Impact of edible coatings on quality of fruits: A review

Novel edible coatings pretreatment for enhancing drying performance and physicochemical properties of cherry fruits during multi-frequency ultrasonic vacuum far infrared radiation - Radio frequency vacuum segmented combination drying

To maximize the drying efficiency and physicochemical quality of cherry fruits while minimizing energy consumption, this study investigated the effects of novel edible coatings (sodium carboxymethyl cellulose (CMC-Na) and sodium alginate (SA)) pretreatment combined with multi-frequency ultrasonic vacuum far infrared radiation-radio frequency vacuum (MUSVFIR-RFV) segmented drying on the drying performance and physicochemical properties of cherries. Results demonstrated that MUSVFIR-RFV segmented drying combined with coating pretreatment reduced the drying time by 11.11 ∼ 25.93 % compared to single drying. At a moisture conversion point of 50 %, the process achieved optimal drying performance and energy efficiency. Remarkably, multi-frequency ultrasound outperformed single-frequency ultrasound in terms of energy transfer intensity and uniformity. Physicochemical quality analysis revealed that the combination of CMC-Na or SA coatings with MUSVFIR-RFV segmented drying significantly improved the retention of soluble solids, individual sugar, natural bioactive compounds, TPC, TFC, and antioxidant activities (DPPH, ABTS, and FRAP). Texture and sensory properties showed that the hardness and adhesiveness of coated cherries were reduced, while elasticity, chewiness, and cohesiveness were significantly enhanced. Cherries subjected to (CMC-Na)-(MUSVFIR-RFV) treatment achieved higher scores in texture, crispness, color, sweet taste, appearance, and aroma, with lower bitterness and off-odor, leading to an overall acceptance score of 9.2, which was significantly higher than that of the control. Hierarchical clustering and PCA analysis further validated that the integration of coatings with segmented drying effectively improved the physicochemical quality of dried cherries. The findings provide scientific evidence for the development of efficient drying technologies for cherry, substantiating the potential advantages of combining edible coatings with MUSVFIR-RFV drying in enhancing drying efficiency, quality, and sensory attributes of cherries.

Effect of sodium alginate edible coating on drying behavior and quality characteristics of ripe pineapple slices

The increasing global demand for tropical fresh cut products is driven by their convenience, quality, and health benefits, highlighting the need for effective preservation methods. Pineapple slices were treated with antioxidant solution, osmodehydrated (OD) and edible sodium alginate coating was applied in different methods to investigate the effect of edible coating on osmotic dehydration, convection drying phenomena, and quality parameters of dried pineapple slices. The findings showed that edible coatings influenced drying kinetics and physicochemical properties of pineapple slices. The optimal drying temperature was identified as 60 °C, while color degradation occurred at 65 °C. Pineapple slices treated with sodium alginate after OD required the highest activation energy (65.93 kJ/mol) for moisture diffusion. Coatings enhanced ash content and moisture retention while reducing shrinkage and improving the rehydration ratio, vitamin C, and total phenolic content (TPC). Sensory assessment indicated improvements in color, flavor, texture, and overall acceptability for all coated samples. Notably, samples coated with sodium alginate after OD exhibited the most favorable physicochemical properties at 60 °C and the highest overall acceptability up to the 15th day of post-processing storage. These results underscore the potential of edible coatings to enhance the preservation and quality of pineapple slices, suggesting scopes for future research in pre-treatment technologies for drying.

Quality Preservation and Shelf-Life Extension of Prickly Pear (Opuntia ficus-indica L. Mill) Using Edible Coatings

Prickly pear consumption is increasing across the world due to its rich variety of nutrients and bioactive compounds. Yet, it is a seasonal and highly perishable fruit, and the application of edible coatings emerges as an alternative to extend its shelf life. In this work, the effects of alginate, starch, chitosan, and pectin as coatings on the physicochemical, bioactive, microbiological, and textural properties of two prickly pear varieties (orange and red), kept under refrigeration (5 ± 2 °C) were evaluated for 6 weeks. Coatings proved to be helpful in the maintenance of the fruits' color and textural properties, especially when pectin was applied. Overall, starch and chitosan can be considered the most effective coatings in preserving the quality of prickly pears among the options studied. A lower weight loss (8-10%) in fruits was achieved when starch and chitosan were applied, while in control fruits (without coating), the loss was 18-23%. Starch and chitosan also contributed to preserving the bioactivity of red fruits and showed good results in the preservation of total phenolic content in the orange fruits. In addition, starch and chitosan coatings also presented the best performance for the reduction of microbial contamination (both yeasts and molds and total mesophilic aerobic microorganisms). These findings highlight the role of edible coatings in preserving prickly pears, for a longer period, meeting consumers' demand for fresh fruit.

