Recent advances for postharvest protection and preservation of mango fruit: a review

Mango fruit is one of the most important cultivars in the world. In postharvest handling, mango fruit can be affected by pathogens. Some of the phytopathogens that severely attack mango fruit are the fungal Colletotrichum , Aspergillus , Alternaria and Botrytis . The presence of these pathogens can generate postharvest losses between 5 - 30% of mango production. Fungicides are used to control these microorganisms. To reduce and eradicate its use in post - harvest, methods that are not harmful to the consumer have been developed and are classified into chemical, physical and biological methods. The selection of a postharvest method depends on its ability to adapt to an established process and its ability to extend its shelf life. Different post - harvest methods have been applied to mango fruit, including cold storage, hydrothermal treatment, UV, edible coatings and 1 - MCP. The result with the application of these methods has been efficient but increases with the application of synergies between different postharvest methods. This review presents a compilation and recent advances of the different postharvest control methods that have been applied individually or in synergy in mango fruits to control and/or prevent the attack of pathogens and preserve the quality parameters to extend the shelf life of the fruit


Introduction
Internationally, the mango fruit stands out among other fruits for its exquisite sweet flavor, its production in the last 10 years has been increasing due to its high demand (Statistica, 2021).This is a crop that, once harvested, accelerates its ripening by increasing its respiration rate and ethylene production.This causes rapid deterioration of the fruit, with the presence and incidence of phytopathogenic agents, mainly Colletotrichum, Aspergillus, Alternaria and Botrytis (Zakawa et al., 2020).During the post-harvest period of mango, different physical, chemical and biological methods are used to inhibit or reduce the presence of fungal agents, as well as a combination of these different methods.Therefore, the objective of this review is to collect relevant information on the different postharvest control methods that have been applied individually or in synergy in mango fruits to control and/or prevent the attack of pathogens and preserve the quality parameters to extend the shelf life of the fruit.

Mango production and marketing
Mango is a tropical fruit appreciable for its fresh and sweet flavor (Zakawa et al., 2020).The mango fruit is produced around the world, specifically in countries with a tropical climate.The global production volume of mangos in 2019 was 55.85 million metric tons, which represented an increase of 37.0% in the last 10 years.The principal, producing countries in the world include India, China, Thailand, Indonesia, Pakistan and Mexico.Specifically, India leading as the principal producer supplying more than 50.0% of mango fruit in the world (Statistica, 2021).About the exportation of this tropical fruit, in 2020 the principal mango exporters were Thailand, Mexico and Peru.The flow of commercialization is different for each country, Thailand exported 18.91% to China and Hong Kong, Mexico exported 11.8% to the United States of America and Canada, while Peru exported to Spain, Germany and the Netherlands.In this sense, the potential consumers of mango around the world are China (25.0%), the United States of America (19.5%) and the Netherlands (10.2%) (Tridge, 2021).

Postharvest losses and mango diseases
Mango is a climacteric fruit that after harvest increases its respiration rate and ethylene production, promoting the development of the fruit's characteristics such as color, flavor and texture.The accelerated development of these parameters reduces the fruit quality at storage and generated postharvest losses by phytopathogenic fungi.These microorganisms are the cause of different postharvest diseases such as anthracnose and stem-end rot that generate damage to the fruit tissue.The phytopathogenic that attack mango fruit has been identified are the genus Alternaria (Luria et al., 2014), Aspergillus, Botrytis (Zakawa et al., 2020), Colletotrichum (Xu et al., 2017), Fusarium (Kausar et al., 2021) and Lasiodiplodia (Montecalvo et al., 2019).
Colletotrichum species have been identified as the causal agent of anthracnose on mango fruit.It has been reported as one of the most aggressive pathogens that attack the different varieties of mango fruit from Indonesia (Benatar et al., 2021), Australia (Giblin et al., 2018), China (Mo et al., 2018), México (Tovar-Pedraza et al., 2019), Philippines (Dela Cueva et al., 2021) and Egypt (Ismail and El-Ganainy, 2022).Colletotrichum could be in a latent phase during preharvest, the beginning of the disease symptoms appears on the postharvest, generating dark spots and tissue putrefaction.The different Colletotrichum species associated to anthracnose include Colletotrichum siamense, C. tropicale, C. asiaunum (Tovar-Pedraza et al., 2019), C. scovillei (Wu et al., 2020), C. plurivorum (Lu et al., 2022), C. theobromicola (Dela Cueva et al., 2021) and C. gloeosporioides (Uddin et al., 2018).It is estimated that 30% of postharvest losses in mango fruit are caused by the infection of Colletotrichum.
The pathogen Alternaria alternata develops the postharvest disease called stem-end rot in mango fruit (Galsurker et al., 2020).This disease is characterized by the development of circular depressions, and subsequent black spots.The incidence of these pathogens has been reported in countries such as China (Li et al., 2018), Israel (Galsurker et al., 2020) and Egypt (Ammar et al., 2022).The Aspergillus species flavus, fumigatus and niger, cause postharvest losses of up to 10%.Its incidence can be present after 4 days of storage, with the development of mycelial growth and rotting on the fruit surface.
Other phytopathogens have been identified in mangoes such as Lasiodiplodia theobromae, Penicillum chrysoenum and Rhizopus stolonifera (Rajmane and Korekar, 2016).The high incidence of postharvest diseases on mango fruit demands the search for postharvest technologies to decrease the negative effects of these phytopathogens and consequently prolong the shelf life of the fruits (Gutiérrez-Martínez et al., 2014).

