P ectin-iron capsules: Novel system to stabilise and deliver lactic acid bacteria

Bioaccessibility of iron in developed pectin iron complex using Citrus limon Burm F. peels subjected to in-vitro gastro-pancreatic digestion

Pectin from the citrus peel waste has novel applications in food and biomedical industries. The present work focused on addressing iron deficiency, which is a global health concern, by developing a functional ingredient using pectin extracted from Assam lemon (Citrus limon Burm. F) and supplementing iron via the pectin‑iron complex (PIC). Extracted pectin was incubated with iron chloride hexahydrate (0.90-1.80 mM) for 180 h to optimize the complexation conditions, with the optimal concentration being 1.36 mM. The iron bioavailability and its absorption in the PIC was assessed using in-vitro simulation digestion and Caco-2 cell monolayers. The bioaccessible form of iron in the developed PIC during the intestinal phase was 5.34 ± 0.16%, which was negligible in pectin. The absorption of bioaccessible iron in the PIC was found to be 2.93 ± 0.03%. The results demonstrated that PIC could reduce iron deficiency and increase fibre intake, leading to several health benefits.

Investigation into pectin extraction and technological implementations in the food industry

Pectin, a complex polysaccharide found abundantly in the cell walls of fruits and vegetables, plays a pivotal role in various food applications owing to its unique gelling, thickening and stabilizing properties. As consumer preferences lean towards natural and sustainable ingredients, the demand for pectin as a food additive has surged. This burgeoning interest has prompted a comprehensive exploration into both the extraction methods of pectin from its natural sources and its diverse technological applications in the food industry. The extraction process involves breaking down the plant cell wall to release the pectin. Traditional methods such as hot acid extraction have been widely used, but advances in technology have spurred the development of novel techniques like enzyme-assisted extraction and microwave-assisted extraction. These methods aim not only to enhance the yield and purity of extracted pectin but also to minimize environmental impact and energy consumption. Pectin's versatility has positioned it as a valuable ingredient in the food industry. Its ability to form gels under specific conditions makes it a key component in the production of jams, jellies and fruit preserves. Additionally, pectin acts as a stabilizer in dairy products, prevents syneresis in baked goods and improves the texture of confectionery items. The application of pectin goes beyond its role as a gelling agent; it is also employed in the encapsulation of bioactive compounds, enhancing the functional properties of various food products. © 2024 Society of Chemical Industry.

Encapsulation of lactic acid bacteria in W1/O/W2 emulsions stabilized by mucilage:pectin complexes

Opuntia silvestri mucilage obtained from dried stems was explored as an emulsifier to prepare double emulsions aiming to encapsulate Lactiplantibacillus plantarum CIDCA 83114. W1/O/W2 emulsions were prepared using a two-step emulsification method. The aqueous phase (W1) consisted of L. plantarum CIDCA 83114, and the oil phase (O) of sunflower oil. The second emulsion was prepared by mixing the internal W1/O emulsion with the W2 phase, consisting of 4 % polysaccharides, formulated with different mucilage:(citric)pectin ratios. Their stability was assessed after preparation (day 0) and during storage at 4 °C (28 days). Determinations included creaming index, color, particle size, viscosity, turbidity, and bacterial viability, along with exposure to simulated gastrointestinal conditions. Significant differences were evaluated by analysis of variance (ANOVA) and Duncan's test (P < 0.05). After 28 days storage, bacterial viability in the W1/O/W2 emulsions was above 6 log CFU/mL for all the pectin:mucilage ratios. Emulsions containing mucilage and pectins showed lower creaming indices after 15 days, remaining stable until the end of the storage period. Formulations including 1:1 pectin:mucilage ratio exhibited the highest bacterial viability under simulated gastrointestinal conditions and were more homogeneous in terms of droplet size distributions at day 0, hinting at a synergistic effect between mucilage components (e.g., proteins, Ca2+) and pectin in stabilizing the emulsions. These results showed that Opuntia silvestri mucilage enhanced the stability of emulsions during refrigerated storage, highlighting its potential for encapsulating lactic acid bacteria. This presents an economical and natural alternative to traditional encapsulating materials.

