Microencapsulation of Lactobacillus acidophilus CGMCC1.2686 via emulsification/internal gelation of alginate using Ca-EDTA and CaCO3 as calcium sources

In Vitro and In Vivo Characterisation of Lactiplantibacillus plantarum LAB12 in Pea Protein-Alginate Microcapsules

The susceptibility of probiotics to high temperature and low pH remains a major challenge in food industries. Numerous commercially available probiotic products were reportedly presented with lower probiotic viability than claimed. To confer health benefits to the host, it is essential that probiotic strain remains viable at optimal amount during food processing procedures, storage and passage through the gastrointestinal tract. This study addressed these issues by immobilising Lactiplantibacillus plantarum LAB12 isolated from tempeh (fermented soybean) in a polymeric matrix made up of alginate (Alg, 0.5% w/v) and denatured pea protein isolate (PPi, 1-10% w/v) using the emulsion/acidification technique. Alg supplemented with 10% PPi (Alg-PPi10) appeared to be optimally small (< 350 µm), substantiated by the improved surface smoothness and uniform dispersion of probiotics in the Alg-PPi core. The findings indicated that microencapsulation enhanced thermal stability of L. plantarum LAB12. The microencapsulated L. plantarum LAB12 remained highly viable (80%) despite exposure to 100 °C for 5 min. The microencapsulated cell number during storage at 4 and 25 °C for 8 weeks was greater than 7 log CFU g-1. L. plantarum LAB12 encapsulated in Alg-PPi10 exhibited high viability (96%) in simulated gastric juice (at pH 1.8 for 120 min) and facilitated maximum release of probiotics (> 9 log CFU g-1) in simulated intestinal fluid (at pH 6.8 for 240 min). Whilst retaining their intrinsic cholesterol lowering effect, microencapsulation conferred additional advantages to L. plantarum LAB12 in terms of lowering serum triglyceride and increasing HDL cholesterol in zebrafish fed with high-cholesterol diet (HCD). Overall, our findings strongly imply the potential use of Alg-PPi10 as an effective medium that confers thermal protection and facilitates pH-sensitive release of cholesterol-reducing L. plantarum LAB12. This will allow the diverse applications L. plantarum LAB12 across health, food and agro-feed industries amongst others.

Simultaneous Encapsulation of Probiotic Bacteria (Lactococcus lactis, and Lactiplantibacillus plantarum) in Calcium Alginate Hydrogels

Encapsulation in alginate hydrogel microspheres is an effective method for protecting and improving the survival of lactic acid bacteria in different environments. This research aims to expand the knowledge about the structure/property relationship of calcium alginate microspheres loaded with a mixture of autochthonous probiotic bacteria (Lactococcus lactis and Lactiplantibacillus plantarum). A novel hydrogel formulation (FORMLAB) was prepared by ionic gelation and the molecular interactions between the FORMLAB constituents, surface morphology, structure, swelling degree, and release profile were characterized. The simultaneous encapsulation of two bacterial cultures in the same compartment does not diminish their viability. The binding of calcium ions to bacterial cells creates favorable conditions for the propagation of the encapsulated bacteria. The molecular interactions between the FORMLAB constituents are complex, involving mainly hydrogen bonds and electrostatic interactions. With a very high degree of swelling followed by low crosslinking, the surface of the microspheres covered with bacterial cells and diffusion through the hydrogel matrix allow for the delivery of probiotics at the right time. The findings suggest that bacterial cells are efficiently delivered from calcium alginate microspheres, offering promising applications in the development of functional foods, especially in cheese production.

