Edible Coatings Research Articles

Bacterial agents for controlling anthracnose and soft rot in strawberries: present status and perspectives

ABSTRACT Anthracnose and soft rot, caused by the fungal pathogens Colletotrichum spp. and Rhizopus spp., respectively, stand as prominent diseases impacting strawberries during the postharvest phase, resulting in significant economic losses. The use of conventional treatments involving chemical fungicides has been discouraged since they negatively impact the environment and human health. In this context, alternative strategies, such as biological control, have been required for organic and sustainable agriculture. While bacterial agents, such as Bacillus spp., are successfully used in commercial formulations to control postharvest diseases, there are other bacteria exhibiting antagonistic activities that hold potential in plant disease management. Hence, the current review aims to investigate studies developed over the past decade describing the primary bacterial genera with the potential to inhibit the causal agents of soft rot and anthracnose. Additionally, it aims to provide an overview of biocontrol mechanisms for suppressing these pathogens, detailing methods of application in both pre and postharvest phases, along with strategies for enhancing the efficacy of biocontrol agents. The findings of this review demonstrate that numerous bacterial species possess the ability to effectively control anthracnose and soft rot, both in growing plants and harvested strawberries. This expands the available forms of control and minimises the occurrence of resistant pathogens. Furthermore, the application of postharvest techniques such as edible coatings and bacterial encapsulation proves advantageous, extending fruit shelf life and reducing strawberry decay.

Recent Highlights in Sustainable Bio-Based Edible Films and Coatings for Fruit and Vegetable Applications.

The present review paper focuses on recent developments in edible films and coatings made of base compounds from biological sources, namely plants, animals, algae, and microorganisms. These sources include by-products, residues, and wastes from agro-food industries and sea products that contribute to sustainability concerns. Chitosan, derived from animal biological sources, such as crustacean exoskeletons, has been the most studied base compound over the past three years. Polysaccharides typically constitute no more than 3-5% of the film/coating base solution, with some exceptions, like Arabic gum. Proteins and lipids may be present in higher concentrations, such as zein and beeswax. This review also discusses the enrichment of these bio-based films and coatings with various functional and/or bioactive compounds to confer or enhance their functionalities, such as antimicrobial, antioxidant, and anti-enzymatic properties, as well as physical properties. Whenever possible, a comparative analysis among different formulations was performed. The results of the applications of these edible films and coatings to fruit and vegetable products are also described, including shelf life extension, inhibition of microbial growth, and prevention of oxidation. This review also explores novel types of packaging, such as active and intelligent packaging. The potential health benefits of edible films and coatings, as well as the biodegradability of films, are also discussed. Finally, this review addresses recent innovations in the edible films and coatings industry, including the use of nanotechnologies, aerogels, and probiotics, and provides future perspectives and the challenges that the sector is facing.

Water Loss: A Postharvest Quality Marker in Apple Storage

AbstractApple fruit can be stored for long periods of time, especially with the use of controlled atmosphere storage, but like many fruits and vegetables are susceptible to water loss. Water loss can result in compromised appearance such as skin shriveling, as well as loss of firmness, and reduced saleable weight, which in turn affect the income of growers and other industry stakeholders. Preharvest factors that can influence water loss in apples during the postharvest period include climate, cultivar, fruit size, tree age, orchard practices, and harvest maturity. Postharvest factors such as the storage temperature, relative humidity, storage type, and duration can also affect water loss in apple fruit during storage. The mechanisms of cuticle biosynthesis in water permeance, the role of stomata and lenticels, microcracking, crosstalk with mechanical injuries, storage disorders, and decay incidence during the storage of apples are reviewed. Additionally, the review summarizes: preharvest and postharvest factors influencing water loss; recent management strategies including pre-cooling, cold storage, controlled atmospheres, packaging, and anti-senescence chemicals; the use of edible coatings, as well as other non-chemical approaches for modulating water loss and maintaining storage quality. The review also provides direction for the industry to manage this destructive problem in the postharvest supply chain of apple fruit.

Recent Approaches to the Formulation, Uses, and Impact of Edible Coatings on Fresh Peach Fruit.