Insights into the impact of modification methods on the structural characteristics and health functions of pectin: A comprehensive review

Pectin is a complex polysaccharide that is widely present in plant cells and has multiple physiological functions. However, most pectin exists in the form of protopectin, which has a large molecular weight and cannot be fully absorbed and utilized in the human gut to exert its effects. The significant differences in the structure of different sources of pectin also limited their application in the food and medical fields. In order to achieve greater development and utilization of pectin functions, this paper reviewed several commonly used methods for pectin modification from physical, chemical, and biological perspectives, and elaborated on the relationship between these modification methods and the structure and functional properties of pectin. At the same time, the functional characteristics of modified pectin and its application in medical health, such as regulating intestinal health, anticancer, anti-inflammatory, and drug transport, were reviewed, so as to provide a theoretical basis for targeted modification of pectin and the development of new modified pectin products.

Microfluidics potential for developing food-grade microstructures through emulsification processes and their application

The food sector continues to face challenges in developing techniques to increase the bioavailability of bioactive chemicals. Utilising microstructures capable of encapsulating diverse compounds has been proposed as a technological solution for their transport both in food and into the gastrointestinal tract. The present review discusses the primary elements that influence the emulsification process in microfluidic systems to form different microstructures for food applications. In microfluidic systems, reactions occur within small reaction channels (1-1000 μm), using small amounts of samples and reactants, ca. 102-103 times less than conventional assays. This geometry provides several advantages for emulsion and encapsulating structure production, like less waste generation, lower cost and gentle assays. Also, from a food application perspective, it allows the decrease in particle dispersion, resulting in a highly repeatable and efficient synthesis method that also improves the palatability of the food products into which the encapsulates are incorporated. However, it also entails some particular requirements. It is important to obtain a low Reynolds number (Re < approx. 250) for greater precision in droplet formation. Also, microfluidics requires fluid viscosity typically between 0.3 and 1400 mPa s at 20 °C. So, it is a challenge to find food-grade fluids that can operate at the micro-scale of these systems. Microfluidic systems can be used to synthesise different food-grade microstructures: microemulsions, solid lipid microparticles, microgels, or self-assembled structures like liposomes, niosomes, or polymersomes. Besides, microfluidics is particularly useful for accurately encapsulating bacterial cells to control their delivery and release on the action site. However, despite the significant advancement in these systems' development over the past several years, developing and implementing these systems on an industrial scale remains challenging for the food industry.

Recent advances in iron encapsulation and its application in food fortification

Iron (Fe) is an important element for our body since it takes part in a huge variety of metabolic processes. However, the direct incorporation of Fe into food fortification causes a number of problems along with undesirable organoleptic properties. Thus, encapsulation has been suggested to alleviate this problem. This study first sheds more light on the Fe encapsulation strategies and comprehensively explains the results of Fe encapsulation studies in the last decade. Then, the latest attempts to use Fe (in free or encapsulated forms) to fortify foods such as bakery products, dairy products, rice, lipid-containing foods, salt, fruit/vegetable-based products, and infant formula are presented. Double emulsions are highly effective at keeping their Fe content and display encapsulation efficiency (EE) > 88% although it decreases upon storage. The encapsulation by gel beads possesses several advantages including high EE, as well as reduced and great Fe release in gastric and duodenal conditions, respectively. Cereals, particularly bread and wheat, are common staple foods globally; they are very suitable for food fortification by Fe derivatives. Nevertheless, the majority of Fe in flour is available as salts of phytic acid (IP6) and phytates, reducing Fe bioavailability in the human body. The sourdough process degrades IP6 completely while Chorleywood Bread Making Process and conventional processes decrease it by 75% in comparison with whole meal flour.

Modification of pectin/starch-based beads with additives to improve Bacillus subtilis encapsulation for agricultural applications

The use of Bacillus as biofertilizer is a sustainable strategy to increase agricultural productivity, but it still requires the development of formulations to protect cells from stressful conditions. Ionotropic gelation using a pectin/starch matrix is a promising encapsulation strategy to achieve this goal. By incorporating additives such as montmorillonite (MMT), attapulgite (ATP), polyethylene glycol (PEG), and carboxymethyl cellulose (CMC), the properties of these encapsulated products could be further improved. In this study, we investigated the influence of these additives on the properties of pectin/starch-based beads for the encapsulation of Bacillus subtilis. FTIR analysis indicated pectin and Ca2+ ions interactions, while the XRD showed good dispersion of clays in the materials. SEM and X-ray microtomography revealed differences in the morphology of the beads due to the use of the additives. The viabilities at the encapsulation were higher than 1010 CFU g-1 for all formulations, with differences in the release profiles. In terms of cell protection, the pectin/starch, pectin/starch-MMT and pectin/starch-CMC formulations showed the highest cell viability after exposure to fungicide, while the pectin/starch-ATP beads showed the best performance after UV exposure. Moreover, all formulations maintained more than 109 CFU g-1 after six months of storage, which meets values required for microbial inoculants.

