The dual function of calcium ion in fruit edible coating: Regulating polymer internal crosslinking state and improving fruit postharvest quality

The edible coating is proved to be a convenient approach for fruit preservation. Among these published explorations, naturally sourced macromolecules and green crosslinking strategies gain attention. This work centers on edible coatings containing Ca2+ as crosslinker for the first time, delving into crosslinking mechanisms, include alginate, chitosan, Aloe vera gel, gums, etc. Additionally, the crucial functions of Ca2+ in fruit's quality control are also elaborated in-depth, involving cell wall, calmodulin, antioxidant, etc. Through a comprehensive review, it becomes evident that Ca2+ plays a dual role in fruit edible coating. Specifically, Ca2+ constructs a three-dimensional dense network structure with polymers through ionic bonding. Moreover, Ca2+ acts directly with cell wall to maintain fruit firmness and serve as a second messenger to participate secondary physiological metabolism. In brief, coatings containing Ca2+ present remarkable effects in preserving fruit and this work may provide guidance for Ca2+ related fruit preservation coatings.

Eugenol and Aloe vera blended natural wax-based coating for preserving postharvest quality of Kaji lemon (Citrus jambhiri)

Edible coatings on fruits and vegetables preserve postharvest quality by reducing water loss and lowering respiration, and metabolic activities. The primary objectives of this study were to develop composite coating formulations using natural waxes (carnauba and shellac wax), eugenol nanoemulsion, and Aloe vera gel, and assess the potential impacts of the coating formulations on the postharvest quality and shelf-life of the Kaji lemon. The results show that eugenol nanoemulsion and Aloe vera gel enhanced the physico-chemical, antimicrobial and antioxidant properties of the developed coating. Notably, the fruits coated with optimized nanocomposite of wax with eugenol and aloe vera gel inclusion (SW + CW/EuNE-20/AVG-2) showed the lowest weight loss (16.56%), while the coatings of wax with only aloe vera gel (SW + CW/AVG-2) exhibited the highest firmness (48 N), in contrast to the control fruit, which had 27.33% weight loss and 9.6 N firmness after 28 days of storage, respectively.

Application of sodium alginate-based edible coating with citric acid to improve the safety and quality of fresh-cut melon (Cucumis melo L.) during cold storage

The safety and quality of fresh-cut melons is reduced by a series of decay processes by enzymatic browning and microbial contamination. This study aimed to assess the impact of a 2% sodium alginate-based edible coating (ALC) combined with different concentrations of citric acid (CA; 0.5%, 1%, 2%, and 3%) on the microbial safety and physical quality of fresh-cut melons during a 7-day storage period at 10 °C. The findings revealed that the combination of ALC and 3% CA was successful in preventing the growth of pathogenic bacteria (Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, and Staphylococcus aureus) and natural microflora on fresh-cut melons during storage. In addition, treating fresh-cut melons with ALC containing 3% CA improved their quality by reducing browning and softening during storage at 10 °C. Based on these findings, it can be concluded that using ALC with 3% CA is an effective method to improve the safety and quality of fresh-cut melons.

Application of gums as techno-functional hydrocolloids in meat processing and preservation: A review

The global consumption of meat products is on the rise, leading to concerns about sustainability, fat content, and shelf life. Synthetic additives and preservatives used to extend the shelf life of meat often have negative health and environmental implications. Natural polysaccharides such as seed gums possess unique techno-functional properties, including water holding capacity, emulsifying, and film forming, offering potential alternatives in meat processing and preservation. This study explores the use of gums in meat and meat product processing and preservation. The water holding and emulsifying properties of gums can potentially bind fat and reduce overall lipid content, while their antimicrobial and film-forming properties can inhibit the microbial growth and reduce oxidation, thereby extending the shelf life. Incorporating gums as a fat replacer and edible coating shows promise for reducing fat content and extending the shelf life of meat and meat products.

Postbiotics-enriched flaxseed mucilage coating: A solution to improving postharvest quality and shelf life of strawberry

This research aimed to assess the effects of flaxseed mucilage (Mu) coatings supplemented with postbiotics (P) obtained from Lactobacillus acidophilus LA-5 on various physical, biochemical, and microbial characteristics of strawberry fruits. Strawberry fruits were immersed for 2 min in Mu2.5 (2.5 % mucilage in distilled water), Mu5 (5 % mucilage in distilled water), P-Mu2.5 (2.5 % mucilage in undiluted postbiotics) and P-Mu5 (5 % mucilage in undiluted postbiotics) solutions and were stored at 4 °C and 85 RH for 12 days. All coatings were effective in reducing fungal count compared to the uncoated control fruits. Mu5 coating exhibited the highest efficacy, reducing fungal count by 2.85 log10 CFU/g, followed by Mu2.5 (1.47 log10 CFU/g reduction) and P-Mu2.5 groups (0.90 log10 CFU/g reduction). The fruits coated with edible coatings showed significant delays in the change of weight loss, pH, and total soluble solids as compared to the uncoated fruits. The coating containing postbiotics i.e., P-Mu5 also showed a significant increase in the total phenolic contents, total flavonoid content, antioxidant capacity, and total anthocyanin content at the end of storage relative to the uncoated fruits. Thus, Mu and P-Mu coatings may be a useful approach to maintaining the postharvest quality of strawberry fruits during cold storage.

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.

Persimmon preservation using edible coating of chitosan enriched with ginger oil and visualization of internal structure changes using X-ray computed tomography

The incorporation of ginger oil (GO) influenced the physical, optical, and structural properties of the chitosan (CH) film including the decreases of moisture content (60.15 %), water solubility (35.37 %) and water vapor permeability (WVP) (32.79 %) and the increases of tensile strength (TS) (125 %), elongation at break (EAB) (2.74 %) and opacity (131.08 %). Antifungal capacity of the CH film was enhanced when GO was added to the film. The CH + GO film showed a less homogeneous surface that the presence of the oil droplets on the film surface. Moreover, the CH and CH + GO coatings reduced weight loss of persimmon by 14.87 %, and 21.13 %, respectively, compared to the control. Moisture content loss of the coated CH- and the coated CH + GO- persimmons was decreased by 1.94 % and 4.92 %, respectively, compared to that of the control persimmon. Furthermore, the CH and CH + GO coatings decreased in color changes, respiration rate, ethylene production, changes in pH and TSS, and remained firmness of persimmon during storage at 25 °C. In addition, X-ray CT images can be used to monitor internal changes and observe the tissue breakdown during storage period. The ΔGS value can be used as a predictor of persimmon internal qualities. Thus, the CH film containing GO can be applied as an active packaging material.

Antimicrobial and biocompatibility nature of methanol extract of Lannea coromandelica bark and edible coating film preparation for fruit preservation

This research was performed to evaluate the antimicrobial activity of methanol extract of Lannea coromandelica bark against fruit damage causing microbes such as fungi: Alternaria sp., Aspergillus sp., Botrytis sp., Cladosporium sp., Fusarium sp., Penicillium sp., Phytophthora sp., and Trichoderma sp. The bacteria: such as Chromobacter sp., Enterobacter sp., Erwinia sp., Flavobacterium sp., Lactobacillus sp., Pseudomonas sp., and Xanthomonas sp. was investigated. Furthermore, their biocompatibility nature was determined through animal (rat) model study and their fruit preserving potential was determined by edible coating preparation with chitosan and other substances. Interestingly, the extract showed dose dependent (1000 μg mL-1) activity against these microbes in the following order: Enterobacter sp. (26.4 ± 1.5) > Chromobacter sp. (25.4 ± 1.6) > Pseudomonas sp. (24.5 ± 1.3) > Flavobacterium sp. (24.3 ± 1.4) > Xanthomonas sp. (23.6 ± 1.6) > Erwinia sp. (23.6 ± 1.6) > Lactobacillus sp. (19.6 ± 1.3). Similarly, the antifungal activity was found as Penicillium sp. (32.6 ± 1.3) > Cladosporium sp. (32.6 ± 1.5) > Alternaria sp. (30.3 ± 1.2) > Aspergillus sp. (29.9 ± 1.8) > Botrytis sp. (29.8 ± 1.2) > Fusarium sp. (28.6 ± 1.5) > Trichoderma sp. (19.8 ± 1.4) > Phytophthora sp. (16.2 ± 1.1). The acute toxicity and histopathological study results revealed that the extract possesses biocompatible in nature. The illumination transmittance and active functional groups involved in interaction among test methanol extract and chitosan investigated by UV-vis and Fourier-transform infrared spectroscopy (FTIR) analyses and found average light transmittance and few vital functional groups accountable for optimistic interaction to creak edible coating. Approximately four (set I-IV) treatment sets were prepared, and it was discovered that all of the coated Citrus maxima fruit quality characteristics including total soluble solids (TSS), weight loss (%), pH of fruit pulp juice, and decay percentage were significantly (p>0.05) better than uncoated fruit.