Global insights and advances in edible coatings or films toward quality maintenance and reduced postharvest losses of fruit and vegetables: An updated review

Transitioning to safe, nonthermal, and edible strategies for maintaining fruit and vegetable (F&V) quality, reducing postharvest losses (up to 55% annually), and ensuring food security requires extensive research and innovation in postharvest technologies. This review aims to provide an updated understanding of edible coatings or films (ECF), focusing on their role in reducing F&V postharvest losses, based on data from the last 40 years retrieved from the Web of Science database. The global ECF research network is represented by publication trends, majorly researched F&V, key research areas, influential and emerging authors, and global research ranking. The role of ECF in preserving F&V quality has been assessed by examining critical quality parameters, including weight loss, total soluble solids, titratable acidity, ripening, softening, sensory and organoleptic characteristics, browning, chilling injury, and microbial safety. Furthermore, recent advancements in ECF formulations, including nanoscale ingredients and application methodologies, have been critically discussed. Sources, categorization, application strategies, mode of action, functional properties, sustainable development goals (SDGs), challenges, safety, legislations, and future perspectives in ECF research have also been discussed. The key findings indicate that China (20.34%) and the USA (9.94%) are the leading countries in ECF research. Studies have demonstrated ECF's potential in reducing F&V postharvest losses by maintaining quality parameters through advanced nanoscale compositions and methodologies. Notably, ECF research supports multiple SDG targets, including SDGs 2, 3, 8, 9, 12, 13, and 15. Future ECF research should explore 3D-printed coatings, nonflavor-altering components, and potential crosslinking agents to enhance F&V quality and reduce postharvest losses.

Development and Application of Mucilage and Bioactive Compounds from Cactaceae to Formulate Novel and Sustainable Edible Films and Coatings to Preserve Fruits and Vegetables-A Review

The accelerated ripening and senescence of fruits and vegetables is characterized by various biochemical changes that hinder the maintenance of their postharvest quality. In this context, developing edible films and coatings formulated with natural and biodegradable materials emerges as a sustainable strategy for preserving the quality parameters of these products in replacement of conventional petroleum-based packaging. Recently, plant-based polymers, including mucilage from different cactus species and/or their bioactive compounds, have been investigated to develop edible films and coatings. As the available literature indicates, the Opuntia genus stands out as the most used for mucilage extraction, with the cladode being the most exploited part of the plant. Conventional extraction methods are widely employed to obtain mucilages, which are applied to fruits and vegetables after being combined with plasticizing and cross-linking agents. In general, these films and coatings have proven effective in prolonging the shelf life and maintaining the nutritional, physical, and sensory quality of fruits and vegetables. Given their preservation potential, combining cactus mucilages with bioactive compounds, probiotics, and prebiotics represents an emerging trend in developing functional films and coatings. However, some limitations have been identified, such as the underutilization of different species and parts of the plant, the lack of standardization in extraction methods, and the absence of studies on the effects of the physicochemical properties of mucilages in the formulation and characteristics of films and coatings. Therefore, overcoming these limitations is essential for developing edible films and coatings with enhanced techno-functional properties and greater commercial viability.

Eco-friendly and flexible polysaccharide-based packaging films for fruit preservation

Food safety and wastage caused by fruit deterioration is a serious global problem. Effective packaging systems for extending the freshness period of fruit play a key role in food safety. In this work, we constructed an eco-friendly and flexible polysaccharide-based packaging film based on hydroxypropyl guar (HPG), cellulose nanocrystals (CNCs), deep eutectic solvents (DES) and anthocyanin (Anth). DES could endow polysaccharide films with multiple hydrogen bond numbers and good stability. Hydroxypropyl guar/cellulose nanocrystals/anthocyanin with 0.2 g deep eutectic solvents (HCA-DES0.2) had good tensile properties, oxygen barrier properties (3.01 cm3/m2·day·Pa), water resistance (WCA 111.97°), antibacterial (CFU ˂ 103), and transparency (55.4 %). The preservation tests of grape and blueberry showed that the shelf life of these two fruits was 12-20 days, and the polysaccharide film had great application potential in fruit preservation.

