Application of Modified Atmosphere Preservation Technology in Cherry Storage: A Review

Abstract

Cherries, as high-value horticultural products, have long faced preservation challenges due to their perishable nature and limited postharvest longevity. During storage and transportation, these stone fruits are particularly susceptible to quality deterioration and pathological decay, significantly impacting commercial viability and consumer acceptance. Modified atmosphere preservation (MAP) technology has emerged as the predominant preservation method for cherry storage, recognized for its operational safety, environmental controllability, and technical reliability. This review systematically examines the physiological degradation mechanisms of cherries during storage, identifies critical environmental factors influencing decay patterns, and synthesizes recent advancements in MAP applications. The analysis encompasses technological principles and efficacy evaluations of atmospheric modification, with particular emphasis on how regulated temperature, humidity, and gas composition parameters affect the bioactive compound retention, organoleptic properties, and overall eating quality—crucial factors for enhancing consumer satisfaction and market value. Furthermore, this paper critically addresses current technological limitations, including implementation costs, operational complexity, and environmental sustainability concerns. Finally, it proposes innovative optimization strategies and outlines future development trajectories to advance technological refinement and promote sustainable innovation in terms of cherry preservation methodologies.

1. Introduction

Cherries (Prunus pseudocerasus Lindl.) have experienced growing consumer popularity and demonstrated substantial agricultural potential in recent years, with expanding cultivation areas and increasing market demand [1]. These stone fruits contain substantial vitamin C, essential minerals (potassium, iron, and calcium), and bioactive antioxidants, including quercetin, anthocyanins, and flavonols [2,3]. These nutritional components demonstrate clinically validated benefits such as immune enhancement, anti-aging properties, and risk reduction for metabolic disorders, including gout, arthritis, diabetes, cancer, and cardiovascular diseases [4,5,6]. Notably, their melatonin content exhibits chronobiotic effects, regulating circadian rhythms to improve sleep quality and mitigate anxiety symptoms, thereby positioning cherries as promising functional foods [7]. However, unlike climacteric fruits from tropical and subtropical regions [8], cherries lack respiratory climacteric characteristics, rendering them particularly vulnerable to postharvest deterioration marked by pericarp browning, moisture loss, textural softening, flavor diminution, and acidity reduction [9,10]. These physiological changes substantially compromise their commercial viability and nutritional value [11], making the development of effective preservation strategies to extend the shelf life while maintaining organoleptic quality a critical priority for the cherry industry.

The escalating consumer demand for premium-quality fresh produce has intensified the need for advanced preservation technologies that extend cherries’ shelf life while reducing postharvest losses. Conventional approaches—including refrigerated storage, controlled atmosphere systems, aqueous treatments [10], fumigation, irradiation, edible coatings, and ozone applications—have been implemented to retard nutrient degradation and microbial spoilage [12,13]. Refrigeration remains the cornerstone preservation technique, extending the shelf life through suppression of metabolic respiration and microbial proliferation [14,15]. However, suboptimal temperatures (≤−1.5 °C) can induce chilling injury, manifesting as surface pitting and compromised epicuticular wax integrity [16]. Alternative methods such as ozone treatment effectively reduce microbial loads but necessitate precise concentration control to prevent cellular oxidative damage [17]. Each technology presents distinct advantages and operational constraints, requiring judicious selection based on specific storage requirements and commercial objectives.

Modified atmosphere preservation (MAP) technology extends cherries’ freshness by precisely modulating respiratory metabolism through controlled gas composition (O₂, CO₂, and N₂), effectively suppressing microbial proliferation [18]. This scientific intervention not only prolongs postharvest longevity but also optimally preserves organoleptic properties and nutritional integrity [19]. Contemporary technological advancements have significantly enhanced MAP implementation through integration with precision gas regulation systems and IoT-enabled monitoring platforms [20], achieving synergistic improvements in preservation efficiency, loss reduction, and economic returns.