Lactiplantibacillus plantarum 299V fermented in microcapsules shows enhanced stability and could improve the microbial quality and safety of oysters through bioaccumulation

In this study, microcapsules of Lactiplantibacillus plantarum 299V were prepared using an emulsification/internal gelation technique. Loads of the probiotics were condensed to 9.86 ± 0.13 log CFU/g after 24 h fermentation of the microcapsules. Physical characterization revealed that L. plantarum 299V cells were uniformly distributed within the core of the microcapsules, with a mean diameter of 109.81 ± 0.39 µm and a span value of 0.36 ± 0.00, which were comparable to those of the unfermented microcapsules (p > 0.05). The viability of L. plantarum 299V in the fermented microcapsules was 2.08 ± 0.15 log higher than that of free cells at the end of 5 h simulated gastrointestinal digestion (p < 0.05). Oysters were able to accumulate the fermented microcapsules through filter feeding, resulting in a load of probiotics exceeding 6.00 log CFU/g. The presence of L. plantarum 299V-carrying microcapsules in oyster tissues significantly suppressed spoilage-causing bacteria during 11 days refrigeration storage, suggested by the tested parameters, including total psychrotrophic bacteria, H2S-producing bacteria, and Pseudomonas spp. (p < 0.05). Pathogenic bacteria, including Vibrio parahaemolyticus and Salmonella enterica artificially introduced into oysters, were also significantly suppressed by over 1.00-log within 4 days compared to control samples (p < 0.05). In summary, oysters bioaccumulated with fermented L. plantarum 299V-carrying microcapsules, justified a novel probiotic-carrying product to exsert the health-promoting effect of probiotics. This solution could also enhance the microbial quality and safety of oysters during storage.

Enhance the resistance of probiotics by microencapsulation and biofilm construction based on rhamnogalacturonan I rich pectin

Microcapsules were always used as functional material carriers for targeted delivery and meanwhile offering protection. However, microcapsule wall materials with specific properties were required, which makes the choice of wall material a key factor. In our previous study, a highly branched rhamnogalacturonan I rich (RG-I-rich) pectin was extracted from citrus canning processing water, which showed good gelling properties and binding ability, indicating it could be a potential microcapsule wall material. In the present study, Lactiplantibacillus plantarum GDMCC 1.140 and Lactobacillus rhamnosus were encapsulated by RG-I-rich pectin with embedding efficiencies of about 65 %. The environmental tolerance effect was evaluated under four different environmental stresses. Positive protection results were obtained under all four conditions, especially under H2O2 stress, the survival rate of probiotics embedded in microcapsules was about double that of free probiotics. The storage test showed that the total plate count of L. rhamnosus encapsulated in RG-I-rich pectin microcapsules could still reach 6.38 Log (CFU/mL) at 25 °C for 45 days. Moreover, probiotics embedded in microcapsules with additional incubation to form a biofilm layer inside could further improve the probiotics' activities significantly in the above experiments. In conclusion, RG-I-rich pectin may be a good microcapsule wall material for probiotics protection.

Microencapsulation of Bifidobacterium bifidum F-35 via modulation of emulsifying technique and its mechanical effects on the rheological stability of set-yogurt

Microencapsulation of B. bifidum F-35 was carried out through emulsification technique in order to increase the microbial load while maintaining the rheological functions of set-yogurt. To produce single-layer (SL) microcapsules of whey protein, the pH was adjusted to 6.4 within Transglutaminase-induced gelation. Sodium alginate was processed as the external layer using calcium-induced gelation (pH 5.5) to produce the double-layer (DL) microcapsule. Scanning electron microscopy revealed that SL and DL microcapsules had sizes of 10 and 280 μm, respectively. The highest microbial load was clearly visible in the DL sample. According to texture profile analysis, the DL sample had the highest levels of gumminess, chewiness, and adhesiveness. The free sample outperformed the encapsulated samples in terms of springiness and cohesiveness. Although the SL sample had the highest viscosity, it produced a deformed gel when firmness was measured. In terms of firmness, the DL sample performed quite well. The viability of encapsulated B. bifidum F-35 in DL was higher than SL microcapsules during storage. Microencapsulation of B. bifidum F-35 with whey protein and sodium alginate is a promising technique that could improve the rheological properties of set-yogurt as a popular vehicle for bioactive ingredients.

