapsulation efficiency reached 85.67%. After simulating saliva, gastric juice, and intestinal juice, the activity of the microcapsules was estimated to be 5.78 × 10⁴ log colony forming unit (CFU)/mL. These data show that the use of SA and PE encapsulated probiotics exhibit enhanced viability. In addition, double-layer beads containing probiotic microspheres and yogurt were prepared, and physical and chemical analysis was performed using scanning electron microscopy, Fourier-transform infrared spectroscopy, and differential scanning calorimetry. Texture and sensory property analysis revealed that the beads had good elasticity, chewiness, and high commercial value. Collectively, these findings indicate that SA and PE can be used for the encapsulation, protection, and gastrointestinal delivery of probiotics. Moreover, these microcapsules exhibit good stability in vitro and improve yogurt characteristics by increasing the survival rate of encapsulated probiotics, thus demonstrating their commercial application potential.

Encapsulation of Plant Biocontrol Bacteria with Alginate as a Main Polymer Material

One of the most favored trends in modern agriculture is biological control. However, many reports show that survival of biocontrol bacteria is poor in host plants. Providing biocontrol agents with protection by encapsulation within external coatings has therefore become a popular idea. Various techniques, including extrusion, spray drying, and emulsion, have been introduced for encapsulation of biocontrol bacteria. One commonly used biopolymer for this type of microencapsulation is alginate, a biopolymer extracted from seaweed. Recent progress has resulted in the production of alginate-based microcapsules that meet key bacterial encapsulation requirements, including biocompatibility, biodegradability, and support of long-term survival and function. However, more studies are needed regarding the effect of encapsulation on protective bacteria and their targeted release in organic crop production systems. Most importantly, the efficacy of alginate use for the encapsulation of biocontrol bacteria in pest and disease management requires further verification. Achieving a new formulation based on biodegradable polymers can have significant effects on increasing the quantity and quality of agricultural products.

Effect of whey protein- and xanthan-based coating on the viability of microencapsulated Lactobacillus acidophilus and physiochemical, textural, and sensorial properties of yogurt

The goal of this study was to investigate the viability of microencapsulated and coated Lactobacillus acidophilus in yogurt during storage in a refrigerator for 28 days and in simulated gastrointestinal conditions. Furthermore, the effect of the microencapsulated and coated L. acidophilus on the physicochemical, textural, and sensory properties of yogurt was assessed. Lactobacillus acidophilus was microencapsulated in sodium alginate and coated with xanthan and/or whey protein. The coating led to the increase in the microcapsule diameter and the microencapsulation yield, while it led to the decreased moisture and water activity (aw) of the microcapsule. The survival of L. acidophilus microcapsule coated with whey protein and xanthan in yogurt during storage and exposure to simulated gastrointestinal conditions was significantly increased. Compared with free bacteria, the L. acidophilus microcapsule coated with whey protein and xanthan had the increased viability in yogurt until 2.16 log CFU/g during storage and 3.52 log CFU/g in simulated gastrointestinal conditions. After the 28th day of storage, a significant difference between the acidity and pH of yogurt containing coated and microencapsulated L. acidophilus and control yogurt was not observed. However, yogurt containing free L. acidophilus had lower pH and higher acidity and showed a significant difference (p < .05) with other samples. Although the coating of L. acidophilus microcapsule did not affect the sensory properties and gumminess of yogurt, it increased the firmness, adhesiveness, and viscosity of this product and caused a significant decrease in syneresis and cohesiveness. In general, the application of whey protein and xanthan coating on L. acidophilus microcapsule surface could increase the viability of this probiotic in yogurt during storage and in simulated gastrointestinal conditions and improve the texture attributes of yogurt.

