Eco-sustainable coatings based on chitosan, pectin, and lemon essential oil nanoemulsion and their effect on strawberry preservation

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.

Emulsion-based edible chitosan film containing propolis extract to extend the shelf life of strawberries

In this study, propolis was first loaded into a conventional oil-in-water emulsion, which was combined with a chitosan film-forming solution to produce propolis emulsion-loaded film (PEF). Strawberries inoculated with Botrytis cinerea coated with PEF and blank emulsion-loaded films (BEF) were stored for 14 days at 4 °C. Compared to BEF, PEF showed superior mechanical and oxygen barrier properties, as well as antioxidant activities, but higher moisture permeability. PEF showed less oil agglomeration on the film surface after drying, as demonstrated by scanning electron microscopy (SEM) analysis. Compared to uncoated strawberries, coatings did not have a significant effect on weight loss or firmness during storage. In contrast, coated strawberries showed elevated total phenolics, anthocyanins, and ascorbic acid retention; however, PEF-coating yielded higher values. Moreover, the PEF coating resulted in a significantly lower reduction of organic acid and total soluble solids. Mold growth was visible in both uncoated and BEF-coated strawberries after 7 days of storage, while PEF-coated fruits showed no visible mold until the end of storage. Starting from day 4, PEF-coated fruits showed lower mold counts (~2 log CFU/g) than other samples. Therefore, the PEF prepared in this study has application potential for the preservation of fresh fruits.

Preparation and application of hydroxypropyl methylcellulose blended with beeswax and essential oil edible coating to enhance the shelf life of sweet cherries

The study involved preparing and applying edible nano-emulsion coatings containing hydroxypropyl methylcellulose (HPMC), beeswax (BW), and essential oils (thyme, cinnamon, clove, and peppermint) onto sweet cherries. The application was conducted at 4 °C, and the coated cherries were stored for 36 days. This research examines synthesized nano-emulsions physicochemical properties and antibacterial and antifungal activities (C1, C2, and C3). Additionally, it evaluates the quality parameters of control and coated sweet cherry samples. The features of the three edible coatings were assessed, and the findings from the zeta sizer, zeta potential, FTIR, and SEM analyses were deemed satisfactory. It was observed that the application of nano-emulsion coating C1 yielded positive results in maintaining quality attributes such as total suspended solids (TSS), total solids (TS), color, weight loss, respiration rate, firmness, total phenolic contents, and sensory evaluations. Nano-emulsion coating C1 demonstrated efficacy as an antibacterial and antifungal agent against foodborne pathogens E. coli and A. niger, respectively. The current research results are promising and applicable in food industries. The implications suggest that composite nano-emulsion, specifically nano-emulsion edible coatings, can be extensively and effectively used to preserve the quality and shelf life of fruits and vegetables. Furthermore, the environmental waste from conventional food packaging will be minimized using edible packaging applications.

Edible chitosan-based Pickering emulsion coatings: Preparation, characteristics, and application in strawberry preservation

The long-term application of plant essential oils in food preservation coatings is limited by their poor water solubility and high volatility, despite their recognized synergistic antimicrobial effects in postharvest fruit preservation. To overcome these limitations, a Pickering emulsion loaded with thyme essential oil (TEO) was developed by utilizing hydrogen bonding and electrostatic interactions to induce cross-linking of chitosan particles. This novel emulsion was subsequently applied in the postharvest storage of strawberries. The shear-thinning behavior (flow index <1) and elastic gel-like characteristics of the emulsion made it highly suitable for spray application. Regarding TEO release, the headspace concentration of TEO increased from 0.21 g/L for pure TEO to 1.86 g/L after two instances of gas release due to the stabilizing effect of the chitosan particles at the oil-water interface. Notably, no phase separation was observed during the 10-day storage of the emulsion. Consequently, the emulsion was successfully employed for the postharvest storage of strawberries, effectively preventing undesirable phenomena such as weight loss, a decrease in firmness, an increase in pH, and microbial growth. In conclusion, the developed Pickering emulsion coating exhibits significant potential for fruit preservation applications, particularly for extending the shelf life of strawberries.