Graphical abstract

Carbohydrate polymer-based carriers for colon targeted delivery of probiotics

Probiotics (PRO) have been recognized for their significant role in promoting human health, particularly in relation to colon-related diseases. The effective delivery of PRO to the colon is a fascinating area of research. Among various delivery materials, carbohydrates have shown great potential as colon-targeted delivery (CTD) carriers for PRO. This review explores the connection between probiotics and colonic diseases, delving into their underlying mechanisms of action. Furthermore, it discusses current strategies for the targeted delivery of active substances to the colon. Unlike other reviews, this work specifically focuses on the utilization of carbohydrates, such as alginate, chitosan, pectin, and other carbohydrates, for probiotic colon-targeted delivery applications. Carbohydrates can undergo hydrolysis at the colonic site, allowing their oligosaccharides to function as prebiotics or as direct functional polysaccharides with beneficial effects. Furthermore, the development of multilayer self-assembled coatings using different carbohydrates enables the creation of enhanced delivery systems. Additionally, chemical modifications of carbohydrates, such as for adhesion and sensitivity, can be implemented to achieve more customized delivery of PRO.

Bacteria-Loaded Gastro-Retention Oral Delivery System for Alcohol Abuse

Alcohol abuse is harmful to human health, and many strategies have been developed to retard this harm through protecting liver or activating relative enzymes. In this study, a new strategy of decreasing the alcohol absorption directly depending on the dealcoholization by the bacteria in the upper gastrointestinal (GI) tract was reported. To realize this, a bacteria-loaded gastro-retention oral delivery system with pore structure was constructed through emulsification/internal gelation, which could relieve acute alcohol intoxication in mice successfully. It was found that this bacteria-loaded system kept the above 30% suspension ratio in the simulated gastric fluid for 4 min, displayed good protection effect for the bacteria, and decreased the alcohol concentration from 50 to 30% below within 24 h in vitro. The in vivo imaging results demonstrated that it remained in the upper GI tract until 24 h and reduced 41.9% alcohol absorption. The mice with oral administration of the bacteria-loaded system were found with normal gait, smooth coat, and less liver damage. Although the intestinal flora distribution was influenced slightly during the oral administration, it could restore to normal levels only one day after stopping oral administration quickly, suggesting good biosafety. In conclusion, these results revealed that the bacteria-loaded gastro-retention oral delivery system might intake alcohol molecules rapidly and has huge potential in the treatment of alcohol abuse.

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.

Recent Development of Alginate-Based Materials and Their Versatile Functions in Biomedicine, Flexible Electronics, and Environmental Uses

Alginate is a natural polysaccharide that is easily chemically modified or compounded with other components for various types of functionalities. The alginate derivatives are appealing not only because they are biocompatible so that they can be used in biomedicine or tissue engineering but also because of the prospering bioelectronics that require various biomaterials to interface between human tissues and electronics or to serve as electronic components themselves. The study of alginate-based materials, especially hydrogels, have repeatedly found new frontiers over recent years. In this Review, we document the basic properties of alginate, their chemical modification strategies, and the recent development of alginate-based functional composite materials. The newly thrived functions such as ionically conductive hydrogel or 3D or 4D cell culturing matrix are emphasized among other appealing potential applications. We expect that the documentation of relevant information will stimulate scientific efforts to further develop biocompatible electronics or smart materials and to help the research domain better address the medicine, energy, and environmental challenges faced by human societies.

Microencapsulation of probiotic lactobacilli with shellac as moisture barrier and to allow controlled release

BACKGROUND

Rapid dissolution in digestive tract and moisture sorption during ambient storage are the two challenges of dry probiotic preparations. To solve these problems, microcapsules with shellac (LAC) addition containing Limosilactobacillus reuteri TMW 1.656 were designed in this work to provide a good moisture barrier and to provide controlled release in digestive tract, based on the hydrophobicity and acid-resistance of LAC. Four microcapsules were prepared using the method of emulsification/external gelation based on the crosslinking reaction between alginate or LAC with calcium ion, including alginate/sucrose (ALG), alginate/shellac/sucrose (ALG/LAC), alginate/whey protein isolate/sucrose (ALG/WPI) and alginate/whey protein isolate/shellac/sucrose (ALG/WPI/LAC).

