Release Of Essential Oil Research Articles

Applications of Plant Essential Oils in Pest Control and Their Encapsulation for Controlled Release: A Review

Essential oils (EOs) are volatile products derived from the secondary metabolism of plants with antioxidant, antimicrobial, and pesticidal properties. They have traditionally been used in medicine, cosmetics, and food additives. In agriculture, EOs stand out as natural alternatives for pest control, as they show biocidal, repellent, and antifeedant effects. However, they are highly volatile compounds and susceptible to oxidation, which has limited their use as pesticides. This has led to exploring micro- and nano-scale encapsulation to protect these compounds, improving their stability and allowing for a controlled release. Various encapsulation techniques exist, such as emulsification, ionic gelation, and complex coacervation. Nanoemulsions are useful in the food industry, while ionic gelation and complex coacervation offer high encapsulation efficiency. Materials such as chitosan, gelatin-gum-Arabic, and cyclodextrins are promising for agricultural applications, providing stability and the controlled release of EOs. Encapsulation technology is still under development but offers sustainable alternatives to conventional agrochemicals. This article reviews the potential of EOs in pest management and encapsulation techniques that enhance their efficacy.

Fabrication of bamboo nanocellulose fibril-based food packaging with dual-antimicrobial property

The development of cellulose-based packaging films with excellent antimicrobial properties and biocompatibility has garnered significant attention. In this work, nanocellulose fibrils (NCFs) derived from from bamboo parenchyma cells were utilized to fabricate nanocomposite film with antimicrobial properties. This system exhibited distinct release behaviors for two antimicrobial agents, with the slow release of Ag nanoparticle (AgNP) in the initial stage contributed to delaying food spoilage, while the subsequent pH change in the microenvironment facilitated the release of essential oil of sour orange blossoms (SEO) for secondary antimicrobial activity. Additionally, the composite film demonstrated improved thermal stability and UV blocking capacity. Moreover, AgNP has been proven to enhance the mechanical properties, with the tensile strength of the novel composite film increasing by 34.85 % compared to control group. The water vapor permeability and oxygen permeability of the novel composite film were reduced, which could potentially reduce weight loss and slow down the rate of after-ripening. Following the acidification treatment, the films containing EO@MPN (essential oil encapsulated with metal-polyphenol network) component performed different antimicrobial patterns, indicating their pH-responsive antimicrobial capabilities, and they are effective against both Gram-positive and Gram-negative bacteria. After a 24-h exposure to a food simulant, the release amount of Ag was measured at 67.6 μg/dm2, within the acceptable limit, and the release profile of Ag was characterized. Cytotoxicity and Live/Dead staining tests confirmed that the novel composite film film had no significant toxicity, thus making it safe for application in food preservation. Furthermore, in a 15-day preservation experiment with mangoes, the novel composite film demonstrated the best performance, underscoring its potential as a sustainable antimicrobial packaging material.

Essential oil release from zein particles as modulated by inorganic coating and biopolymeric networking

Zein particles (ZPs) have emerged as a popular delivery carrier for hydrophobic bioactive substances. However, some lipophilic compounds are easily released from ZPs because of the low polarity compatibility between zein and the compounds. The loss of encapsulated substances is particularly evident for citrus essential oil (CEO), an extremely hydrophobic ingredient. The premature release of CEO from ZPs was mitigated by developing a modification approach using ZPs coated with calcium phosphate (CaP) and networked with Ca2+-alginate gel (CaAlg). The approach involved the preparation of ZPs (through the antisolvent addition procedure) in phosphate buffer, and supplementation of the particles consecutively with sodium alginate and Ca2+ ions (as CaCl2). This procedure resulted in retention of up to 28% of CEO within ZPs after the accelerated storage experiment. Under in vitro gastric and intestinal digestion condition, the CaP-coated and CaAlg-networked ZPs had a significantly lower release of CEO compared to their non-coated and non-networked counterparts. The morphology of the particles was investigated by scanning (SEM) and transmission (TEM) electron microscopies, as well as confocal laser scanning microscopy. SEM imaging showed that sodium alginate could facilitate the formation of CaP coating through preventing CaP crystallization. CaP coating also decreased the ZPs fusion/aggregation as evidenced by comparing the ζ-potential and microscopic morphology of the particles. Examination of the infrared spectra of the particles revealed that the formation of CaP coating occurred at Ca2+ ion concentrations ≥ 10 mM.