The current technological evolution incorporates cutting-edge material science innovations, including gas-selective nanocomposite films and multifunctional bioactive coatings [21]. Nanostructured polymeric films demonstrate superior barrier performance through optimized gas permeability ratios, while bio-based edible coatings leverage natural antimicrobials and ROS scavengers to synergistically inhibit spoilage mechanisms [22]. These material innovations collectively enhance quality retention indices, including firmness maintenance, anthocyanin stability, and respiration rate control.

This review synthesizes the current mechanistic understanding of cherry senescence pathways with recent breakthroughs in MAP optimization strategies. Through systematic evaluation of various preservation protocols and their differential impacts on quality parameters, we establish an evidence-based framework for technological innovation. The progressive refinement of MAP systems promises to revolutionize cherry supply chains through extended market presence, diversified product offerings, and optimized consumer satisfaction metrics, ultimately driving sustainable development in the horticultural sector.

2. Physiological and Quality Changes in Cherries After Harvest

The quality evaluation of cherries is commonly performed through physicochemical parameters, including firmness, mass loss percentage, browning index, decay incidence, and soluble solids content [23]. Implementing optimal postharvest storage protocols is crucial for cherry preservation, as storage condition variations profoundly influence quality parameters, particularly in terms of preserving the nutritional profile. The vitamin C levels in cherries demonstrate a distinctive temporal pattern under varying temperature regimes, exhibiting a transient increase attributable to ongoing ripening-related biochemical activity during early storage phases, followed by progressive degradation. Notably, this ascorbic acid depletion becomes pronounced in late-harvested fruits subjected to prolonged storage durations [2]. Extended storage periods induce progressive quality deterioration characterized by accelerated mass loss, elevated decay rates, intensified browning reactions, and pH elevation. Concomitant declines in the fruit firmness and soluble solids content are observed, alongside potential sugar–acid ratio disruption, collectively compromising marketability and consumer acceptability [9]. This multidimensional quality degradation underscores the importance of optimized storage strategies for maintaining cherries’ postharvest integrity.

2.1. Respiration of Cherries

The postharvest physiological activities in fruits persist through ongoing respiratory and metabolic processes [24]. Cellular respiration—an essential biochemical mechanism—entails redox reactions that catabolize stored substrates into CO₂ with concomitant energy release. This respiratory metabolism is characterized by dynamic phase-specific patterns, where heightened respiratory activity typically correlates with accelerated metabolic rates during postharvest handling and storage [25]. In cherries, oxygen consumption during aerobic respiration generates elevated CO₂ concentrations that progressively suppress respiratory efficiency through feedback inhibition [26]. Whereas diminished oxygen concentrations can rapidly suppress respiratory activity, CO₂ accumulation exerts minimal influence on the respiration magnitude [27].

As prototypical non-climacteric fruits, cherries maintain basal respiratory rates post-ripening without undergoing the characteristic respiratory climacteric and associated biochemical transformations observed in climacteric species (e.g., bananas, mangoes) [28]. However, emerging evidence reveals a nuanced respiratory pattern: peak respiratory activity occurs within 1–4 days postharvest, with early-maturing cultivars demonstrating elevated respiratory quotients and enhanced susceptibility to quality degradation [29,30]. This temporal profile suggests a potential divergence from classical non-climacteric physiology, manifesting in a moderate respiratory upsurge during advanced ripening or senescence phases [31], corresponding to maximal respiratory intensity in deteriorating fruits.

The respiratory dynamics of horticultural produce are governed by multifactorial regulation, where genotypic variation interacts with environmental determinants, including storage temperature and atmospheric composition (O₂, CO₂, C₂H₄). Notably, cherry respiration displays marked thermosensitivity, with the respiratory rates exhibiting an approximate doubling response per 10 °C temperature increment—a critical consideration for cold chain optimization [32].

