Essential oils microencapsulated obtained by spray drying: a review

Microencapsulation to Harness the Antimicrobial Potential of Essential Oils and Their Applicability in Dairy Products: A Comprehensive Review of the Literature

This literature review explores cutting-edge microencapsulation techniques designed to enhance the antimicrobial efficacy of essential oils in dairy products. As consumer demand for natural preservatives rises, understanding the latest advancements in microencapsulation becomes crucial for improving the shelf life and safety of these products. The bibliometric analysis utilized in this review highlighted a large number of documents published on this topic in relation to the following keywords: essential oils, AND antimicrobials, AND dairy products, OR microencapsulation. The documents published in the last 11 years, between 2013 and 2023, showed a diversity of authors and countries researching this topic and the keywords commonly used. However, in the literature consulted, no study was identified that was based on bibliometric analysis and that critically evaluated the microencapsulation of essential oils and their antimicrobial potential in dairy products. This review synthesizes findings from diverse studies, shedding light on the various encapsulation methods employed and their impact on preserving the quality of dairy goods. Additionally, it discusses the potential applications and challenges associated with implementation in the dairy industry. This comprehensive analysis aims to provide valuable insights for researchers, food scientists, and industry professionals seeking to optimize the use of essential oils with antimicrobial properties in dairy formulations.

Microencapsulated essential oils alleviate diarrhea in weaned piglets by modulating the intestinal microbial barrier as well as not inducing antibiotic resistance: a field research

Microencapsulated essential oils (MEO)have been used as antibiotic alternatives that can be applied to alleviate diarrhea in weaning piglet. We examined a large group of weaned piglets and incorporated essential oil containing thymol (2%), carvacrol (5%) and cinnamaldehyde (3%) in the feed of weaned piglets on an intensive production farm. The piglets were divided into four groups; Control (no additions) and chlortetracycline (Chl), essential oil (EO) and microencapsulated essential oil (MEO) were fed ad libitum over a 28-day trial period. We found MEO significantly reduced the incidence of diarrhea in the piglets that was also accompanied by increased average daily weight gains from days 14-28 (p < 0.05). MEO enhanced the antioxidant capacity in the piglets and serum total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-px) levels were significantly increased (p < 0.05). MEO also significantly reduced expression of genes related to ileal inflammation (IL-6, TNF-α and TGF-β1) (p < 0.05) and significantly (p < 0.05) increased in sIgA antibody levels. MEO influenced the composition of the intestinal microbiome and reduced Bacteroidota (p < 0.05) and thus altered the Firmicutes/Bacteroidota ratio. However, none of the treatments produced significant changes in the most common tetracycline resistance genes (p > 0.05). Metagenomic analysis indicated that MEO impacted DNA expression, virulence factors, antioxidant activity and antimicrobial activity. Metabolomic analysis of the intestinal content also indicated that MEO impacted tyrosine metabolism and primary bile acid biosynthesis suggesting improved intestinal health and nutrient absorption. This study paves the way for further research into the development and optimization of MEO-based interventions aimed at improving piglet health and performance while also providing a reference for reducing reliance on antibiotics in animal agriculture.

Insights from Syzygium aromaticum Essential Oil: Encapsulation, Characterization, and Antioxidant Activity

Alginate encapsulates loaded with clove essential oil (CEO) were prepared by ionic gelation, with subsequent freeze-drying. The objective of the present work was to develop a product with the ability to protect CEO against its easy volatility and oxidation. The following techniques were used to characterize the formulations: eugenol release, degree of swelling, GC/MS, TGA/DSC, and SEM. The alginate solution (1.0%) containing different concentrations of CEO (LF1: 1.0%; LF2: 0.5%; LF3: 0.1%) was dropped into a 3.0% CaCl2 solution. After lyophilization, the encapsulated samples were wrinkled and rigid, with high encapsulation power (LF3: 76.9% ± 0.5). Three chemical components were identified: eugenol (the major one), caryophyllene, and humulene. The antioxidant power (LF1: DPPH IC50 18.1 µg mL-1) was consistent with the phenol content (LF1: 172.2 mg GAE g-1). The encapsulated ones were thermally stable, as shown by analysis of FTIR peaks, eugenol molecular structure was kept unaltered. The degree of swelling was 19.2% (PBS). The release of eugenol (92.5%) in the PBS solution was faster than in the acidic medium. It was concluded that the low-cost technology used allows the maintenance of the content and characteristics of CEO in the three concentrations tested, offering a basis for further research with essential oil encapsulates.