Pickering emulsion of pepper essential oil stabilized by Octenyl succinic acid starch: Characterization, in vitro release and anticancer activity.

Under high humidity and high temperature conditions, the quality of pepper essential oil easily deteriorates, and the oxidation of oil restricts its application, especially for the insolubility in water. This study investigated pepper essential oil encapsulated in Pickering emulsion with octenyl succinic acid starch, which was effectively able to reduce 100 times of the release rate. The smooth surface and complete particles of the emulsion were observed and no new chemical bonds were formed. The minimum particle sizes were 2.05µm and 1.89µm, when the Pickering emulsion was set to different storage conditions at pH 5 and 0.1M NaCl, respectively. During gastrointestinal digestion, the release of essential oils was effectively delayed in the Pickering emulsion and the digestibility of the emulsion was 16.93% in 120min. Compared with untreated cells, Pickering emulsion can effectively inhibit the proliferation of MCF-7 (52.71%). All these results indicate that OSA starch stabilized pepper essential oil can effectively increase solubility, improve stability, and expand the application range. Therefore, it can provide a theoretical basis for applications of pepper essential oil, especially for the functional drug application.

Formulation and evaluation of nanoemulgel loaded with essential oils with mosquito repellent activities

The mosquito repellent potential of plant materials, including essential oils, has been exploited for centuries. However, due to the volatility of essential oils, the protection against mosquitoes is short-lived. This study aimed to formulate citronella oil (CO) (Cymbopogon nardus) and palmarosa oil (PO) (C. martini) in the form of nanoemulgel (NEG) to delay their volatility and prolong protection time against mosquitoes. Nanoemulsions (NE) of both essential oils were prepared using ultrasonication after suitable hydrophilic-lipophilic balance (HLB) selection and phase diagram development. NEGs were formulated by mixing NEs and Carbopol 934 gel. Physicochemical characterizations, including in vitro release and permeation studies were conducted. Tween 80, Transcutol P and distilled water with 40 % glycerol were selected as surfactant, co-surfactant and aqueous components of the NEs, respectively. HLB values of 11 and 12 were found to be appropriate for CO and PO NEs preparation, respectively. The NEGs were kinetically stable and the formulation components were chemically compatible with each other. The NEG formulations prolonged the release of both essential oils for 24 h and significantly reduced the percentage permeation via cellulose acetate membrane as compared to NEs. Consequently, NEG could be a potential formulation to prolong the mosquito repellent activity of essential oils.

Double-layer films based on konjac gum and hydroxypropyl methyl cellulose loaded with thyme essential oil Pickering emulsion: Preparation, characterization, and application

Due to the challenges posed by petroleum-based plastics in terms of degradation and their contribution to environmental pollution, researchers have focused on natural biodegradable packaging materials. Herein, a biodegradable, unidirectional released, bilayer active film based on Konjac gum/hydroxypropyl methylcellulose (KGM/HPMC) were developed. Specifically, Pickering nano-emulsion was formed via ultrasonic self-assembly of Thyme essential oil (TEO) and a suspension of oxidized chitin nanocrystals. The dual-network form by KGM/HPMC effectively incorporated the TEO droplets in Pickering nano-emulsion through intermolecular hydrogen bonding, demonstrating good solubility between the TEO droplets and film matrix. The mechanical properties of the active film are greatly improved due to the protective effect provided by the outer layer in the double-layer active emulsion film design. Furthermore, the double-layer active film enables a unidirectional release of essential oils, thereby enhancing the efficiency of essential oil utilization. In addition, the double-layer active film has beneficial properties, including antioxidation, antibacterial effects, ultraviolet radiation protection, and biodegradability compared to cling film. This film was employed for the preservation of salmon, and the findings indicated that the bilayer active film, formulated with 15% Pickering emulsion content, notably retarded the escalation of total volatile basic nitrogen (TVB-N) and pH levels in salmon. Furthermore, it successfully reduced the proportion of dominant bacteria (specifically Pseudomonas) in salmon samples. The double-layer active film developed in this study demonstrates the potential for extending the shelf life of aquatic products.

