Enhancing the functionality of chitosan- and alginate-based active edible coatings/films for the preservation of fruits and vegetables: A review.

Background Numerous studies have been conducted to investigate the capability of edible coatings for preserving the quality and prolonging the shelf life of fresh/fresh-cut fruits. Evidence has shown that an edible coating could function as a barrier on the fruit surface, modify the internal gas atmosphere, decrease water losses and delay fruit ripening. Efforts have been exerted to introduce new natural coating materials to sustain the safety and quality of fresh/fresh-cut fruits. Scope and approach This review attempts to provide a summary of the recent studies on the application of edible coatings on different fresh/fresh-cut fruit categories, namely pome fruits (apple and pear), citrus, stone fruits, tropical and exotic fruits, berries, melon, and tomatoes. A fundamental theory behind the edible coating treatment and the effect on the physiological, physicochemical, sensory, and antimicrobial properties of fresh/fresh-cut fruits is discussed. The future perspective of this preservation method is also highlighted. Key findings and conclusions Edible coating can be used as an alternative strategy to prolong the shelf life of fresh/fresh-cut fruits. The materials selection for edible coating play a key role in determining its effectiveness and consumers acceptability. The ability of the selected materials in extending the shelf life of fresh/fresh-cut fruits without reducing the sensory and nutritional characteristics are the main challenges in the edible coating techniques, which demands attention for further research.

Recent advance in edible coating and its effect on fresh/fresh-cut fruits quality

Citrus fruits are subjected to a diversity of postharvest diseases caused by various pathogens during picking, packing, storage and transportation. Green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, are two major postharvest citrus diseases and cause significant economic losses during the commercialization phase. Currently, the control of postharvest citrus diseases relies mainly on the use of synthetic fungicides, which usually result in the resistance against fungal attack, environment pollution and health hazards. In recent years, much attention has been given to the preservation of citrus by naturally isolated edible plant extracts, medicinal plant extracts, Citrus extracts and volatiles, et al. Scientists worldwide devote their time and energy to discover the high effect, low toxicity, safety and inexpensive plant-derived fungicides. The current review will highlight plant-derived fungicides and chemical constituents that aim to inhibit P. digitatum and P. italicum in vitro and in vivo. Coatings enriched with plant extracts could be good alternative methods for Citrus fruits preservation. Problems and prospects of the research and development of plant-derived natural fungicides will also be discussed in this article.

https://www.mdpi.com/2223-7747/8/2/26/pdf

Inhibition of Key Citrus Postharvest Fungal Strains by Plant Extracts In Vitro and In Vivo: A Review.

Emerging chitosan-essential oil films and coatings for food preservation - A review of advances and applications.

The extension of commercial life and the reduction of postharvest losses of perishable fruits is mainly based on storage at low temperatures alone or in combination with modified atmospheres (MAs) and controlled atmospheres (CAs), directed primarily at reducing their overall metabolism thus delaying ripening and senescence. Fruits react to postharvest conditions with desirable changes if appropriate protocols are applied, but otherwise can develop negative and unacceptable traits due to the onset of physiological disorders. Extended cold storage periods and/or inappropriate temperatures can result in development of chilling injuries (CIs). The etiology, incidence, and severity of such symptoms vary even within cultivars of the same species, indicating the genotype significance. Carbohydrates and amino acids have protective/regulating roles in CI development. MA/CA storage protocols involve storage under hypoxic conditions and high carbon dioxide concentrations that can maximize quality over extended storage periods but are also affected by the cultivar, exposure time, and storage temperatures. Pyruvate metabolism is highly reactive to changes in oxygen concentration and is greatly affected by the shift from aerobic to anaerobic metabolism. Ethylene-induced changes in fruits can also have deleterious effects under cold storage and MA/CA conditions, affecting susceptibility to chilling and carbon dioxide injuries. The availability of the inhibitor of ethylene perception 1-methylcyclopropene (1-MCP) has not only resulted in development of a new technology but has also been used to increase understanding of the role of ethylene in ripening of both non-climacteric and climacteric fruits. Temperature, MA/CA, and 1-MCP alter fruit physiology and biochemistry, resulting in compositional changes in carbon- and nitrogen-related metabolisms and compounds. Successful application of these storage technologies to fruits must consider their effects on the metabolism of carbohydrates, organic acids, amino acids and lipids.