Postharvest disease control methods
Postharvest attack by pathogens causes serious damage and loss of fruit.Fungicides have been the most widely used postharvest method in the world to control diseases in crops.These chemicals are considered toxic to the consumer and the environment (Mamane et al., 2015).Different alternatives have been developed to replace them and have been classified as physical, chemical and biological.This review presents a recompilation of the recent postharvest control methods applied individually and in synergy to mango fruit to extend shelf life, preserve quality parameters and reduce pathogen infection.

1-Methylcyclopropane
The application of 1-methylcyclopropane (1-MCP) in mango fruits has been used as a ripening suppressant.This compound is an analog of the phytohormone ethylene and acts as a receptor blocker, increasing the shelf life of fruits (Ortiz-Franco et al., 2016).Ethylene synthesis promotes the accelerated softening of the fruits by the synthesis of cell wall degrading enzymes.Pectinesterase (PE) and polygalacturonase (PG) are the enzymes responsible for this effect.Li, Li, Sun et al. (2020) reported that the postharvest application of 1-MCP in mango fruits cv."Tainong" delay the ethylene synthesis and respiration reducing the synthesis of cell wall enzymes and fruit softening after 10 d of storage.In a similar study by these authors, treatment with 1-MCP delayed ethylene synthesis and respiration in mango fruits for 16 days stored at 25°C.To understand the mechanism of action of 1-MCP to control ethylene biosynthesis, molecular identification of the ETR family was realized.Molecular analysis indicated that 1-MCP suppressed the ethylene receptor genes, MiETR1 and MiERS1, part of the ETR receptor family.This suppression delays ethylene biosynthesis and prolongs fruit shelf life (Li, Shuai, Sun et al., 2020).
For the control of pathogens, Osuna-García et al. (2007) reported that the application of 1-MCP in "Keitt" mango fruits failed to control the symptoms of anthracnose, concluding that 1-MCP does not have antifungal action.Xu et al. (2017) evaluated the antifungal effect of the application of 1-MCP, the results indicated an accumulation of Reactive Oxygen Species "ROS" and mitochondrial degradation in the mycelium and spores of the fungus C. gloeosporioides and consequently inhibition of germination and growth of the pathogen.(Kang et al., 2016).This effect was confirmed by Hu et al. (2014), these authors reported a 30.0%reduction of anthracnose in mango fruits with exposure to NO.Also, the application of NO induced the synthesis of defence enzymes such as phenylalanine ammonia-lyase (PAL), chitinase (CHI), b-1,3-glucanase (GLU), and polyphenol oxidase (PPO).Later, Ren et al. (2020) reported NO generates the accumulation of antifungal compounds such as lignin, total phenols, anthocyanin, and flavonoids that protect the fruits.To understand the effect of exogenous NO application, peach fruit were analyzed and identified differentially accumulated proteins using a transcriptome analysis.The results showed an increase in the abundance of proteins involved in energy and metabolism (30.7%), the response to stress and defence (25.0%), and ripening and senescence (5.7%).In this sense, these increases in protein abundance indicate that NO could protect the fruit in stressful situations such as the attack of pathogens (Kang et al., 2016).