Encapsulation and delivery systems of cinnamon essential oil for food preservation applications

Food safety threats and deterioration due to the invasion of microorganisms has led to economic losses and food-borne diseases in the food industry; so, development of natural food preservatives is urgently needed when considering the safety of chemically synthesized preservatives. Because of its outstanding antioxidant and antibacterial properties, cinnamon essential oil (CEO) is considered a promising natural preservative. However, CEO's low solubility and easy degradability limits its application in food products. Therefore, some encapsulation and delivery systems have been developed to improve CEO efficiency in food preservation applications. This work discusses the chemical and techno-functional properties of CEO, including its key components and antioxidant/antibacterial properties, and summarizes recent developments on encapsulation and delivery systems for CEO in food preservation applications. Since CEO is currently added to most biopolymeric films/coatings (BFCs) for food preservation, most studies have shown that encapsulation systems can improve the food preservation performance of BFCs containing CEOs. It has been confirmed that various delivery systems could improve the stability and controlled-release properties of CEO, thereby enhancing its ability to extend the shelf life of foods. These encapsulation techniques include spray drying, emulsion systems, complex coacervation (nanoprecipitation), ionic gelation, liposomes, inclusion complexation (cyclodextrins, silica), and electrospinning.

Application of Physical-Chemical Approaches for Encapsulation of Active Substances in Pharmaceutical and Food Industries

BACKGROUND

Encapsulation is a valuable method used to protect active substances and enhance their physico-chemical properties. It can also be used as protection from unpleasant scents and flavors or adverse environmental conditions.

METHODS

In this comprehensive review, we highlight the methods commonly utilized in the food and pharmaceutical industries, along with recent applications of these methods.

RESULTS

Through an analysis of numerous articles published in the last decade, we summarize the key methods and physico-chemical properties that are frequently considered with encapsulation techniques.

CONCLUSION

Encapsulation has demonstrated effectiveness and versatility in multiple industries, such as food, nutraceutical, and pharmaceuticals. Moreover, the selection of appropriate encapsulation methods is critical for the effective encapsulation of specific active compounds. Therefore, constant efforts are being made to develop novel encapsulation methods and coating materials for better encapsulation efficiency and to improve properties for specific use.

Recent Advances in the Microencapsulation of Essential Oils, Lipids, and Compound Lipids through Spray Drying: A Review

In recent decades, the microcapsules of lipids, compound lipids, and essential oils, have found numerous potential practical applications in food, textiles, agricultural products, as well as pharmaceuticals. This article discusses the encapsulation of fat-soluble vitamins, essential oils, polyunsaturated fatty acids, and structured lipids. Consequently, the compiled information establishes the criteria to better select encapsulating agents as well as combinations of encapsulating agents best suited to the types of active ingredient to be encapsulated. This review shows a trend towards applications in food and pharmacology as well as the increase in research related to microencapsulation by the spray drying of vitamins A and E, as well as fish oil, thanks to its contribution of omega 3 and omega 6. There is also an increase in articles in which spray drying is combined with other encapsulation techniques, or modifications to the conventional spray drying system.

Encapsulation of Origanum onites essential oil with different wall material using spray drying

INTRODUCTION

Origanum onites has antibacterial, antifungal, and antioxidant properties due to its essential oil. The fact that these oils are sensitive to environmental conditions causes the need for advanced processing technologies.

OBJECTIVE

This study was aimed to encapsulate essential oil of O. onites by spray drying to extend its shelf life.

METHODS

Spray drying was used to encapsulate the essential oil of O. onites, which was then mixed with maltodextrin, arabic gum, and β-cyclodextrin using response surface methodology. After 60 days of storage, aroma analysis was performed on the essential oil of O. onites and the essential oil powder that was produced under ideal conditions.

RESULTS

O. onites essential oil powder was subjected to GC-MS analysis to identify 72 aroma components. Carvacrol and linalool concentrations varied from 22.66 to 30.11 mg/g and from 32.25 to 53.57 mg/g, respectively. The spray-dried microcapsules' D_4.3 values ranged from 40.75 to 48.95 μm. For every trial, the drying yield and solubility values were higher than 60% and 90%, respectively. The results of the surface optimization showed that the ideal inlet air temperature was 190°C and the ideal concentration of β-cyclodextrin in the wall material was 1%.

CONCLUSION

The findings indicate that O. onites essential oil was successfully encapsulated via spray drying. The preservation of critical aroma compounds in the resulting capsules is high.

Nutmeg Essential Oil, Red Clover, and Liquorice Extracts Microencapsulation Method Selection for the Release of Active Compounds from Gel Tablets of Different Bases

The current study presents the most suitable method for encapsulating nutmeg essential oil with liquorice and red clover. Two widely used methods, spray-drying and freeze-drying, were employed to find the most suitable for essential oil volatile compounds’ protection. Results showed that freeze-dried capsules (LM) had a higher yield (85.34%) compared to the exact formulation of spray-dried microcapsules (SDM)—45.12%. All the antioxidant and total phenolic compounds’ results obtained with the LM sample were significantly higher compared with SDM. LM microcapsules were incorporated in two different bases with no additional sugar (gelatin and pectin) for targeted release. Pectin tablets had firmer and harder texture properties, while gelatin tablets had a more elastic texture. There was a significant impact on texture changes caused by microcapsules. Microencapsulated essential oil with extracts can be used alone or in a gel base (pectin or gelatin, depending on user preferences). It could be an effective product to protect the active volatile compounds and regulate the release of active compounds and give a pleasant taste.

