Carboxymethylpachymaran/alginate gel entrapping of natural pollen capsules for the encapsulation, protection and delivery of probiotics with enhanced viability

Modulation of protein glutaminase α-helix and disulfide bonds in a sunflower pollen microgel microenvironment: A strategy to enhance enzyme activity and stability

Protein glutaminase (PGase) can improve plant protein solubility, but its activity tends to decline under the influence of external factors. Here, we developed a novel PGase-stabilizing agent (sunflower pollen microgel, SPMG) and investigated the mechanism for its stabilizing effect on PGase. Alkali treatment could regulate the physicochemical microenvironment of SPMG, and its ability to stabilize PGase declined with prolonged treatment time. SPMG increased PGase activity by a maximum of 49.24 %, while enhanced its storage stability by 30.61 %, 21.64 %, and 26.00 % at 4 °C, 25 °C, and 37 °C, respectively. SPMG improved PGase properties through hydrophobic interaction, resulting in the burying of inner hydrophobic groups and enhancement of intermolecular hydrogen bonding, which promoted the α-helix content from 23.28 % to 26.19 %. Additionally, these interactions facilitated the sulfhydryl-disulfide bond exchange reaction between PGase molecules, significantly increasing the disulfide bond content by nearly 80 %. This compact structure ultimately enhanced the activity and stability of PGase.

Sodium alginate/low methoxyl pectin composite hydrogel beads prepared via gas-shearing technology for enhancing the colon-targeted delivery of probiotics and modulating gut microbiota

The probiotic encapsulation system has the potential to enhance the prebiotic effects of probiotics. However, challenges arise from the release behavior of this system in vivo and the large size of hydrogel beads. This study aims to address the issues related to the size of previous hydrogel beads and assess the colon-targeted delivery of probiotic polysaccharides composite hydrogel beads (PPHB). PPHB prepared by gas-shearing technique significantly reduced the average particle size and demonstrated a high protective capacity for probiotics (after simulating intestinal conditions for 4 h, the viability of encapsulated probiotics remained at 107 CFU/g). The use of indocyanine green along with near-infrared-II in vivo imaging technology demonstrated the colon-targeted delivery of PPHB in vivo, which also extended the retention time of probiotics in the cecum and colon. Additionally, the colon-targeted delivery of PPHB was also demonstrated by dietary supplementation in vivo. PPHB significantly enhanced the diversity and richness of intestinal microflora species, increased the levels of short-chain fatty acids, raised the relative abundance of beneficial bacteria, and significantly decreased the relative abundance of harmful bacteria. Alginate-based PPHB is more suitable for encapsulating functional ingredients for colon-targeted delivery and modulating gut microbiota.

Correia V, Silva Pereira C. The Chemistry of Sporopollenin Ektexine and Endexine Layers Isolated from Sunflower Pollen through an Ionic Liquid-Mediated Process

Sporopollenin is a plant polymer present in the exine of the pollen grains that comprises two layers: the endexine and the ektexine. It possesses remarkable mechanical, thermal, and chemical stability and is also highly recalcitrant to hydrolysis. The chemical backbone of sporopollenin mostly consists of a polyhydroxylated aliphatic component and polyketide-derived aliphatic α-pyrone elements. Recent works have provided important insights into its molecular structure, yet due to the extreme inertness of the polymer, outstanding questions still exist. In this work, we produced and characterized sporopollenin enriched materials obtained from dewaxed sunflower pollen using conventional acetolysis and two ionic liquid solvents or combinations of both. Microscopic (SEM) and spectroscopic analyses (mostly NMR) showed that either method alone could render sporopollenin enriched fractions. Only the acetolyzed materials showed an increase in acetate content. Ionic liquids used alone led to the isolation of naked spore capsules containing only the endexine layer, suggesting that the ektexine layer could be solubilized by the ionic liquid. On the contrary, the acetolyzed sporopollenin capsules could not be further modified by the ionic liquid treatment, preserving the two exine layers and an echinate surface. Our results suggest that the acetolysis altered the surface hydrophobicity of sporopollenin due to the introduction of acetate. The ionic liquid process led to the isolation of either exine layer, with both showing virtually the same chemistry.