The potential of carboxylmethyl cellulose from empty fruit bunch as versatile material in food coating: A review

The rising demand for food packaging has led to a growing interest in sustainable and eco-friendly food coatings. Carboxymethyl cellulose (CMC), being a versatile cellulose derivative produced from various lignocellulosic sources, has emerged in edible food coatings. This review evaluates the research trends on CMC production from empty fruit bunch (EFB) as a potential edible food coating material by systematic review approach. It explores sustainable pre-treatment for green cellulose and different CMC synthesis methods. The review compares CMC-based coatings to other materials, focusing on formulation processes, coating quality, safety, and commercial feasibility. The bibliometric analysis is performed to correlate food coating and CMC. As a result, the study discovered the rapid growth in research on edible food coatings made from CMC for various food industry applications. The green approach such as ozone pre-treatment appear as promising method for cellulose isolation from EFB to be used as raw material for CMC. The synthesis conditions of the treatment would affect the CMC characteristics and usage. Herein, utilizing CMC from cellulose EFB in coating formulation and on coated food shows different benefits. This review provides a road map for future research with potential to make important contributions to the food industry's long-term evolution.

Gelatin based preservation technologies on the quality of food: a comprehensive review

Gelatin has played a great potential in food preservation because of its low price and superior film forming characteristics. This review provides a comprehensive overview of the latest research progress and application of gelatin preservation technologies (film, coating, antifreeze peptide, etc.), discussing their preservation mechanisms and efficiency through the viewpoints of quality and shelf life of animal and aquatic products as well as fruits and vegetables. It showed that bioactive and intelligent gelatin-based films exhibit antibacterial, antioxidant, water resistance and pH responsive properties, making them excellent for food preservation. In addition, pH responsive properties of films also intuitively reflect the freshness of food by color. Similarly, gelatin and its hydrolysate can be widely used in antifreeze peptides to reduce the mass loss of food during freezing and extend the shelf life of frozen food. However, extensive works are still required to extend their commercial application values.

Polysaccharide-Based Edible Biopolymer-Based Coatings for Fruit Preservation: A Review

Over the last decades, a significant rise in fruit consumption has been noticed as they contain numerous nutritional components, which has led to the rise in fruit production globally. However, fruits are highly liable to spoilage in nature and remain vulnerable to losses during the storage and preservation stages. Therefore, it is crucial to enhance the storage life and safeness of fruits for the consumers. To keep up the grade and prolong storage duration, various techniques are employed in the food sector. Among these, biopolymer coatings have gained widespread acceptance due to their improved characteristics and ideal substitution for synthetic polymer coatings. As there is concern regarding the safety of the consumers and sustainability, edible coatings have become a selective substitution for nurturing fruit quality and preventing decay. The application of polysaccharide-based edible coatings offers a versatile solution to prevent the passage of moisture, gases, and pathogens, which are considered major threats to fruit deterioration. Different polysaccharide substances such as chitin, pectin, carrageenan, cellulose, starch, etc., are extensively used for preparing edible coatings for a wide array of fruits. The implementation of coatings provides better preservation of the fruits such as mango, strawberry, pineapple, apple, etc. Furthermore, the inclusion of functional ingredients, including polyphenols, natural antioxidants, antimicrobials, and bio-nanomaterials, into the edible coating solution matrix adds to the nutritional, functional, and sensory attributes of the fruits. The blending of essential oil and active agents in polysaccharide-based coatings prevents the growth of food-borne pathogens and enhances the storage life of the pineapple, also improving the preservation of strawberries and mangoes. This paper aims to provide collective data regarding the utilization of polysaccharide-based edible coatings concerning their characteristics and advancements for fruit preservation.

Recent advancements in polysaccharides, proteins and lipids based edible coatings to enhance guava fruit shelf-life: A review

Fresh fruits are highly needed for the health benefits of human beings because of the presence of high content of natural nutrition in the form of vitamins, minerals, antioxidants, and other phenolic compounds. However, some nutritional fruits such as guava are climacteric in nature with very less post-harvest shelf-life because of the ripening in a very short period and possibility of microbial infections. Thus security of natural nutrients is a serious concern in order to properly utilize guava without generating a huge amount of waste. Among reported various methods for the enhancement of fruits shelf-life, the application of edible coatings with antimicrobial activities on the outer surface of fruits have attracted significant attention because of their eco-friendly nature, easy applicability, high efficacy, and good durability. In recent years, researchers are paying more and more attention in the development of antimicrobial edible coatings to enhance the post-harvest shelf-life of guava using polysaccharides, protein and lipids. In this review, basic approaches and recent advancements in development of antimicrobial and edible coatings on guava fruit by the application of polysaccharides and protein and lipids along with the combination of nanomaterials are summarized. In addition, improvements in basic properties of edible coatings to significantly control the permeation of gases (O2/CO2) by the optimization of coating components as well as delay in ripening process are reviewed and discussed.