Peaches are among the most well-known fruits in the world due to their appealing taste and high nutritional value. Peach fruit, on the other hand, has a variety of postharvest quality issues like chilling injury symptoms, internal breakdown, weight loss, decay, shriveling, and over-ripeness, which makes a challenging environment for industries and researchers to develop sophisticated strategies for fruit quality preservation and extending shelf life. All over the world, consumers prefer excellent-quality, high-nutritional-value, and long-lasting fresh fruits that are free of chemicals. An eco-friendly solution to this issue is the coating and filming of fresh produce with natural edible materials. The edible coating utilization eliminates the adulteration risk, presents fruit hygienically, and improves aesthetics. Coatings are used in a way that combines food chemistry and preservation technology. This review, therefore, examines a variety of natural coatings (proteins, lipids, polysaccharides, and composite) and their effects on the quality aspects of fresh peach fruit, as well as their advantages and mode of action. From this useful information, the processors could benefit in choosing the suitable edible coating material for a variety of fresh peach fruits and their application on a commercial scale. In addition, prospects of the application of natural coatings on peach fruit and gaps observed in the literature are identified.

Characterization of antifungal properties of avocado leaves and majagua flowers extracts and their potential application to control Alternaria alternata

Plant extracts are used as an alternative to a wide range of foods against different types of fungal pathogens. In the present study, the extracts of avocado leaves (Persea americana) and majagua flowers (Talipariti elatum) were tested according to their antifungal activity against different fungi. The most promising extracts were those of majagua flowers that were applied lyophilized and in aqueous extract, being very effective against Alternaria alternata and reaching a 50 % in vitro reduction. Antifungal properties were also evaluated during infection of apples by A. alternata. A decrease in infection progression was confirmed with up to a 30 % reduction in disease incidence and a 20 % reduction in disease severity. Majagua extracts were also tested combined with edible pectin coatings, greatly increasing their effectiveness up 60 % reduction. Thus, extracts of majagua could provide a feasible alternative to control fungal pathogens during postharvest.

Aloe vera/Chitosan-Based Edible Film with Enhanced Antioxidant, Antimicrobial, Thermal, and Barrier Properties for Sustainable Food Preservation.

Food bioactive packaging has received increasing attention from consumers and the food industry for its potential to reduce food waste and environmental issues. Several materials can be used to produce edible films/coats; however, bio-based, cost-effective, and sustainable coatings have gained a high reputation these days. For instance, Aloe vera gel (AV) is a promising bio-based material for edible coatings and films; therefore, the present study aimed to investigate the film-forming abilities of AV and Chitosan (CH) combination as a potential active food packaging material. The physicochemical and mechanical characteristics of formed films of various combinations were prepared at different concentrations, i.e., CH (0.5% w/v), AV (100%), CH:AV (75:25), and CH:AV (60:40). The results showed significant differences among all the prepared edible films wherein these differences were mainly on account of incorporating AV gel. The rheological and antioxidant properties of the formulations improved with the inclusion of AV gel. The films composed of CH:AV (60:40) positively affected the water solubility, thermal properties, and water vapour permeability of the edible films. The X-ray Diffraction (XRD) and Scanning electron microscopy (SEM) results showed that the films composed of CH:AV, (60:40) were amorphous and had smooth morphology. Further, the edible film solutions were applied to fresh figs (Ficus carica) to investigate their role in preserving fruits during storage. A significant reduction in microbial growth was found in coated fruits after 28 days of cold storage. The films composed of CH and AV showed overall improved results compared to the CH (0.5%, w/v). Therefore, the used formulations (CH:AV, 60:40) can form a sustainable film that has the potential to be utilized for fresh product preservation to maintain its quality and shelf life.

Effect of soybean protein-isolate-catechin edible film and coating on the storage quality of bean bun