Seed coating with biocontrol bacteria encapsulated in sporopollenin exine capsules for the control of soil-borne plant diseases

Coating seeds with biocontrol agents represents an effective approach for managing soil-borne plant diseases. However, improving the viability of biocontrol microorganisms on the seed surface or in the rhizosphere remains a big challenge due to biotic and abiotic stresses. In this work, we developed a microbial seed coating strategy that uses sporopollenin exine capsules (SECs) as carriers for the encapsulation of the biofilm-like biocontrol bacteria. SECs was extracted from camellia bee pollen, and then characterized by Fourier Transform infrared spectroscopy (FTIR), elemental analysis and thermal gravity analysis (TG). The Paenibacillus polymyxa ZF129, a biocontrol bacterium, was introduced into SECs using the vacuum-incubation method and characterized by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Notably, the ZF129 cell formed a biofilm-like structure inside the SECs, which enhanced their tolerance to acidic stress. As a proof of concept, we applied ZF129-loaded SECs to coat pak choi seeds using a straightforward plate-shaking technique. The coated seeds demonstrated a high control efficacy of up to 60.46 % against clubroot disease. Overall, this study sheds light on the application of SECs as promising carrier for the encapsulation of biofilm-like biocontrol bacteria, further augmenting the biocontrol functionality of microbial seed coating.

Oral delivery of probiotics using single-cell encapsulation

Adequate intake of live probiotics is beneficial to human health and wellbeing because they can help treat or prevent a variety of health conditions. However, the viability of probiotics is reduced by the harsh environments they experience during passage through the human gastrointestinal tract (GIT). Consequently, the oral delivery of viable probiotics is a significant challenge. Probiotic encapsulation provides a potential solution to this problem. However, the production methods used to create conventional encapsulation technologies often damage probiotics. Moreover, the delivery systems produced often do not have the required physicochemical attributes or robustness for food applications. Single-cell encapsulation is based on forming a protective coating around a single probiotic cell. These coatings may be biofilms or biopolymer layers designed to protect the probiotic from the harsh gastrointestinal environment, enhance their colonization, and introduce additional beneficial functions. This article reviews the factors affecting the oral delivery of probiotics, analyses the shortcomings of existing encapsulation technologies, and highlights the potential advantages of single-cell encapsulation. It also reviews the various approaches available for single-cell encapsulation of probiotics, including their implementation and the characteristics of the delivery systems they produce. In addition, the mechanisms by which single-cell encapsulation can improve the oral bioavailability and health benefits of probiotics are described. Moreover, the benefits, limitations, and safety issues of probiotic single-cell encapsulation technology for applications in food and beverages are analyzed. Finally, future directions and potential challenges to the widespread adoption of single-cell encapsulation of probiotics are highlighted.

Chitosan entrapping of sodium alginate / Lycium barbarum polysaccharide gels for the encapsulation, protection and delivery of Lactiplantibacillus plantarum with enhanced viability

To preserve the viability of probiotics during digestion and storage, encapsulation techniques are necessary to withstand the challenges posed by adverse environments. A core-shell structure has been developed to provide protection for probiotics. By utilizing sodium alginate (SA) / Lycium barbarum polysaccharide (LBP) as the core material and chitosan (CS) as the shell, the probiotic load reached 9.676 log CFU/mL. This formulation not only facilitated continuous release in the gastrointestinal tract but also enhanced thermal stability and storage stability. The results obtained from Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed that the addition of LBP and CS affected the microstructure of the gel by enhancing the hydrogen bond force, so as to achieve controlled release. Following the digestion of the gel within the gastrointestinal tract, the released amount was determined to be 9.657 log CFU/mL. The moisture content and storage stability tests confirmed that the encapsulated Lactiplantibacillus plantarum maintained good activity for an extended period at 4 °C, with an encapsulated count of 8.469 log CFU/mL on the 28th day. In conclusion, the newly developed core-shell gel in this study exhibits excellent probiotic protection and delivery capabilities.