Effects of konjac glucan-nan/low-acyl gellan edible coatings loaded thymol-β-cyclodextrin microcapsules on postharvest blueberry

This study developed an edible antimicrobial coating using a blend of konjac glucomannan (KGM) and low acyl gellan gum (LAG) hydrogel to incorporate thymol nanoparticles (TKL). The optimized TKL formulation (TKL60) comprised 0.22% thymol microcapsules (TMs), 0.075% total polysaccharide content (KGM:LAG = 1:2), and 99.63% distilled water. When applied to blueberries, TKL60 significantly extended their shelf life to 42 d at 2 ± 0.5 °C, tripling that of control fruit. TKL60 reduced decay rate, weight loss, and respiration rate, delayed softening and senescence during cold storage. It preserved the outer epidermis by retaining cuticular waxes, curbing lipid oxidation, and sustaining defense-related enzyme activities. Flavor analysis revealed altered volatile compound concentrations in TKL60-treated berries, including decreased terpenes and benzaldehyde, and increased esters and aldehydes like 2-methylbutanol, 3-methylbutanol, and linalool. Discriminant Analysis highlighted TKL60's efficacy in delaying aroma deterioration by over 21 d. TKL60 exhibits potential as a substitute for synthetic coatings and chemical insecticides.

Development and characterization of pomegranate peel extract-functionalized jackfruit seed starch-based edible films and coatings for prolonging the shelf life of white grapes

In the current research, the pomegranate peel extract of varying concentrations (0.02, 0.04, 0.06, 0.08, and 0.1 g/mL) were incorporated into jackfruit seed starch (5 % w/w) based edible films and coatings for the evaluation their effects on the mechanical, physical, barrier and thermal properties. Furthermore, the effects of the optimized edible coating were investigated on the postharvest shelf life of white grapes at room storage (30 ± 5 °C, RH = 70 ± 5 %) conditions for up to 8 days. The obtained results showed a significant increment in thickness (p ≤ 0.05) with higher concentration (0.1 g/mL) of pomegranate peel extract (PPE), total phenolic content (959.33 ± 43.36 mg/100 g) and antioxidant activity (87.35 ± 1.64 %) of the prepared edible films but have negative impacts on the water vapor permeability (2.82 × 10-6 ± 6.48 × 10-7 g-1h-1pa-1) and oxygen permeability (1.62 × 10-14 ± 9.32 × 10-15 cm3·cm/cm2·s·cmHg), solubility (23.24 ± 3.21 %), and tensile strength (1.60 ± 0.43 MPa). The edible film enriched with 0.4 g/mL of PPE showed higher thermal stability in terms of glass transition temperature (98.2 ± 0.21 °C) and peak temperature (110.3 ± 0.35 °C). Additionally, the application of coating treatment significantly maintains the postharvest shelf life of white grapes throughout the storage period.

Characterization, antioxidant and antibacterial activities of gelatin-chitosan edible coated films added with Cyclocarya paliurus flavonoids

In this study, gelatin-chitosan (GEL-CS) composite films added with 0.1 %, 0.2 %, and 0.3 % Cyclocarya paliurus flavonoids (CPF) were prepared. Then their appearance properties, mechanical properties, barrier properties, microstructure, thermal stability properties, antioxidant activity, and antibacterial properties were investigated. As compared with GEL-CS film, the GEL-CS films with CPF were darker in color, had higher water vapor barrier, higher elongation at break, and higher thermal stability. Additionally, microstructure analysis with Fourier infrared spectroscopy, scanning electron microscopy, and X-ray diffraction demonstrated that hydrogen bonding was the main force for cross-linking CPF with other membrane substrates. Moreover, the addition of CPF strengthened the antioxidant and antimicrobial properties of the membranes. These results indicated that the CPF addition could endow membranes with more excellent functional properties and bioactivity, accompanied by environmentally friendly and edible features. The GEL-CS-CPF composite film would be a potential and prospective packing material for food preservation applications.

Prolonging the shelf life of fresh-cut guava (Psidium guajaya L.) by coating with chitosan and cinnamon essential oil

This study investigated the effect of a coating of chitosan (CH) and cinnamon essential oil (CEO; 0-1 %) on the quality attributes of fresh-cut guava (Psidium guajaya L.) during storage at 4 ± 1 °C for 17 days, with uncoated fresh-cut guava used as control. The CH coating significantly (p < 0.05) delayed changes in weight loss, firmness, colour, total soluble solids and titratable acidity compared to the control sample. Furthermore, the effects were more prominent with the incorporation of higher CEO concentrations. The bacterial, yeast and mould counts were also significantly lower (p < 0.05) in the CH-coated samples than in the control, with the coating containing 1 % CEO exhibiting the best quality preservation effect. In addition, CH and CEO coatings extended the shelf life of fresh-cut guava up to 17 days compared to the control sample (shelf life of only 3 days). In conclusion, combining CH and CEO as a coating matrix effectively preserves the quality and enhances fresh-cut guava's shelf life.

Current and emerging applications of carrageenan in the food industry

Carrageenan, a polysaccharide derived from red algae, has a long history of use as a food additive in food. Carrageenan comes in three classes, κ-, ι-, and λ-carrageenan, with different properties attributed to their organosulfate substitution levels, and their interactions with other food components give rise to properties such as water holding, thickening, gelling, and stabilizing. Over the years, carrageenan has been used in wide variety of food products such as meat, dairy, and flour-based products, and their mechanisms and functions in these matrices have also been studied. With the emergence of novel food technologies, carrageenan's potential applications have been extensively explored alongside, including encapsulation, edible films/coatings, plant-based analogs, and 3D/4D printing. As the food technology evolves, the required functions of food ingredients have changed, and carrageenan is being investigated for its role in these new areas. However, there are many similarities in the use of carrageenan in both classic and emerging applications, and understanding the underlying principles of carrageenan will lead to a proper use of carrageenan in emerging food products. This review focuses on the potential of carrageenan as a food ingredient in these emerging technologies mainly based on papers published within the past five years, highlighting its functions and applications to better understand its role in food products.

