Physical Properties and Stabilization of Microcapsules Containing Thyme Oil by Complex Coacervation

Preparation and characterization of vitamin A microcapsules nutrient fortified salt

Vitamin A, also known as retinol, is a fat-soluble vitamin that plays crucial role in various physiological functions In vivo. However, factors such as light, oxygen, and others may impact the stability of VA. To enhance its stability. This study microencapsulated VA, Gelatin, carboxymethyl cellulose, and salt were mixed in a ratio of 5:1:0.1 as the shell material. Additionally, 12% TG and 3.5% sucrose ester were added with core-shell ratio of 1:8. The experimental results indicated that VA microcapsules exhibited an encapsulation efficiency of 81.12%, after 9 weeks of storage this rate decreased to 75.38%, and the encapsulated VA oil did not exhibit extravasation. The addition of an appropriate amount of salt to the shell material enhanced the mechanical properties of the shell material, compared to the shell material without added salt, the leakage of VA in the salt-added sample decreased by 5.8% for 30 min and 14.5% for 60 min. In vitro release experiments showed that after 3 h of incubation in simulated gastric fluid, the microcapsules had an 18.52% release rate. In simulated intestinal fluid, this increased to 66.58%, indicating strong enteric solubility.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05962-w.

Insight on Incorporation of Essential Oils as Antimicrobial Substances in Biopolymer-Based Active Packaging

The increasing interest in microbiological food safety requires the development of sensitive and reliable analyses and technologies for preserving food products' freshness and quality. Different types of packaging systems are one of the solutions for controlling microbiological activity in foods. During the last decades, the development of biopolymer-based active packaging with essential oil incorporation systems has resulted in technologies with exceptional application potential, primarily in the food industry. There is no doubt that this principle can facilitate food status monitoring, reduce food waste, extend the shelf life, improve the overall quality of food, or indicate a larger problem during the storage, production, and distribution of foodstuffs. On the other hand, most antimicrobial packaging systems are in the development phase, while the sensitivity, selectivity, complexity, and, above all, safety of these materials are just some of the essential questions that need to be answered before they can be widely used. The incorporation of essential oils as antimicrobial substances in biopolymer-based active packaging holds significant promise for enhancing food safety, extending shelf life, and offering more sustainable packaging solutions. While challenges exist, ongoing research and innovation in this field are likely to lead to the development of effective and environmentally friendly packaging systems with enhanced antimicrobial properties.

Colloidal carriers of almond gum/gelatin coacervates for rosemary essential oil: Characterization and in-vitro cytotoxicity

The potential of almond gum and gelatin complex coacervates as a colloidal carrier for rosemary essential oil (REO) was investigated along with in-vitro gastrointestinal release and cytotoxicity. The optimum formulation (1 gelatin:2 almond gum and 7% (w/w) REO) was selected based on encapsulation efficiency (43.6%) and encapsulation yield (99.3%). The particle size was 6.9 µm with a high negative zeta-potential (-37.3 mV). FTIR and XRD data revealed that REO was properly loaded within carriers and there were interactions between gelatin and almond gum. Thermal stability of REO was enhanced after complex coacervation according to TGA. REO released slowly from carriers under simulated gastrointestinal fluid. Cytotoxicity of pure REO and REO-loaded complexes was evaluated on 4 T1 cell lines. Encapsulation of REO caused a reduction in toxicity. Overall, coacervates of gelatin-almond gum could be a promising carrier to enhance the application of bioactives in the food and drug industry with low toxicity.

Encapsulation of volatile compounds in liquid media: Fragrances, flavors, and essential oils in commercial formulations