2.2. Ethylene Release and Sensory Changes

Ethylene is a crucial hormone that facilitates fruit ripening and senescence [33,34,35]. Meanwhile, cherries with high ethylene content are more prone to cracking [36]. As cherries ripen, their ethylene synthesis and release increase noticeably [37,38], although the release levels remain lower compared to those in climacteric fruits. Hartmnna et al. [39] reported a positive correlation between the ethylene content and the ripening or senescence degree of sweet cherries, indicating ethylene’s critical role in these processes. Although the ethylene release was low, it still increased significantly during ripening and senescence [40]. The appearance and color of cherries are key indicators of their quality. Ripe cherries usually have a deep or dark red color, which is closely related to their anthocyanin content [41]. Due to the poor stability of anthocyanosides, they are susceptible to chemical reactions leading to discoloration during storage and processing. Studies have shown that storage at low temperatures (1 °C) helps to reduce changes in the anthocyanin content, while higher temperatures (20 °C) increase the anthocyanin content [42], which may be related to changes in the fruit pH and total sugar content. Additionally, the flavor and texture of cherries are predominantly determined by the ratio of soluble solids to titratable acidity [43]. Over-ripening during storage leads to reductions in the titratable acid content and firmness, significantly affecting the fruit quality.

2.3. Microbial Changes

Cherries, with a pH typically below 4.6, possess sufficient acidity to inhibit bacterial spoilage. However, their low pH environment creates favorable conditions for fungal growth, making them susceptible to fungal infections postharvest and during cold storage [44]. The predominant pathogenic fungi affecting cherries include Penicillium (particularly various Penicillium species), Aspergillus, and Candida [45]. During cherry storage, the surface microbial community exhibits dynamic shifts in the taxonomic composition and population density. Postharvest microbial contamination of cherry surfaces constitutes a key challenge to food safety and preservation quality, with the primary contamination vectors including irrigation water (e.g., Salmonella spp., Escherichia coli), soil contact (e.g., Botrytis cinerea), manual handling (e.g., Staphylococcus aureus), and processing equipment biofilms (e.g., Pseudomonas spp.). While refrigeration (0–4 °C) effectively suppresses microbial growth in most bacterial populations, exemplified by the extended generation time of Pseudomonas spp. from 2 h to 24 h, particular attention must be directed toward psychrotrophic pathogens. Notably, despite low-temperature storage conditions, Listeria monocytogenes demonstrate persistent proliferative capacity even at subzero temperatures (–0.4 °C) [46]. Therefore, taking into account the temperature, humidity, gas composition, and treatment measures can help control spoilage caused by microorganisms, ensuring the food safety of cherries. Although the risk of mycotoxin contamination in cherries is relatively low, it can still occur due to improper temperature and humidity management during storage and transport. For instance, Penicillium and Fusarium thrive in damp and warm environments, where they can produce mycotoxins, which pose potential health hazards to humans [47]. Good control of the temperature, humidity, and ventilation is crucial to preventing the generation of mycotoxins. Furthermore, if cherries suffer damage from insects or mechanical means before harvest, they are more susceptible to mold infection, increasing the risk of mycotoxins.

High-temperature and -humidity conditions can rapidly exacerbate mold growth on cherry skins, with the decay rates varying between cherry varieties; thinner-skinned cherries are generally more susceptible than thicker-skinned varieties. Cherries with more surface cracks are particularly prone to pathogen entry, accelerating decay [47]. For instance, Penicillium can infiltrate cherries through skin damage, multiplying quickly after infection and potentially spreading throughout the batch. These fungi not only deplete cherries of nutrients but also produce toxic metabolites harmful to human health Wang et al. [48] showed that altering the physical environment can stimulate enzymatic activities related to disease resistance within the fruit, and the combined action of chitinase and β-1,3-glucanase can effectively inhibit fungal growth [49]. Additionally, the moderate accumulation of reactive oxygen species (ROS) in fruits may serve as a natural defense against pathogen invasion [50].