New coating containing chitosan and Hyssopus officinalis essential oil (emulsion and nanoemulsion) to protect shrimp (Litopenaeus vannamei) against chemical, microbial and sensory changes

In this study, the effect of chitosan coating containing emulsion and nanoemulsion of Hyssopus officinalis essential oil (EO) on the chemical, microbiological and sensory characteristics of shrimp (Litopenaeus vannamei) was investigated. The minimum value of TVB-N (Total volatile basic nitrogen), TBARS (Thiobarbituric acid reactive substances), PV (peroxide value), TMA-N (Trimethylamine-nitrogen) and FFA (Free fatty acids) after 12 days were shown in NE + HEO 1% (coating containing chitosan with nanoemulsion of EO) with 20.53 mg N/100 g, 0.5 µg/kg, 0.88 MAQ peroxide/kg, 1.3 mg/100 g and 12.16 mg 100% of oleic acid, respectively. Also, minimum value of pH after 12 days was related to the CE + HEO 1% (coating containing chitosan with emulsion of EO) with 7.60. The minimum value of psychrophilic and mesophilic microbial count after 12 days were shown in NE + HEO 1%, 4.40 ± 0.36 and 4.03 ± 0.06 cfu/g, respectively. The best score of sensory evaluation was observed in the NE-HEO 1% treatment. As a result, the edible coating containing chitosan-based nanoemulsion could be effective to the preservation of shrimp's microbiological, chemical, and sensory characteristics.

Sonochemical treatment of packaging materials for prolonging fresh produce shelf life

Packaging bags made of polyethylene (PE) were sonochemically coated with edible antibacterial nanoparticles of chitosan (CS). In this work, the nanoparticles (NPs) were deposited on the surface of PE packaging bags by applying sonication waves on an acetic solution of chitosan. The characterization of CS NPs and PE bags was conducted by physicochemical techniques. The results showed that the coated bags had longer freshness than the uncoated ones. Furthermore, the characterization of cucumber, mushroom, and garlic placed into coated and uncoated PE bags was conducted by monitoring various parameters such as mass loss, total soluble solids, pH, and visual inspection. The study revealed that the PE bags coated with CS NPs showed a noticeable result in extending the shelf life of fresh produce. Finally, the antibacterial activity of PE bags was evaluated against various bacterial species. Hence, the PE bags coated with CS NPs could be a promising candidate for elongating the shelf life of packaged fresh produce.

Effect of chitosan-gelatine edible coating containing nano-encapsulated clove ethanol extract on cold storage of chilled pork

Meat safety and quality are the main concerns of consumers in the present food market. Chitosan-gelatin edible coatings containing nano-encapsulated clove ethanol extracts (CNPs), designated as CHI-GEL-CNPs, on the quality preservation of chilled pork were studied. Results showed that the mean particle diameters of CNPs were 346.15 ± 37.30 nm. Nano-modification improved the antibacterial activity of free clove ethanol extract. The increasing rate order of TVB-N and TBARS was CHI-GEL-CNPs < CHI-GEL-Clove < CHI-GEL < CHI < CON group. The CHI-GEL-CNPs coating inhibited the elevation of pH and total viable count (TVC) of chilled pork. The TVB-N and TVC values demonstrated that the CHI-GEL-CNPs coating effectively extended the shelf life of chilled pork up to 13 days. In addition, the sensory properties of CHI-GEL-CNPs chilled pork loins were superior to that of control samples. Therefore, the developed CHI-GEL-CNPs coatings have great promise as a nanocomposite for meat preservation.

Biomacromolecule assembly of soy glycinin-potato starch complexes: Focus on structure, function, and applications

The effect of the cross-linking mechanism and functional properties of soy glycinin (11S)-potato starch (PS) complexes was investigated in this study. The results showed that the binding effecting and spatial network structure of 11S-PS complexes via heated-induced cross-linking were adjusted by biopolymer ratios. In particular, 11S-PS complexes with the biopolymer ratios of 2:15, had a strongest intermolecular interaction through hydrogen bonds and hydrophobic force. Moreover, 11S-PS complexes at the biopolymer ratios of 2:15 exhibited a finer three-dimensional network structure, which was used as film-forming solution to enhance the barrier performance and mitigate the exposure to the environment. In addition, the 11S-PS complexes coating was effective in moderating the loss of nutrients, thereby extending their storage life in truss tomato preservation experiments. This study provides helpful to insights into the cross-linking mechanism of the 11S-PS complexes and the potential application of food-grade biopolymer composite coatings in food preservation.

Development of Plantago ovata seed mucilage and xanthan gum-based edible coating with prominent optical and barrier properties

This study investigates the fabrication of edible coating based on Plantago ovata seed mucilage (POSM). The films were prepared from POSM (1 %, w/v), glycerol (75 %, based on POSM mass), and xanthan gum (XG: 20, 30 and 40 %, based on POSM mass) by a casting method, and their physicochemical, mechanical, thermal, morphological, and barrier properties were determined. Results indicated the development of highly transparent (transparency values: 1.36 ± 0.05 to 2.42 ± 0.09) and hydrophobic films (contact angle: 101.57 ± 0.34 to107.08 ± 0.55o) with very low water vapor permeability (WVP: 2.77 ± 0.02 × 10-12 to 1.98 ± 0.04 × 10-12 g s-1m-1Pa-1), slight water solubility (31.14 ± 0.46 to 23.08 ± 0.82 %), and good mechanical properties (tensile strength: 30.87 ± 0.96 to 61.80 ± 0.71 MPa). Morphological studies also indicated smooth and uniform surfaces without pores and cracks. In addition, the films showed good antioxidant activity (61.46 to 68.71 %), and their antibacterial activity against E. coli, S. aureus and P. aeruginosa was also demonstrated. The applicability of the developed films to extend the shelf life of strawberries was shown by comparing the appearance of dip-coated strawberries and the control sample within 8 days at room temperature. Based on the results, the developed biofilms have great potential for edible coating and packaging applications.

Quantification of Bioactive Metabolites Derived from Cell-Free Supernatant of Pediococcus acidilactici and Screening their Protective Properties in Frankfurters

The specific aims of the current study were to determine and quantify the bioactive compounds derived from the cell-free supernatant (CFS) of Pediococcus acidilactici and screen their protective effect in frankfurters by applying an edible coating. This was achieved by immersing the peeled frankfurters in the CFS (CFS: 50% and 100%) alone or in combination with chitosan (CH: 0.5% and 1%) solutions for 3 min. Untreated frankfurter samples (control) exceeded the maximum acceptable total viable count limit (7.0 log10) on the 14th day, whereas samples treated with 100% CFS + 1% chitosan reached the limit on day 28 during refrigerated storage (P < 0.05). This treatment provided a 14-day extension to the shelf life of frankfurters without causing any significant changes in color and sensory attributes (P > 0.05). Additionally, this treatment inhibited oxidation in the frankfurters, leading to no significant changes in TBA and TVB-N within this group during storage (P > 0.05). This protective effect was mainly attributed to the wide variety of bioactive compounds identified in the CFS, including a total of 5 organic acids, 20 free amino acids, 11 free fatty acids, 77 volatiles, and 10 polyphenols. Due to these bioactive compounds, CFS exhibited a strong radical scavenging capacity (DPPH: 435.08 TEAC/L, ABTS: 75.01 ± 0.14 mg TEAC/L; FRAP: 1.30 ± 0.03 mM FE/L) and antimicrobial activity against microorganisms primarily responsible for the spoilage of frankfurters. In conclusion, the results indicate that the CFS contains high levels of bioactive metabolites, and an edible chitosan coating impregnated with CFS can be utilized to extend the shelf life of frankfurters through its antimicrobial effects and oxidation stabilization.

Alginate-based edible coating with oregano essential oil/β-cyclodextrin inclusion complex for chicken breast preservation

A sodium alginate (SA) edible coating containing oregano essential oil (OEO)/β-cyclodextrin (β-CD) inclusion complexes (SA/OEO-MP coating) was developed to extend the shelf life of fresh chicken breast during refrigeration storage. First, OEO was inserted into the hydrophobic interior of β-CD to form an inclusion complex (OEO-MP) that maintained its excellent antioxidant and antibacterial activities. The formed OEO-MP was characterized using fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). In addition, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results demonstrated that β-CD could improve the thermal stability of OEO. The encapsulation efficiency reached 71.6 %, and OEO was released continuously from the OEO-MP. The lipid oxidation, total viable count (TVC) and sensory properties of chicken breasts were regularly monitored when OEO-MP was incorporated into the SA coating for chicken breast preservation. Compared with the uncoated group, the SA/OEO-MP-coated groups showed significantly reduced increases in pH, thiobarbituric acid reactive substances (TBARS), total volatile base nitrogen (TVB-N), and TVC, especially in the SA/OEO-MP1 group. In summary, the SA/OEO-MP coating could preserve the chicken breast by reducing lipid oxidation and inhibiting the proliferation of microorganisms. It would be developed as a prospective edible packaging for chicken preservation.