Encapsulated Food Products as a Strategy to Strengthen Immunity Against COVID-19

In December 2019, the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2)-a novel coronavirus was identified which was quickly distributed to more than 100 countries around the world. There are currently no approved treatments available but only a few preventive measures are available. Among them, maintaining strong immunity through the intake of functional foods is a sustainable solution to resist the virus attack. For this, bioactive compounds (BACs) are delivered safely inside the body through encapsulated food items. Encapsulated food products have benefits such as high stability and bioavailability, sustained release of functional compounds; inhibit the undesired interaction, and high antimicrobial and antioxidant activity. Several BACs such as ω-3 fatty acid, curcumin, vitamins, essential oils, antimicrobials, and probiotic bacteria can be encapsulated which exhibit immunological activity through different mechanisms. These encapsulated compounds can be recommended for use by various researchers, scientists, and industrial peoples to develop functional foods that can improve immunity to withstand the coronavirus disease 2019 (COVID-19) outbreak in the future. Encapsulated BACs, upon incorporation into food, offer increased functionality and facilitate their potential use as an immunity booster. This review paper aims to target various encapsulated food products and their role in improving the immunity system. The bioactive components like antioxidants, minerals, vitamins, polyphenols, omega (ω)-3 fatty acids, lycopene, probiotics, etc. which boost the immunity and may be a potential measure to prevent COVID-19 outbreak were comprehensively discussed. This article also highlights the potential mechanisms; a BAC undergoes, to improve the immune system.

Influence of Different Prebiotics on Viability of Lactobacillus casei, Lactobacillus plantarum and Lactobacillus rhamnosus Encapsulated in Alginate Microcapsules

As the production and maintenance of a sufficient number of microencapsulated probiotics is still a test for the food industry, the present study addressed the testing of three prebiotics: chicory inulin, soluble potato starch, oligofructose and a control carbon source, namely glucose, as a component part of the encapsulation matrix. Using the extrusion encapsulation technique, it was possible to obtain microcapsules whose matrix composition and dimensions correspond to the requirements of the food industry. The microcapsules obtained showed significantly different physicochemical properties, with different survival rates during processing, storage and in simulated gastrointestinal conditions. The encapsulation efficiency was very high in relation to the dimensions of the microcapsules and the technique used (between 87.00–88.19%). The microcapsules obtained offered a very good viability (between 8.30 ± 0.00–9.00 ± 0, 02 log10 cfu/g) during the 30 days of storage at 2–8 degrees and also in the simulated gastrointestinal conditions (between 7.98–8.22 log10 cfu/g). After 30 days, the lowest viability was registered in the microcapsules with glucose 6.78 ± 0.15 log10 cfu/g. It was found that after 4 h of action of gastrointestinal juices on the microcapsules stored for 30 days, cell viability falls within the limits recommended by the Food and Agriculture Organization of the United Nations (FAO) (10⁶–10⁷ CFU/mL or g of food. This study demonstrated that using prebiotic encapsulation matrix increases cell viability and protection and that the extrusion encapsulation method can be used in the production of probiotic microcapsules for the food industry.

Electrosprayed mucoadhesive alginate-chitosan microcapsules for gastrointestinal delivery of probiotics

Besides viability protection, a sufficiently prolonged gastrointestinal retention of probiotics has emerged as critically important in improving the functional effectiveness of gastrointestinal delivery of these microorganisms. In this work, we formulated pure, resistant starch-reinforced and chitosan-coated alginate microparticles using an electrospray technique and evaluated their performance as mucoadhesive probiotic formulations for gastrointestinal delivery. In addition, we designed and successfully validated a novel experimental set-up of in vitro wash-off mucoadhesion test, using a portable and low-cost USB microscope for fluorescence imaging. In our test, pure chitosan microparticles (positive control) exhibited the greatest mucoadhesive property, whereas the alginate-resistant starch ones (negative control) were the least retentive on a gastric mucosa. These electrosprayed formulations were spherically shaped, with a size range of 30-600 µm (60-1300 µm with chitosan coating). Moreover, model probiotic Lactobacillus plantarum loaded in alginate-starch formulations was better protected against simulated gastric conditions than in alginate ones, but not better than in the chitosan-coated ones.