2.4. Enzymatic Browning of Cherries

The browning of cherries is primarily caused by the catalytic action of polyphenol oxidase (PPO, EC 1.10.3.1). PPO is a copper-containing oxidoreductase that catalyzes the oxidation of monophenols and diphenols to form quinones, which further polymerize into brown pigments through non-enzymatic reactions [51]. Enzymatic browning not only leads to changes in cherries’ color and the degradation of antioxidants but also causes quinones to undergo condensation reactions with amino acids, proteins, phenolic compounds, and sugars, ultimately diminishing the sensory quality and nutritional value [52]. The activity of PPO is influenced by factors such as the temperature, pH, substrate concentration, and reaction time. During the storage and processing of fruits and vegetables, damaged tissues and ruptured plastids release a higher concentration of phenolic compounds, increasing the contact between PPO and these substrates. To mitigate this process, a chitosan coating combined with low-temperature (2 °C) storage can effectively slow down enzymatic browning [53]. As the storage time increases, the polyphenol content of cherries gradually decreases, correspondingly slowing the rate of the browning reaction. Furthermore, PPO activity is highly sensitive to changes in pH, with an optimal pH of 4.0.

2.5. Cherry Cracking

Postharvest cuticular cracking in cherries constitutes a critical postharvest physiological disorder characterized by pericarp failure through complex hydro-mechanical processes. This phenomenon initiates with cuticular stress accumulation from preharvest osmotic imbalances and culminates in epidermal rupture, creating exudative microcracks that serve as pathogenic invasion portals [54]. The pathogenesis involves synergistic interactions between preharvest predispositions (e.g., cuticular tension from maturation-phase precipitation patterns) and postharvest destabilizers, where thermal oscillations (>3 °C diurnal amplitude) induce cuticular fatigue through cyclic expansion–contraction, while hygroscopic stress gradients (RH > 90% → rapid desorption) generate differential swelling stresses across epidermal microdomains [55]. Effective mitigation strategies require a three-pronged intervention: (1) ultra-precise cold chain thermoregulation (0 ± 0.5 °C) to minimize the cuticular phase transitions; (2) multi-stage gradient precooling to optimize the cuticular viscoelastic properties; and (3) MAP-mediated humidity buffering (85–90% RH) through selective gas permeability membranes, achieving 62–78% cracking reduction via synergetic control of transpirational water loss and cuticular hydration dynamics [56].

3. Research on Modified Atmosphere Preservation

MAP technology is an advanced preservation method based on low-temperature storage. The low-temperature storage temperature range of MAP technology is usually 0–12 °C, and the specific temperature needs to be adjusted according to the type of food and storage requirements [57]. This technique adjusts the gas composition of the environment to slow down the respiration rate of food, inhibit ethylene production, and reduce moisture evaporation, thereby effectively lowering the enzyme activity and metabolic rates in fruits and vegetables within the packaging [58]. Compared to traditional chemical preservation methods, this approach is preferred for its safety, environmental protection, and non-polluting characteristics.

Currently, the research on cherry preservation is primarily focused on MAP and controlled atmosphere (CA) storage [59]. MAP effectively slows metabolic processes in cherries by modifying the gas composition of the storage environment, which reduces the chilling injury and suppresses the onset of other diseases. By decreasing the oxygen levels and increasing the carbon dioxide concentrations, MAP minimizes the chilling injuries—such as fruit discoloration and textural deterioration—and inhibits the growth of decay-causing microorganisms. However, excessively high carbon dioxide concentrations may lead to high CO₂ disorders, resulting in skin spots or discoloration, necessitating precise adjustments of the gas concentrations. Overall, while MAP extends the shelf life of cherries and maintains their quality, careful adjustments are required based on the different varieties and storage conditions to achieve optimal results.

MAP is also effective in inhibiting mold growth and mycotoxin production. By reducing the oxygen concentration within the packaging, MAP slows down or inhibits many aerobic molds, as oxygen is essential for their metabolic activities. Additionally, elevated carbon dioxide levels help suppress the growth and reproduction of mold cells, thereby reducing the potential for mycotoxin production. Furthermore, MAP can regulate the humidity levels within the packaging, preventing excessive moisture that promotes mold growth. While MAP cannot completely eliminate the formation of mycotoxins, it remains effective in reducing mold proliferation and extending the shelf life of the fruit.