Effectiveness of aloe vera gel coating and paraffin wax-coated paperboard packaging on post-harvest quality of hog plum (Spondius mangifera L.)

In this research work, hog plum (Spondius mangifera L.) was treated with Aloe vera gel (AVG) coating and paraffin wax-coated box (PWB) packaging and stored at ambient condition (25 ± 3 °C and 80-85% relative humidity) for 12 d to evaluate their impact on postharvest quality and storability. The physicochemical properties, microbiological analysis, and decay evaluation were analyzed throughout the storage period. The AVG and PWB coating treatments both demonstrated a significant effect on the quality of fruits during storage. The results showed that fruits with AVG coating and PWB packaging exhibited lower decay rates, weight loss, color difference, total microbial population, total soluble solids, titratable acidity, and higher fruit firmness and pH than uncoated (control) fruits. The AVG coating was the most effective treatment, followed by the PWB packaging treatment. Our findings show that the AVG coating and PWB packaging treatment can be a promising solution for preserving the quality of hog plums and also helps in increasing the lifetime of hog plums during storage.

Comparison of chitosan and gelatin-based films and application to antimicrobial coatings enriched with grapefruit seed extract for cherry tomato preservation

Bio-based single, composite, and bilayer edible films were developed based on chitosan and gelatin, including grapefruit seed extract (GSE) as an antimicrobial agent. The physicochemical and antimicrobial properties of films were analyzed, and it was found that compounding and laminating two polymers could enhance their physicochemical properties. The composite film was strong, endurable, and flexible compared with the single ones. In addition, the composite and bilayer films had lower water vapor permeability than the single ones. Edible films and coatings with GSE presented a greater bactericidal effect than the inactive ones. In addition, the hardness, weight, and color changes of the coated cherry tomatoes during 7-day storage did not differ, whereas a bacterial reduction against Salmonella Typhimurium was revealed. Taken together, composite and bilayer films with CH and GL and enriched with GSE were developed for food packaging applications, and it showed improved mechanical, water barrier, and antimicrobial properties.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01254-9.

Exploiting the bioactive properties of essential oils and their potential applications in food industry

Fruits are an abundant source of minerals and nutrients. High nutritional value and easy-to-consume property have increased its demand. In a way to fulfil this need, farmers have increased production, thus making it available for consumers in various regions. This distribution of fruits to various regions deals with many associated problems like deterioration and spoilage. In a way, the common practices that are being used are stored at low temperatures, preservation with chemicals, and many more. Recently, edible coating has emerged as a promising preservation technique to combat the above-mentioned problems. Edible coating stands for coating fruits with bioactive compounds which maintains the nutritional characteristics of fruit and also enhances the shelf life. The property of edible coating to control moisture loss, solute movement, gas exchange, and oxidation makes it most suitable to use. Preservation is uplifted by maintaining the nutritional and physicochemical properties of fruits with the effectiveness of essential oils. The essential oil contains antioxidant, antimicrobial, flavor, and probiotic properties. The utilization of essential oil in the edible coating has increased the property of coating. This review includes the process of extraction, potential benefits and applications of essential oils in food industry.

Recent advances on postharvest technologies of bell pepper: A review

The bell pepper (Capsicum annuum L.) is a commercially important horticultural crop grown in tropical and sub-tropical areas across the world. Despite this importance, it is a perishable vegetable with a limited shelf life and high disease susceptibility. Bell pepper output has expanded significantly in recent years. However, this crop is still experiencing close to 40% postharvest losses annually. Chemical fumigation for postharvest disease control of bell pepper has been shown to be efficient against fungal infections, but environmental impact and consumption hazards limit its full use. Recently, non-chemical techniques including biological and botanical methods, non-destructive technologies and Artificial intelligence have been demonstrated to be effective as postharvest management of bell pepper. The paper provides exciting information on recent and emerging techniques for curtailing these losses in bell pepper, alongside their mechanism and existing benefits. The current limitations of these techniques as well as recommendations for potential applications are also addressed.

Characterizations of konjac glucomannan/curdlan edible coatings and the preservation effect on cherry tomatoes

In this study, konjac glucomannan (KGM) and curdlan were used to fabricate composite coating (KC). The coating solutions were investigated using a rheological method, and the coatings were characterized by water solubility tests, water vapor permeability (WVP), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The preservation effect of KC coating on cherry tomatoes stored at room temperature was determined. Results indicated that the curdlan addition can adjust the hydrophilicity/hydrophobicity of KGM coatings. Curdlan addition enhanced intermolecular entanglement and film-forming property. Increasing curdlan content in KC coatings significantly decreased the moisture content, dissolution and swelling ratio, and WVP. The KGM-curdlan composites behaved as high-performance coatings with good compatibility and uniformity. The K₃C₂ coating showed the best uniformity, water barrier, and thermal stability. The application of K₃C₂ coating significantly reduced the weight loss, decay loss, and delayed the decreases of firmness, soluble solids, total acid, and VC contents of cherry tomatoes. The KGM/curdlan edible coatings have promising potential for prolonging the shelf life of cherry tomatoes and applications in fruits preservation in the future.

Recent progress in pectin extraction, characterization, and pectin-based films for active food packaging applications: A review

Pectin is an abundant complex polysaccharide obtained from various plants. Safe, biodegradable, and edible pectin has been extensively utilized in the food industry as a gelling agent, thickener, and colloid stabilizer. Pectin can be extracted in a variety of ways, thus affecting its structure and properties. Pectin's excellent physicochemical properties make it suitable for many applications, including food packaging. Recently, pectin has been spotlighted as a promising biomaterial for manufacturing bio-based sustainable packaging films and coatings. Functional pectin-based composite films and coatings are useful for active food packaging applications. This review discusses pectin and its use in active food packaging applications. First, basic information and characteristics of pectin, such as the source, extraction method, and structural characteristics, were described. Then, various methods of pectin modification were discussed, and the following section briefly described pectin's physicochemical properties and applications in the food sector. Finally, the recent development of pectin-based food packaging films and coatings and their use in food packaging were comprehensively discussed.

A comprehensive approach to chitosan-gelatine edible coating with β-cyclodextrin/lemongrass essential oil inclusion complex - Characterization and food application

Biopolymer-based films present an ideal matrix for the incorporation of active substances such as antimicrobial agents, giving active packaging a framework of green chemistry and a step forward in food packaging technology. The chitosan-gelatine active coating has been prepared using lemongrass oil as an antimicrobial compound applying a different approach. Instead of surfactants, to achieve compatibilization of compounds, β-cyclodextrin was used to encapsulate lemongrass oil. The antimicrobial effect was assessed using the dip-coating method on freshly harvested cherry tomatoes artificially contaminated by Penicillium aurantiogriseum during 20 days of cold storage. According to the evaluation of the antimicrobial effect of coating formulation on cherry tomato samples, which was mathematically assessed by predictive kinetic models and digital imaging, the applied coating formulation was found to be very effective since the development of fungal contamination for active-coated samples was observed for 20 days.