An “intelligent-sensing and targeted release” antimicrobial pickering emulsion for banana preservation

Conventional Pickering emulsions can kill microorganisms by slow release of active substances to prevent foodborne contamination; however, their low bactericidal efficiency due to the absence of bacterial inducibility is a problem that needs to be addressed. Inspired by the fact that the growth of bacteria depends on the consumption of proteins and polysaccharides by microbial enzymes, the present study prepared a novel Pickering emulsion capable of intelligent sensing and targeted release using chitosan (CS)-soy protein isolate (SPI) colloidal particles as stabilizers and plant essential oils as active substances. The Pickering emulsion demonstrated optimal performance in achieving these goals when prepared with a CS:SPI ratio of 1:4, an oil fraction of 40%, at a homogeneous speed of 25 000 rpm, and utilizing cinnamon oil as the plant essential oil. This was evidenced by the emulsion having the smallest droplet size and the greatest stability, which can increase the chances of coming into contact with microorganisms and avoid premature demulsification. Antibacterial experiments demonstrated that the emulsion could control the bacteria-mediated release of essential oils, realizing intelligent sterilization. Experiments on banana preservation showed that the released essential oils effectively delayed banana spoilage. These findings contribute to the development of intelligent food preservation systems.

Lyophilized Emulsions of Thymol and Eugenol Essential Oils Encapsulated in Cellulose.

Efforts to tap into the broad antimicrobial, insecticidal, and antioxidant activities of essential oils (EOs) are limited due to their strong odor and susceptibility to light and oxidation. Encapsulation of EOs and subsequent drying overcome these limitations and extend their applications. This study characterized freeze-dried (lyophilized) emulsions of eugenol (EU) and thymol (TY) EOs, encapsulated by chemically unmodified cellulose, a sustainable and low-cost resource. High-resolution scanning electron microscopy showed successful lyophilization. While the observed "flake-like" structure of the powders differed significantly from that of the emulsified microcapsules, useful properties were retained. Fourier transform infrared spectroscopy confirmed the presence of EOs in their corresponding powders and thermo-gravimetric analysis demonstrated high encapsulation efficiency (87-88%), improved thermal stability and resistance to evaporation, and slow EO release rates in comparison to their free forms. The lightweight and low-cost cellulose encapsulation, together with the results showing retained properties of the dried powder, enable the use of EOs in applications requiring high temperatures, such as EO incorporation into polymer films, that can be used to protect agricultural crops from microbial infections.

Enhancing Encapsulation Efficiency of Chavir Essential Oil via Enzymatic Hydrolysis and Ultrasonication of Whey Protein Concentrate-Maltodextrin.

