Nano-emulsification essential oil of Monarda didyma L. to improve its preservation effect on postharvest blueberry

Rhamnolipids stabilized essential oils microemulsion for antimicrobial and fruit preservation

Essential oils, well-known for their antifungal properties, are widely utilized to combat fruit decay. However, their application faces big challenges due to their high volatility and hydrophobic traits, which leads to strong odor, short effective time and poor dispersivity. This study aimed to address these challenges by formulating microemulsions consisting of essential oils and rhamnolipids. The optimized microemulsion, featuring a small particle size of 6.8 nm, exhibited higher stability and lower volatility than conventional emulsion. Notably, the prepared microemulsions demonstrated remarkable antimicrobial efficacy against E. coli, S. aureus, C. albicans, S. cerevisiae, and A. niger. The application of these microemulsions proved to be highly effective in preventing blueberry decay while preserving fruit's quality, particularly by minimizing the loss of essential nutrients such as anthocyanins. Consequently, essential oil microemulsions emerge as a highly effective postharvest preservative for fruits, offering a promising solution to extend their shelf life and enhance overall quality.

A Novel Preservative Film with a Pleated Surface Structure and Dual Bioactivity Properties for Application in Strawberry Preservation due to Its Efficient Apoptosis of Pathogenic Fungal Cells

Botrytis cinerea (B. cinerea) and Colletotrichum gloeosporioides (C. gloeosporioides) were isolated from the decaying strawberry tissue. The antifungal properties of Monarda didyma essential oil (MEO) and its nanoemulsion were confirmed, demonstrating complete inhibition of the pathogens at concentrations of 0.45 μL/mL (0.37 mg/mL) and 10 μL/mL, respectively. Thymol, a primary component of MEO, was determined as an antimicrobial agent with IC50 values of 34.51 (B. cinerea) and 53.40 (C. gloeosporioides) μg/mL. Hippophae rhamnoides oil (HEO) was confirmed as a potent antioxidant, leading to the development of a thymol-HEO-chitosan film designed to act as an antistaling agent. The disease index and weight loss rate can be reduced by 90 and 60%, respectively, with nutrients also being well-preserved, offering an innovative approach to preservative development. Studies on the antifungal mechanism revealed that thymol could bind to FKS1 to disrupt the cell wall, causing the collapse of mitochondrial membrane potential and a burst of reactive oxygen species.

Essential oil-nanoemulsion based edible coating: Innovative sustainable preservation method for fresh/fresh-cut fruits and vegetables

Utilizing plant-based sources for the preservation of fresh and fresh-cut fruits and vegetables offers a natural and chemical-free method. However, the inherent instability of plant bioactive compounds underscores the necessity for encapsulation techniques. Essential oil-based nanoemulsions (EO-NEs) stand out among food additives due to their distinctive antibacterial and antioxidant properties. This review delves into recent advancements in the application of EO-NEs as edible coatings for fresh and fresh-cut produce. It examines the efficacy of EO-NEs in enhancing the preservation of fruits and vegetables by harnessing their bioactive compounds for antibacterial, antifungal, and antioxidant activities. Additionally, the review accentuates the efficacy of EO-NEs in inhibiting biofilm formation on fruits and vegetables. It reveals that coatings derived from plant-source nanoemulsions exhibit exceptional mechanical, optical, and microstructural qualities, as well as superior water barrier properties. In contrast to conventional emulsions, nanocoatings facilitate the gradual and controlled release of antimicrobial and antioxidant compounds during food storage. This feature enhances bioactivity, extends shelf life, and enhances the nutritional profile of products. By preserving and protecting shelf stability, EO-NEs contribute to the maintenance of vegetable freshness. Nonetheless, ensuring their commercial viability necessitates additional research into the toxicity of EO-based nanoemulsions.

Preparation of Perilla frutescens L. essential oil hydrogel beads and preservation application research in strawberry

Perilla frutescens L. essential oil (PLEO) has antibacterial and antioxidant properties, which can effectively maintain the quality of fruits and extend their shelf life. In this study, sodium alginate and chitosan were used as wall materials, and PLEO microcapsule powder was used as the core materials to prepare PLEO hydrogel beads. The best results were obtained by using 2%w/v sodium alginate and 1.5%w/v chitosan as wall materials, with a core-to-wall ratio of 2:1 and homogenized for 15 min producing PLEO hydrogel beads with encapsulation efficiency of 82.61 %. For strawberries preservation, PLEO hydrogel beads preservation group had a better effect after 5 d of storage, showing a lower decay rate (15.71 %), better maintaining the hardness of 1.75 kg/cm2, and a weight loss of 3.29 %. Furthermore, organic acids and total phenols were retained more in this group, the number of microorganisms was significantly reduced, and sensory qualities were improved, especially taste and color. This study provides important insights into the application of natural preservatives in the food industry and promotes sustainable practices in food preservation.