This study focused on creating an edible film and coating using soy isolate protein (SPI) and catechin (CC) composite, which were then applied to bean buns. The objective was to assess the changes in quality during storage. Initially, SPI films were enriched with different concentrations of CC (1%, 2%, 3%, and 4%) and were examined for their optical and barrier properties. The addition of CC improved the optical barrier of SPI films, resulting in reduced water vapor permeability (WVP) and oxygen permeability (OP), thereby enhancing their suitability for food preservation. Subsequently, the produced edible coatings were applied to bean buns to evaluate their impact on quality attributes and sensory evaluation. The results of the scanning electron microscopy (SEM) analysis showed that the SPI/CC coating exhibited a smoother and more compact surface compared to the uncoated sample. After 15 days of storage, the SPI/CC 3% coated samples displayed the lowest moisture loss of 4.6% and the lowest hardness of 342.97 ± 8.17 N. Additionally, the Avrami equation revealed a significant 31% reduction in crystallinity (K) when comparing the SPI/CC 3% coated samples to the uncoated samples. XRD measurements further confirmed the decrease in crystallinity of the coated samples, indicating that the SPI/CC coating effectively inhibits the aging of bean buns. Moreover, the SPI/CC coating enhances the antioxidant activity of the bean buns and prevents microbial deterioration. These findings suggest that the utilization of SPI/CC coating holds great promise for the preservation of bean buns.

Comparison of the Properties of Pullulan-Based Active Edible Coatings Implemented for Improving Sliced Cheese Shelf Life.

The development of active edible coatings with improved mechanical and barrier properties is a huge challenge. In this study, active edible coatings for sliced cheese have been developed using pullulan (Pull) in combination with two different biopolymers, chitosan (CS) and gelatine (Gel), and a combination of hydrolats as a source of active compounds with antimicrobial effects. In comparison to the monolayer coating, the bilayer coating system demonstrates improved barrier and mechanical properties. A preliminary assessment of the antimicrobial effect of lemongrass and curry plant hydrolats has revealed that both hydrolats exhibited antimicrobial activity against the targeted bacterium Staphylococcus aureus, albeit at different levels. The obtained results suggest that a mixture of 1.56% lemongrass and 12.5% curry plant hydrolats yielded a lower fractional inhibitory concentration (FIC) value. Bilayer coating systems (Pull/CS and Pull/Gel) with an incorporated mixture of hydrolats have demonstrated effectiveness in both cases: artificial contamination before application of the coating system and after application of the coating system. In both contamination scenarios, the coating systems consistently effectively limited bacterial proliferation, indicating the antimicrobial effect of the hydrolat mixture in the coating layers. In the case of artificial contamination before applying the coating system, both coatings demonstrated antimicrobial effectiveness, but the formulation with chitosan had a biocide effect, while the other, with gelatine, had only a bacteriostatic effect in a long-term setting. In the second case, both Pull/CS and Pull/Gel coatings demonstrated effectiveness in inhibiting bacterial growth regardless of the moment of contamination of the sample; the Pull/CS coating showed slightly better antimicrobial activity, achieving complete elimination of bacteria earlier compared with the Pull/Gel coating system.

Sustainable Solutions for Postharvest Berry Protection: Natural Edible Coatings

Sustainable Solutions for Postharvest Berry Protection: Natural Edible Coatings

Effectiveness of sugar palm fruit (Arenga pinnata (Wurmb) Merr.) and chitosan as edible coating on cherry tomatoes (Solanum lycopersicum var. cerasiforme)

Cherry tomatoes are a highly consumed yet highly perishable fruit. One of the postharvest treatments to extend the shelf-life of the fruits is edible coating technology. This study was conducted to evaluate and compare the effectiveness of commercial liquid chitosan and sugar palm fruit as an edible coating in delaying the ripening of cherry tomatoes. Edible coatings were applied to cherry tomatoes using the dipping method. The analyses consisted of weight loss, pH and colour changes during an 18-day storage. The rates of the quality changes were calculated to compare the effectiveness of both edible coatings. The results showed that edible coating from chitosan and sugar palm fruit slurry (sugar palm fruit-water with the ratio of 1:6 added with 1% glycerol (b/v)) could significantly retard weight loss and changes in pH, L*, a*, b* and ΔE* values of cherry tomatoes stored at room temperature. Analysis of variance for the rates of changes of all measured parameters showed no significant difference (p>0.05) between commercial liquid chitosan and sugar palm fruit as an edible coating. These results inferred that both coating materials had similar effectiveness in delaying the ripening process of cherry tomatoes stored at room temperature.