Cold storage
Storage at low temperatures is a postharvest method used for the preservation of fruits (Brizzolara et al., 2020).Tropical or subtropical fruits are cold-sensitive, on mango fruit the optimum storage temperature is between 10 and 12.5°C.Low-temperature storage is a postharvest method used for the conservation of fruits (Brizzolara et al., 2020).Tropical or subtropical fruits are sensitive to cold, the optimal storage temperature in mango fruit ranges between 10 and 12.5°C (Osuna-García, 2015).Pathogen infection can be prevented and controlled with the application of cold storage.For C. gloeosporioides, the optimal temperature for growth and sporulation is between 25-30°C.Sangeetha and Rawal (2009) reduced the mango storage temperature to 15°C and the results showed complete inhibition of the pathogen."Shally" mango fruits are reported to be a variety resistant to storage at low temperatures (5-12°C) and anthracnose infection was minimal.On the other hand, the "Keitt" mango was sensitive to exposure to cold storage (5°C) and showed symptoms of chilling injury.After two days of cold storage, the transcriptomic analysis revealed an increase in gene expression involved in the plant's stress response.This effect was related to the presence of cell death around the discolored lenticels in the mango fruit peel.At the end of storage, the fruits showed cuticular opening and consequently decomposition possibly due to fungal penetration (Sivankalyani et al., 2016).

Hot water treatment
Hot water treatment (HWT) is a postharvest requirement for the export of mango fruit to the United States of America.HWT has been efficient in controlling pests and pathogens, reducing cold injuries, and extending fruit quality during storage (Lurie and Pedreschi, 2014).In mango cv."Carabao" HWT (53°C, 20 mins) inhibited anthracnose by 49-53% and stem-end rot (SER) by 48-61% (Alvindia and Acda, 2015).An increase in temperature to 55°C and immersion for 10 min, controlled 70.0% of SER, concerning untreated fruits (Montecalvo et al., 2019).For the pathogen Alternaria alternata, Luria et al. (2014) reported a decrease in incidence between 60-80% with the application of HWT in different mango varieties.In "Shelly" mango fruits, the application of HWT extended shelf life up to 4 weeks in cold storage.A proteomic profile revealed that hydrothermal treatment increases the expression of genes that contribute to the preservation of its quality and control of damage by pathogens.RNA-seq analysis was used for the identification and characterization of the expressed genes.The expressed genes were classified into three groups associated with a response to HWT.The expressed genes were found to the associated with pathogen defense mechanisms, chlorophyll degradation, photosynthesis, cell defense and regulation, and flavonoid metabolism (Luria et al., 2014).

Ultraviolet radiation
Ultraviolet (UV) radiation is widely used on fruits as a postharvest disinfectant method.Different studies have confirmed that the application of UV can stimulate the defense mechanism of the fruit, acting as an elicitor in the synthesis of enzymes and bioactive compounds.Srepong et al. (2013) confirmed this effect in mango fruits, where UV radiation decreased the attack of C. gloeosporioides.This postharvest alternative induced the synthesis of pathogenic enzymes, including PAL, CHI, GLU and peroxidase (POD).Antifungal compounds such as phenolic compounds increased as an elicitor effect in the mango peel.For the control of Botryosphaeria dothidea, the application of UV (2.5 kJ/ m 2 ) controlled 36.4% of the microorganism.The UV irradiation of the "Chokanan" mango increased by 45.0% the expression of the proteins involved in the stress and defence mechanism of the fruit.As a consequence of irradiation, the fruits were able to extend their shelf life by 15 days (George et al., 2016).The UV method is applied in the previous stage of fruit storage to keep the presence of pathogens under control.After this, efficient postharvest practices are required to preserve the quality MINI REVIEW of the fruit and be free of pathogens until it reaches the consumer.

Active modified atmospheres
The active atmosphere consists of modifying the gas concentration in a packaged product, with the reduction of O 2 gas or its replacement by some other gas such as Nitrogen (N 2 ) or Argon (Ar) (Kargwal et al., 2020).For Keitt mango fruits, the author Hailu (2016) reported an extension of the shelf life, for more than 6 weeks when the fruits are packed in an airtight plastic bag.The conditions used were storage at 7°C and atmospheric conditions in the packaging of 10% CO 2 + 6% O 2 + 84% N 2 .Ntsoane et al. (2020) evaluated the optimal gas compositions for storage of 'Shelly' mango fruit, and the best conditions to preserve the quality were 5-8% O 2 , 5-9% CO 2 , and 86-91% N 2 stored at 13°C for 4 weeks.The increase in the concentration of CO 2 is not favorable for the development of pathogens, this affects enzymatic and biochemical processes that cause stress and generates a reduction in the development of these microorganisms.