The first marketed example of the application of microcapsules dates back to 1957. Since then, microencapsulation techniques and knowledge have progressed in a plethora of technological fields, and efforts have been directed toward the design of progressively more efficient carriers. The protection of payloads from the exposure to unfavorable environments indeed grants enhanced efficacy, safety, and stability of encapsulated species while allowing for a fine tuning of their release profile and longer lasting beneficial effects. Perfumes or, more generally, active-loaded microcapsules are nowadays present in a very large number of consumer products. Commercial products currently make use of rigid, stable polymer-based microcapsules with excellent release properties. However, this type of microcapsules does not meet certain sustainability requirements such as biocompatibility and biodegradability: the leaking via wastewater contributes to the alarming phenomenon of microplastic pollution with about 4% of total microplastic in the environment. Therefore, there is a need to address new issues which have been emerging in relation to the poor environmental profile of such materials. The progresses in some of the main application fields of microencapsulation, such as household care, toiletries, cosmetics, food, and pesticides are reviewed herein. The main technologies employed in microcapsules production and the mechanisms underlying the release of actives are also discussed. Both the advantages and disadvantages of every technique have been considered to allow a careful choice of the most suitable technique for a specific target application and prepare the ground for novel ideas and approaches for encapsulation strategies that we expect to be proposed within the next years.

Development of New Formula Microcapsules from Nutmeg Essential Oil Using Sucrose Esters and Magnesium Aluminometasilicate

Essential oils are volatile liquids which evaporate and lose their pharmacological effect when exposed to the environment. The aim of this study is to protect nutmeg essential oil from environmental factors by encapsulation (shell material, sodium alginate) and determine the influence of crosslinker concentration (2%, 5% calcium chloride), different emulsifiers (polysorbate 80, sucrose esters), and magnesium aluminometasilicate on microcapsule physical parameters, encapsulation efficiency (EE), swelling index (SI), and other parameters. Nutmeg essential oil (NEO)-loaded calcium alginate microcapsules were prepared by extrusion. The swelling test was performed with and without enzymes in simulated gastric, intestinal, and gastrointestinal media. This study shows that the crosslinker concentration has a significant influence on EE, with 2% calcium chloride solution being more effective than 5%, and capsules being softer with 2% crosslinker solution. Using sucrose esters, EE is higher when polysorbate 80 is used. The swelling index is nearly three times higher in an intestinal medium without enzymes than in the medium with pancreatin. Microcapsule physical parameters depend on the excipients: the hardest capsules were obtained with the biggest amount of sodium alginate; the largest with magnesium aluminometasilicate. Sucrose esters and magnesium aluminometasilicate are new materials used in extrusion.

Antimicrobial potential of spray drying encapsulated thyme (Thymus vulgaris) essential oil on the conservation of hamburger-like meat products

Synthetic preservatives can have harmful effects on the body, so plant essential oils appear to be an attractive natural alternative. However, the use of essential oils is limited due to the low stability and possible negative effects on the sensory properties of food. Oil encapsulation was suggested as a way to overcome these drawbacks. The objective of this study was to encapsulate thyme essential oil and to evaluate its antioxidant and antimicrobial potential in vitro and in situ in of hamburger-like meat products. The casein-maltodextrin capsules produced by spray-drying were assessed for encapsulation efficiency, thermal stability, chemical compounds and morphology. Antioxidant activity was evaluated by DPPH, hydroxyl and nitric oxide methods, while antimicrobial activity was evaluated in vitro against four bacteria and in situ in hamburger-like products. The capsule showed high encapsulation efficiency and thermal stability, and spherical and irregular morphology. The casein-maltodextrin encapsulated essential oil showed antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Listeria monocytogenes and Salmonella Typhimurium tested in vitro and against thermotolerants coliforms and Escherichia coli in situ, showing potential for application as a natural preservative in food.

Controllable synthesis of three-dimensional nitrogen-doped hierarchical porous carbon and its application in the detection of lead

In this study, gelatin-based microcapsules were first proposed as a carbon source for the synthesis of nitrogen-doped hierarchical porous carbon (N-HPC) via a facile one-pot high-temperature treatment. The morphologies of the microcapsules could be well controlled by adjusting the synthesis parameters; this ensured the repeatability of the calcined products. The as-prepared N-HPC possesses a favorable three-dimensional network structure and hierarchical porous structure. As a promising modified electrode, N-HPC displayed remarkably improved stability and sensitivity for lead ion (Pb²⁺) detection. Moreover, two factors are responsible for the good analytical performance: (i) the morphologies of the microcapsules are controllable and reproducible; this improves the detection stability; and (ii) the nitrogen atoms in the shells of the microcapsules can efficiently interact with Pb²⁺; this enhances the detection sensitivity. The influences of various experimental parameters, including the pH value of the supporting electrolyte, deposition potential and deposition time, on the stripping signal of Pb²⁺ were investigated. The method displayed a wide linear range of the Pb²⁺ concentration from 7 nM to 7000 nM with the detection limit of 1.44 nM under the optimized conditions. The modified electrode possessed high selectivity, which might be due to the high binding affinity of the NH₂ ^- groups to Pb²⁺. The developed method has been successfully applied to the detection of Pb²⁺ in actual water samples; this demonstrates that the N-HPC-based electrochemical sensors have prospective applications in the environmental monitoring of Pb²⁺.