RESULTS

Measurements of physical properties showed that microcapsules with LAC addition (ALG/WPI/LAC and ALG/LAC) had larger particle size, much denser structure, lower hygroscopicity and slower solubilization in water, which agreed with the primary microcapsule design. Probiotic survivals in digestive juices followed the order of ALG/WPI/LAC ≥ ALG/WPI ≥ ALG/LAC > ALG. Probiotic stability after heating and ambient storage both exhibited the order of ALG/WPI/LAC > ALG/LAC ≈ ALG/WPI > ALG, which can be explained by the decreased hygroscopicity with adding LAC.

CONCLUSION

LAC addition contributed to better probiotic survivals after freeze drying, simulated digestion, heating and ambient storage, and whey protein isolate (WPI) addition had a synergistic effect. Microcapsule hygroscopicity was closely related with probiotic survivals after heating and ambient storage, while microcapsule solubilization was closely related with probiotic survivals in simulated juices. Within our knowledge, this is the first report to improve probiotic stability during ambient storage based on LAC hydrophobicity. © 2020 Society of Chemical Industry.

Development of a microencapsulated probiotic delivery system for New Zealand black-footed abalone (Haliotis iris)

Conventional methods of probiotics delivery to farmed aquatic animals are not efficient due to loss of probiotic's viability before the probiotics can reach their site of action. This study aims to develop a microencapsulated probiotic delivery system for black-footed abalone (Haliotis iris). An emulsion technique was used to encapsulate probiotic bacteria within chitosan-coated alginate microparticles (CALG). The efficacy of CALG microparticles in delivering probiotics to abalone was assessed using ex vivo and in vivo experiments. Microparticles (113 ± 4 µm) with encapsulation efficiency of more than 75% were developed using an internal gelation formulation approach. The ex vivo release experiments revealed the lack of probiotic discharge in the first 6 h of incubating CALG in seawater followed by a slight bacterial release within the next 20 h. The exposure of CALG microparticles to simulated gastric and intestinal media showed a significantly higher release of encapsulated bacteria in the simulated intestinal medium. The results of feeding trial revealed that the number of probiotic bacteria in probiotic-fed abalone was significantly higher than the one in the control animals. The results suggest that CALG microparticles can be used as a controlled release system for delivering viable probiotic bacteria to the gastrointestinal tract of abalone.

Co-Microencapsulation of Flavonoids from Yellow Onion Skins and Lactic Acid Bacteria Lead to Multifunctional Ingredient for Nutraceutical and Pharmaceutics Applications

In this study, flavonoids extracted from yellow onion skins and Lactobacillus casei were encapsulated in a combination of whey protein isolate, inulin and maltodextrin with an encapsulation efficiency of 84.82 ± 0.72% for flavonoids and 72.49 ± 0.11% for lactic acid bacteria. The obtained powder showed a flavonoid content of 89.49 ± 4.12 mg quercetin equivalents/g dry weight (DW) and an antioxidant activity of 39.27 ± 0.45 mM Trolox/g DW. The powder presented a significant antidiabetic and anti-inflammatory potential, with an inhibitory effect on α-amylase, lipase and lipoxygenase of 76.40 ± 2.30%, 82.58 ± 3.36% and 49.01 ± 0.62%, respectively. The results obtained for in vitro digestion showed that the coating materials have a protective effect on the flavonoids release. Cytotoxicity results indicated that the powder was cytocompatible up to a concentration of 500 μg/mL. The functional potential of the powder was tested by adding in a selected food matrix, highlighting a good stability of the phytochemicals, whereas an increase with 1 log cell forming unit (CFU)/g DW was observed after 21 days of storage. The obtained results are promising in the valorization of natural antioxidants in combination with lactic acid bacteria in order to develop multifunctional ingredients with value-added for food and pharmaceutics applications.

