Revolutionizing tropical fruits preservation: Emerging edible coating technologies.

Tropical fruits, predominantly cultivated in Southeast Asia, are esteemed for their nutritional richness, distinctive taste, aroma, and visual appeal when consumed fresh. However, postharvest challenges have led to substantial global wastage, nearly 50 %. The advent of edible biopolymeric nanoparticles presents a novel solution to preserve the fruits' overall freshness. These nanoparticles, being edible, readily available, biodegradable, antimicrobial, antioxidant, Generally Recognized As Safe (GRAS), and non-toxic, are commonly prepared via ionic gelation owing to the method's physical crosslinking, simplicity, and affordability. The resulting biopolymeric nanoparticles, with or without additives, can be employed in basic formulations or as composite blends with other materials. This study aims to review the capabilities of biopolymeric nanoparticles in enhancing the physical and sensory aspects of tropical fruits, inhibiting microbial growth, and prolonging shelf life. Material selection for formulation is crucial, considering coating materials, the fruit's epidermal properties, internal and external factors. A variety of application techniques are covered such as spraying, and layer-by-layer among others, including their advantages, and disadvantages. Finally, the study addresses safety measures, legislation, current challenges, and industrial perspectives concerning fruit edible coating films.

Chitosan/aloe vera gel coatings infused with orange peel essential oils for fruits preservation.

Continuous fruit waste poses significant environmental and economic challenges, necessitating innovative fruit coating technologies. This research focuses on harnessing discarded orange peels to extract essential oil (OPEO), which is then integrated into a chitosan/aloe vera (CTS/AVG) matrix. The study comprehensively characterised the coating in terms of its physicochemical properties, antioxidant capacity, and antimicrobial efficacy. The investigation involved an analysis of particle size and distribution in the coating solutions, highlighting changes induced by the incorporation of orange peel essential oil (1 %, 2 % and 3 % v/w) into the chitosan/aloe vera (4:1 v/v) matrix, including particle size reduction and enhanced Brownian motion. The study quantifies a 33.21 % decrease in water vapour transmission rate and a reduction in diffusion coefficient from 9.26 × 10-11 m2/s to 6.20 × 10-11 m2/s following the addition of OPEO to CTS/AVG. Assessment of antioxidant potential employing DPPH radical scavenging assays, revealed that CTS/AVG/3 %OPEO exhibited notably superior radical scavenging activity compared to CTS/AVG, CTS/AVG/1 %OPEO, and CTS/AVG/2 %OPEO, demonstrated by its IC50 value of 17.01 ± 0.45 mg/mL. The study employs the well diffusion method, demonstrating a higher susceptibility of gram-negative bacteria to the coating solutions than gram-positive counterparts. Remarkably, CTS/AVG/3 %OPEO displayed the most pronounced inhibition against Escherichia coli, generating an inhibitory zone diameter of 14 ± 0.8 mm. The results collectively emphasised the potential of CTS/AVG/3 %OPEO as a viable natural alternative to synthetic preservatives within the fruit industry, attributed to its exceptional antioxidant and antimicrobial properties.

Tannic Acid and Ca2+ Double-Crosslinked Alginate Films for Passion Fruit Preservation.

In this study, the interaction of different concentrations of tannic acid (TA) (10%, 20%, and 30% w/w) and Ca2+ with alginate (SA) was utilized to create double-crosslinked SA films. The resulting films were evaluated for their optical, mechanical, water resistance, and barrier properties, and their microstructure and intermolecular interactions were also characterized. The SA films containing 20% TA showed the best mechanical properties, with an observed increase in tensile strength of 22.54%. In terms of water vapor permeability, the SA film containing 30% TA exhibited the highest barrier property, which was 25.36% higher than that of the pure SA film. Moreover, TA demonstrated a strong UV absorption ability, resulting in a nearly 0% UV transmittance of the SA film at 280 nm. It can be seen that SA films containing 20% TA have excellent barrier and mechanical properties, and the development of such films will be applied to the storage and packaging of fresh food. It is worth noting that this work also investigated the effect of SA coatings containing different concentrations of TA on the preservation of passion fruits for 7 days. The results revealed that passion fruits treated with SA coatings containing a 30% TA concentration maintained a better appearance on the 7th day and had the lowest weight loss and crumpling indices of approximately 8.98% and 2.17, respectively, compared to the other treatment groups. Therefore, based on the overall results, the addition of 30% TA to SA coatings proved to be more effective and can be considered a promising approach for delaying fruit senescence and decay.