Controlled release of Lactiplantibacillus plantarum by colon-targeted adhesive pectin microspheres: Effects of pectin methyl esterification degrees

The aim of this study is to report the preparation of pectin microspheres by varying degrees of methyl esterification (DM) cross-linked with divalent cationic calcium to encapsulate Lactiplantibacillus plantarum STB1 and L. plantarum LJ1, respectively. Scanning electron microscopy revealed the compact and smooth surface of pectin of DM 28 %, and the stochastic distribution of L. plantarum throughout the gel reticulation. And the pectin of DM 28 % considerably increased probiotics tolerance after continuous exposure to stimulated gastrointestinal tract conditions, with viable counts exceeding 10⁹ CFU/mL. This data indicated that low methoxy-esterification pectin was more efficient to improve the targeted delivery of probiotics in GIT. Additionally, the controlled release of microspheres was dependent on various pH levels. At pH 7.4, the release rates of L. plantarum STB1 and L. plantarum LJ1 reached up to 97.63 % and 95.33 %, respectively. Finally, the Caco-2 cell adhesion model was used to evaluate the cell adhesion rate after encapsulation, which exhibited better adhesion at DM of 60 %.

Effect of the molecular structure and mechanical properties of plant-based hydrogels in food systems to deliver probiotics: an updated review

Probiotic products' economic value and market popularity have grown over time as more people discover their health advantages and adopt healthier lifestyles. There is a significant societal and cultural interest in these products known as foods or medicines. Products containing probiotics that claim to provide health advantages must maintain a "minimum therapeutic" level (107-106 CFU/g) of bacteria during their entire shelf lives. Since probiotic bacteria are susceptible to degradation and reduction by physical and chemical conditions (including acidity, natural antimicrobial agents, nutrient contents, redox potential, temperature, water activity, the existence of other bacteria, and sensitivity to metabolites), the most challenging problem for a food manufacturer is ensuring probiotic cells' survival and stability enhancement throughout the manufacturing stage. Currently, the use of plant-based hydrogels for improved and targeted probiotic delivery has gained substantial attention as a potential approach to overcoming the mentioned restrictions. To achieve the best possible results from hydrogels, whether used as a coating for encapsulated probiotics (with the goal of stomach protection) or as carriers for direct encapsulation of live microorganisms should be applied kind of procedures that ensure high bacterial survival during hydrogels application. This paper summarizes polysaccharides, proteins, and lipid-based hydrogels as carriers of encapsulated probiotics in delivery systems, reviews their structures, analyzes their advantages and disadvantages, studies their mechanical characteristics, and draws comparisons between them. The discussion then turns to how the criterion affects encapsulation, applications, and future possibilities.

AI-2E Family Transporter Protein in Lactobacillus acidophilus Exhibits AI-2 Exporter Activity and Relate With Intestinal Juice Resistance of the Strain

The function of the autoinducer-2 exporters (AI-2E) family transporter protein of Lactobacillus acidophilus is still unclear. The phylogenetic analysis was used to analyze the relationship between the AI-2E protein of the L. acidophilus CICC 6074 strain and other AI-2E family members. Escherichia coli KNabc strain was used to verify whether the protein has Na⁺ (Li⁺)/H⁺ antiporter activity. The AI-2E protein overexpression strain was constructed by using the pMG36e expression vector, and the overexpression efficiency was determined by real-time quantitative PCR. The vitality and AI-2 activity of L. acidophilus CICC 6074 strains were determined. The results showed that the AI-2E protein of Lactobacillus formed a single branch on the phylogenetic tree and was closer to the AI-2E family members whose function was AI-2 exporter group I. The expression of AI-2E protein in the E. coli KNabc strain did not recover the resistance of the bacteria to the saline environment. Overexpression of AI-2E protein in L. acidophilus CICC 6074 could promote the AI-2 secretion of L. acidophilus CICC 6074 strain and enhance their survival ability in intestinal juice.