Viability of microencapsulated Lactobacillus acidophilus by complex coacervation associated with enzymatic crosslinking under application in different fruit juices

The objective of this study was to produce microcapsules containing Lactobacillus acidophilus LA-02 by complex coacervation followed by crosslinking with transglutaminase and to evaluate the effect of their addition on different fruit juices, as well as the probiotic viability of L. acidophilus and its effect on fruit juices during storage. To this end, L. acidophilus was microencapsulated by complex coacervation, followed by crosslinking with transglutaminase at different concentrations. Probiotics, in their free and microencapsulated forms, were added to orange juice and apple juice at concentrations of 10% and 30%. The obtained microcapsules were characterized in terms of morphology. The viability of probiotics and the effects of their addition on fruit juices were assessed and the juices characterized (with respect to pH and total soluble solids) during 63 days of storage at 4 °C. Orange juice proved to be more suitable for the addition of probiotics, and the survival of probiotics was directly related to pH. The microcapsules had a protective effect on L. acidophilus, prolonging their survival, and the crosslinking process proved to be adequate and promising, ensuring probiotic viability. Thus, the complex coacervation process associated with induced enzymatic crosslinking provided protection for L. acidophilus in different fruit juices, showing an adequate methodology for adding probiotics to this adverse food matrix, guaranteeing the survival of L. acidophilus for up to 63 days, and generating products with innovative and promising probiotic appeal.

A SH3_5 Cell Anchoring Domain for Non-recombinant Surface Display on Lactic Acid Bacteria

Lactic acid bacteria (LAB) are a group of gut commensals increasingly recognized for their potential to deliver bioactive molecules in vivo. The delivery of therapeutic proteins, in particular, can be achieved by anchoring them to the bacterial surface, and various anchoring domains have been described for this application. Here, we investigated a new cell anchoring domain (CAD4a) isolated from a Lactobacillus protein, containing repeats of a SH3_5 motif that binds non-covalently to peptidoglycan in the LAB cell wall. Using a fluorescent reporter, we showed that C-terminal CAD4a bound Lactobacillus fermentum selectively out of a panel of LAB strains, and cell anchoring was uniform across the cell surface. Conditions affecting CAD4a anchoring were studied, including temperature, pH, salt concentration, and bacterial growth phase. Quantitative analysis showed that CAD4a allowed display of 10⁵ molecules of monomeric protein per cell. We demonstrated the surface display of a functional protein with superoxide dismutase (SOD), an antioxidant enzyme potentially useful for treating gut inflammation. SOD displayed on cells could be protected from gastric digestion using a polymer matrix. Taken together, our results show the feasibility of using CAD4a as a novel cell anchor for protein surface display on LAB.

Intestinal Bacteria Encapsulated by Biomaterials Enhance Immunotherapy

The human intestine contains thousands of bacterial species essential for optimal health. Aside from their pathogenic effects, these bacteria have been associated with the efficacy of various treatments of diseases. Due to their impact on many human diseases, intestinal bacteria are receiving increasing research attention, and recent studies on intestinal bacteria and their effects on treatments has yielded valuable results. Particularly, intestinal bacteria can affect responses to numerous forms of immunotherapy, especially cancer therapy. With the development of precision medicine, understanding the factors that influence intestinal bacteria and how they can be regulated to enhance immunotherapy effects will improve the application prospects of intestinal bacteria therapy. Further, biomaterials employed for the convenient and efficient delivery of intestinal bacteria to the body have also become a research hotspot. In this review, we discuss the recent findings on the regulatory role of intestinal bacteria in immunotherapy, focusing on immune cells they regulate. We also summarize biomaterials used for their delivery.

Microencapsulation of Lactobacillus rhamnosus GG with flaxseed mucilage using co-extrusion technique

AIM

This study aimed to evaluate the protective effect of flaxseed mucilage on the co-extrusion microencapsulation of Lactobacillus rhamnosus GG.

METHODS

Core flow rate, chitosan coating, and flaxseed mucilage concentration were optimised for the microencapsulation of L. rhamnosus. The microbeads were characterised and evaluated on microencapsulation efficiency and cell released after 6 h of sequential digestion.