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

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

Effect of Aloe vera and carboxymethyl cellulose-derived binary blend edible coating on the shelf life of fresh-cut apple

In recent years, the demand and market for minimally processed fruits are increasing worldwide. Fresh-cut apples are extremely sensitive to environmental factors including oxygen, temperature, and microorganisms in resulting the browning of apples. Therefore, in this study, different concentration of blended edible-coating solution was prepared using Aloe vera and carboxymethyl cellulose (1:1, 1:2, 2:1, 3:3, 3:2, 4:2, 2:4, 3:4, and 4:3, respectively). Lease particle size (101.74 ± 0.67 nm) of the coating solution was observed with 3% A. vera and 2% carboxymethyl cellulose (CMC). Afterward, the shelf life of the apples was evaluated for 10 days at refrigeration condition. Results showed that a significant difference was found in weight loss of coated (6.42%-10.26%) and uncoated apples (8.12%-15.32%) for 2-10 days. Moreover, the titrable acidity of the cut apples increased during the storage time. Rheological data emerged that the viscosity of the coating solution decreases with the increasing temperature from 0 to 50°C. Fourier transform infrared spectroscopy data confirmed the presence of hydroxyl group (-OH), C=O, C-O, and N-H banding in the A. vera, CMC, and blend-coating solution. The blend solution indicated excellent antimicrobial efficiency. Total phenolic content of coated and uncoated apples at 0 day was 737.55 mg GAE kg-1 for uncoated and 717.88 mg GAE kg-1, respectively. Whereas, aerobic and psychrotrophic bacteria counts for edible coated apples significantly lower than control apples. For coated apples, aerobic and psychrotrophic bacteria counts were 1.59 ± 0.84 and 1.25 ± 0.49 log CFU g-1 were 4.26 ± 0.67 and 2.68 ± 0.22 log CFU g-1 at 10th day, respectively. Overall, it can be inferred that blend of A. vera and carboxymethyl cellulose could be used as a nontoxic potential anti-browning and antimicrobial component for the enhancement of the shelf life and additional nutritional value of fresh-cut apples.

Films Based on Biopolymers Incorporated with Active Compounds Encapsulated in Emulsions: Properties and Potential Applications-A Review

The rising consumer demand for safer, healthier, and fresher-like food has led to the emergence of new concepts in food packaging. In addition, the growing concern about environmental issues has increased the search for materials derived from non-petroleum sources and biodegradable options. Thus, active films based on biopolymers loaded with natural active compounds have great potential to be used as food packaging. However, several lipophilic active compounds are difficult to incorporate into aqueous film-forming solutions based on polysaccharides or proteins, and the hydrophilic active compounds require protection against oxidation. One way to incorporate these active compounds into film matrices is to encapsulate them in emulsions, such as microemulsions, nanoemulsions, Pickering emulsions, or double emulsions. However, emulsion characteristics can influence the properties of active films, such as mechanical, barrier, and optical properties. This review addresses the advantages of using emulsions to encapsulate active compounds before their incorporation into biopolymeric matrices, the main characteristics of these emulsions (emulsion type, droplet size, and emulsifier nature), and their influence on active film properties. Furthermore, we review the recent applications of the emulsion-charged active films in food systems.

Effect of Edible Coating Enriched with Natural Antioxidant Extract and Bergamot Essential Oil on the Shelf Life of Strawberries

In this study, the effects of the application of edible coatings on the shelf life of the strawberry were evaluated, with the aim of extending the fruit's availability and shelf life while preserving its qualitative characteristics. In particular, the application of edible coatings enriched with a natural antioxidant to strawberries was evaluated for their physicochemical, microbial, and structural properties, during a storage period (up to 14 days) at refrigerated temperature. The experimental plan provided the formulation for edible coatings enriched with different concentrations of a natural antioxidant extract obtained from bergamot (Citrus bergamia Risso) pomace (1, 2.5, and 5%), bergamot essential oil (0.1% v/v and 0.2% v/v), and a synthetic antioxidant, butylated hydroxytoluene (BHT, 100 ppm). Moreover, a control test with untreated strawberries was considered. The enriched gum Arabic coatings provided good results related to the preservation of the qualitative parameters of the strawberries. The samples coated with the antioxidant extract (2.5%, sample D) and bergamot essential oil (0.1%, sample F) showed the best maintenance of the qualitative parameters after 14 days, showing lower decay rates (36% D and 27% F), good acceptability by consumers (between 5 and 6), and good retention of ascorbic acid (>30 mg 100 g^-1).