This study focused on the characterization of emulsions and microparticles encapsulating Chavir essential oil (EO) by application of modified whey protein concentrate-maltodextrin (WPC-MD). Different physical, chemical, morphological, thermal, and antioxidant properties and release behavior of spray-dried microparticles were assessed. Antioxidant, solubility, emulsifying, and foaming activities of modified WPC were increased compared to those of primary material. The results indicated that the particle size distribution varied depending on the type of carriers used, with the smallest particles formed by hydrolyzed WPC (HWPC). Binary blends of modified WPC-MD led to improved particle sizes. The spray-drying yield ranged from 64.1% to 85.0%, with higher yields observed for blends of MD with sonicated WPC (UWPC). Microparticles prepared from primary WPC showed irregular and wrinkled surfaces with indentations and pores, indicating a less uniform morphology. The UWPC as a wall material led to microparticles with increased small cracks and holes on their surface. However, HWPC negatively affected the integrity of the microparticles, resulting in broken particles with irregular shapes and surface cracks, indicating poor microcapsule formation. Encapsulating EO using WPC-MD increased the thermal stability of EO significantly, enhancing the degradation temperature of EO by 2 to 2.5-fold. The application of primary WPC (alone or in combination with MD) as wall materials produced particles with the lowest antioxidant properties because the EO cannot migrate to the surface of the particles. Enzymatic hydrolysis of WPC negatively impacted microparticle integrity, potentially increasing EO release. These findings underscore the crucial role of wall materials in shaping the physical, morphological, thermal, antioxidant, and release properties of spray-dried microparticles, offering valuable insights for microencapsulation techniques.

Antibacterial Microfibrillated Cellulose as Stimuli-Responsive Carriers with Enhanced UV Stability for Sustained Release of Essential Oils and Pesticides

Antibacterial Microfibrillated Cellulose as Stimuli-Responsive Carriers with Enhanced UV Stability for Sustained Release of Essential Oils and Pesticides

A gentle conditioning agent consisted of oppositely-charged-induced cellulose nanocrystal and cationic cellulose: Stability, conditioning and delivery

The concerns about the health and environmental effects of the conditioning agent in current hair care products have attracted attention to seeking out a gentle and biosafe alternative, especially from nature. Cationic cellulose is a gentle conditioning agent from natural resource, but is rarely used in emulsion due to its hydrophilicity. In this study, cellulose-based complexes were prepared by opposite-charged-induced cellulose nanocrystals and cationic cellulose to replace cationic surfactants as conditioning agent. We demonstrated that the presence of cellulose nanocrystals effectively improved the emulsifying property of cationic cellulose, thereby could be used to prepare stable silicone oil emulsion. More importantly, by analyzing the relationship between emulsion morphology and the deposition of silicone oil, it was proposed for the first time that emulsion flocculation was positively correlated with deposition of silicone oil. Based on this, a method for rapid comparison of deposition of silicone oil was creatively proposed using ultraviolet absorbance of emulsion. Besides, we found that the resulting emulsion could be used as platform for delivery of essential oil to control the release of essential oil. In summary, this study has developed a gentle and clean cellulose-based complexes for personal care, which is expected to produce safer and cleaner emulsion to reduce potential health risks.

Enhanced stability and antibacterial efficacy of edible oleogels-in-water high internal phase emulsions prepared from soybean lipophilic protein

Recently, convenience-driven consumers have increasingly embraced prepared aquatic foods, facilitating a significant shift within the food industry. However, this change has presented a challenge for maintaining the quality of aquatic products in prepared food items since aquatic products are highly susceptible to microbial contamination during processing or storage. Herein, smart oleogels-in-water high internal phase emulsions (GHIPEs) stabilized solely by soybean lipophilic protein (LP) were prepared via oil phase gelation induced by glycerol monolaurate (GML). The purpose of this system is to act as an effective carrier and facilitate the precise release of thyme essential oils to extend the shelf life of food products. The gelation of the oil phase has significantly enhanced the stability of GHIPEs when compared to traditional HIPEs. When the GML reached 2%, the GHIPEs retained up to 87.18% ± 4.23 of thyme essential oil after 14 d. Moreover, the highest antioxidant potential of GHIPEs (with 2% GML) was confirmed through DPPH and ABTS free radical scavenging assays. Furthermore, the GHIPEs can release thyme essential oil in response to microbial growth, demonstrating their “smart sensing and targeted release” ability. Ultimately, the application of the GHIPEs in the preservation of Cololabis saira significantly reduced the total colony count, pH, TVB-N, and TBARS values (P < 0.05). Consequently, a ready-to-eat Cololabis saira product with an extended shelf life of 7 d at 4 °C was successfully realized, indicating the effectiveness of GHIPEs in preserving seafood freshness. These findings offer novel approaches to maintaining the freshness of prepared aquatic foods.