RESULTS

The optimised parameters for the L. rhamnosus microencapsulation were 1.0 mL/min core flow rate, 0.4% (w/v) chitosan coating, and 0.4% (w/v) flaxseed mucilage. The L. rhamnosus microbeads with flaxseed mucilage in core and wall materials had a smooth surface with 781.3 µm diameter, the highest microencapsulation efficiency (98.8% w/w), lowest swelling (5196.7% w/w) and erosion ratio (515.5% w/w), and least cell release (<40% w/w) with 9.31 log₁₀ CFU mL^-1 after sequential digestion.

CONCLUSIONS

This study showed the protective capacity of flaxseed mucilage towards the L. rhamnosus GG during microencapsulation and gastrointestinal environment.

Chitosan-Coated Alginate Microcapsules Loaded with Herbal galactagogue Extract: Formulation Optimization and Characterization

Many herbs and spices have been recommended traditionally as galactagogues and several commercial formulations prepared using herbs. Due to the presence of various compounds such as polyphenols, flavonoids, isoflavones, and terpenes, bitter and stringent taste is elicited that make the consumption of these herbal preparations unpleasant. Moreover, these compounds are unstable when exposed to environmental conditions. In this regard, different approaches are used for taste masking such as microencapsulation. In the present study, microcapsules containing herbal galactagogue extract were developed through emulsification/external gelation and Box-Behnken design was used to investigate the effects of independent variables (sodium alginate: 1-1.5%, calcium chloride: 0.2-1% and extract concentrations: 1-5%) on encapsulation efficiency (EE%). Following evaluation of the model, the optimum condition of encapsulation process was selected as 1.49% sodium alginate, 0.84 CaCl₂, and 1.58% extract with EE% of 77.97%. Microcapsules had an acceptable spherical morphology and the results of Fourier transform-infrared spectroscopy (FTIR) revealed the presence of the extract within the microcapsules. The mean diameters of the uncoated and chitosan-coated microcapsules were 52 and 123 μm and encapsulation yield was 50.21 and 69.7%, respectively. The polydispersity index of 0.45 and 0.48 were an indicative of polydisperse nature of the microcapsules. The loss of flavonoids in microcapsules stored at two different temperatures was insignificant. The in-vitro release in simulated gastric fluid (SGF; pH 1.2) and simulated intestinal fluid (SIF; pH 7.4) were 48.1% and 80.11%, respectively during 24 h. The prepared extract-loaded microcapsules have potential to be used in matrices with neutral pH.

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

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

Development of chitosan-coated agar-gelatin particles for probiotic delivery and targeted release in the gastrointestinal tract

This study reports the development of a novel and simple formulation for probiotic delivery using chitosan-coated agar-gelatin gel particles. This methodology involves the production of agar-gelatin particles by thermally treating a mixture of agar and gelatin solutions at high temperatures (121 °C) and subsequently coating with chitosan. The particles were able to protect the probiotic strain Lactobacillus plantarum NCIMB 8826 during incubation for 2 h in simulated gastric fluid (pH 2), as no statistically significant loss (P > 0.05) in cell concentration was observed, and also resist dissolution in simulated intestinal fluid (pH 7.2). Interestingly, this protection is related to the fact that the intense thermal treatment affected the physicochemical properties of agars and resulted in the formation of a strong and tight polymer network, as indicated by the X-ray diffraction (XRD) analysis. Using an in vitro faecal batch fermentation model simulating the conditions of the distal part of the large intestine (pH 6.7–6.9), it was demonstrated by quantitative real-time PCR that the majority of L. plantarum cells were released from the agar-gelatin particles within 30 to 48 h. Overall, this work led to the development of a novel methodology for the production of probiotic-containing particles, which is simpler compared with current encapsulation technologies and has a lot of potential to be used for the controlled release of probiotics and potentially other solid bioactives in the large intestine.

Key Points

• Chitosan gel particles is a simple and scalable method of probiotic encapsulation.