Preparation and characterization of pH-responsive microgel using arabinoxylan from wheat bran for BSA delivery

Wheat bran arabinoxylan (AX) discard from wheat production was utilized to form pH-responsive microgels. AX was modified by carboxymethylation, and the carboxymethylated arabinoxylans (CMAX) were characterized by FT-IR, NMR, gel permeation chromatography (GPC), and rheological analysis. The CMAX microgel was cross-linked by Fe³⁺ using an inverse emulsification polymerization. The morphology, particle size, pH sensitivity, and mechanism of cross-linking between COO^- and Fe³⁺ of the CMAX microgel was investigated. The CMAX microgel was used to be an oral protein drug carrier. The CMAX microgel particles exhibited a stable spherical structure. FT-IR spectral analysis of the CMAX microgel indicated that the microgel was crosslinked by bridging Fe³⁺ and COO^- with unidentate binding. The CMAX microgel exhibited good pH sensitivity and high stability in acid condition. Additionally, BSA was used as the embedding protein, and the controlled release effect of CMAX microgel was explored in gastrointestinal tract simulation.

Iron encapsulated microstructured gel beads using an emulsification-gelation technique for an alginate-caseinate matrix

Iron-deficiency anemia is an important health problem in global public issues, and development of iron fortifiers in diets is essential for the decrease of iron deficiency. However, there are problems for iron fortification in food because the common bioavailable iron compounds would contribute to iron-promoted lipid oxidation and unpleasant iron odor, presenting an adverse food quality. Ferrous fumarate loaded microstructured gel beads were prepared by an emulsification-gelation method using an alginate-caseinate matrix, and the gel network was formed by crosslinking of Ca²⁺ or Fe²⁺. Internal gelated beads showed relatively symmetrical and homogeneous spheres with no adhesion due to the simultaneous release of Fe²⁺ to initiate gelation in situ. External gelated beads displayed an irregular and adhesive structure, probably because the random contact between Na-ALG and Ca²⁺ occurred on the droplet surface, and the immediately gelated hardening layer provided a delay for further Ca²⁺ diffusion. The gel beads exhibited a lag phase in the promotion of lipid oxidation of the emulsion and restrained the iron odor release from ferrous fumarate. Ferrous ion release from microstructured gel beads in the simulated gastric juice was obviously delayed before a more progressive high release in the simulated intestinal juice, beneficial for iron absorption in the duodenum. The iron encapsulated microstructured gel beads might be developed as a promising safe iron fortifier by relieving lipid oxidation and iron odor.

Kinetic Study of Controlled Asphaltene Inhibitor Release from Nanoemulsions

Asphaltene aggregation and subsequent precipitation in the nonpolar medium may have a profound effect on plugging wellbores and production equipment. Continuing our work on controlled release of asphaltene inhibitor (AI) by using nanoemulsions (NEs), this work provides new evidence about long-term asphaltene stability by using optical measurement and reveals the kinetic processes of inhibitor transport/release mechanisms. Multiple light scattering (Turbiscan) and dynamic light scattering have been used to study "in situ" the effectiveness and performance of the proposed controlled release in three cases of asphaltene aggregation/precipitation in the presence of: (i) strong organic acids (dodecyl benzene sulfonic acid, DBSA), (ii) NEs (blank NEs), and (iii) NEs loaded with DBSA (DBSA NEs). The results suggested that the new approach reduced the amount of AI by ∼20 times and achieved high asphaltene inhibition efficiency of ∼84% with a prolonged release time. A mechanistic understanding of the controlled release effect was proposed based on the effect of DBSA NEs on the asphaltene particle morphology variation, which was related to the hydrophilicity of DBSA and the strong intermolecular interactions among all DBSA NE components. The release mechanism of the AI from the NE was evaluated using eight release models and was found to follow the Korsmeyer-Peppas kinetic model.

Encapsulation of Probiotics: Proper Selection of the Probiotic Strain and the Influence of Encapsulation Technology and Materials on the Viability of Encapsulated Microorganisms

Probiotic encapsulation is an entire system that not only involves but also depends on many factors. Elements such as the encapsulation method itself, materials, environmental conditions, and last, but not least, the strain; all play an important role in the encapsulation process. The current paper focuses on the right selection of probiotics, the various stress factors that impact the survival capacity of probiotics during and after encapsulation, and the rational selection of appropriate protection strategies to overcome these factors and achieve the highest possible encapsulation efficiency under optimal conditions. This review discusses the effects of temperature, moisture content, and water activity as well as pH, oxygen, and pressure on the viabilities of microorganisms. The effect of the surface and structure of the capsules on the encapsulated microorganisms and the impact of the materials used for the encapsulation are discussed as well. Last, but not least, the importance of choosing the right bacteria is reviewed.