Improving blueberry cold storage quality: the effect of preharvest hexanal application on chilling injuries and antioxidant defense mechanisms

Blueberries are vulnerable to chilling injury (CI). This can lead to limited longevity when they are subjected to cold storage conditions. This study investigated the effectiveness of a preharvest spray containing 0.02% hexanal in reducing CI and improving the postharvest storage quality of 'Star' and 'Biloxi' blueberries. The blueberries were stored for a period of 5 weeks at 2 °C and in 90% relative humidity (RH). The findings revealed that the preharvest hexanal spraying of both cultivars delayed senescence by mitigating CI, as evidenced by the bolstering of the antioxidant defense system through increased superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), catalase (CAT), and phenylalanine ammonia lyase (PAL) enzyme activity. The treated fruit also maintained elevated levels of total phenol content (TPC), total flavonoids (TFC), and vitamin C, demonstrating enhanced free radical scavenging capacity (FRSC), while exhibiting reduced polyphenoloxidase (PPO) activity, and reduced malondialdehyde (MDA), and H2O2 content in comparison with the control group. The preharvest hexanal treatment also suppressed fruit softening by maintaining greater firmness and higher membrane stability index (MSI) scores, inhibiting the activity of polygalacturonase (PG), pectinmethylesterase (PME), xylanase, and α-amylase, and reducing microbial counts (MC) and incidence of decay (DI) in comparison with the control. Preharvest hexanal treatment also improved the overall storage quality by reducing weight loss, total soluble solids (TSS), pH, and the TSS/acid ratio, while increasing titratable acidity (TA) in comparison with the control during cold storage. The findings suggest that hexanal, as a preharvest application, delays senescence effectively and preserves overall quality by enhancing cold tolerance through antioxidant defense mechanisms in blueberry storage under cold conditions. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Modified halloysite nanotubes as GRAS nanocarrier for intelligent monitoring and food preservation

Conventional "all-in-one" methods for multi-component active packaging systems are not wholly adequate for fresh food. Given the need for multifunctional properties, introducing halloysite nanotubes (HNTs) could be a promising way to achieve controllable release of active ingredients while endowing with pH-sensitive performance. Here, we pioneered a GRAS composite with multifunctional properties, employing natural HNTs as a nanocarrier, citral (Cit) as an active antimicrobial agent, and myricetin (Myr) for monitoring freshness. The Cit-HNTs-Myr had excellent DPPH, ABTS and ·OH radical scavenging capacity, dual-model (contact and fumigant) antibacterial properties, and pH-sensitive performance. Subsequently, a smart tag prepared by dipping cellulose fibers into Cit-HNTs-Myr, which extended the shelf life of shrimp and blueberries, and provided freshness information for the shrimp. These results demonstrate the applicability of Cit-HNTs-Myr in the preservation of perishable goods and freshness monitoring.

Paper-based material with hydrophobic and antimicrobial properties: Advanced packaging materials for food applications

The environmental challenges posed by plastic pollution have prompted the exploration of eco-friendly alternatives to disposable plastic packaging and utensils. Paper-based materials, derived from renewable resources such as wood pulp, non-wood pulp (bamboo pulp, straw pulp, reed pulp, etc.), and recycled paper fibers, are distinguished by their recyclability and biodegradability, making them promising substitutes in the field of plastic food packaging. Despite their merits, challenges like porosity, hydrophilicity, limited barrier properties, and a lack of functionality have restricted their packaging potential. To address these constraints, researchers have introduced antimicrobial agents, hydrophobic substances, and other functional components to improve both physical and functional properties. This enhancement has resulted in notable improvements in food preservation outcomes in real-world scenarios. This paper offers a comprehensive review of recent progress in hydrophobic antimicrobial paper-based materials. In addition to outlining the characteristics and functions of commonly used antimicrobial substances in food packaging, it consolidates the current research landscape and preparation techniques for hydrophobic paper. Furthermore, the paper explores the practical applications of hydrophobic antimicrobial paper-based materials in agricultural produce, meat, and seafood, as well as ready-to-eat food packaging. Finally, challenges in production, application, and recycling processes are outlined to ensure safety and efficacy, and prospects for the future development of antimicrobial hydrophobic paper-based materials are discussed. Overall, the emergence of hydrophobic antimicrobial paper-based materials stands out as a robust alternative to plastic food packaging, offering a compelling solution with superior food preservation capabilities. In the future, paper-based materials with antimicrobial and hydrophobic functionalities are expected to further enhance food safety as promising packaging materials.