Phytochemicals-based edible coating for photodynamic preservation of fresh-cut apples

Nature-derived chemicals have recently gained increased attention to settle down the challenges in the food industry. Quercetin has long been used as a natural medicine but its photoactivity has been neglected. In this work, by combining photodynamic bacteria inactivation (PDI) with an edible coating (Pectin/Quercetin) derived from FDA-approved chemicals, extend shelf-life and protected commercial quality of fresh-cut apples were achieved. Firstly, the potential photoactivated antibacterial performance of Quercetin (a natural plant flavonoid) was clarified with the treatment of a simulated sunlight lamp, realizing antibacterial efficacy of 100 % towards S. aureus (50 min) and L. monocytogenes (80 min) with light treatment. To develop safe and effective preservation of fresh-cut apples, Pectin/Quercetin edible coatings with 100 μmol/L quercetin were adopted. The results showed that the prepared edible coatings form a protective barrier over the surface of apples, effectively resisting bacterial infection and extending shelf life to 10 days while maintaining good commercial quality (including preferable color, keeping 100 % hardness, 80 % sugar content and 17.3 % weightlessness rate). Therefore, the prepared light-driven Pectin/Quercetin in this work has the potential to develop as fresh-cut fruit preservation technology.

Postharvest chitosan-arginine nanoparticles application ameliorates chilling injury in plum fruit during cold storage by enhancing ROS scavenging system activity

BACKGROUND

Plum (Prunus domestica L.) has a short shelf-life period due to its high respiration rate and is sensitive to low storage temperatures, which can lead to the appearance of chilling injury symptoms. In this investigation, we applied new coating treatments based on chitosan (CTS) and arginine (Arg) to plum fruit (cv. 'Stanley').

RESULTS

Fruit were treated with distilled water (control), Arg at 0.25 and 0.5 mM, CTS at 1% (w/v) or Arg-coated CTS nanoparticles (CTS-Arg NPs) at 0.5 and 1% (w/v), and then stored at 1 °C for days. The application of CTS-Arg NPs at 0.5% attenuated chilling injury, which was accompanied by accumulation of proline, reduced levels of electrolyte leakage and malondialdehyde, as well as suppressed the activity of polyphenol oxidase. Plums coated with CTS-Arg NPs (0.5%) showed higher accumulation of phenols, flavonoids and anthocyanins, due to the higher activity of phenylalanine ammonia-lyase, which in turn resulted in higher DPPH scavenging capacity. In addition, CTS-Arg NPs (0.5%) treatment delayed plum weight loss and retained fruit firmness and ascorbic acid content in comparison to control fruit. Furthermore, plums treated with CTS-Arg NPs exhibited lower H₂O₂ accumulation than control fruit due to higher activity of antioxidant enzymes, including CAT, POD, APX and SOD.

CONCLUSIONS

The present findings show that CTS-Arg NPs (0.5%) were the most effective treatment in delaying chilling injury and prolonging the shelf life of plum fruit.

Recent advances in polysaccharide-based edible coatings for preservation of fruits and vegetables: A review

Harvested fruits and vegetables are prone to decay and quality deterioration during storage. Although traditional packaging and chemical treatments are effective, they are harmful to the environment and human health. Hence, higher requirements for food preservation technology are increasingly proposed. Nontoxic, renewable, degradable, and edible packaging for fruits and vegetables has become a research hotspot in recent years. Chitosan, alginate, cellulose, pectin, starch, and other polysaccharides as coating materials have been widely used. Compared with traditional plastic packaging and chemical treatment, these coatings exhibited a better preservation effect and higher safety. In this paper, the preservation mechanism of fruits and vegetables by edible coatings treatment was described, and the research on edible coatings used in fruits and vegetables was summarized. The effects polysaccharide-based edible coatings on physicochemical quality and antimicrobial effect of fruits and vegetables were reviewed.

A green and environmental sustainable approach to synthesis the Mn oxide nanomaterial from Punica granatum leaf extracts and its in vitro biological applications

Pathogenic fungal infections in fruit cause economic losses and have deleterious effects on human health globally. Despite the low pH and high water contents of vegetables and fresh, ripened fruits, they are prone to fungal and bacterial diseases. The ever-increasing resistance of phytopathogens toward pesticides, fungicides and bactericides has resulted in substantial threats to plant growth and production in recent years. However, plant-mediated nanoparticles are useful tools for combating parasitic fungi and bacteria. Herein, we synthesized biogenic manganese oxide nanoparticles (MnONPs) from an extract of Punica granatum (P. granatum), and these nanoparticles showed significant antifungal and antibacterial activities. The production of MnONPs from plant extracts was confirmed by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and UV visible spectroscopy (UV). The surface morphology and shape of the nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using a detached fruit method, the MnONPs were shown to exhibit significant antimicrobial activities against two bacterial strains, E. coli and S. aureus, and against the fungal species P. digitatum. The results revealed that the MnONPs had a minimum antimicrobial activity at 25 µg/mL and a maximum antimicrobial activity at 100 µg/mL against bacterial strains in lemon (citrus). Furthermore, the MnONPs exhibited significant ROS scavenging activity. Finally, inconclusive results from the green-synthesized MnONPs magnified their significant synergetic effects on the shelf life of tomatoes (Lycopercicum esculantum) and indicated that they could be used to counteract the phytopathological effects of postharvest fungal diseases in fruits and vegetables. Overall, this method of MnONPs synthesis is inexpensive, rapid and ecofriendly. MnONPs can be used as potential antimicrobial agents against different microbial species.

Sodium alginate edible coating containing Ferulago angulata (Schlecht.) Boiss essential oil, nisin, and NaCl: Its impact on microbial, chemical, and sensorial properties of refrigerated chicken breast

This study aimed to investigate the effects of sodium alginate (ALG) coating incorporated with Ferulago angulata (Schlecht.) Boiss essential oil (FAEO, 10 and 20 mg/mL), nisin (N, 500 and 1000 IU/mL), and NaCl (2 %) on microbial (lactic acid bacteria, LAB; total viable bacteria, TVC; psychrotrophic bacteria; Pseudomonas; Enterobacteriaceae, and yeast and mold), chemical (pH, PV, TVB-N, and TBARS), sensory (color, odor, texture, and overall acceptance), and antioxidant properties of refrigerated (4 °C) chicken breasts. GC-MS analysis revealed that trans-β-ocimene (45.36 %) and α-pinene (18.01 %) constituted most of the components in FAEO. The antioxidant properties of FAEO were evaluated via the DPPH method. The IC₅₀ value of FAEO was 562 mg/mL. The results of antimicrobial evaluations indicated that there was no significant difference between control and ALG treatments (p > 0.05). The highest antimicrobial effect was associated with ALG + FAEO2 + N2 + NaCl treatment. The logarithmic reduction of the TVC, psychrotrophic count, Pseudomonas count, Enterobacteriaceae, LAB, as well as yeast and mold count in the ALG + FAEO2 + N2 + NaCl treatment were 1.40, 0.92, 1.20, 1.02, 0.88, and 1 log CFU/g, respectively compared to the control treatment. The initial level of TVB-N in the control treatment was 8.26 mg/100 g, which reached 42.84 mg/100 g at the end of the storage period. In ALG+ FAEO2 + N2 + NaCl treatment, the lowest TVB-N was observed, being 36.37 mg/100 g at the end of the storage period. The initial level of PV in the control treatment was 0.14 meq/kg, which reached 3.04 meq/kg at the end of the storage period. In the treatments containing FAEO, PV was lower than in other treatments, indicating the antioxidant properties of FAEO. There was a significant difference between control and other treatments in pH and TBARS evaluation (p < 0.05). The samples treated with FAEO had a lower pH than control. At the end of the storage period, the TBARS level in the control treatment reached 1.20 mg MDA/kg, while in the treatment of ALG+ FAEO2 + N2 + NaCl treatment, its level was 0.36 mg MDA/kg. The results of sensory properties indicated that in evaluating the color, odor, texture, and overall acceptance on the final days, treatments containing FAEO, nisin, and NaCl had higher scores due to their antimicrobial and antioxidant properties. In conclusion, this study indicated that adding FAEO, nisin, and NaCl to ALG coating would enhance the shelf-life of chicken meat.