Emulsion Cross-Linking Technique for Human Fibroblast Encapsulation

Microencapsulation with biodegradable polymers has potential application in drug and cell delivery systems and is currently used in probiotic delivery. In the present study, microcapsules of human fibroblast cells (CRL2522) were prepared by emulsion cross-linking technique. Tween 80 surfactant at a 2% concentration through phase inversion resulted in the most efficient and stable size, morphology, and the cells survival at least 50% on day 14. Emulsion cross-linking microcapsule preparation resulted in smaller and possibly more diverse particles that can be developed clinically to deliver encapsulated mammalian cells for future disease treatments.

Weissella paramesenteroides encapsulation and its application in the use of fish waste

The goal of the present study was to evaluate the encapsulation of Weissella paramesenteroides, isolated from bee bread, as a technological tool for its use in biological fish silage. The pH decrease in fish silages using the bacteria encapsulated and in a non-encapsulated form was compared. W. paramesenteroides showed a good performance in the development of biological fish silage. The alginate encapsulation method showed an encapsulation efficacy of 85% and provides a reliable technological application.

Soymilk residue (okara) as a natural immobilization carrier for Lactobacillus plantarum cells enhances soymilk fermentation, glucosidic isoflavone bioconversion, and cell survival under simulated gastric and intestinal conditions

Cell immobilization is an alternative to microencapsulation for the maintenance of cells in a liquid medium. However, artificial immobilization carriers are expensive and pose a high safety risk. Okara, a food-grade byproduct from soymilk production, is rich in prebiotics. Lactobacilli could provide health enhancing effects to the host. This study aimed to evaluate the potential of okara as a natural immobilizer for L. plantarum 70810 cells. The study also aimed to evaluate the effects of okara-immobilized L. plantarum 70810 cells (IL) on soymilk fermentation, glucosidic isoflavone bioconversion, and cell resistance to simulated gastric and intestinal stresses. Scanning electron microscopy (SEM) was used to show cells adherence to the surface of okara. Lactic acid, acetic acid and isoflavone analyses in unfermented and fermented soymilk were performed by HPLC with UV detection. Viability and growth kinetics of immobilized and free L. plantarum 70810 cells (FL) were followed during soymilk fermentation. Moreover, changes in pH, titrable acidity and viscosity were measured by conventional methods. For in vitro testing of simulated gastrointestinal resistance, fermented soymilk was inoculated with FL or IL and an aliquot incubated into acidic MRS broth which was conveniently prepared to simulate gastric, pancreatic juices and bile salts. Survival to simulated gastric and intestinal stresses was evaluated by plate count of colony forming units on MRS agar. SEM revealed that the lactobacilli cells attached and bound to the surface of okara. Compared with FL, IL exhibited a significantly higher specific growth rate, shorter lag phase of growth, higher productions of lactic and acetic acids, a faster decrease in pH and increase in titrable acidity, and a higher soymilk viscosity. Similarly, IL in soymilk showed higher productions of daizein and genistein compared with the control. Compared with FL, IL showed reinforced resistance to simulatedgastric and intestinal stresses in vitro that included low pH, low pH plus pepsin, pancreatin, and bile salt. Our results indicate that okara is a new potential immobilization carrier to enhance the growth and glucosidic isoflavone bioconversion activities of L. plantarum in soymilk and improve cell survivability following simulated gastric and intestinal conditions.

Effect of acidification on the protection of alginate-encapsulated probiotic based on emulsification/internal gelation

BACKGROUND

The method of emulsification/internal gelation is commonly used to prepare alginate microspheres for lactic acid bacteria (LAB). This paper focused on the influence of acidification parameters, i.e. acid/Ca molar ratio and acidification time, on the physical properties and cell protection efficiency of microspheres and their correlations.