High transparency, water vapor barrier and antibacterial properties of chitosan/carboxymethyl glucan/poly(vinyl alcohol)/nanoparticles encapsulating citral composite film for fruit packaging

Utilizing antibacterial packaging material is an effective approach to delay fruit rotting and spoilage thereby minimizing financial losses and reducing health harm. However, the barrier and mechanical properties of biodegradable antibacterial packaging materials are barely compatible with transparency. Herein, antimicrobial nanoparticles encapsulating citral (ANPs) were first prepared by emulsification under the stabilization of oxidized dextran (ODE) and ethylene diamine. Then, composite films with high transparency, good water vapor barrier, and mechanical and antibacterial properties for fruits packaging were prepared from chitosan (CS), carboxymethyl-glucan (CMG), poly(vinyl alcohol) (PVA), and ANPs by solvent casting strategy. The synergistic effects of electrostatic interaction and hydrogen bonding could regulate crystalline architecture, generating high transparency of the composite films (90 %). The mechanical properties of the composite film are improved with elongation at break up to 167 % and stress up to 32 MPa. The water vapor barrier property of the film is appropriate to the packed fruit for less weight loss and firmness remaining. Simultaneously, the addition of ANPs endowed the film with excellent antimicrobial and UV-barrier capabilities to reduce fruit mildew, thereby extending the shelf life of fruits. More importantly, the composite polymer solution could be sprayed or dipped directly on fruits as a coating for food storage to improve food shelf life, substantially expanding its ease of use and scope of use.

Effects of high power pulsed microwave on the enhanced color and flavor of aged blueberry wine

A new method of high-power pulsed microwave (HPPM) was applied to accelerate the aging of blueberry wine. The color changes of blueberry wines during aging were investigated through Chemical Wine Age and CIE-LAB measurement. Results showed that the blueberry wines treated by HPPM at low frequencies (50 and 100 Hz) exhibited improved color characteristics with L* value reaching 47.04 at 100 Hz, an increased maturity of wine body, and a shortened chemical wine age from 90 days to 75 days. Moreover, the aroma changes determined by GC-MS showed that HPPM accelerated the formation of esters in blueberry wine, which were increased by 18.44% and 56.97% respectively under the conditions of 50 and 150 Hz. The formation of acid substances was reduced compared with the original wine, with contents of acetic acid, caproic acid, and octanoic acid of 29.46 µg/mL, 15.60 µg/mL, 17.74 µg/mL, respectively, displaying an enhanced wine flavor.

Inhibition of Salmonella Enteritidis by Essential Oil Components and the Effect of Storage on the Quality of Chicken

This research investigates the antibacterial potential of plant essential oil components including thymol, carvacrol, citral, cinnamaldehyde, limonene, and β-pinene against Salmonella Enteritidis (S. Enteritidis). Through the determination of minimum inhibitory concentration, three kinds of natural antibacterial agents with the best inhibitory effect on S. Enteritidis were determined, namely thymol (128 μg/mL), carvacrol (256 μg/mL), and cinnamaldehyde (128 μg/mL). Physical, chemical, microbial, and sensory characteristics were regularly monitored on days 0, 2, 4, and 6. The findings of this study reveal that both thymol at MIC of 128 μg/mL and carvacrol at MIC of 256 μg/mL not only maintained the sensory quality of chicken, but also decreased the pH, moisture content, and TVB-N value. Additionally, thymol, carvacrol and cinnamaldehyde successfully inhibited the formation of S. Enteritidis biofilm, thereby minimizing the number of S. Enteritidis and the total aerobic plate count in chicken. Hence, thymol, carvacrol, and cinnamaldehyde have more effective inhibitory activities against S. Enteritidis, which can effectively prevent the spoilage of chicken and reduce the loss of its functional components.

Advances in Controllable Release Essential Oil Microcapsules and Their Promising Applications

Essential oils (EOs) have emerged as natural and popular ingredients used in the preparation of safe and sustainable products because of their unique characteristics, such as antibacterial and antioxidant activity. However, due to their high volatility, poorly solubility in water, and susceptibility to degradation and oxidation, the application of EOs is greatly limited. One of the promising strategies for overcoming these restrictions is encapsulation, which involves in the entrapment of EOs inside biocompatible materials to utilize their controllable release and good bioavailability. In this review, the microencapsulation of the controllable release EOs and their applications are investigated. The focus is on the antimicrobial mechanism of various EOs on different bacteria and fungi, release mechanism of microencapsulated EOs, and preparation research progress of the controllable EOs microcapsules. In addition, their applications are introduced in relation to the food, textiles, agriculture, and medical fields.