Probiotic-loaded seed mucilage-based edible coatings for fresh pistachio fruit preservation: an experimental and modeling study

In this study, Lallemantia royleana mucilage (LRM) based edible coating containing 1.5 × 108 and 3 × 109 CFU/mL Lacticaseibacillus casei XN18 (Lbc1.5 and Lbc3) was designed to improve the quality and shelf-life of fresh pistachio. The fresh pistachios were coated with LRM + Lbc and their physicochemical, microbial, and sensory properties were evaluated after 1-, 5-, 15-, 25-, and 35-day storage at 4 °C. By the end of storage day, in comparison to control, the presence of probiotic isolate in the edible coating (particularly LRM + Lbc3) led to a marked decrease in fungal growth (3.1 vs. 5.8 Log CFU/g), weight loss (6.7 vs. 8.1%), and fat oxidation (0.19 vs. 0.98 meq O2/kg), and preserved total chlorophylls (8.1 vs. 5.85 mg/kg) and phenols (31.5 vs. 20.32 mg GAE/100 g), and antioxidant activity (38.95 vs. 15.18%) of samples during storage period. Furthermore, LRM + Lbc3-coated samples had a probiotic number above the recommended level (6.85–9.29 log CFU/g) throughout storage. The pistachios coated with probiotic-enriched edible coatings were greatly accepted by panelists. In the next section, Gaussian Process Regression (GPR) was used for predicting some parameters including: weight loss, TSS, Fat content, PV, Soluble carbohydrate content, Viability, Total phenolic compounds, Antioxidant activity, Mold and yeast, Total chlorophylls, Total carotenoids, Color, Odor and Overall acceptance. The results indicated that, there is a good agreement between the actual and predicted data by GPR model and it can be used for similar situation to decrease the cost of laboratory tests and increase the respond of analysis.

The Effect of Casein-Chitosan Edible Coating with Garlic Essential Oil Addition on pH, Haugh Unit and Egg Yolk Index Fresh Chicken Egg on Different Storage

Eggs are a source of animal protein needed by the body and contain complete essential amino acids. Chicken eggs are easily damaged or changed so the quality of the eggs decreases with the length of storage. This damage can be prevented by coating. Past studies concluded that edible coating can maintain the quality of chicken eggs. The purpose of this study was to determine the effect of coating chicken eggs using chitosan and casein edible coating with the addition of garlic essential oil. The materials used are fresh chicken eggs, edible coating solution and garlic essential oil. The method used in this study was a laboratory experiment with Completely Randomized Nested Design with 2 treatments and 3 replications. Edible coating with the addition of garlic essential oil is expected to improve egg quality with a long shelf life. The result showed that chicken eggs coated with chitosan casein edible coating with the addition of garlic essential oil 1% for storage time of 0 days, 7 days, 14 days, 21 days and 28 days gave a very significant effect (P<0,01) on egg yolk pH, egg albumen pH, haugh unit and egg yolk index.

EDIBLE COATING FROM CHITOSAN-MODIFIED YOUNG COCONUT SHELL LIQUID SMOKE AS A PHYTOPRESERVATIVE FOR SAUSAGE

This study examines the use of edible coatings from liquid smoke and chitosan as natural preservatives to extend the shelf life of sausages. Liquid smoke was obtained from the pyrolysis of young coconut shells at 300°C (A1), 340°C (A2), 380°C (A3), and 420°C (A4), which were then purified by distillation to remove tar and other harmful compounds. The resulting liquid smoke was then used to dissolve the chitosan (1–2% w/w) to form an edible coating to be applied to the sausages. The ability of the edible coating to preserve sausage was analyzed using the total plate count (TPC), total volatile base nitrogen (TVB-N), and organoleptic tests. The results of the organoleptic and antibacterial tests were statistically analyzed using the least significant difference (LSD) on SPSS v22. The results showed that different pyrolysis temperatures in liquid smoke preparation affected the properties of edible coatings, which, in turn, affected the endurance of sausage samples. The resulting edible coating maintained the freshness of sausages for up to 100 hours in the TVB-N test and 96 hours in the TPC test. The results of the organoleptic test revealed that the edible coating prolonged the sausage aroma and texture for up to 88 hours, which was achieved by the sample with A4 liquid smoke and a 2% chitosan concentration.