• Autoclaving agar-gelatin particles increases their stability at low pH.

• Chitosan gel particles protected L. plantarum during gastrointestinal conditions.

• Probiotics could be controlled release in the colon using chitosan gel particles.

In-vitro GIT Tolerance of Microencapsulated Bifidobacterium bifidum ATCC 35914 Using Polysaccharide-Protein Matrix

Longevity of probiotic is the main concern for getting maximum benefits when added in food product. Bifidobacterium, a probiotic, tends to lose its viability during gastrointestinal track (GIT) transit and storage of food. Their viability can be enhanced through microencapsulation technology. In this study, Bifidobacterium bifidum (B. bifidum) ATCC 35914 was encapsulated by using two experimental plans. In the first plan, chitosan (CH) at 0.6, 0.8, and 1.0% and sodium alginate (SA) at 4, 5, and 6% were used. Based on encapsulation efficiency, 6% sodium alginate and 0.8% chitosan were selected for single coating of the bacteria, and the resulting micro beads were double coated with different concentrations (5, 7.5, and 10%) of whey protein concentrate (WPC) in the second plan. Encapsulation efficiency and GIT tolerance were determined by incubating the micro beads in simulated gastrointestinal juices (SIJ) at variable pH and exposure times, and their release (liberation of bacterial cells) profile was also observed in SIJ. The microencapsulated bacterial cells showed significantly (P < 0.01) higher viability as compared to the unencapsulated (free) cells during GIT assay. The double-coated micro beads SA 6%-WPC 5% and CH 0.8%-WPC 5% were proven to have the higher survival at pH 3.0 after 90 min of incubation time and at pH 7.0 after 3-h exposure in comparison to free cells in simulated conditions of the stomach and intestine, respectively. Moreover, double coating with whey protein concentrate played a significant role in the targeted (10^6-9 CFU/mL) delivery under simulated intestinal conditions.

The Inoculation of Probiotics In Vivo Is a Challenge: Strategies to Improve Their Survival, to Avoid Unpleasant Changes, or to Enhance Their Performances in Beverages

The inoculation of probiotics in beverages (probiotication) requires special technologies, as probiotic microorganisms can experience stress during food processing (acid, cold, drying, starvation, oxidative, and osmotic stresses) and gastrointestinal transit. Survival to harsh conditions is an essential prerequisite for probiotic bacteria before reaching the target site where they can exert their health promoting effects, but several probiotics show a poor resistance to technological processes, limiting their use to a restricted number of food products. Therefore, this paper offers a short overview of the ways to improve bacterial resistance: by inducing a phenotypic modification (adaptation) or by surrounding bacteria through a physical protection (microencapsulation). A second topic briefly addressed is genetic manipulation, while the last section addresses the control of metabolism by attenuation through physical treatments to design new kinds of food.

Development of Whey Protein Concentrate-Pectin-Alginate Based Delivery System to Improve Survival of B. longum BL-05 in Simulated Gastrointestinal Conditions

Bifidobacterium longum BL-05 encapsulated beads were developed by using whey protein concentrate (WPC) and pectin (PE) as encapsulating material through extrusion/ionic gelation technique with the objective to improve survival of probiotics in harsh gastrointestinal conditions. B. longum BL-05 was grown in MRS (de man rogosa and sharpe) broth, centrifuged and mixed with polymeric gel solution. Bead formulations E₄ (2.5% WPC + 1.5% PE) and E₅ (2% PE) showed the highest value for encapsulation efficiency, size, and textural properties (hardness, cohesiveness, springiness) due to increasing PE concentration. The survivability and viability of free and encapsulated B. longum BL-05 was assessed through their resistance to simulated gastric juice (SGJ), tolerance to bile salt, release profile in simulated intestinal fluid (SIF), and storage stability during 28 days at 4 °C. The microencapsulation provided protection to B. longum BL-05 and encapsulated cells were exhibited significant (p < 0.05) resistance to SGJ and SIF as compared to free cells. Bead formulations E₃ (5.0% WPC + 1.0% PE) and E₄ (2.5% WPC + 1.5% PE) exhibited more resistance to SGJ (at pH 2 for 2 h) and at 2% bile salt solution but comparatively slow release as compared to other bead formulations. Free cells lost their viability when stored at 4 °C after 28 days but microencapsulated cells demonstrated promising results during storage and viable cell count was > 10⁷ CFU/g. This study revealed that extrusion using WPC and PE as encapsulating material could be considered as one of the novel technologies for protection and effective delivery of probiotics.