Leveraging gas generation for Humidity-Responsive release of Thyme essential oil via nanofiber film for fresh fruits

The preservation of fruits using slow-release packaging for Thyme essential oil (THY) encounters a significant challenge associated with premature release. Therefore, the development of a controlled release system for essential oils is essential to enhance preservation and reduce wastage. This study introduces a novel humidity-responsive nanofiber film enhanced by gas generation for controlled THY release. This film can generate CO2 gas within its nanofibers in high humidity environments, facilitating the release of loaded THY. The film exhibits excellent humidity-responsive release properties and possesses notable antimicrobial and antifungal characteristics. It effectively extends the shelf life of strawberries, inhibits microbial growth, reduces weight loss, and mitigates hardness reduction. The humidity-responsive nanofiber film effectively addresses the issue of premature THY release, presenting significant potential for fruit preservation applications. Furthermore, this gas-enhanced release approach enhances the sensitivity of stimulus-responsive release, providing novel insights into the design of nanofiber-based controlled release systems.

Edible nano-encapsulated cinnamon essential oil hybrid wax coatings for enhancing apple safety against food borne pathogens

Post-harvest losses of fruits due to decay and concerns regarding microbial food safety are significant within the produce processing industry. Additionally, maintaining the quality of exported commodities to distant countries continues to pose a challenge. To address these issues, the application of bioactive compounds, such as essential oils, has gained recognition as a means to extend shelf life by acting as antimicrobials. Herein, we have undertaken an innovative approach by nano-encapsulating cinnamon-bark essential oil using whey protein concentrate and imbibing nano-encapsulates into food-grade wax commonly applied on produce surfaces. We have comprehensively examined the physical, chemical, and antimicrobial properties of this hybrid wax to evaluate its efficacy in combatting the various foodborne pathogens that frequently trouble producers and handlers in the post-harvest processing industry. The coatings as applied demonstrated a static contact angle of 85 ± 1.6°, and advancing and receding contact angles of 90 ± 1.1° and 53.0 ± 1.6°, respectively, resembling the wetting properties of natural waxes on apples. Nanoencapsulation significantly delayed the release of essential oil, increasing the half-life by 61 h compared to its unencapsulated counterparts. This delay correlated with statistically significant reductions (p = 0.05) in bacterial populations providing both immediate and delayed (up to 72 h) antibacterial effects as well as expanded fungal growth inhibition zones compared to existing wax technologies, demonstrating promising applicability for high-quality fruit storage and export. The utilization of this advanced produce wax coating technology offers considerable potential for bolstering food safety and providing enhanced protection against bacteria and fungi for produce commodities.

Prolonging broccoli shelf life through controlled release of plai essential oil using palm wood sachet as a novel absorbent material with reusable properties.

Palm wood powder derived from palm wood waste was utilized as a novel absorbent material. The investigation involved exploring its pore structure and size to achieve the controlled release of bioactive compounds from plai oil, providing protection against pathogenic bacteria and thereby extending the shelf life of broccoli. The palm wood sachet was prepared before being placed into the broccoli bag. The process to create the sachet involved freezing the palm wood at -10°C and then drying it at a temperature of 200°C. After drying, the material was ground to achieve a particle size of 20 mesh and then packaged into sachets made from wood pulp. The optimized palm wood plai oil sachet (PWPS), measuring 5×7cm, with a thickness of 0.58µm, was produced by soaking 2g of palm powder in plai oil at a concentration of 30µL/mL before drying and packing it inside a 5-L polyethylene plastic bag (24×34cm) along with broccoli (150g). The packages were kept at 4°C for 20days to determine the antimicrobial activity of the PWPS and broccoli quality. PWPS significantly inhibited the growth of Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus, and Listeria monocytogenes in broccoli for at least 20days. The sachet demonstrated complete inhibition of all bacteria when reused at least two times and an 80% reduction in efficacy after three uses. Moreover, the PWPS controlled the growth of total aerobic bacteria and yeast and mold in broccoli, meeting microbiological criteria for up to 14days. Broccoli stored with PWPS showed good quality results and contained high antioxidant value. These results demonstrate the potential application of PWPS in controlling food pathogens and spoilage microbes during storage. PRACTICAL APPLICATION: This study introduces a novel absorbent material made from palm wood powder, addressing the need for utilizing abundant waste palm wood in the food industry. The material benefits the safe transportation of vegetables from farms to markets. Its porous structure allows efficient absorption of plai oil emulsion, ensuring pathogen-free and high-quality treated broccoli. The reusable sachets benefit farmers seeking to extend the shelf life of fresh produce. This cost-effective method utilizes plai oil vapor, making it suitable for large-scale production.