Passive modified atmospheres
The application of the edible coating on fruits reduces gas exchange between the environment and the fruit.The physical barrier of the edible coating reduces the respiratory rate and the production of ethylene, promoting extending the shelf life of fruit (Mshora et al., 2021).The major materials used in edible coatings are polysaccharides as gums, starches, chitosan, and pectin considered natural and viable compounds for their commercial use (Abd El-gawad et al., 2019;Shah and Hashmi, 2020;Hmmam et al., 2021).Specifically, in mango fruit, different edible coatings have been applied to preserve quality parameters and control diseases (Table 1).Edible coatings are currently used as an encapsulation matrix for the incorporation of compounds with biological activity, this generates a synergistic effect that can increase the preservation of quality parameters and the control of diseases (Suryadi et al., 2020;Ochoa-Velasco et al., 2021).

Antagonists
The antagonists are biological agents that can be applied pre-and post-harvest.Antagonists include yeast and bacteria with the capacity to compete for nutrients and space and promote the synthesis of antifungal compounds that attack the infectious pathogen (Aguirre-Güitrón et al., 2019;Konsue et al., 2020).Yeasts such as Meyerozyma caribbica and Torulaspora indica have been applied to control of anthracnose incidence in mango fruit.Aguirre-Güitrón et al. (2019) and Konsue et al. (2020) reported a range of control above 40.0%with the applications of these yeasts.Bacteria B. subtilis and P. fluorescens reduced anthracnose between 42.0% and 43.0% after 10 days of storage.A similar effect was reported with the application of the marine bacterium Stenotrophomonas rhizophila (Reyes-Perez et al., 2019).In vivo application of Bacillus siamensis treatment on mango fruit reduced the anthracnose index after 9 d of storage.RNA-seq analysis indicates an increase in disease-resistance genes influenced by B. siamensis treatment (Jiang et al., 2022).Antagonists are bioagents that are not considered hazardous to human health and the environment; however, different abiotic factors can interfere with their effectiveness in postharvest control.

Extracts and essential oils
Essential oils (EOs) are secondary metabolites produced by plants that have shown antifungal activity against pathogens, including those that attack mango fruit (Mesa et al., 2019).Thymol essential oil applied to mango fruits in concentrations of 0.075% and 0.1% completely controlled the development of C.  (Chillet et al., 2020).The same effect was reported by Kalupahana et al. (2020) with the application of AE of Cinnamomum zeylanicum (Cinnamon) and Syzygium aromaticum (Clove).Kaffir lime essential oil (immature) at 1500 ppm was reduced above 60.0%anthracnose and, based on chromatographic analysis, the major compounds in the extract were betapinene, limonene and beta-citronellol (Chit-aree et al., 2021).To control A. niger in mangoes, the application of 500 μL/L of R. officinalis reduced the incidence of A. niger by 82.0% compared to the untreated control (Javadpour et al., 2018).Moringa oleifera leaf extracts were used to control Botrytis cinerea and A. flavus phytopathogens present in mango fruit, their application was efficient by controlling both pathogens above 75.0%(Zakawa et al., 2020).EOs continue to show promising results for the control of a wide spectrum of pathogens, and research on these compounds is increasing.