3.1. Passive MAP of Cherries

Passive MAP is an innovative method for preserving fruit freshness by encasing the fruit in a semi-permeable film. This technique utilizes the fruit’s respiration and the film’s permeability to precisely regulate the ratios of O₂, CO₂, and N₂ within the package. The technology effectively reduces the respiratory activity of cherries, significantly extending their freshness. However, various factors—including the cherry variety, maturity, and storage temperature—also influence the optimal concentrations and ratios of O₂ and CO₂ [60]. In the MAP system, the gaseous environment inside the package is a complex and finely balanced system affected by several factors, including the permeability of the packaging film, the surface area of the package, the weight of the fruit, and the rate of respiration [61]. The barrier performance of the film is particularly critical, as it has a decisive impact on the permeabilities of O₂, CO₂, and water vapor, thereby significantly affecting the cherry quality.

The commonly used film materials include low-density polyethylene (LDPE), polyvinyl chloride (PVC), and bi-oriented polypropylene (BOPP), which dominate the MAP preservation of fruits and vegetables, accounting for up to 90% of applications [62]. Depending on the structure and performance of air-conditioning cling films, they can be further categorized into various types, such as silicone window MAP, microporous cling film, and edible cling film. Typically, in practice, MAP involves initially filling the package with nitrogen to rapidly reduce the O₂ concentration, achieving the desired gas conditioning effect. Mathematical models based on the mass balance of O₂, CO₂, and N₂, as well as gas composition variations in MAP, have been developed and validated by several studies to confirm their reliability and versatility.

High-concentration CO₂ treatment (≥5%) has been widely employed in preserving cherries and other fruits by significantly reducing the activity of respiratory terminal oxidative enzymes (e.g., CCO and PPO) involved in aerobic respiration. This effectively inhibits the postharvest respiration rate, reduces the depletion of nutrients such as organic acids, and mitigates damage to cherry cell membranes. However, it is essential to note that the gas composition within the package may differ from the optimal gas composition for cryo-stored fruits. D’Aquino et al. [59] found that microperforated packaging films produced moderate CO₂ concentrations (partial pressure of 2–4 kPa) and suitable O₂ partial pressures (15–18 kPa) while maintaining a relative humidity close to 100%. The combined effects of these conditions help to reduce the respiration rates and decrease the degradation of the active substances in fruits, such as sugars, organic acids, and vitamin C, thereby ensuring the eating quality, freshness, and firmness of cherries. Anese et al. [63] established that when the O₂ concentration falls below 1 kPa (approximately 1%), it effectively reduces the browning phenomenon caused by PPO in fruits and vegetables. MAP enriched with reactive oxygen species (ROS) has been shown to effectively delay the onset of the respiration peak in cherries, inhibit ethylene production, maintain fruit firmness, and increase the content of soluble proteins and sugars. However, extremely low O₂ concentrations or very high CO₂ concentrations can lead to anaerobic fermentation, causing fruit damage, off-flavors, and spoilage. In fact, O₂ concentrations below 1% may increase the risk of surface pitting and anaerobic fermentation in the pulp, while CO₂ concentrations above 30% can result in peel discoloration and off-flavor issues. Therefore, harmonizing the gas component ratios in terms of the MAP technique is essential for optimizing the eating quality of cherries.

MAP can also inhibit fungal growth to some extent, as higher CO₂ partial pressures exhibit antibacterial effects during storage. Paiva et al. [46] demonstrated that M50 microporous film increased the headspace CO₂ concentration to 11–15 kPa, significantly reducing the counts of inoculated Penicillium expansum PE-M639 (from 3.52 to 2.94 log CFU/g) and the disease damage scale (from 15.4 mm to 13.3 mm), whereas the M10 film was less effective, with a headspace CO₂ concentration of 4–6 kPa. This indicates a positive correlation between the membrane pore density and the inhibitory effect on Penicillium.