Novel Developments on Stimuli-Responsive Probiotic Encapsulates: From Smart Hydrogels to Nanostructured Platforms

Biomaterials engineering and biotechnology have advanced significantly towards probiotic encapsulation with encouraging results in assuring sufficient bioactivity. However, some major challenges remain to be addressed, and these include maintaining stability in different compartments of the gastrointestinal tract (GIT), favoring adhesion only at the site of action, and increasing residence times. An alternative to addressing such challenges is to manufacture encapsulates with stimuli-responsive polymers, such that controlled release is achievable by incorporating moieties that respond to chemical and physical stimuli present along the GIT. This review highlights, therefore, such emerging delivery matrices going from a comprehensive description of addressable stimuli in each GIT compartment to novel synthesis and functionalization techniques to currently employed materials used for probiotic’s encapsulation and achieving multi-modal delivery and multi-stimuli responses. Next, we explored the routes for encapsulates design to enhance their performance in terms of degradation kinetics, adsorption, and mucus and gut microbiome interactions. Finally, we present the clinical perspectives of implementing novel probiotics and the challenges to assure scalability and cost-effectiveness, prerequisites for an eventual niche market penetration.

Dietary pectic substances enhance gut health by its polycomponent: A review

Pectic substances, one of the cell wall polysaccharides, exist widespread in vegetables and fruits. A surge of recent research has revealed that pectic substances can inhibit gut inflammation and relieve inflammatory bowel disease symptoms. However, physiological functions of pectins are strongly structure dependent. Pectic substances are essentially heteropolysaccharides composed of homogalacturonan and rhamnogalacturonan backbones substituted by various neutral sugar sidechains. Subtle changes in the architecture of pectic substances may remarkably influence the nutritional function of gut microbiota and the host homeostasis of immune system. In this context, developing a structure-function understanding of how pectic substances have an impact on an inflammatory bowel is of primary importance for diet therapy and new drugs. Therefore, the present review has summarized the polycomponent nature of pectic substances, the activities of different pectic polymers, the effects of molecular characteristics and the underlying mechanisms of pectic substances. The immunomodulated property of pectic substances depends on not only the chemical composition but also the physical structure characteristics, such as molecular weight (M_w ) and chain conformation. The potential mechanisms by which pectic substances exert their protective effects are mainly reversing the disordered gut microbiota, regulating immune cells, enhancing barrier function, and inhibiting pathogen adhesion. The manipulation of pectic substances on gut health is sophisticated, and the link between structural specificity of pectins and selective regulation needs further exploration.

Synthesis and Characterization of a Novel Apple Pectin-Fe(III) Complex

In the present study, apple pectin (AP) extracted from apple pomace was used to chelate with Fe(III) to synthesize an AP-Fe(III) complex. The obtained AP-Fe(III) complex was characterized by UV-vis spectroscopy, FTIR, XPS, and TG analysis. The Fe content in the AP-Fe(III) complex was determined to be 24.5%. Moreover, the reduction properties of the complex were also investigated. The AP-Fe(III) complex was found to be soluble in water and maintained stability in the pH range of 3-8. The complex was reduced to Fe(II) after 6 h. In addition, the AP-Fe(III) complex did not release iron ions in the simulated gastric fluid, and Fe release of the complex reached 96.5% after 4 h of digestion in simulated intestinal fluid. In particular, the antioxidant activity of the AP-Fe(III) complex against free DPPH and ABTS radicals was evaluated. The results obtained in this study demonstrate the potential of the AP-Fe(III) complex as a novel iron supplement.

Microencapsulation of Lactobacillus plantarum in W/O emulsions of okara oil and block-copolymers of poly(acrylic acid) and pluronic using microfluidic devices