Production of encapsulated (25R)-Spirost-5-en-3β-ol powder with composite coating material and its characterization

The potential of the (25R)-Spirost-5-en-3β-ol (diosgenin) is underutilized due to its astringent mouthfeel and aftertaste. To make the consumption more, this research rivets over the use of suitable techniques for encapsulating the diosgenin to use its health benefits for preventing the health disorders. The (25R)-Spirost-5-en-3β-ol(diosgenin) is gaining popularity in the food market by proving its potential health benefits. This study rivets over the encapsulation of diosgenin due to its high bitter taste which restricts its incorporation in functional foods. Maltodextrin and whey protein concentrates were used as the carrier for encapsulating diosgenin at varying concentrations from 0.1 to 0.5 % and evaluated for powder properties. The optimal conditions were obtained based on the most suited data ranged from the selected properties for the powder. The spray dried 0.3% diosgenin powder produced most suitable properties for powder recovery, encapsulation efficiency, moisture content, water activity, hygroscopicity, and particle size as 51.69-72.18%, 54.51-83.46%, 1.86-3.73%, 0.38-0.51, 10.55-14.08% and 40.38-88.02 μm respectively. The significance of this study relies on the more and better utilization of the fenugreek diosgenin in edible form by masking the bitterness. After encapsulation the spray dried diosgenin is more accessible in powder format with edible maltodextrin and whey protein concentrate. The spray dried diosgenin powder could be a potential agent that fulfils nutritional demands along with protection from some chronic health perturb.

Yeast Particles for Encapsulation of Terpenes and Essential Oils

Terpenes and essential oils are materials of great commercial use due to their broad spectra of antibacterial, antifungal, membrane permeation enhancement and antioxidant biological properties, as well as for their use as flavors and fragrances. Yeast particles (YPs) are 3-5 µm hollow and porous microspheres, a byproduct of some food-grade yeast (Saccharomyces cerevisiae) extract manufacturing processes, that have been used for the encapsulation of terpenes and essential oils with high payload loading capacity (up to 500% weight) and efficiency, providing stability and sustained-release properties. This review focuses on encapsulation approaches for the preparation of YP-terpene and essential oil materials that have a wide range of potential agricultural, food and pharmaceutical applications.

Effects of Microencapsulated Essential Oils on Equine Health: Nutrition, Metabolism and Methane Emission

This review examines the available data regarding the positive effects of microencapsulated essential oils (EOs) on the nutrition, metabolism, and possibly the methane emission of horses. A literature review was conducted on the effect of microencapsulated (EOs) on the health of horses. The information comprises articles published in recent years in indexed journals. The results indicate that mixtures of microencapsulated EOs may be beneficial to equine health due to their antimicrobial and antioxidant activity, as well as their effects on enteric methane production, nutrient absorption, and immune system enhancement. Moreover, encapsulation stabilizes substances such as EOs in small doses, primarily by combining them with other ingredients.

Optimal conditions for anthocyanin extract microencapsulation in taro starch: Physicochemical characterization and bioaccessibility in gastrointestinal conditions

This research aims to find the optimal conditions for the encapsulation of anthocyanin extract using taro starch to increase the retention of active compounds (RAC), drying yield (DY), antioxidant activity, stability, and bioaccessibility. The microencapsulation is carried out in a spray dryer, and the process is optimized using response surface method (RSM), applying starch concentration and inlet air temperature as independent parameters. Optimized microcapsules (OM) are obtained with solids concentration of 20.9 % and inlet temperature of 125 °C as optimal conditions. Drying yield (70.1 %), moisture content (5.2 %), water activity (0.211), phenolic compound content (797.8 mg GAE/g), anthocyanins (469.4 mg CE3G/g), ABTS (116.2 mg AAE/g) and DPPH (104.4 mg AAE/g) are analyzed through RSM. Retention percentage in OM show values of 60 % in bioactive compounds up to four weeks of storage under accelerated storage conditions. Bioaccessibility of OM is 10 % higher than that observed in the extract without encapsulation during gastrointestinal digestion. The results in this study show that OM made with taro starch and obtained with RSM effectively protect through digestion and ensure bioactive compound stability during storage.

Flavour encapsulation: A comparative analysis of relevant techniques, physiochemical characterisation, stability, and food applications

Flavour is an important component that impacts the quality and acceptability of new functional foods. However, most flavour substances are low molecular mass volatile compounds, and direct handling and control during processing and storage are made difficult due to susceptibility to evaporation, and poor stability in the presence of air, light, moisture and heat. Encapsulation in the form of micro and nano technology has been used to address this challenge, thereby promoting easier handling during processing and storage. Improved stability is achieved by trapping the active or core flavour substances in matrices that are referred to as wall or carrier materials. The latter serve as physical barriers that protect the flavour substances, and the interactions between carrier materials and flavour substances has been the focus of many studies. Moreover, recent evidence also suggests that enhanced bioavailability of flavour substances and their targeted delivery can be achieved by nanoencapsulation compared to microencapsulation due to smaller particle or droplet sizes. The objective of this paper is to review several relevant aspects of physical-mechanical and physicochemical techniques employed to stabilize flavour substances by encapsulation. A comparative analysis of the physiochemical characterization of encapsulates (particle size, surface morphology and rheology) and the main factors that impact the stability of encapsulated flavour substances will also be presented. Food applications as well as opportunities for future research are also highlighted.