Controlled Release Mechanism and Antibacterial Effect of Layer-By-Layer Self-Assembly Thyme Oil Microcapsule

Thyme essential oil-loaded microcapsules (TMS) were fabricated using natural polysaccharide chitosan (CS) and sodium alginate (SA) as the shell material via the method of layer-by-layer (LBL) assembly. The accumulated release rates of thyme oil and microcapsules at 4 °C were 42.50% and 10.16%, respectively. After heating at 100 °C for 5 hr, the release rate of the 0, 2, 4, 6 layers assembled microcapsules were 100%, 48.84%, 28.38%, 19.3%, severally. Microcapsules also had good pH sensitivity in the range of 4 to 10. Antimicrobial function studies showed that the microcapsules are more effective than thyme oil for three tested microorganisms. When the temperature rose from 37 °C to 121 °C, the antibacterial zone of thyme oil gradually decreased from 18.5 ± 0.6 mm to 12.3 ± 0.6 mm, although inhibition rate of microcapsules increased from 87.97% to 99.75%. The antibacterial effect of thyme oil declined with the increase of pH, in terms of microcapsules, the efficiency was better under acidic or alkaline conditions. The thyme oil microcapsules can suppress the growth of Staphylococcus aureus in milk and prolong its shelf life. It was determined that this microcapsule could be a potential alternative as a natural antimicrobial agent in food and pharmaceutical industries. PRACTICAL APPLICATION: This work provided release performance and mechanism of layer-by-layer (LBL) thyme oil microcapsule under different conditions, and further studies showed its antibacterial ability to explore how herb essential oils can be potentially applied in food packaging and antibacterial areas.

Complex Coacervation Between Gelatin and Chia Mucilage as an Alternative of Encapsulating Agents

Complex coacervation between gelatin type B (GE) and chia mucilage (ChM) was studied. GE-ChM were mixed at mass ratios of 1:1, 2:1, 3:1, 4:1, and 1:2 in a pH range of 1.50 to 5.00, maintaining a total solid concentration of 0.2% (w/w), using turbidity and viscosity tests to obtain the highest yield of complex coacervates. To characterize the complex coacervates, morphology and Fourier-transform infrared spectroscopy (FTIR) were determined. The optimum yield for complex coacervation was achieved with a GE-ChM mass ratio of 2:1 and pH value of 3.6. The critical pH values associated with the formation of soluble (pH_c ) and insoluble (pH_ɸ1 ) complexes, and complete dissociation (pH_ɸ2 ) at the optimum GE-ChM ratio were found to be 4.50, 4.10, and 2.00, respectively. It was observed that increasing the mass ratio of GE or ChM, the yield of complex coacervates decreased; the higher yields were obtained with the proportions of 2:1 and 1:1 with values of 68.25 ± 0.05% and 61.04 ± 0.05%, respectively. Capsules formed at mass ratios of 1:1, 2:1, and 3:1, had the characteristic grape agglomerate shape for complex coacervates. Further characterization with scanning electron microscopy (SEM) showed a spherical shape for capsules. FTIR spectrum of complex coacervates at optimum conditions had a combination of bands corresponding to GE and ChM, suggesting an interaction between GE-ChM during the formation of complex coacervates. Therefore, complex coacervates between GE-ChM can be formed, and could be used as an alternative as encapsulating agents to be applied in the food industry. PRACTICAL APPLICATION: Complex coacervation is a technique that is being studied in several applications in the food industry. However, studies are still being made to explore different possibilities of natural sources to be used in complex coacervation. This study showed that the combination of gelatin and chia mucilage may be an alternative as encapsulating agents for complex coacervation to be applied in the food industry.