Survivability of alginate-microencapsulated Lactobacillus plantarum during storage, simulated food processing and gastrointestinal conditions

A comparison between the most investigated alginate-based encapsulating agents was performed in the current study. Here, the survivability of Lactobacillus plantarum microencapsulated with alginate (Alg) combined with skim milk (Sm), dextrin (Dex), denatured whey protein (DWP) or coated with chitosan (Ch) was evaluated after exposure to different heat treatments and in presence of some food additives, during storage and under simulated gastrointestinal condition. In addition, the encapsulated cells were evaluated for production of different bioactive compounds such as exopolysacchar. ides and antimicrobial substances compared with the unencapsulated cells. The results showed that only Alg-Sm maintained the viability of the cells >106 cfu/g at the pasteurization temperature (65 °C for 30 min). Interestingly, storage under refrigeration conditions increased the viability of L. plantarum entrapped within all the tested encapsulating agents for 4 weeks. However, under freezing condition, only Alg-DWP and Alg-Sm enhanced the survival of the entrapped cells for 3 months. All the microencapsulated cells were capable of growing at the different NaCl concentrations (1%-5%) except for cells encapsulated with Alg-Dex, showed viability loss at 3% and 5% NaCl concentrations. Tolerance of the microencapsulated cells toward organic acids was varied depending on the type of organic acid. Alg-Ch and Alg-Sm provide better survival for the cells under simulated gastric juice; however, all offer a good survival for the cells under simulated intestinal condition. Our findings indicated that Alg-Sm proved to be the most promising encapsulating combination that maintains the survivability of L. plantarum to the recommended dose level under almost all the stress conditions adopted in the current study. Interestingly, the results also revealed that microencapsulation does not affect the metabolic activity of the entrapped cells and there was no significant difference in production of bioactive compounds between the encapsulated and the unencapsulated cells.

A Brief Review of Edible Coating Materials for the Microencapsulation of Probiotics

The consumption of probiotics has been associated with a wide range of health benefits for consumers. Products containing probiotics need to have effective delivery of the microorganisms for their consumption to translate into benefits to the consumer. In the last few years, the microencapsulation of probiotic microorganisms has gained interest as a method to improve the delivery of probiotics in the host as well as extending the shelf life of probiotic-containing products. The microencapsulation of probiotics presents several aspects to be considered, such as the type of probiotic microorganisms, the methods of encapsulation, and the coating materials. The aim of this review is to present an updated overview of the most recent and common coating materials used for the microencapsulation of probiotics, as well as the involved techniques and the results of research studies, providing a useful knowledge basis to identify challenges, opportunities, and future trends around coating materials involved in the probiotic microencapsulation.

Viability of Lactobacillus rhamnosus GG microencapsulated in alginate/chitosan hydrogel particles during storage and simulated gastrointestinal digestion: role of chitosan molecular weight

Sodium alginate hydrogel particles coated with cationic biopolymers have been shown to be one of the promising means for probiotic encapsulation and protection. In this study, we aimed to systematically explore the effect of molecular weight of chitosan coating on the functional performance of sodium alginate hydrogel particles for improving the viability of Lactobacillus rhamnosus GG (LGG). We first electrostatically deposited three different molecular weights of chitosan coatings, i.e., chitosan oligosaccharide (COS), low molecular weight chitosan (LMW-chitosan) and medium molecular weight chitosan (MMW-chitosan) on sodium alginate hydrogel particles. Both SEM and FTIR results indicated that chitosan was successfully deposited onto the surface of the hydrogel particles. We then evaluated the effect of chitosan MW on the viability of LGG encapsulated in the hydrogels during long-term storage and simulated gastrointestinal digestion. Among them, the hydrogel particles coated with COS prevented the viability loss of LLG during long-term storage at different temperatures (4, 25 and 37 °C). However, we did not find any improvement in the viability of the encapsulated LGG by all three chitosan coatings during simulated digestion.