Effects of thermal treatments on the characterisation of microencapsulated chlorophyll extract of Caulerpa racemosa

Caulerpa racemosa is a macroalga that has a green pigment, that is, chlorophyll. Chlorophyll is highly sensitive to damage during heat processing. In the present work, C. racemosa chlorophyll extract was microencapsulated with fish gelatine and Arabic gum coatings, using a freeze-drying technique, to protect against heat damage. The microcapsules were subjected to high temperatures (120, 140, and 160°C) for 5 h. The protective effect of microcapsules on chlorophyll stability was assessed by measuring chlorophylls a and b degradation, total phenolic content, antioxidant activity, functional group analysis, colour, particle size, and morphology via scanning electron microscopy. Chlorophyll b significantly decreased by 87.78% in comparison with chlorophyll a (61.49%) during heating; the characteristic green colour of chlorophyll changed to brownish-green following heat exposure. However, chlorophyll was still present in the microcapsules as detected by the presence of the functional group C=O bond at 1600 nm wavelength. The heat treatment did not affect microcapsule particle size and morphology. Particle size distribution ranged from 91.58 to 112.51 µm, and the microcapsule was flake-shaped. The activation energy of chlorophyll a was 19336.96 kJ/mol·K; this was higher than that of chlorophyll b, which was 1780.53 kJ/mol·K. Based on the results, microcapsules produced using fish gelatine and Arabic gum as coating materials were able to protect chlorophyll in C. racemosa extract from heat damage.

Controlled Release of Thymol by Cyclodextrin Metal-Organic Frameworks for Preservation of Cherry Tomatoes

Thymol is a phenol monoterpene with potential antifungal, antioxidant and antibacterial activities. Due to the low water solubility and high volatility of thymol, encapsulation serves as an effective tool during application. In the present study, cyclodextrin (CD)-based metal-organic-frameworks (MOFs) were synthesized using α-CD, β-CD, and γ-CD as organic building blocks, and further complexed with thymol to produce three CD-MOF-THY inclusion complexes (ICs). The encapsulation content, release kinetics and fruit preservation effect of ICs were analyzed. Results showed that thymol was well embedded in γ-CD-MOFs, with the highest encapsulation content of 286.7 ± 8.4 mg/g. Release kinetics revealed that CD-MOFs exhibited a controlled release effect toward thymol for 35 days. The release kinetics of three ICs fit the Rigter-Peppas model well, with γ-CD-MOF-THY showing the lowest release rate constant of 2.85 at 50 °C, RH 75%. Moreover, γ-CD-MOF-THY exhibited a remarkable preservation performance on cherry tomatoes with the lowest decay index (18.75%) and weight loss (5.17%) after 15 days of storage, suggesting this material as a potential fresh-keeping material for fruit and vegetable preservation.

A Narrative Review on Various Oil Extraction Methods, Encapsulation Processes, Fatty Acid Profiles, Oxidative Stability, and Medicinal Properties of Black Seed (Nigella sativa)

The current review investigates the effects of black seed (Nigella sativa) on human health, which is also used to encapsulate and oxidative stable in different food products. In recent decades, many extraction methods, such as cold pressing, supercritical fluid extraction, Soxhlet extraction, hydro distillation (HD) method, microwave-assisted extraction (MAE), ultrasound-assisted extraction, steam distillation, and accelerated solvent extraction (ASE) have been used to extract the oils from black seeds under optimal conditions. Black seed oil contains essential fatty acids, in which the major fatty acids are linoleic, oleic, and palmitic acids. The oxidative stability of black seed oil is very low, due to various environmental conditions or factors (temperature and light) affecting the stability. The oxidative stability of black seed oil has been increased by using encapsulation methods, including nanoprecipitation, ultra-sonication, spray-drying, nanoprecipitation, electrohydrodynamic, atomization, freeze-drying, a electrospray technique, and coaxial electrospraying. Black seed, oil, microcapsules, and their components have been used in various food processing, pharmaceutical, nutraceutical, and cosmetics industries as functional ingredients for multiple purposes. Black seed and oil contain thymoquinone as a major component, which has anti-oxidant, -diabetic, -inflammatory, -cancer, -viral, and -microbial properties, due to its phenolic compounds. Many clinical and experimental studies have indicated that the black seed and their by-products can be used to reduce the risk of cardiovascular diseases, chronic cancer, diabetes, oxidative stress, polycystic ovary syndrome, metabolic disorders, hypertension, asthma, and skin disorders. In this review, we are focusing on black seed oil composition and increasing the stability using different encapsulation methods. It is used in various food products to increase the human nutrition and health properties.