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Primary Metabolism in Fresh Fruits During Storage.

Quality and biochemical changes of navel orange fruits during storage as affected by cinnamaldehyde -chitosan coating

Changes of peel color and fruit quality in navel orange fruits under different storage methods

The current work aimed to evaluate the efficacy of four coating formulations—chitosan coating (CH), 0.5% cinnamaldehyde + chitosan (0.5% CI–CH), 1.0% cinnamaldehyde + chitosan (1.0% CI–CH), and 1.5% cinnamaldehyde + chitosan (1.5% CI–CH)—on fresh mandarin fruit cv. Ponkan quality maintenance (weight loss, decay rate, total soluble solids, titratable acidity, vitamin C, color index, malondialdehyde, and antioxidant activity) over 100 days of storage at 20 °C. Compared to the control, chitosan treatment effectively reduced the decay and weight loss rates of mandarin fruit cv. Ponkan during storage at room temperature, delayed the decline of nutritional quality in fruits, increased the antioxidant capacity, and inhibited the accumulation of malondialdehyde (MDA). In comparison to chitosan coating, 1.5% CI–CH did not improve the fruit storage effect, but inhibited the normal color change of fruits and increased the accumulation of MDA. Both 0.5% CI–CH and 1.0% CI–CH effectively reduced the rate of fruit decay, improved the quality of fruits after harvest, and delayed fruit aging. Our study suggests that 0.5% CI–CH and 1.0% CI–CH might be good formulations for maintaining the quality of mandarin fruit cv. Ponkan during room-temperature storage.

https://www.mdpi.com/2079-6412/8/10/372/pdf

Effects of Chitosan-Based Coatings Enriched with Cinnamaldehyde on Mandarin Fruit cv. Ponkan during Room-Temperature Storage

In citrus fruit, citric acid is the predominant organic acid which influence fruit taste, flavor and quality. The effect of hot air treatment (HAT 40°C, 48 h) and 1.0% chitosan coating on the change of organic acids and the related gene expression of citric acid synthesis and degradation in ponkan (Citrus reticulata Blanco) fruit during cold storage have been studied. The results showed that citric acid was the main organic acid in fruit, the trend change of citric acid content was consistent with total organic acids and titratable acidity (TA) content, which decreased with the prolongation of storage time, hot air treatment significantly promoted but chitosan coating treatment significantly delayed citric acid degradation in Ponkan fruit. Hot air treatment could induced CitAco2/3, CitIDH2/3, CitGAD4, CitACLs, CitPEPCKs and CitFBPases expression during fruit storage period, but had no significant effect on CitGSs expression, The enhanced expression of degradation-related genes was closely related to the degradation of citric acid. The expressions of CitAco3, CitGAD4 CitACLα2/β, CitPEPCKs and CitFBPases were inhibited, which leading to the degradation rate of citric acid was slowed by chitosan coating during storage. These results showed that the degradation of citric acid in fruit was regulated by ATP citrate lyase (ACL) pathway and γ-aminobutyric acid (GABA) pathway.

/pdf/effects-of-hot-air-treatment-and-chitosan-coating-on-citric-1ez7cvw0bn.pdf

Chaonan Kan

Papers

Quality and biochemical changes of navel orange fruits during storage as affected by cinnamaldehyde -chitosan coating

Changes of peel color and fruit quality in navel orange fruits under different storage methods

Effects of Chitosan-Based Coatings Enriched with Cinnamaldehyde on Mandarin Fruit cv. Ponkan during Room-Temperature Storage

Effects of hot air treatment and chitosan coating on citric acid metabolism in ponkan fruit during cold storage

Influence of different cold storage times on quality of “Cuiguan” pear fruits during shelf life