Effect of novel edible coating formulations on post-harvest quality of Chilli (Capsicum annuum var. Pusa Jwala): A review

Chilli (Capsicum annuum L.) holds a prominent position as a key spice crop, being widely utilized globally. Despite its agricultural significance, chilli is characterized by high moisture content (60–85%) at harvest, necessitating reduction to 8-12% for prolonged storage in a dehydrated form. However, it remains highly perishable, with a short shelf life and susceptibility to postharvest challenges such as fungal diseases, quality degradation, chilling injury, and rapid weight loss. Edible coatings have emerged as a solution to extend the postharvest shelf life of fruits and vegetables, enhancing mechanical handling properties and acting as a barrier to respiratory gases and water vapor. The possibility of hydrocolloid gums, such as gum arabic, as edible coatings has drawn interest. The purpose of this study is to determine whether an edible coating based on gum arabic (GA) can effectively preserve the quality of chiles when stored at room temperature. The goal of the research is to extend the storage life of chiles while improving their physiological and microbiological quality. A composite chitosan – gelatin (CH–GL) edible covering will be used to accomplish this. The effects of pure chitosan, cassava starch, gum arabica, and gelatin coatings on chillies will also be investigated in this study. In order to improve the marketability and resilience of chilli and possibly other horticultural commodities, the research aims to offer insights into the development of efficient and sustainable postharvest strategies by methodically evaluating the effects of these coatings on weight loss, firmness, colour retention, and nutritional content.

Application of duck bone gelatin and sodium alginate-based edible coating materials on beef sausage quality during chilled storage

Edible coating is an eco-friendly packaging that is starting to be widely used as a primary packaging for processed meats such as sausages. One of the raw materials for making edible coatings was gelatin extracted from duck bones. The combination of gelatin with sodium alginate was expected to improve the quality of sausages. This research was conducted to study the efficacy of duck bone gelatin and sodium alginate coating materials on beef sausage quality during chilled storage. A randomized group design was used as an experimental design with four replications. The independent variable was storage time. The result showed that free fatty acid, protein content, total microbial count, and weight loss increased during storage. Meanwhile, moisture content, pH, color, aroma, and texture decreased. Non-coated sausage during 2 weeks of storage had a free fatty acid value of 1.23%, protein content of 16.21%, TPC of 7.38 log cfu/g, weight loss of 13.94%, moisture content of 60.43%, pH of 5.62, color of 2.3, aroma of 1.5, and texture of 1.9. Sausages with edible coating for 4 weeks of storage had a free fatty acid of 1.34%, protein content of 15.95%, TPC of 6.92 log cfu/g, weight loss of 14.72%, moisture content of 59.73%, pH of 5.67, color of 1.9, aroma of 1.8, and texture of 2.1.

Total phenolic content and antioxidant properties of hydrophobic compounds edible coating Spirulina snack bar

Snack bars, known for their convenience and easy consumption, amalgamate various ingredients such as cereals, fruits, and nuts. Their portable and on-the-go nature makes them a favored choice for individuals engaged in various activities. The integration of natural additives, such as Spirulina platensis, to elevate the nutritional profile of snack bars represents a novel and ambitious initiative. This study delves into the innovative realm of edible coating for spirulina snack bars using maltodextrin and gelatin. The investigation explores the correlation between total phenol content and antioxidant activity through the FRAP method, employing two solvents, methanol, and n-hexane. Results demonstrate that varying concentrations of edible coating significantly enhance the appearance and texture of Spirulina Snack Bars (SSB). Notably, the SSB coated with 6% maltodextrin and 1% gelatin exhibits superior visual appeal and a firmer texture compared to its counterpart coated with 3% maltodextrin and 1% gelatin. Moreover, the n-hexane extract showcases higher antioxidant activity (19.971 mg/g) than the methanol extract (16.400 mg/g). This study underscores the effectiveness of n-hexane-based edible coatings in elevating the antioxidant potential and total phenol content of spirulina snack bars, offering essential insights for the development of functional foods with enhanced nutrition and prolonged shelf life.