Valorization of waste biomass for synthesis of carboxy-methyl-cellulose as a sustainable edible coating on fruits: A review.

The coating on fruits and vegetables increases the shelf-life by providing protection against their spoilage. The existing petroleum-based coating materials have considerable health threats. Edible coating materials prepared with the cellulose derivative extracted from the waste biomass could be a sustainable alternative and environment friendly process to increase the shelf-life periods of the post-harvest crops. Selection of suitable waste biomass and extraction of cellulose are the critical steps for the synthesis of cellulose-based edible film. Conversion of extracted cellulose into cellulosic macromolecular derivatives such as carboxy-methyl-cellulose (CMC) is vital for synthesizing edible coating formulation. Applications of sophisticated tools and methods for the characterization of the coated fruits would be helpful to determine the efficiency of the coating material. In this review, we focused on: i) criteria for the selection of suitable waste biomass for extraction of cellulose, ii) pretreatment and extraction process of cellulose from the different waste biomasses, iii) synthesis processes of CMC by using extracted cellulose, iv) characterizations of CMC as food coating materials, v) various formulation techniques for the synthesis of the CMC based food coating materials and vi) the parameters which are used to evaluate the shelf-life performance of different coated fruits.

Development and Evaluation of Chitosan-Based Food Coatings for Exotic Fruit Preservation.

Chitosan has gained agro-industrial interest due to its potential applications in food preservation. In this work, chitosan applications for exotic fruit coating, using feijoa as a case of study, were evaluated. For this, we synthetized and characterized chitosan from shrimp shells and tested its performance. Chemical formulations for coating preparation using chitosan were proposed and tested. Mechanical properties, porosity, permeability, and fungal and bactericidal characteristics were used to verify the potential application of the film in the protection of fruits. The results indicated that synthetized chitosan has comparable properties to commercial chitosan (deacetylation degree > 82%), and, for the case of feijoa, the chitosan coating achieved significant reduction of microorganisms and fungal growth (0 UFC/mL for sample 3). Further, membrane permeability allowed oxygen exchange suitable for fruit freshness and natural physiological weight loss, thus delaying oxidative degradation and prolonging shelf-life. Chitosan's characteristic of a permeable film proved to be a promising alternative for the protection and extension of the freshness of post-harvest exotic fruits.

Pre-harvest application of chitosan and postharvest Aloe vera gel coating enhances quality of table grape (Vitis vinifera L. cv. 'Yaghouti') during postharvest period.

The present study evaluated impact of pre-harvest foliar spraying with chitosan (2.0% and 3.0%) and post-harvest Aloe vera gel (AVG) coating (25% and 33%) to determine the quality of table grape during storage. The results showed that both treatments significantly influenced the storage lifetime of this fruit. In addition, the chitosan and AVG combinations minimized the incidence of decay and reduced the weight loss more than that of chitosan, AVG and control samples. 25 days once the foliar application of chitosan 3.0% with AVG 33% coating extending the storage life of fruit up to 15 days by significantly reducing decay index, malondialdehyde, weight loss and polyphenol oxidase also, maintaining the overall quality index, firmness, antioxidant capacity, peroxidase, total phenols, anthocyanin, SSC and vitamin C. Based on the findings, these natural compound treatments could be considered as suitable alternatives to extend the marketable period of table grapes and minimize post-harvest losses.

Postharvest sour cherry quality and safety maintenance by exposure to Hot- water or treatment with fresh Aloe vera gel.

Iranian sour cherries (Prunus cerasus) were coated with fresh Aloe vera gel or treated with hot water (40 ± 2 °C) for 2 min and stored for 17 days at 4 ± 1 °C. The physicochemical characteristics of gel coated and hot water treated samples were compared with untreated fruit during the cold storage period. Untreated fruit showed increased respiration rate, rapid weight loss and colour change, accelerated aging and ripening. On the contrary, sour cherries, particularly those coated with gel significantly delayed the above mentioned parameters allowing a fruit storability extension. The sensory analysis in both treatments revealed beneficial effects in terms of delaying dehydration, maintenance of fruit visual aspect without any detrimental effect on taste, aroma or flavours. Consequently, Aloe vera gel coating and immersion in hot water maintained the properties during postharvest storage of sour cherries and could be introduced as two valuable, simple and non-contaminating treatments.