Essential Oil—Loaded Nanofibers for Pharmaceutical and Biomedical Applications: A Systematic Mini-Review

Essential oils (EOs) have been widely exploited for their biological properties (mainly as antimicrobials) in the food industry. Encapsulation of EOs has opened the way to the utilization of EOs in the pharmaceutical and biomedical fields. Electrospinning (ES) has proved a convenient and versatile method for the encapsulation of EOs into multifunctional nanofibers. Within the last five years (2017–2022), many research articles have been published reporting the use of ES for the fabrication of essential oil—loaded nanofibers (EONFs). The objective of the present mini-review article is to elucidate the potential of EONFs in the pharmaceutical and biomedical fields and to highlight their advantages over traditional polymeric films. An overview of the conventional ES and coaxial ES technologies for the preparation of EONFs is also included. Even though EONFs are promising systems for the delivery of EOs, gaps in the literature can be recognized (e.g., stability studies) emphasizing that more research work is needed in this field to fully unravel the potential of EONFs.

Spray drying encapsulation of essential oils; process efficiency, formulation strategies, and applications

Essential oils (EOs) have many beneficial qualities, including antimicrobial, antioxidant, antiviral, and antifungal activities, along with good aroma, which have played a significant role in pharmaceutical, textile, and food industries. However, their high volatility and sensibility to external factors, as well as susceptibility to deterioration caused by environmental and storage conditions, or even common processing, and consequently limited water solubility, makes it difficult to incorporate them into aqueous food matrices and limits their industrial application. Spray-drying encapsulation has been proposed as a solution and a challenging research field to retard oil oxidation, extend EO's shelf life, improve their physicochemical stability, achieve controlled release, suggest novel uses, and therefore boost their added value. The objective of this review is to discuss various used wall materials, infeed emulsion properties, the main formulation and process variables affecting the physicochemical properties and release characteristics of the EOs-loaded particles obtained by spray-drying, the stability of EOs during storage, and the applications of encapsulated EOs powders in foods and nutrition, pharmaceuticals, and textile industries. The current review also summarizes recent advances in spray drying approaches for improving encapsulation efficiency, flavor retention, controlled release, and applicability of encapsulated EOs, thereby expanding their use and functionalities.

Coacervation as a Novel Method of Microencapsulation of Essential Oils-A Review

These days, consumers are increasingly "nutritionally aware". The trend of "clean label" is gaining momentum. Synthetic additives and preservatives, as well as natural ones, bearing the E symbol are more often perceived negatively. For this reason, substances of natural origin are sought tfor replacing them. Essential oils can be such substances. However, the wider use of essential oils in the food industry is severely limited. This is because these substances are highly sensitive to light, oxygen, and temperature. This creates problems with their processing and storage. In addition, they have a strong smell and taste, which makes them unacceptable when added to the product. The solution to this situation seems to be microencapsulation through complex coacervation. To reduce the loss of essential oils and the undesirable chemical changes that may occur during their spray drying-the most commonly used method-complex coacervation seems to be an interesting alternative. This article collects information on the limitations of the use of essential oils in food and proposes a solution through complex coacervation with plant proteins and chia mucilage.

Microfluidic preparation of antimicrobial microparticles composed of l-lactide/1,3-dioxolane (co)polymers loaded with quercetin

The resistance of microorganisms against commonly used antibiotics is becoming an increasingly important problem in the food and pharmaceutical industries. Therefore, the development of novel bactericidal agents, as well as the design of drug delivery systems based on materials composed of biocompatible and biodegradable building blocks, has attracted increasing attention. To address this challenge, microparticles composed of l-lactide homopolymer and l-lactide/1,3-dioxolane (co)polymers loaded with quercetin (Q) were fabricated by using a microfluidic technique. This method enables the preparation of homogeneous particles with sizes ranging from 60 to 80 µm, composed of degradable semicrystalline or amorphous (co)polyesters. The microencapsulation of Q in a (co)polymeric matrix enables prolonged release of the antimicrobial agent. The antibacterial properties of the obtained biocompatible microparticles are confirmed by the agar diffusion plate method for various bacterial strains. Therefore, Q-loaded microparticles can have important applications in food preservation as a novel antimicrobial system.

Functional Coatings by Natural and Synthetic Agents for Insect Control and Their Applications

Insect repellent textiles offer protection against disease-causing vectors such as mosquitoes, flies, and ticks. Protection is based on the incorporation of insect repellent compounds present in plant oil derivatives or synthetic oils. The effectiveness and application of natural insect repellents such as citronella grass, lemongrass, rosemary, peppermint, holy basil, tea tree, neem, lavender, thyme, lemon eucalyptus, clove, and cinnamon oils, as well as synthetic compounds permethrin, allethrin, malathion, DEET, DETA, IR3535, and picaridin, are compared here. The insect repellent and insecticidal effectiveness of natural compounds in their pure form are very low due to their high volatility. The effectiveness has been greatly improved through slow-release systems such as encapsulation of the essential oils and is comparable to synthetic compounds used for insect control purposes. Due to the lasting toxicity of synthetic compounds to humans and the environment, the use of natural compounds should become a more preferred method of insect control.