Okara oil is a by-product remaining from defatting okara, the solid residue generated after extracting the aqueous fraction of grounded soybeans in the elaboration of soy beverages. The goal of this work was to encapsulate the probiotic Lactobacillus plantarum CIDCA 83114 into W/O emulsions composed of a block-copolymer constituted of pluronic® and acrylic acid (PPP12) and okara oil, prepared in microfluidic devices. For comparative purposes, alginate was also included as a second dispersed phase. Lactobacillus plantarum CIDCA 83114 was suspended in PPP12 or alginate giving rise to dispersed phases with different compositions, named I, II, III and IV. Controls were prepared by suspending microorganisms in water as dispersed phase. 6-carboxyfluorescein was added as bacterial marker in all the emulsions. The presence of green dyed bacteria in the dispersed phases, inside the droplets of the emulsions and the absence of fluorescence outside them, confirmed the complete encapsulation of bacteria in the dispersed phases. After being prepared, emulsions were freeze-dried. The exposure to gastric conditions did not lead to significant differences among the emulsions containing polymers. However, in all cases bacterial counts were significantly lower than those of the control. After exposing emulsions to the simulated intestinal environment, bacterial counts in assays I, II and III (emulsions composed of only one dispersed phase or of two dispersed phases with bacteria resuspended in the PPP12 one) were significantly greater than those of the control (p < 0.05) and no detectable microorganisms were observed for assay IV (emulsions composed of two dispersed phases with bacteria resuspended in the alginate one). In particular, bacterial cultivability in emulsions corresponding to assay I (only PPP12 as dispersed phase) exposed to the intestinal environment was 8.22 ± 0.02 log CFU/mL (2 log CFU higher than the values obtained after gastric digestion). These results support the role of PPP12 as an adequate co-polymer to protect probiotics from the gastric environment, enabling their release in the gut, with great potential for food or nutraceutical applications.

Pectin Hydrolysates from Different Cultivars of Pink/Red and White Grapefruits (Citrus Paradisi [macf.]) as Culture and Encapsulating Media for Lactobacillus Plantarum

Citrus pectin hydrolysates (Citrus paradisi [Mafc.]) from "Foster," "Red Shambar," "Tangelo Orlando," and "Citrumelo Swingle" cultivars were obtained by partial chemical hydrolysis and their properties as culture media (sole carbon/nutrient source) and encapsulating agents of Lactobacillus plantarum CIDCA 83114 were evaluated. The concentration of neutral sugars was maximal after 2-hour hydrolysis. All hydrolysates were rich in glucose >xylose >galactose >galacturonic acid >mannose >arabinose. "Citrumelo Swingle" cultivar was the one with the highest concentration of xylose. After 24 hr of fermentation with L. plantarum CIDCA 83114, bacterial viability increased from 6.76 ± 0.14 to almost 9 log CFU/mL, and lactic acid concentration, from 2.63 ± 0.41 to 7.82 ± 0.15 mmol/L in all hydrolysates. Afterwards, bacteria were entrapped in pectate-calcium beads by ionotropic gelation. Bacterial viability did not significantly decrease after freeze-drying and storage the beads at 4 °C for 45 days. PRACTICAL APPLICATION: Pectin hydrolysates were adequate culture media for microorganisms, as determined by the viabililty and lactic acid production. Considering that citrus peels are agro-wastes obtained in large quantities, their use as encapsulating materials provides a solution to overcome the environmental problem they entail.

Pectin-decorated magnetite nanoparticles as both iron delivery systems and protective matrices for probiotic bacteria

The goal of this work was to investigate biophysical stability of iron-pectin nanoparticles and analyze the feasibility of using them as delivery systems for the probiotic strain Lactobacillus plantarum CIDCA 83114. Iron oxide (Fe₃O₄) nanoparticles were synthesized from 0.25M FeCl₂/0.5 M FeCl₃.6H₂O, and coated with citrus pectins. Their physico-chemical properties [FTIR, X-ray diffraction (XRD), ζ-potential, particle size, SEM, TEM] and their effect on bacterial stabilization (viability after freeze-drying/storage, stability when exposed to simulated gastro-intestinal conditions) were assessed. XRD indicated the almost exclusive presence of magnetite crystalline phases. FTIR spectra confirmed the adsorption of pectin on magnetite nanoparticles surface. SEM and TEM images evidenced agglomerated nanoparticles, and a morphological surface change after adsorption of pectin. DLS and ζ-potential results proved the solvation of the ionizable groups in the hydrophilic network which induced chain expansion and agglomeration. Iron from nanoparticles demonstrated to be non-toxic for microorganisms up to 1.00 mg/mL. Simulated saliva and gastric solutions prevented nanoparticles from dissolution. The higher pH of the intestinal conditions (solvated -COO- and Fe-O- groups) facilitated the dispersion and partial dissolution of nanoparticles. Pectins adsorption on magnetite nanoparticles significantly enhanced electrostatic repulsion, which aided the solvation of ionized iron forms. The soluble species diffused out from the aggregates, being detected in the simulated intestinal fluid. Regarding bacterial viability, no decays were observed neither when pectin-decorated nanoparticles were exposed to simulated fluids nor when stored at 4 °C for 60 days. The composites engineered in this work appear as adequate delivery systems for probiotic bacteria, whose target is the gut.