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

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

Sodium alginate/carboxymethyl starch/κ-carrageenan enteric soft capsule: Processing, characterization, and rupture time evaluation

Although gelatin has good characteristics in preparing soft capsules, its noticeable shortcomings force researchers to further develop substitutes for gelatin soft capsules. In this paper, sodium alginate (SA), carboxymethyl starch (CMS) and κ-carrageenan (κ-C) were used as matrix materials, and the formula of the co-blended solution was screened through rheological method. In addition, films of the different blends were characterized by thermogravimetry analysis, SEM, FTIR, X-ray, water contact angle and mechanical properties. The results showed that κ-C had strong interaction with CMS and SA and the mechanical properties of capsule shell were greatly improved by the addition of κ-C. When the ratio of CMS/SA/κ-C was 2:0.5:1.5, the microstructure of the film was more dense and uniform. In addition, this formula had the best mechanical properties and adhesion properties, and was more suitable for the production of soft capsules. Finally, a novel plant soft capsule was successfully prepared by dropping method, and its appearance and rupture properties met the requirements of enteric soft capsules. In simulated intestinal juice, the soft capsule was almost completely degraded within 15 min, and it was superior to the gelatin soft capsule. Therefore, this study provides an alternative formula for preparing enteric soft capsules.

Extraordinary microcarriers derived from spores and pollens

Spores and pollens refer to the reproductive cells of seed plants and asexually reproducing sporophytes, exhibiting a natural core-shell structure and exquisite surface morphology. They possess extraordinary dimensional homogeneity, porosity, amphiphilicity and adhesion. Their sporopollenin exine layer endows them with chemically stable, UV resistant, and biocompatible properties, which can also be facilely functionalized due to sufficient groups on the surface. The unique characteristics of spores and pollens have facilitated a wide range of applications in drug carriers, biological imaging, food science, microrobotics, environmental purification, flexible electronics, cell scaffolds, 3D printing materials and biological detection. This review showcases the common structural composition and physicochemical properties of spores and pollens, describes the extraction and processing methods, and summarizes the recent research on their applications in various fields. Following these sections, this review analyzes the existing challenges in spores and pollen research and provides a future outlook.

Calcium carbonate-modified plant sporopollen capsule as an eco-friendly microvehicle for controlled release of pesticide

BACKGROUND

In this work, natural club moss (Lycopodium clavatum, LC) spores with a porous surface morphology and highly uniform size distribution were engineered into controlled-release microvehicles for pesticide delivery. As a proof of concept, a widely used fungicide, fluazinam (FLU), was successfully loaded into LC spores and then modified with different amounts of CaCO₃ (CaC) to extend the efficacy duration of FLU. Significantly, as the control target of FLU, clubroot disease is a worldwide destructive disease of cruciferous crops, and its development is favored by acidic soils and can be suppressed at high Ca concentrations.

RESULTS

Fabricated FLU@LC-CaC microcapsules, FLU loading and CaCO₃ deposition were systematically characterized by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The as-prepared FLU@LC-CaC microcapsules showed sustained-release behaviors and were potentially able to supplement the Ca concentration in acidic environments. This approach synergistically enhanced in vivo bioactivity for the on-demand control of clubroot disease. An in vivo bioassay revealed that the control efficacy of FLU@LC-CaC against clubroot disease in pak choi (Brassica chinensis) (66.4%) was 1.7-fold higher than that of a commercial FLU suspension concentrate (38.2%) over the course of the cultivation period (35 days).