Characterization of a Clove Essential Oil Slow-Release Microencapsulated Composite Film and Its Preservation Effects on Blueberry

In order to extend the shelf life of fruits and vegetables, a sodium alginate-sodium carboxymethyl cellulose composite film loaded with poly(vinyl alcohol) microcapsules was prepared in this paper. The optimal film substrate ratios were obtained after the response surface optimization. Poly(vinyl alcohol) microcapsules were prepared, clove essential oil was loaded into them to investigate the effects of microcapsules on the composite film properties, and the microcapsule composite film with the best overall performance was selected to be applied to blueberry preservation. The results showed that the composite film of 0.84% sodium alginate, 0.25% sodium carboxymethyl cellulose, and 0.56% glycerol presented excellent mechanical properties after adding 1.75% microcapsules. It had a good inhibitory effect on Escherichia coli, Staphylococcus aureus, and Penicillium and had a DPPH clearance rate of 83.78%. The low-temperature bonded composite film could slow down the respiration rate of blueberry, inhibit browning and water loss, effectively maintain the quality of blueberry, and have a significant preservation effect on the anthocyanin and soluble solid content of blueberry. The clove essential oil slow-release microencapsulated composite film can be used for blueberry preservation.

Antibacterial properties of hexanal-chitosan nanoemulsion against Vibrio parahaemolyticus and its application in shelled shrimp preservation at 4 °C

Vibrio parahaemolyticus has been considered as the leading pathogen associated with seafood-borne disease. Hexanal possesses antibacterial property but the hydrophobicity and volatility limit its application. The purpose of this study was to prepare hexanal-chitosan nanoemulsion (HCN), investigate its antibacterial ability against V. parahaemolyticus, and examine the combination of HCN with sodium alginate coating on the quality attributes of shrimp during cold storage. The mean droplet size of HCN fabricated by ultrasonic emulsification was 91.28 nm. HCN showed regular spherical shape and exhibited good centrifugation stability and storage stability at 4 °C. HCN exerted anti-V. parahaemolyticus effect with the minimum inhibitory concentration and minimal bactericidal concentration of both 5 mg/mL. Furthermore, HCN induced morphological changes and destroyed bacterial membrane, resulting in cell death. The results of preservation test showed that HCN alone and its combination with sodium alginate coating effectively retarded the quality deterioration and microbial spoilage of shelled shrimps during refrigerated storage. Comparatively, the combination treatment exhibited better preservation effect. The present study suggested that HCN prepared by ultrasonic emulsification is an effective alternative to control V. parahaemolyticus contamination in seafood and also shows great application potential in the quality maintaining of seafood during cold storage.

Development of hyaluronic acid based polysaccharide-protein composite edible coatings for preservation of strawberry fruit

With the growing demand for extending the shelf-life of perishable goods such as fruits and vegetables, there is continued interest towards the development of edible coatings derived from natural sources. To avoid rapid dissolution, water insoluble polysaccharide such as chitosan has been widely explored. In this work, we developed robust hyaluronic acid-based edible polysaccharide-protein coatings by combining it (hyaluronic acid) with chitosan and gelatin to introduce additional antioxidant properties. This work is the first example of using hyaluronic acid in edible coatings for fruit preservation. The effect of developed edible composite coatings on the quality of coated strawberries was investigated over a 15 day storage period with 3-day examination intervals. The obtained results revealed hyaluronic acid dose-dependent improvement in intrinsic properties of coated strawberries including weight loss, pH, titratable acidity (TA) and total solids content (TSS). Furthermore, the inclusion of hyaluronic acid significantly enhanced the antioxidant properties of developed edible coatings as measured using total phenolic content, change in ascorbic acid content and DPPH assay prolonging the shelf-life of coated strawberries.