Effect of shiitake mushrooms polysaccharide and chitosan coating on softening and browning of shiitake mushrooms (Lentinus edodes) during postharvest storage

We investigated the browning and softening of fresh Lentinula edodes (LE) coated with polysaccharides (LEP) isolated from LE stalks and stored at 4 °C for 15 days. The results showed that compared to the chitosan-coated and uncoated LE, the LEP-treated mushrooms showed significant improvements in several qualities during storage, such as reduced weight loss, retention of hardness and springiness, improved soluble protein content, and reduced browning, malondialdehyde content, and electrolyte leakage rate. The best results were obtained with 1.5 % LEP. LEP improved the activities of peroxidase, catalase, superoxide dismutase, ascorbate peroxidase, and phenylalanine ammonialyase and significantly reduced the accumulation of hydrogen peroxide during storage compared to the control samples. In addition, the LEP treatment maintained the high antioxidant activity of LE during storage. Notably, LEP inhibited browning-related enzymes (polyphenol oxidase and tyrosinase) to reduce browning. It also maintained high levels of cellulase, chitinase, and β-1,3 glucanase to improve softening during storage. These findings suggest the potential of LEP to improve the post-harvest quality of mushrooms, allowing a storage period of up to 15 days (extending the shelf life by six days) and indirectly suggesting that the polysaccharide component of LEP can act as a self-defense additive to protect against spoilage during storage.

Comprehensive approach to the protection and controlled release of extremely oxygen sensitive probiotics using edible polysaccharide-based coatings

The human intestinal system is a complex of various anaerobes including extremely oxygen-sensitive (EOS) bacteria, some of which have been credited with significant health benefits. Among these, Faecalibacterium prausnitzii, which is one of the most abundant anaerobic bacterial strains in the human intestinal tract, has been proved to be a promising probiotic for the treatment of inflammatory bowel diseases. However, because of its extremely sensitive nature, there are many difficulties when passing through the harsh environment of the gastrointestinal tract. Hence, in this study, a comprehensive physicochemical characterization was performed for the use of polysaccharides from several origins (hydroxypropyl methyl cellulose, methyl cellulose, hydroxypropyl cellulose, chitosan, low-methoxylated pectin, kappa-carrageenan, sodium alginate and pullulan) as encapsulating agents to protect and deliver this bacterium. First, the apparent viscosity and surface tension of the polymer solutions were tested. Then, the mechanical properties, water vapor and oxygen barrier properties of these biopolymers as self-standing films were investigated. Lastly, in vitro release profiles of small molecules and bacterial cells from these biopolymer matrices in contact with a simulated gastrointestinal tract were evaluated. The results showed that chitosan, low-methoxylated pectin, kappa-carrageenan, sodium alginate and pullulan films exhibited good oxygen barrier properties to protect EOS probiotics. Among all the biopolymers tested, sodium alginate exhibited the best oxygen barrier properties and release profile. The release kinetics can be modulated by several factors including biopolymer type, plasticizer concentration and active molecules or bacteria to be encapsulated. On that basis and integrating the other parameters analyzed, a multicriteria strategy for probiotic encapsulation was proposed.

Inhibition of browning via aqueous gel solution of Aloe vera: a new method for preserving fresh fruits as a case study on fresh kernels of Persian walnut

Aloe Vera (AV) gel is commonly used as a natural, inexpensive, edible coating that can improve the quality and shelf life of fruits. The objective of this study was to evaluate how two methods of applying AV, i.e. as an edible coating (dry environment) and as a gel solution (aqueous environment: a new method), prevent browning and maintain quality characteristics of fresh kernels of Persian walnut for 60 days during cold storage. Distilled water was used as a control group for both environments. In general, AV caused a reduction in the peroxide value (POV) of kernels, while preserving Total Phenolic Compound and Total Antioxidant Activity (TAA). The AV treatment slowed down the process of color change and maintained sensory properties during storage, compared to the control groups of both methods. The AV gel solution performed better than the AV edible coating in terms of POV, color (L* and h°) and microbial growth. In contrast, the AV edible coating was more effective in preserving TPC and TAA. Also, TAA was found to have a significant, positive correlation with L* and, simultaneously, a negative correlation with POV. As far as we know, this is the first instance that the AV gel was used as a formulated solution and as an edible coating on fresh fruits. This innovative method can be used in commercial practice, while being ecofriendly and non-chemical as a treatment for the maintenance of postharvest quality in fruits.

Application of composite coating of Nostoc commune Vauch polysaccharides and sodium carboxymethyl cellulose for preservation of salmon fillets

The spoilage of fish products and the growth of pathogenic bacteria cause great economic loss and serious harm to human health, so fish preservation is very important issue. In this study, Nostoc commune Vauch polysaccharides (NVP) was added into sodium carboxymethyl cellulose (CMC) to form a mixed coating to prepare an active packaging material. The antibacterial and antioxidant activities of NVP, physicochemical properties of the mixed coating, and preservative effects of the coating on salmon fillets were evaluated. The results showed that NVP had good antibacterial and antioxidant activities. Physical characterization of the coating solution showed that when the ratio of NVP to CMC was 1:3, the coating had the best dispersion, denser structure and strongest hydrogen bond. On this basis, NVP/CMC coating can significantly prolong the shelf life of salmon fillets during cold storage by reducing pH, improving the color and texture, delaying the oxidation of fat and protein, inhibiting the growth of microorganisms. At the same time, the coated salmon fillets had good sensory acceptance. The results showed that the edible coating has a broad application prospect in the preservation of fish products.

Combination of chitosan coating and heat shock treatments to maintain postharvest quality and alleviate cracking of Akebia trifoliate fruit during cold storage

Akebia trifoliata fruit cracks easily, which shortens the shelf life and declines commercial value. This work aimed to evaluate the effects of heat shock and coating treatments on postharvest quality of A. trifoliata fruit and to elucidate the mechanism underlying retarding cracking by cell wall metabolism. Coating could decline cracking incidence (from 16.05% to 3.61%), decay incidence (from 31.21% to 18.06%), total soluble solids (TSS), and malondialdehyde (MDA) content compared to uncoated treatment during 35 days of storage. Heat shock could further decrease decay incidence but did not influence TSS, pH, firmness, and starch. Heat shock at 40 °C combined with coating treatment had the best preservation performance with the highest synthetic score (4.41). Furthermore, coated fruit displayed lower β-glucosidase and polygalacturonase activities which resulted in higher cellulose and Na₂CO₃-soluble pectin. These modifications together with lower weight loss, MDA, and ion leakage contributed to the lower cracking incidence.

Development of alginate-based edible coatings of optimized UV-barrier properties by response surface methodology for food packaging applications

Despite the outstanding characteristics of alginate, it suffers from bad UV-barrier, water barrier, and antimicrobial properties limiting its wide usage in food packaging. For this concern, Box-Behnken design (BBD) was applied to prepare an alginate-based edible coating of the best optimized UV-shielding properties upon the incorporation of both Aloe vera (AV) and zinc oxide nanoparticles (ZnO-NPs). The optimized minimum UV-transmittance was 4.96% when the optimized compositions of alginate (1.05 g), AV (2.95 g), and ZnO-NPs (4.93 wt%) were used. FTIR was used to verify the successful edible coating preparation while the wide-angle X-ray diffraction (XRD) was used to identify the interactions between the film's components. The incorporation of both AV and ZnO-NPs significantly improved alginate's thermal, water vapor permeability (WVP), mechanical and antimicrobial properties. In addition, the films incorporated with both AV and ZnO-NPs exhibited excellent UV-barrier properties compared with neat alginate. The optimized alginate film incorporated with both ZnO-NPs and AV significantly extended the shelf-life of tomato fruits up to 16 days without any defects. Due to the outstanding physical, UV-shielding, and antimicrobial properties of the optimized alginate/AV/ZnO-NPs film, it could be used potentially in food packaging industries.