Protein Characterization in Edible Coating for Snack Bar Enriched with Spirulina

Spirulina, renowned for its impressive protein content of 55-70% of dry weight, surpasses commonly used plant sources like soybeans, peanuts, or cereals. However, Spirulina snack bars, with their inherent texture, may face challenges like moisture absorption and microbial growth. In this context, edible coatings emerge as a solution to prevent moisture ingress, microbial growth, and preserve the bars. This study delves into analyzing the protein content of edible coatings, specifically maltodextrin with a 6% concentration and 1% gelatin, aiming to assess their efficacy in safeguarding against ambient moisture and oxygen. The findings reveal that the snack bar with the specified coating concentration showcases enhanced visual appeal and a denser texture. Protein analysis using SDS PAGE identifies bands with molecular weights of 17kDa, 25kDa, and 35kDa, likely corresponding to αs-CN and β-CN proteins. Chromatogram analysis of the Spirulina snack bar using the HPX-87H column unveils a peak at 6.195 minutes in the methanol extract, indicating abundance in α-tocopherol, a vitamin E variant. This comprehensive exploration underscores the potential of edible coatings, providing insights into their role in preserving Spirulina snack bars and contributing to food industry advancements.

Validade de espargos verdes usando revestimento de mistura de mandioca e quitosana

Abstract Polysaccharide coating is a biodegradable alternative to conventional packings used for delaying senescence in vegetables. This work investigated the properties of cassava and chitosan biopolymeric film and its use as edible coatings to preserve the shelf-life (7 °C and 70% relative humidity (RH)) of green asparagus, with previous cold storage (1 °C and 90% RH) for 7 days. Based on a previous assessment of the films obtained from a) cassava (2.5%), b) chitosan (0.5%), and c) a blend of cassava-chitosan (Cassava+) (2.5 + 0.5%), it could be verified that cassava-chitosan blend films showed improved barrier property (water vapor transmission rate (WVTR) of 38.06 g/(m2.h)) and mechanical properties, with tensile strength of 0.021 MPa, elongation at break of 1.93% and Young’s module of 0.011 MPa. Cassava+ based coating resulted in a lower weight loss and colour L* parameter and minimized textural changes in basal-section of commercial green asparagus spears during a shelf-life of seven days (7 °C and 70% RH), with previous cold storage. All coated spears maintained overall higher carbohydrate levels than the control, except to sucrose which gradually decreased in basal sections and increased in the apical sections of asparagus spears, irrespective of treatment. Edible coating did not affect asparagine concentrations which steadily increased throughout the shelf-life of the spears. The blend (Cassava+) kept for a longer the green asparagus quality. However, spears under a shelf-life of seven days (7 °C and 70% RH), with previous cold storage under 1 °C and 90% RH conditions, developed tip-rot physiological disorder.

Alginate Based Aloe Vera Gel And/Or Pomegranate Seed Essential Oil Added Edible Coating Film Production Using Casting Method To Extend Strawberries and Cherries Shelf Life

Many type of material used, for coating food to extend shelf life and that may be eaten together with the coated food. Today, environmentally friendly technologies, like edible films produced from biodegradable materials, are preferred in food coating. In this study alginate-based (3g) aloe vera gel (1.5g) and/or pomegranate seed essential oil (1%) added plasticized with glycerol (2g) edible films were produced by casting method for use in food coating at 5 different composition. Aloe vera gel and pomegranate seed essential oil (3%) added edible composite films have the lowest (72.56%) water solubility value. Pomegranate seed essential oil added edible films have lower water vapor transmission rate (0,0897*10-3), and lower moisture content (19.95%) values. 1% pomegranate seed essential oil added film has the lowest film thickness (0.125 mm). FTIR spectra of the films confirmed the interactions between alginate, aloe vera gel and pomegranate seed essential oil thus proving that the films were prepared successfully. Strawberries and cherries were coated with produced edible coating films and weight loss and color analysis were carried out to observe coating performance. It was seen that alginate based and pomegranate seed essential oil added edible coatings reducing moisture loss, color change and surface deformation of strawberries and cherries. The biggest difference of this study from previous studies is that pomegranate seed essential oil was used for the first time in this study, for edible coating film production and the results were quite successful especially for the cherry’s coating.

Effect of chitosan/plant oils edible coatings on minimally processed peach quality during storage

The edible coatings are capable to extend the shelf-life of minimally processed fruits and reduce the synthetic packaging’s waste. The used coating materials are obtained from renewable plant sources and byproducts of the food production. In addition, they are functional active ingredients. In this study, low-molecular weight fungal chitosan-based coatings with plant oil emulsions were used for coating of sliced peach. For characterization of the differently coated fruit pieces physical, physicochemical, microbiological and sensorial properties were examined during refrigeration. The used coatings extended the shelf-life time up to 10 days and the coated fruits had acceptable sensory parameters even at the end of the storage.