Postharvest control methods synergies
The efficiency in the application of each postharvest alternative is affected by different factors such as the cultivar, application conditions, pathogen species and resistance and its mechanism of action and/or control.Each control alternative has a specific mechanism of action to attack fruit pathogens and protect the fruits.The mechanisms of action are classified into three effects antifungal, ripening suppressor and elicitor (Figure 1).The antifungal effect consists of a direct attack on the structure and/or vital functions of the pathogen by the presence of antifungal compounds (Alvindia and Mangoba, 2020;Shah and Hashmi, 2020).Ripening suppressors delay fruit metabolic processes such as ethylene production and respiration rate to avoid the signaling that promotes the initiation of infection by the pathogen (Sivankalyani et al., 2016;Xu et al., 2017).The elicitor effect is the activation of the induced defense system that reinforces the internal protection of the fruit with the synthesis of pathogenicity proteins (PR) and phenols and phytoalexins compounds (Gutiérrez-Martínez et al., 2017;Ren et al., 2017).
Few postharvest alternatives promote all three effects to control pathogen attacks (Shah and Hashmi, 2020;Ngo et al., 2021).To reinforce protection against infection by pathogens, different postharvest alternatives have been applied in synergy.Among the postharvest alternatives that are most used to generate synergies are edible coatings, which can encapsulate ingredients with antifungal potential.Edible coatings such as chitosan, hydroxypropylmethylcellulose, carboxymethylcellulose, sodium alginate, gums, and pectins have been incorporated with ingredients such as lacto-fermented antifungal substances, spirulina (Ranjith et al., 2022), metal nanoparticles (Hmmam et al., 2021), peel extract (Kumar et al., 2021), and essential oils such as ginger (Klangmuang and Sothornvit, 2018), thyme (Shah andHashmi, 2020), Mentha (de Oliveira et al., 2020), cinnamon (Yu et al., 2021) and oregano (Sánchez-Tamayo et al., 2021) generating efficient results in the control of postharvest diseases and extending the shelf life of mango fruits.
Furthermore, edible coatings are combined with physical alternatives such as 1-MCP (Makka et al., 2019), HWT (Khalil et al., 2022) and cold storage (Shah and Hashmi, 2020).Specifically, cold storage is the postharvest alternative that performs synergy with most physical, chemical, and biological alternatives, it is preestablished as a storage condition that prolongs the useful life during the commercialization of the fruit.An analysis of the results of different reports in which different synergies have been applied to mango fruits showed a control effect on the development of postharvest diseases greater than 60% and more efficient than the individual application of each alternative (Table 2).This may indicate that the applied synergies may be combining action mechanisms to control pathogen infection and preserve fruit quality.

Quality parameters
The preservation of the quality parameters in the fruits is a determining factor for the acceptability of the consumer.Physicochemical parameters such as firmness, weight loss, color, pH, acidity and soluble solids reflect the quality of the fruit during postharvest storage.For marketing purposes, the quality and shelf life of the fruit

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REVIEW must be extended for as long as possible, to ensure that it reaches its destination market free of damage (Javadpour et al., 2018;Mustari et al., 2020).The shelf life of mango fruit is 8-10 days when stored at room temperature.According to different investigations, the application of postharvest control methods reduces the incidence of diseases and can preserve quality parameters to extend the shelf life of mango fruit (Table 3).

Future trends
The different postharvest methods applied to the mango fruit have helped to reduce the incidence of diseases and extend its shelf life.In this review, we present some of the recent synergies between different postharvest methods that have been applied to mango fruit.The results of these synergies showed a potentiated control effect by the combination of the mode of action of each method, increasing the preservation and protection of the fruit.The search for new synergies must continue to provide a broad spectrum of protection alternatives that could be applied in postharvest marketing.
To understand the response effect of the application of postharvest methods in the fruit, in the last decade proteomic techniques have been a useful tool.In mango, the changes in gene expression have been analyzed after exposure to cold storage, HWT, UV, and the results showed an increase in the expression of the proteins involved in the stress and defense mechanism of the fruit.Future trends should be focused on evaluating the response effect of the different postharvest methods applied individually and in synergy to understand the control effect and the changes in protein expression that are generated.

Conclusion
Research on postharvest control methods applied to mango fruit has increased the incidence of infectious pathogens that limit their quality and shorten their shelf life for marketing.This review provides updated information on the control effect of postharvest methods applied individually and in synergies to the fruit.The results obtained are efficient and promising in reducing the incidence of infectious pathogens.Likewise, the implementation of omics techniques has helped to understand the mode of action involved in the control effect and thus have sustainable agricultural products.It is important to have updated information that indicates the current postharvest situation of the fruit and that shows where future research is heading and to be able to reinforce or improve it.

Figure 1 .
Figure 1.Action mechanisms of postharvest methods to preservation and protection of mango fruit.HWT: hot water treatment, MAP: passive modified atmospheres, UV: ultraviolet radiation, NO: nitric oxide, SA: salicylic acid.
Nitric oxide (NO) is a signaling molecule in plants with physiological functions.Postharvest is applied as an exogenous agent to the control of pathogens https://doi.org/10.26656/fr.2017.8(2).105© 2024 The Authors.Published by Rynnye Lyan Resources MINI REVIEW 5.2 Nitric oxide

Table 1 .
Edible coatings applied to mango fruit to control postharvest diseases.

Table 2 .
Synergistic application of postharvest methods to mango fruit diseases control.

Table 3 .
Effect of postharvest methods on the shelf life of mango fruit *Cold storage