Polysaccharides as wall materials in spray-dried microencapsulation of bioactive compounds: Physicochemical properties and characterization

Natural bioactive compounds (BCs) are types of chemicals found in plants and certain foods that promote good health, however they are sensitive to processing and environmental conditions. Microencapsulation by spray drying is a widely used and cost-effective approach to create a coating layer to surround and protect BCs and control their release, enabling the production of high functional products/ingredients with extended shelf life. In this process, wall materials determine protection efficiency, and physical properties, bioavailability, and storage stability of microencapsulated products. Therefore, an understanding of physicochemical properties of wall materials is essential for the successful and effective spray-dried microencapsulation process. Typically, polysaccharide-based wall materials are generated from more sustainable sources and have a wider range of physicochemical properties and applications compared to their protein-based counterparts. In this review, we highlight the essential physicochemical properties of polysaccharide-based wall materials for spray-dried microencapsulation of BCs including solubility, thermal stability, and emulsifying properties, rheological and film forming properties. We provide further insight into possibilities for the chemical structure modification of native wall materials and their controlled release behaviors. Finally, we summarize the most recent studies involving polysaccharide biopolymers as wall materials and/or emulsifiers in spray-dried microencapsulation of BCs.

Development of Microcapsule Bioactive Paper Loaded with Chinese Fir Essential Oil to Improve the Quality of Strawberries

Essential oils are natural antibacterial substances and have potential value for application in fruit and vegetable packaging. In this study, Chinese fir essential oil (CFEO) was microencapsulated to prepare food packaging materials for the first time to overcome its volatilization and oxidation shortcomings and to obtain a sustained-release form of the oil. CFEO was effectively encapsulated in gelatin and chitosan using the complex coacervation method, and the encapsulation efficiency, microstructure, infrared spectrum and thermal stability of the microcapsules were evaluated. Experiments confirmed that the microcapsules had some antibacterial activity. A bioactive paper was developed by combining CFEO microcapsules (CFEO-Ms) with paper-based material using the film-forming property of polyvinyl alcohol (PVA). The coated paper showed good mechanical, air permeability and moisture permeability properties. Environmental scanning electron microscopy confirmed that CFEO-Ms bonded well with PVA and was successfully introduced into the paper fiber after coating, forming an obvious coating film on the surface to facilitate the continuous release of CFEO. The shelf life of strawberries was significantly prolonged when the PVA-coated paper mixed with 3% CFEO-Ms was used for packaging. The results demonstrated that the CFEO-Ms coated paper has the potential to become an effective packaging material for the preservation of strawberries.

Volatile Organic Compounds from Basil Essential Oils: Plant Taxonomy, Biological Activities, and Their Applications in Tropical Fruit Productions

Basils of the genus Ocimum are aromatic plants grown widely throughout the tropical and temperate regions. The essential oils obtained from their aerial parts are enriched with volatile organic compounds with high market demand for food and pharmaceutical industries. The volatile organic compounds have been shown to exhibit biological activities. Therefore, their novel applications have been extensively explored in the last few decades. The most widely available basils in the tropical areas include white holy basil (O. sanctum var. Shyama), red holy basil (O. sanctum var. Rama), Thai basil (O. basilicum var. thyrsiflorum), lemon basil (O. citriodorum), and tree basil (O. gratissimum). Over 60 volatiles of different classes have been exclusively described, and some of them could be useful as biomarkers for genotype specification. The major volatile ingredient is the phenylpropanoids, such as methyl eugenol, which has the potential as a natural product for mitigating Oriental fruit fly (Bactrocera dorsalis) during tropical fruit production. Moreover, basil essential oils are also used to control diseases of the fruits during post-harvest storage. As a result, the application of basil essential oils as a sustainable defect control strategy for tropical fruit value chains seems intriguing. This review provides comprehensive information on plant taxonomy and volatile compositions of the essential oil fractions from different basil species. Their biological activities and applications are also discussed, mainly during the pre- and post-production of tropical fruits. Additionally, the available techniques to enhance the efficacy of the volatile active compounds are also described.

Biosynthesis and characterisation of solid lipid nanoparticles and investigation of toxicity against breast cancer cell line

Solid lipid nanoparticles (SLNs) comprise non-toxic surface-active lipidic agents combined with appropriate ratios of drugs or essential oils. The goal of this research was to investigate the effects of the SLN synthesised using essential oils of Foeniculum vulgare on the MCF-7 breast cancer cell line. SLNs were prepared by homogenisation and ultrasound techniques and characterised by dynamic light scattering (DLS), zeta potential assessment, and transmission electron microscopy (TEM). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay (MTT assay), flow-cytometry, and Acridine-Orange assay were employed for assessing the biological activities of the SLNs. The average particle size was 55.43 nm and the net surface charge was -29.54 ± 11.67 mV. TEM showed that the mean particle size was 33.55 nm and the synthesised SLNs had a uniform round morphology. The MTT assay showed that the prepared SLNs had high toxicity against MCF-7 cells and low toxicity against normal HUVECs cells. Flow-cytometry revealed a noteworthy rise in the subG1 peak of the cell cycle in the cancer cells treated with SLNs compared to the controls, indicating apoptosis in cancer cells. The results also showed discolouration in SLNs-treated cells, which further confirmed the induction of apoptosis and the toxicity of the SLNs against MCF-7 cells.