Nanochitosan functionalized hydrophobic starch/guar gum biocomposite for edible coating application with improved optical, thermal, mechanical, and surface property

The current work demonstrates a unique approach of utilizing nanochitosan (NCS) based edible nanomodifier for functionalizing starch (ST)/guar gum (GG) biocomposite with superior packaging properties targeting stringent edible food packaging on fresh cuts. The effectiveness of NCS in terms of structure-property-performance analysis of ST/GG biocomposites was done. The inclusion of NCS to the biocomposites of ST/GG converts its hydrophilic surface nature to hydrophobic (contact angle of ~114°) by modifying the surface features. The addition of NCS improved the thermal stability, where the observed 10% weight degradation of ST biocomposites were ~79.36, ~80.49, and ~186.89 °C for neat ST, ST/GG biocomposites, and ST/GG/NCS (3% w/v) (ST-GG-NCS3), respectively. The observed transparency of ST, ST-GG, and ST-GG-NCS3 were 21, 8, and 48%, respectively in the visible region suggesting consumer preference for transparent packaging materials. The wt% of O, C and N elements in ST-GG-NCS3 as observed by EDX spectra were ~ 50.2, ~47.6, and ~ 2.2%, respectively, which confirm the safety of the materials. Additionally, it is noteworthy to mention that the storage quality in terms of microbial growth, pH change, color attributes, and weight loss are better preserved when used as an edible coating on cut apple fruits.

Application of Glycine betaine coated chitosan nanoparticles alleviate chilling injury and maintain quality of plum (Prunus domestica L.) fruit

The use of edible coatings can lead to significant extension of the postharvest life of fresh horticultural products through the regulation of water and gaseous exchange during storage. In this regard, nano-engineered materials are of great interest to design novel and multifunctional edible coatings and are increasingly employed. Chitosan and glycine betaine have been reported to enhance fruit tolerance to chilling stress during cold storage. The current study applied new coating treatments to plum (Prunus domestica L. cv. 'Stanley') fruit at maturity stage in a completely randomized factorial design with three replicates. Plums were treated with distilled water (control), glycine betaine (GB) at 2.5 and 5 mM, chitosan (CTS) at 1% (w/v) or glycine betaine-coated chitosan nanoparticles (CTS-GB NPs) at 0.5 and 1% (w/v) and stored at 1 °C for up to 40 days. The application of CTS-GB NPs (0.5% w/v) was the most effective treatment and induced lower electrolyte leakage, MDA and H₂O₂ content, and significantly alleviated chilling injury. Furthermore, this treatment remarkably increased the activity of PAL enzyme, resulting in higher levels of phenolics, flavonoids and anthocyanins content, and enhanced DPPH scavenging capacity. In addition, CTS-GB NPs treatment increased endogenous GB (9.25 mg g^-1 DW) and proline (1929.29 μg g^-1 FW) accumulation leading to higher activity of CAT, POD, SOD and APX enzymes. Based on the obtained results, the commercial application of CTS-GB NPs could effectively reduce chilling injury, preserve nutritional quality, and prolong the storage potential and shelf life of plum fruit.

Effect of a chitosan-based nanocomposite containing ZnO and Zataria multiflora essential oil on quality properties of Asian sea bass (Lates calcarifer) fillet

This research aimed to estimate the effects of chitosan (CH) coating in combination with zinc oxide nanoparticles (ZnONPS) and Zataria multiflora essential oil (ZEO) on the bacterial and biochemical properties of the Asian sea bass (Lates calcarifer) fillets during refrigeration storage (4 ± 1 °C). The fillets were randomly divided into five treatments (CH, CH-ZnONPS, CH-ZEO, CH-ZnONPs-ZEO, and control). Then, the treated fillets were kept at 4 °C and quality analysis was performed on days 0, 4, 8, 12, and 16. The results revealed that the combination of ZnONPs and ZEO with CH coating is an active coating with antimicrobial effects. Also, the coated fillets improved the biochemical properties (such as FFA, TBA, TVBN, pH) as well as color properties during refrigeration storage. The highest rate of FFA (3.59 ± 0.08%oleic acid), TBA (1.43 ± 0.00 mg MDA/kg), TVBN (30.82 ± 0.30 mg/N100g), and pH (7.38 ± 0.03) was recorded in control fillets while the lowest rate of FFA (2.19 ± 0.00%oleic acid), TBA (0.61 ± 0.00 mg MDA/kg), TVBN (19.60 ± 0.20 mg/N100g), and pH (6.99 ± 0.04) was recorded in CH-ZnONPs-ZEO coated fillets (p < 0.05) on day 16. The sensory acceptance score was better than that of the control treatment on days 8 and 12 in Sea bass fillet coated with CH-ZnONPs, and CH-ZnONPS/CH-ZEO, respectively, and it was lower the critical score for fishery products. The combination of nanoparticles or essential oils (individually or in combination together) with edible coatings (chitosan) could increase and optimize the storage time of refrigerated seafood.

Chitosan nanoparticles embedded with curcumin and its application in pork antioxidant edible coating

Curcumin (Cur) exhibits low water solubility and insufficient dispersibility in food systems, and cannot exert its excellent antioxidant properties. In this work, Chitosan (CS) nanoparticles were prepared by ionic crosslinking method using chitosan as carrier and sodium tripolyphosphate (TPP) as crosslinking agent, then Cur was loaded to obtain curcumin nanoparticles (CNPs). CNPs presented a spherical morphology with average size of 278.9 nm. Compared with the solubility of native Cur (0.017 μg/mL) at 25 °C, the water solubility of CNPs increased to 35.92 μg/mL of more than 2100 times. In addition, the antioxidant capacity of Cur was also studied based on DPPH free radical scavenging, the results showed that with the increase of the concentration, the antioxidant capacity of CNPs was significantly increased (p < 0.05), which was higher than that of Cur at the same concentration. The edible coating was prepared by adding CNPs into sodium carboxymethyl cellulose (CMC) to study the effects of CMC-CNPs coatings in improving the quality and shelf life of fresh pork stored at 4 ± 1 °C for 15 days. The results showed that CMC-CNPs edible coating could significantly inhibit lipid oxidation of fresh pork (p < 0.05) and could be further applied in lipid rich food packaging.

Ultrasonics as a tool for development of pine-needle extract loaded bee wax edible packaging for value addition of Himalayan cheese

In the present study, Himalayan cheese, kradi was coated with beeswax loaded with pine needle extract (PNE) to increase its shelf life and nutraceutical potential. PNE was extracted via ultrasonication and incorporated into beeswax at concentrations, 2:1, 1:1, and 2:3 (grams of beeswax to mL of PNE). The dispersion of PNE in the coatings was carried out using an ultrasonic probe at a frequency of 20 kHz for 15 min and at power rating of 500 W. The coatings were characterised using scanning electron microscopy, light microscopy, dynamic light scattering (DLS), fourier transmission infrared spectroscopy. DLS revealed a hydrodynamic diameter and zeta potential of 12.11 ± 0.41 µm and -19.32 ± 0.61 mV for coating loaded with highest concentration of PNE. The bioactivities of the coating including antioxidant, antidiabetic and antibacterial assays revealed significantly higher values with the increase in PNE concentration. Shelf life and sensory evaluation study including microbiological and sensory analysis revealed inhibition of mould growth and good score of texture and appearance with the increase in concentration of PNE. The study provides a future perspective for application of beeswax loaded PNE coatings in cheese industry.