CONCLUSIONS

This work provides new ideas not only for developing eco-friendly and scalable microvehicles for pesticide delivery based on natural sporopollen, but also for unconventional research perspectives in on-demand pest management based on their occurrence characteristics. © 2022 Society of Chemical Industry.

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.

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

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

Potential Food and Nutraceutical Applications of Alginate: A Review

Alginate is an acidic polysaccharide mainly extracted from kelp or sargassum, which comprises 40% of the dry weight of algae. It is a linear polymer consisting of β-D-mannuronic acid (M) and α-L-guluronic acid (G) with 1,4-glycosidic linkages, possessing various applications in the food and nutraceutical industries due to its unique physicochemical properties and health benefits. Additionally, alginate is able to form a gel matrix in the presence of Ca²⁺ ions. Alginate properties also affect its gelation, including its structure and experimental conditions such as pH, temperature, crosslinker concentration, residence time and ionic strength. These features of this polysaccharide have been widely used in the food industry, including in food gels, controlled-release systems and film packaging. This review comprehensively covers the analysis of alginate and discussed the potential applications of alginate in the food industry and nutraceuticals.

Current Trends in the Production of Probiotic Formulations

Preparations containing probiotic strains of bacteria have a beneficial effect on human and animal health. The benefits of probiotics translate into an increased interest in techniques for the preservation of microorganisms. This review compares different drying methods and their improvements, with specific reference to processing conditions, microorganisms, and protective substances. It also highlights some factors that may influence the quality and stability of the final probiotic preparations, including thermal, osmotic, oxidative, and acidic stresses, as well as dehydration and shear forces. Processing and storage result in the loss of viability and stability in probiotic formulations. Herein, the addition of protective substances, the optimization of process parameters, and the adaptation of cells to stress factors before drying are described as countermeasures to these challenges. The latest trends and developments in the fields of drying technologies and probiotic production are also discussed. These developments include novel application methods, controlled release, the use of food matrices, and the use of analytical methods to determine the viability of probiotic bacteria.

Biopolymer-Based Multilayer Microparticles for Probiotic Delivery to Colon

The potential health benefits of probiotics may not be realized because of the substantial reduction in their viability during food storage and gastrointestinal transit. Microencapsulation has been successfully utilized to improve the resistance of probiotics to critical conditions. Owing to the unique properties of biopolymers, they have been prevalently used for microencapsulation of probiotics. However, majority of microencapsulated products only contain a single layer of protection around probiotics, which is likely to be inferior to more sophisticated approaches. This review discusses emerging methods for the multilayer encapsulation of probiotic using biopolymers. Correlations are drawn between fabrication techniques and the resultant microparticle properties. Subsequently, multilayer microparticles are categorized based on their layer designs. Recent reports of specific biopolymeric formulations are examined regarding their physical and biological properties. In particular, animal models of gastrointestinal transit and disease are highlighted, with respect to trials of multilayer microencapsulated probiotics. To conclude, novel materials and approaches for fabrication of multilayer structures are highlighted.

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.

Probiotics in Citrus Fruits Products: Health Benefits and Future Trends for the Production of Functional Foods—A Bibliometric Review

The relationship between food and human health drives the search for knowledge of food components that are related to these benefits. The scientific community shows a growing interest in the knowledge of the interactions between components of citrus fruits and probiotics to develop ways to improve the quality of the food produced. In this bibliometric review, a study of scientific publications is carried out on the potential of probiotics in citrus fermentation, addressing the importance and future trends of plant-based products in the functional food group as an alternative to the dairy market. The review process of the articles initially took place with a bibliometric analysis and was followed by a literature review. The Scopus database was used in the search for articles, carried out in May 2021. The use of foods as carriers of probiotics is an alternative that has been growing and the surveys evaluated show the desire to diversify the probiotics available on the market. In addition, it was observed that citrus fruits have great potential for the development of functional foods due to their high acceptability and possibilities of development and application in various products.