Effect of emulsifiers on the properties of corn starch films incorporated with Zanthoxylum bungeanum essential oil

The use of natural and safe ingredients in green food packaging material is a hot research topic. This study investigated the effect of different emulsifiers on starch film properties. Three types of emulsifiers, including Tween 80 as a small-molecule surfactant, sodium caseinate (CAS), whey protein isolate (WPI), and gelatin (GE) as macromolecule emulsifiers, whey protein isolate fibril (WPIF) as a particle emulsifier, were utilized to prepare Zanthoxylum bungeanum essential oil (ZBO) emulsions. The mechanical, physical, thermal, antibacterial properties, microstructure and essential oil release of starch films were investigated. CAS-ZBO nanoemulsion exhibited the smallest particle size of 198.6 ± 2.2 nm. The film properties changed with different emulsifiers. CAS-ZBO film showed the highest tensile strength value. CAS-ZBO and WPIF-ZBO films exhibited lower water vapor permeability than Tween-ZBO. CAS-ZBO film showed good dispersion of essential oil, the slowest release rate of essential oils in all food simulants, and the best antibacterial effect against Staphylococcus aureus and Listeria monocytogenes. The films composed of CAS-ZBO nanoemulsion, corn starch, and glycerol are considered more suitable for food packaging. This work indicated that natural macromolecule emulsifiers of CAS and WPIF are expected to be used in green food packaging material to offer better film properties.

Grafting bacterial cellulose nanowhiskers into whey protein/essential oil film composites: Effect on structure, essential oil release and antibacterial properties of films

The development of bio-based primary packaging is imperative to improve food safety and quality, along with mitigating the environmental pollution resulting from the increasing production of packaging wastes. Whey protein concentrate (WPC) has received significant attention as an alternative raw material for edible films production, whereas an area of many ongoing researches has been the inclusion of bio-based compounds to formulate functional edible films. This study elaborated the development of WPC edible films fortified with different essential oils (EO) to assess antimicrobial activity against gram-positive (Staphylococcus aureus and Listeria monocytogenes) and gram-negative (Salmonella enteritidis and Pseudomonas aeruginosa) food-borne pathogens. Subsequently, the effect of grafting bacterial cellulose nanowhiskers (BCNW) in film composites was evaluated for WPC/oregano EO (WPC/OEO) films, which showed the highest antibacterial activity. Notably, increasing the concentration of grafted BCNW entailed a proportional increase on the inhibitory activity. In specific, antibacterial activity increased up to 80% when 10% BCNW was grafted in WPC/OEO films. Inclusion of BCNW and homogenous distribution of OEO into the film blend was pointed out through Raman analysis. In addition, AFM and SEM analysis revealed that inclusion of BCNW and OEO into the film matrix led to the formation of rough films with pores. This structural change enhanced the release capacity of OEO, that was further confirmed through a release kinetic experiment. This study indicated that BCNW addition positively affected whey protein films properties, thereby envisaging the potential development of sustainable food packaging materials with tailor-made properties.