RESULTS

With increasing acid/Ca molar ratio and acidification time, the average diameter of microspheres decreased and their mechanical strength increased. Interestingly, wet alginate microspheres shrank in simulated gastric juice (SGJ) while they swelled in bile salts solution (BS). The shrinkage or swelling ratio decreased with increasing mechanical strength. Correlation analysis showed that the encapsulated cell survivals in both SGJ and BS were positively correlated with the mechanical strength of microspheres but negatively with the shrinkage or swelling ratio. BacLight LIVE/DEAD assay suggested that the viability of encapsulated cells in fresh, SGJ-treated and BS-treated microspheres was closely related to cell membrane integrity.

CONCLUSION

Acidification is a key step during microsphere preparation, which strongly affected the physical properties of alginate microspheres, resulting in different cell protection efficiency. The resulting well-protected LAB can be applied in probiotics foods. © 2016 Society of Chemical Industry.

Use of Pistacia terebinthus resin as immobilization support for Lactobacillus casei cells and application in selected dairy products

Resin from Pistacia terebinthus tree was used for the immobilization of L. casei ATCC 393 cells. The encapsulated L. casei cells biocatalysts were added as adjuncts during yogurt production at 45 °C and probiotic viability was assessed during storage at 4 °C. For comparison reasons yogurt with free L. casei cells were prepared. The effect of encapsulated bacteria as adjuncts in yogurt on pH, lactic acid, lactose and other physicochemical parameters were studied for 60 storage days at 4 °C. Samples were also tested for the microbiological and organoleptic characteristics during storage at 4 °C. Encapsulation matrix seems to sustain the viability of embedded L. casei cells at levels more than 7 logcfug(-1) after 60 days of storage at 4 °C. Furthermore, the absence of pathogens such as Salmonella, Staphylococci, Enterobacteriaceae and coliforms in the produced yogurts is noteworthy where spoilage microorganisms such as yeasts and molds seem to affect yogurt quality only in absence of Pistacia terebinthus resin. The effect of the resin on production of aroma-related compounds responsible for yogurt flavor was also studied using the solid phase microextraction gas chromatography/mass spectrometry technique. Alpha and beta- pinene were the major aroma compounds detected in produced yogurts (over 60 % of total aromatic compounds detected). Yogurts with immobilized cells on P.terebintus resin had a fine aroma and taste characteristic of the resin.

Long-Term Retention of Small, Volatile Molecular Species within Metallic Microcapsules

Encapsulation and full retention of small molecular weight active ingredients is a challenging task that remains unsolved by current technologies used in industry and academia. In particular, certain everyday product formulations provide difficult environments in which preventing active leakage through capsule walls is not feasible. For example, a continuous phase that can fully dissolve an encapsulated active will typically force full release over a fraction of the intended lifetime of a product. This is due to the inherent porosity of polymeric membranes typically used as capsule wall material in current technologies. In this study, we demonstrate a method for preventing undesired loss of encapsulated actives under these extreme conditions using a simple threestep process. Our developed methodology, which forms an impermeable metal film around polymer microcapsules, prevents loss of small, volatile oils within an ethanol continuous phase for at least 21 days while polymeric capsules lose their entire content in less than 30 min under the same conditions. Polymer shell-oil core microcapsules are produced using a well-known cosolvent extraction method to precipitate a polymeric shell around the oil core. Subsequently, metallic catalytic nanoparticles are physically adsorbed onto the microcapsule polymeric shells. Finally, this nanoparticle coating is used to catalyze the growth of a secondary metallic film. Specifically, this work shows that it is possible to coat polymeric microcapsules containing a model oil system or a typical fragrance oil with a continuous metal shell. It also shows that the coverage of nanoparticles on the capsule surface can be controlled, which is paramount for obtaining a continuous impermeable metal film. In addition, control over the metal shell thickness is demonstrated without altering the capability of the metal film to retain the encapsulated oils.