Antimicrobial Activity of Chitosan/Gelatin/Poly(vinyl alcohol) Ternary Blend Film Incorporated with Duchesnea indica Extract in Strawberry Applications

Chitosan (CTS)/gelatin (GEL)/poly(vinyl alcohol) (PVA)-based composite films with different concentrations of Duchesnea indica extract (DIE) (6.25 and 25 mg/mL), an antimicrobial agent, were manufactured using a casting technique. Results indicated that elongation at break decreased as DIE was added at higher concentrations. Composite films showed no significant differences in thickness, tensile strength, and water vapor permeability. Scanning electron microscopy images revealed that DIE was successfully incorporated into film matrices to interact with polymers. The addition of DIE to the film inhibited the growth of S. aureus by up to 4.9 log CFU/mL. The inhibitory effect on S. aureus using DIE-incorporated coating applied to strawberries was greatest at room temperature storage for 24 h only when it was coated twice or more. The maximum inhibition in strawberries was 2.5 log CFU/g when they were coated twice and 3.2 log CFU/g when they were coated three times. The results of this study suggest that DIE could be used as a natural antimicrobial agent, and DIE-integrated CTS/GEL/PVA films or coatings have potential as a food packaging alternative for preventing foodborne pathogen contamination.

Investigation on the potential of applying bio-based edible coatings for horticultural products exemplified with cucumbers

Plastic packaging for fresh horticultural produce has many advantages but generates plastic waste and ecological alternatives are required. Edible coatings can retard many processes related to loss of quality. Hydrophobic lipid-based coatings are preferably applied for fresh fruits and vegetables. The approval of such coatings for products with edible peels in EU is increasingly under discussion. However, investigations on the efficiency of various edible coatings on soft-skinned fruit and vegetables are rare and it is currently unclear whether the consumer will accept them. Therefore, this study investigates (1) important characteristics of a lipid-based coating and (2) its ability to maintain the post-harvest quality of fresh cucumbers. This was evaluated by a comparative storage test under common suboptimal retail conditions (20 °C; 65% RH). The study also evaluates (3) the general perception of consumers about and their acceptance of the application of edible coatings on fresh fruit and vegetables with edible peels. The investigated coating was able to drastically reduce water loss (54-68%) and fruit respiration (approx. 33%) of fresh cucumber. The reduction of tissue stiffness was delayed by 2 days, thus, prolonged shelf life. Majority of consumer (77%) endorse the application of edible coatings as an alternative to plastic packaging, but emphasized important requirements for them.

Hydrocolloid edible coatings extend shelf life, reduce postharvest decay, and maintain keeping quality of mango fruits (Mangifera indica L.) under ambient storage

Mango fruit exhibit high postharvest losses due to physiological, biochemical, and pathological deterioration during storage. Edible coatings such as hydrocolloids (HC) bear promising potential for fruit quality preservation at ambient storage due to its triple action (physiological, biochemical and pathological) on fruit and thus widely researched in recent years. This study demonstrates the influence of health and eco-safe hydrocolloid edible coatings such as "Carboxymethyl cellulose" (CMC) (1%), "Guar gum" (1.5%), "Gum Arabica" (10%), and "Xanthan gum" (0.3%) as dip treatment to enhance the postharvest quality and storage life of mangoes at ambient storage (25 ± 4°C and 65 ± 5% RH). "Xanthan gum" (0.3%) treatment exhibited the highest efficacy in reducing the decay loss by more than threefold and physiological loss by twofold over control fruit. It lowered the physiological and fruit softening enzyme activities (PG, PME, and LOX), while maintaining the biochemicals. Moreover, it maintained both internal as well as external (consumer preference) quality of fruit and extended 6 days shelf life on the physiological loss standard basis (≤10%) than that of the control. The results recommend the application of "Xanthan gum" (0.3%) as an efficacious ecological, sustainable, and health-friendly surface edible coating for quality preservation and storage period extension of mango fruit under ambient storage. PRACTICAL APPLICATIONS: The selected hydrocolloid edible coatings dip treatment showed promising potential in controlling the physiological, biochemical, and pathological deterioration of mango fruit stored under ambient condition. The selected treatments extended the shelf life without diminishing fruit quality. However, among the attempted HC treatments, the "Xanthan gum" (0.3%) (XG) coating displayed the excellent results. It added the storage life of mango fruit by 6 days over the control. XG treated fruit displayed the excellent results in terms of storage period extension, quality retention, consumer preference, and control over the fruit decay and softening enzymes activities. Postharvest preservation of mango fruit using HC is nonchemical, cost-effective approach which is GRAS (generally recognized as safe), health, and eco safe.