Sustained release and insect repellent activity of cinnamon essential oil active label based on three-step encapsulating

To address the issue of rapid release of cinnamon essential oil (CEO) in active packaging applications, this study aimed to develop a sustained-release active label. CEO was encapsulated step by step to form cinnamon essential oil microemulsions (CEO-MEs), cinnamon essential oil microcapsules (CEO-MPs), and cinnamon essential oil sustained-release active labels (CEO-SRAL). Microstructure, thermal property and release property of the intermediate and final products obtained through the three-step embedding method were characterized, along with their anthelmintic activity. Results showed that the average particle size of CEO-MEs was 29.02 nm. The BJH pore size of porous CS/β-CD complex was 44.36 nm. CEO was encapsulated step by step and evenly distributed. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that multiple encapsulations of CEO didn't result in any adverse chemical reactions. The active label began to degrade at 290–400 °C with great thermal stability. The cumulative release days of CEO-SRAL were 20 days. The cumulative release concentration of CEO in CEO-SRAL was 31.99 mg/mL. Furthermore, the fumigation and repellent rates of three-step packaging products containing CEO to S.oryzae were more than 90%. These results indicated that the three-step encapsulation method could improve the performance of CEO to enhance the use of essential oil.

Incorporation of cinnamaldehyde, carvacrol, and eugenol into zein films for active food packaging: enhanced mechanical properties, antimicrobial activity, and controlled release.

Active packaging with antimicrobial functions to improve the quality and extend the shelf life of food products has gained great interest. Because commercial plastic packaging materials are not biodegradable and cause great environmental problems, plant-derived natural materials have been widely studied for the application of biodegradable packaging materials. Herein, we reported a study of essential oils (EOs)-loaded zein film. Cinnamaldehyde (CIN), carvacrol, and eugenol were added to equip the films with antimicrobial effects, while polyethylene glycol (PEG) and oleic acid (OA) were selected for the improvements of mechanical properties. The results showed that PEG efficiently improves the tensile strength and elongation (%E) of zein films compared to OA, although PEG induced weaker water barrier properties of the films than OA. FTIR spectra confirmed the formation of the hydrogen bonds between zein and PEG/OA. The EO-embedded zein film showed better antimicrobial effects than EO themselves. CIN-embedded films showed the highest antimicrobial effect among the three EOs. The sizes of the inhibition zones against Staphylococcus aureus of PEG-added zein films with 1%, 3%, and 5% CIN were 5.67, 12.67, and 16.67mm, which were larger than that of pure CIN, with the sizes of 0.00, 3.00, and 4.67mm, respectively. The developed films demonstrate a gradual release of EOs and show antimicrobial effects up to 96 h, indicating their high potential for the applications as active food packaging.

Potential benefits of short-term indoor exposure to sweet orange essential oil for relaxation during mental work breaks

With people's pursuit of a high-quality life, the use of essential oils to improve perceived indoor air quality has increased in recent years because of their pleasant odor. The smell-scape is increasingly being considered with respect to healthy building practices. To close the gap between the health benefits of essential oils and the incidental pollution problems, a cross-over study was conducted in an environment with lower concentrations of ozone and particulate matter based on a realistic method for their use. We compared the physiological parameters blood pressure, heart rate (HR), and heart rate variability (HRV), as well as various cognitive performance indicators, perceived indoor air quality, odor, and mood states between indoor environments with and without sweet orange essential oil. We alleviated the secondary pollution problem of essential oil by maintaining low-ozone spaces. During mental work breaks, the participants' HRV in the environment with sweet orange essential oil emission increased during four rest periods by 36.4%, 47.5%, 33.4%, and 25.0%, respectively, although there was no significant effect on cognitive performance between the control phase and the exposure phase. A significant increase in diastolic blood pressure following mental work indicated emotional stress and was confirmed by mood state evaluation. This stress was alleviated by exposure to sweet orange essential oil. The present study indicates that following a mental work period, the release of sweet orange essential oil has the potential benefits of promoting relaxation during a rest period, provided that the dose follows scientific dosage guidance, and that ozone and particulate matter concentrations are controlled.