Encapsulation of B. bassiana in Biopolymers: Improving Microbiology of Insect Pest Control

The fungus Beauveria bassiana is widely used for pest control; however, biostability and dispersion for broth pulverization are limiting factors for its application in the field. In this context, formulation techniques such as microencapsulation are viable alternatives. The aim of this work is to optimize B. bassiana formulations by spray dryer and evaluate its stability and biological activity against Spodoptera cosmioides compared to ionic gelatinization formulations. The fungus was biocompatible with all evaluated biopolymers (lignin, cellulose, starch, humic substances, and alginate). The encapsulation by spray drying was optimized by factorial design in an inlet and outlet air temperature of 120°C and 68°C, respectively; aspirator rate of 35 m³·h⁻¹, feed flow rate of 12 mL·min⁻¹; and drying gas flow at 35 L·h⁻¹. The ionic gelation capsules were obtained using a 0.5% quantity of conidia in a 1% sodium alginate solution dropped into a 0.5 mol·L⁻¹ CaCl₂ solution using a peristaltic pump. Spray drying provided smaller microcapsules than those by ionic gelation. Both techniques produced more stable conidia when exposed to temperature and UV-radiation than non-formulated B. bassiana. The formulations prepared by spray drying showed gains at aqueous dispersion. Biological assays against Spodoptera cosmioides showed a mortality rate of up to 90%. These results demonstrate the suitability of encapsulating B. bassiana conidia stably in aqueous dispersion without loss of viability and virulence.

The impact of essential oils on the qualitative properties, release profile, and stimuli-responsiveness of active food packaging nanocomposites

Food industries attempt to introduce a new food packaging by blending essential oils (EOs) into the polymeric matrix as an active packaging, which has great ability to preserve the quality of food and increase its shelf life by releasing active compounds within storage. The main point in designing the active packaging is controlled-release of active substances for their enhanced activity. Biopolymers are functional substances, which suggest structural integrity to sense external stimuli like temperature, pH, or ionic strength. The controlled release of EOs from active packaging and their stimuli-responsive properties can be very important for practical applications of these novel biocomposites. EOs can affect the uniformity of the polymeric matrix and physical and structural characteristics of the composites, such as moisture content, solubility in water, water vapor transmission rate, elongation at break, and tensile strength. To measure the ingredients of EOs and their migration from food packaging, chromatographic methods can be used. A head-space-solid phase micro-extraction coupled to gas chromatography (HS-SPME-GC-MS) technique is as a good process for evaluating the release of Eos. Therefore, the aims of this review were to evaluate the qualitative characteristics, release profile, and stimuli-responsiveness of active and smart food packaging nanocomposites loaded with essential oils and developing such multi-faceted packaging for advanced applications.

Microencapsulation of Curcumin in Crosslinked Jelly Fig Pectin Using Vacuum Spray Drying Technique for Effective Drug Delivery

Microencapsulation of curcumin in jelly fig pectin was performed by the vacuum spray drying (VSD) technique. The VSD was advanced with a low inlet temperature of 80-90 °C and low pressure of 0.01 mPa. By the in situ cross-linking with multivalent calcium ions, jelly fig pectin produced stable curcumin encapsulated microparticles. The physiochemical characteristics of microparticles were thoroughly investigated. The results revealed that 0.75 w/w% of jelly fig pectin and inlet temperature of 90 °C could be feasible for obtaining curcumin microparticles. The VSD technique showed the best encapsulation efficiency and yield and loading efficiency was up to 91.56 ± 0.80%, 70.02 ± 1.96%, and 5.45 ± 0.14%, respectively. The curcumin was readily released into simulated gastrointestinal fluid with 95.34 ± 0.78% cumulative release in 24 h. The antioxidant activity was stable after being stored for six months and stored as a solution for seven days at room temperature before analysis. Hence, the VSD technique could be applicable for the microencapsulation of bioactive compounds such as curcumin to protect and use in the food/pharmaceutical industry.

Modified cyclodextrin type and dehydration methods exert a significant effect on the antimicrobial activity of encapsulated carvacrol and thymol

BACKGROUND

The antimicrobial activity of essential oils and their constituents has led to increasing interest in using them as natural preservative agents. However, their high sensitivity to light and oxygen, their volatility and their low aqueous solubility are all obstacles to their application in the food, cosmetic or pharmaceutical industries. Encapsulation in cyclodextrins (CDs) is a solution for the application of such essential oils.

RESULTS

The complexation of carvacrol and thymol with hydroxypropyl (HP)-α-, HP-β- and HP-γ-CD, the behavior of the solid complexes prepared by freeze-drying and spray-drying methods and the antibacterial activity of solid complexes were studied. K_c values of HP-α- and HP-γ-CD complexes with carvacrol (118.4 and 365.7 L mol^-1 ) and thymol (112.5 and 239.7 L mol ^-1 ) were far lower than those observed for HP-β-CD complexes with carvacrol (2268.2 L mol ^-1 ) and thymol (881.6 L mol ^-1 ). The lower stability of HP-α- and HP-γ-CD complexes increased the release of compounds, thereby affecting the antimicrobial activity of carvacrol and thymol to a lesser extent than complexation with HP-β-CD, normally used in the encapsulation of carvacrol and thymol. HP-β-CD encapsulation of carvacrol and thymol markedly reduced their antimicrobial activity. The freeze-drying method barely affected the antimicrobial activity of carvacrol and thymol after encapsulation, while spray drying could be considered for the production of solid complexes in combination with the appropriate CD.