Polymeric carriers for enhanced delivery of probiotics

Probiotics are live microorganisms (usually bacteria), which are defined by their ability to confer health benefits to the host, if administered adequately. Probiotics are not only used as health supplements but have also been applied in various attempts to prevent and treat gastrointestinal (GI) and non-gastrointestinal diseases such as diarrhea, colon cancer, obesity, diabetes, and inflammation. One of the challenges in the use of probiotics is putative loss of viability by the time of administration. It can be due to procedures that the probiotic products go through during fabrication, storage, or administration. Biocompatible and biodegradable polymers with specific moieties or pH/enzyme sensitivity have shown great potential as carriers of the bacteria for 1) better viability, 2) longer storage times, 3) preservation from the aggressive environment in the stomach and 4) topographically targeted delivery of probiotics. In this review, we focus on polymeric carriers and the procedures applied for encapsulation of the probiotics into them. At the end, some novel methods for specific probiotic delivery, possibilities to improve the targeted delivery of probiotics and some challenges are discussed.

Effect of different strategies of Lactobacillus plantarum incorporation in chorizo sausages

BACKGROUND

Chorizo is a high-value Spanish-type dry fermented sausage, highly appreciated by consumers. In this kind of product, Lactobacillus plantarum plays an important role in the fermentation process and can also be considered as a probiotic. The impact of different strategies for incorporating probiotic L. plantarum into the physico-chemical, microbiological, and sensorial characteristics of chorizo sausages was studied. These strategies were: free cells (Cfc); alginate beads (Calg); water-in-oil emulsion (Cwo), and water-in-oil-in-water emulsion (Cwow). Proximate composition, weight loss, pH, a_w , color, and microbiological behavior were evaluated during the ripening (20 days) of chorizo.

RESULTS

The strategy of incorporating L. plantarum significantly affected the proximate composition, pH, and a_w of sausages. However, the traditional red color of chorizo was maintained for all formulations. The incorporation of probiotics as free cells or encapsulated in alginate beads resulted in higher counts of lactic acid bacteria and L. plantarum, lower counts of Enterobacteriaceae, and in acceptable sensory scores.

CONCLUSION

Overall, the quality of chorizo sausages was conditioned by the incorporation strategy, and the addition of probiotics in alginate beads (Calg) was the most effective strategy. © 2019 Society of Chemical Industry.

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

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

Probiotics in Food Systems: Significance and Emerging Strategies Towards Improved Viability and Delivery of Enhanced Beneficial Value

Preserving the efficacy of probiotic bacteria exhibits paramount challenges that need to be addressed during the development of functional food products. Several factors have been claimed to be responsible for reducing the viability of probiotics including matrix acidity, level of oxygen in products, presence of other lactic acid bacteria, and sensitivity to metabolites produced by other competing bacteria. Several approaches are undertaken to improve and sustain microbial cell viability, like strain selection, immobilization technologies, synbiotics development etc. Among them, cell immobilization in various carriers, including composite carrier matrix systems has recently attracted interest targeting to protect probiotics from different types of environmental stress (e.g., pH and heat treatments). Likewise, to successfully deliver the probiotics in the large intestine, cells must survive food processing and storage, and withstand the stress conditions encountered in the upper gastrointestinal tract. Hence, the appropriate selection of probiotics and their effective delivery remains a technological challenge with special focus on sustaining the viability of the probiotic culture in the formulated product. Development of synbiotic combinations exhibits another approach of functional food to stimulate the growth of probiotics. The aim of the current review is to summarize the strategies and the novel techniques adopted to enhance the viability of probiotics.