Effects of konjac glucomannan/pomegranate peel extract composite coating on the quality and nutritional properties of fresh-cut kiwifruit and green bell pepper

The effects of an edible coating, based on konjac glucomannan (KG) incorporated with pomegranate peel extracts (PE), on the physicochemical and nutritional properties of fresh-cut kiwifruit and green bell pepper during storage were investigated. The optimal extract time (40.6 min), temperature (54.5 °C), and ultrasound power (255.5 W) with response surface method, provided a high total antioxidant activity (TAA) of (92.31 ± 1.43)%. Fresh-cut kiwifruit and green bell pepper were coated by dipping using five treatments (distilled water, ascorbic acid, KG, PE, KG + PE), packed into polymeric film and stored for 8 days at 10 °C. Distilled water treatment was used as control. KG + PE treatment resulted in the highest total soluble solid and titratable acidity in fresh-cut kiwifruit, while the maximum firmness in fresh-cut green bell pepper. The weight loss was both effectively decreased in samples treated with KG or KG + PE. All samples treated with KG + PE had significantly higher contents of chlorophyll, ascorbic acid, total phenolic and TAA than others. Moreover, the KG + PE group had the lowest counts of microorganisms in all samples. KG coating incorporated with PE was proved to be efficient in maintaining the physico-chemical and nutritional properties of fresh-cut kiwifruit and green bell pepper during low temperature storage compared with control.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-021-05006-7.

Enhancing safety and quality of shrimp by nanoparticles of sodium alginate-based edible coating containing grapefruit seed extract

Edible coatings are safe and effective in extending the shelf life of foods. In this study, a nanoparticle-based edible coating solution was prepared, containing alginate as a coating agent and grapefruit seed extract as an antibacterial agent to improve the safety and quality of shrimp during storage. Shrimp coated with this formulation were maintained at 4°C for 8 days, and periodically analyzed for changes in sensory, chemical [total volatile basic nitrogen (TVB-N) and pH] and microbial parameters. The uncoated shrimp exceeded the microbiological limits at 7.87 log CFU/g on Day 4 of storage, whereas the nanoparticle-based coated shrimp did not exceed the limit by Day 8 of storage. In addition, uncoated shrimp tended to maintain their quality, while uncoated shrimp deteriorated due to increased TVB-N values, pH values, and off-flavors. Nanoparticles are easily dispersed in food to minimize flavor impact and enhance diffusion and bioactivity. We concluded that the nanoparticles coating extended the shelf life of shrimp by more than 5 days. Therefore, the use of nanoparticle-based coatings could be a new and effective way to maintain shrimp quality.

Quality of Physalis peruviana fruits coated with pectin and pectin reinforced with nanocellulose from P. peruviana calyces

Physalis peruviana is marketed without its calyx, which generates byproducts and a decrease in the shelf life of these fruits. The aim of this study was to evaluate the effect of edible pectin-coatings reinforced with nanocellulose from calyx on the physical-chemical and physiological parameters of P. peruviana fruits during refrigerated storage (5 °C) for ten days. The nanocellulose extraction was carried out using a combined extraction method (chemical procedures and ultrasound radiation). The characterization of the fibers showed that the maximum degradation temperatures ranged between 300 and 311 °C. The SEM analysis revealed the presence of fibers after the chemical treatment. The removal of lignin and hemicellulose was validated using Fourier Transform Infra Red (FTIR) spectroscopy. The results showed that the fruits treated with pectin and pectin reinforced with nanocellulose at 0.5 % (w/w) had an adequate visual appearance and showed a minor color change (ΔE of 19.04 and 21.04, respectively) and the highest retention of L∗ during storage. Although the addition of nanocellulose at 0.5% presented the lowest respiratory rate (29.60 mgCO₂/kg h), the treatment with pectin offered the least weight loss and showed the highest firmness retention at the end of storage. Thus, the edible pectin-coating may be useful for improving the postharvest quality and storage life of fresh P. peruviana fruit. Nanocellulose from P. peruviana calyces can be used under the concept of a circular economy; although, its use as a reinforcement of pectin showed some limitations.

Edible coatings and lipid oxidation data in walnuts

The information presented is part of an investigation that seeks a better understanding of lipid oxidation in walnuts. The data shown regarding edible coating, are one of the strategies used to investigate the effect over oxidation stability. For the present experiments, unshelled walnuts were coated with different formulations, and then stored at 37 °C, 20% RH for 6 weeks. After that time, coated nuts were taken out, cold pressed to extract the oil and analysed. The main data obtained from the oil analysis of walnuts were acid value, peroxide value, and thiobarbituric acid reactive substances (TBARS). Data show the variation of the parameters during the storage time at 37 °C, considering the different formulations of edible coatings and the control. These data are relevant to walnuts exporters to have a comparison point.

Curcumin doped functionalized cellulose nanofibers based edible chitosan coating on kiwifruits

The developed edible coating with curcumin facilitated iron functionalized cellulose nanofiber (f-CNF) reinforced chitosan (CS) were applied on kiwifruits for maintaining the quality during storage life. The f-CNF was fabricated via anchoring iron particles onto the surface of CNF as evident by FESEM, FETEM, and XRD analysis. The inclusion of f-CNF and curcumin as a component of edible coating can provide a synergistic effect in maintaining the quality of kiwifruits. The f-CNF (1.5 wt%) dispersed CS edible coating assisted by curcumin provided a lamellar and heterogonous surface morphology with a hazy appearance. The used edible coating materials were effective in reducing mass loss, firmness loss, respiration rate, and microbial count of the kiwifruits during storage life (10 days at 10 °C). Additionally, color, and physiological properties of kiwifruits can be modified by using the addressed edible coating materials.

Influence of chitosan-gelatin edible coating incorporated with longkong pericarp extract on refrigerated black tiger Shrimp (Penaeus monodon)

Chitosan-Gelatin (CHI-Gel) based edible coating incorporated with longkong pericarp extract (LPE) was developed and investigated for its impact on the quality of black tiger shrimp (Penaeus monodon) during refrigerated storage (4 ​°C) for 20 days. Shrimp coated with CHI-Gel-LPE (1.5%) had better quality indices than control (no coating), those coated with CHI, CHI-Gel, and CHI-Gel-LPE at lower concentrations (0.5 and 1%). The CHI-Gel-LPE inhibited melanosis and polyphenol oxidase (PPO) and controlled the pH changes in a dose-dependent manner. Lipid oxidation indices such as TBARS, PV, p-anisidine, and totox values were significantly controlled by the treatments throughout the storage. The CHI-GEL-LPE-1.5% coated sample had the lowest protein oxidation, and it's ascertained by the lowest loss of sulfhydryl groups, with the lowest carbonyl content throughout the storage (P ​< ​0.05). CHI-Gel-LPE (0.5-1.5%) coated samples had the lowest microbial growth (total viable count, lactic acid bacteria, Enterobacteriaceae, and Psychrotrophic bacteria) relative to the other treatments. Efficacy in quality maintenance of shrimp by LPE incorporated coating was improved with augmenting concentration used. Overall, LPE in the CHI-Gel edible coating served as a natural antioxidant, with antimicrobial activity and inhibiting melanosis, thus retain the quality and extend the shelf-life of shrimp stored at a refrigerated temperature.

Eugenol-chitosan nanoemulsion as an edible coating: Its impact on physicochemical, microbiological and sensorial properties of hairtail (Trichiurus haumela) during storage at 4 °C

Effects of the eugenol-chitosan nanoemulsion as an edible coating on the quality of hairtail (Trichiurus haumela) during storage at 4 °C were evaluated. For all samples, such parameters as pH, thiobarbituric acid (TBA), total volatile basic nitrogen (TVB-N), water holding capacity (WHC), electrical conductivity (EC), total bacteria count (TVC) and sensory were examined periodically. The results demonstrated that eugenol-chitosan nanoemulsion coating showed better preservative effects than chitosan nanoemulsion alone. Therefore, a coating based on eugenol-chitosan nanoemulsion could be regarded as an effective food-grade biopreservative to maintain the quality of hairtail fish and prolong its shelf life during chilled storage.