CONCLUSIONS

It was thus demonstrated that HP-α- and HP-γ-CD are very suitable alternatives for the encapsulation of carvacrol and thymol with the purpose of preserving their bacteriostatic and bactericidal activities. © 2020 Society of Chemical Industry.

Microencapsulation of Essential Oils by Spray-Drying and Influencing Factors

Essential oils (EOs) are known as any aromatic oily organic substances which are naturally synthesized in plants. Exhibiting a broad range of biological activities, EOs have played a key role in numerous industries for ages, including pharmaceutical, textile, and food. However, the volatility and high sensitivity to environmental influences pose challenges to the application of EOs on industrial scale. Microencapsulation via the spray-drying method is one of the promising techniques to overcome these challenges, thanks to the presence of wall materials that properly protect the core EOs from oxidation and evaporation. By optimization of key factors related to the infeed emulsion properties and spray-drying process, the encapsulation efficiency and retention of encapsulated EOs could be significantly improved, thus allowing a wide range of EO applications. This review attempts to discuss on different determining factors of the spray-drying process to develop an effective encapsulation formula for EOs. Furthermore, recent applications of encapsulated EOs in the fields of foods, pharmaceuticals, and textile industries are also thoroughly addressed.

Polymeric Carriers Designed for Encapsulation of Essential Oils with Biological Activity

The article reviews the possibilities of encapsulating essential oils EOs, due to their multiple benefits, controlled release, and in order to protect them from environmental conditions. Thus, we present the natural polymers and the synthetic macromolecular chains that are commonly used as networks for embedding EOs, owing to their biodegradability and biocompatibility, interdependent encapsulation methods, and potential applicability of bioactive blend structures. The possibilities of using artificial intelligence to evaluate the bioactivity of EOs—in direct correlation with their chemical constitutions and structures, in order to avoid complex laboratory analyses, to save money and time, and to enhance the final consistency of the products—are also presented.

Encapsulation of Flavours and Fragrances into Polymeric Capsules and Cyclodextrins Inclusion Complexes: An Update

Flavours and fragrances are volatile compounds of large interest for different applications. Due to their high tendency of evaporation and, in most cases, poor chemical stability, these compounds need to be encapsulated for handling and industrial processing. Encapsulation, indeed, resulted in being effective at overcoming the main concerns related to volatile compound manipulation, and several industrial products contain flavours and fragrances in an encapsulated form for the final usage of customers. Although several organic or inorganic materials have been investigated for the production of coated micro- or nanosystems intended for the encapsulation of fragrances and flavours, polymeric coating, leading to the formation of micro- or nanocapsules with a core-shell architecture, as well as a molecular inclusion complexation with cyclodextrins, are still the most used. The present review aims to summarise the recent literature about the encapsulation of fragrances and flavours into polymeric micro- or nanocapsules or inclusion complexes with cyclodextrins, with a focus on methods for micro/nanoencapsulation and applications in the different technological fields, including the textile, cosmetic, food and paper industries.

Extraction of Essential Oils from Medicinal Plants and their Utilization as Food Antioxidants

BACKGROUND

The use of essential oils is receiving increasing attention worldwide, as these oils are good sources of several bioactive compounds. Nowadays essential oils are preferred over synthetic preservatives thanks to their antioxidant and antimicrobial properties. Several studies highlight the beneficial effect of essential oils extracted from medicinal plants to cure human diseases such as hypertension, diabetes, or obesity. However, to preserve their bioactivity, the use of appropriate extraction technologies is required.

METHODS

The present review aims to describe the studies published so far on the essential oils focusing on their sources and chemical composition, the technologies used for their recovery and their application as antioxidants in food products.

RESULTS

The review has been structured in three parts. In the first part, the main compounds present in essential oils extracted from medicinal plants have been listed and described. In the second part, the most important technologies used for extraction and distillation, have been presented. In detail, conventional methods have been described and compared with innovative and green technologies. Finally, in the last part, the studies related to the application of essential oils as antioxidants in food products have been reviewed and the main findings discussed in detail.

CONCLUSION

In summary, an overview of the aforementioned subjects is presented by discussing the results of the most recent published studies.

Spray Drying for the Encapsulation of Oils-A Review

The application of the spray drying technique in the food industry for the production of a broad range of ingredients has become highly desirable compared to other drying techniques. Recently, the spray drying technique has been applied extensively for the production of functional foods, pharmaceuticals and nutraceuticals. Encapsulation using spray drying is highly preferred due to economic advantages compared to other encapsulation methods. Encapsulation of oils using the spray drying technique is carried out in order to enhance the handling properties of the products and to improve oxidation stability by protecting the bioactive compounds. Encapsulation of oils involves several parameters-including inlet and outlet temperatures, total solids, and the type of wall materials-that significantly affect the quality of final product. Therefore, this review highlights the application and optimization of the spray drying process for the encapsulation of oils used as food ingredients.