The equilibrium modified atmosphere packaging (EMAP) system is derived from MAP and creates a balanced gas-conditioned environment by matching the transmission rates of the gases (O₂, CO₂) inside and outside the package with the O₂ consumption rate of the packaged product. Tumwesigye et al. optimized the gas parameters of bitter cassava membranes (IBCs) for EMAP (3.72% O₂, 4.89% CO₂), finding that continuous or micro-perforation (0.27 μm) had no significant effect on the freshness retention quality [61]. Bio-based IBC films exhibited superior performance in regulating the gas composition and extending the shelf life of cherry tomatoes compared to conventional polymer films like OPP [62]. MAP adjusts the ratios of CO₂ and O₂ to suppress the respiration rates, preserve the firmness, maintain the total soluble solids content, and enhance the storage quality and aroma of cherries (Figure 1A) [63].

In addition to addressing the nutrient changes and lesions in cherries during storage, gas-conditioning techniques must also consider the flavor and color of the fruit. Research has shown that the aroma and flavor of fruits and vegetables are directly influenced by the distribution of volatile organic compounds (VOCs). Since flavor loss occurs before noticeable sensory changes, the postharvest life of fruit can be more accurately assessed based on flavor rather than appearance and texture (Figure 1B). Wang et al. [64] confirmed that the “Lapins” and “Skeena” sweet cherry varieties can retain their flavor and color after ocean transport when refrigerated in MAP. Under MAP2 conditions (O₂ 6.5–7.5%, CO₂ 8.0–10.0%), these settings help reduce the loss of ascorbic acid and lipid peroxidation, maintaining the flavor by slowing the reduction of titratable acids and the formation of bitterness, while preserving a brighter color by inhibiting anthocyanin synthesis. Cozzolino et al. [65] investigated the sensitivity of “Ferrovia” cherries to high CO₂ levels, finding that CO₂ concentrations above 20% and O₂ levels around 1% in MAP could trigger fermentative metabolism, increasing the content of ethyl esters and γ-butyrolactone. Conversely, high CO₂ treatments maintained the organoleptic qualities and prevented off-flavors when the initial gas composition included a higher O₂ concentration (16%).

MAP effectively maintains the sensory quality of cherries, including the color, texture, flavor, and aroma, by adjusting the gas composition within the packaging. By lowering the oxygen levels and increasing the carbon dioxide concentrations, MAP slows the respiratory rate and metabolic activity of cherries, thereby extending the freshness and preserving the fruit’s desirable characteristics [66]. Additionally, MAP regulates humidity to reduce evaporation, maintaining the moisture content of cherries and keeping them crisp and juicy. The high carbon dioxide and low oxygen environment inhibits the growth of many spoilage-causing microorganisms, which helps preserve the appearance and aroma of cherries while preventing the development of off-flavors. By controlling the gas ratios, MAP slows the degradation of compounds associated with flavor and aroma, maintaining the inherent sweetness of cherries.

The freshness of MAP technology extends the shelf life of fruits and vegetables by adjusting the gas composition within the packaging, thereby reducing the respiration rates and minimizing pathogen growth. However, the technology faces challenges, such as the precise control required for different fruit varieties and ripeness levels, along with limitations posed by current packaging materials. Future developments should focus on creating smart packaging materials that can automatically adjust the gas permeability, optimizing the gas composition using mathematical models and big data, exploring environmentally friendly packaging options, and integrating supply chain management with Internet of Things (IoT) technologies. These innovations aim to achieve more efficient, eco-friendly, and intelligent solutions for the preservation of fruits and vegetables, thereby meeting modern food quality and safety standards. Overall, MAP technology is expected to continuously enhance the effective preservation of fruits and vegetables, ensuring adherence to high standards of food quality and safety.

3.2. The Active Gas-Conditioning Freshness of Cherries

Controlled atmosphere (CA) storage technology extends the storage life of fruits and vegetables by regulating the conditions of the gas composition, temperature and air pressure in the storage environment so that the gas concentration is maintained near a constant value [67]. Compared with the ambient atmosphere, controlled atmosphere preservation usually uses a low concentration of O₂ and a high concentration of CO₂. In contrast, passive air-conditioning preservation storage is cheaper and simpler to operate, whereas active air-conditioning preservation is more precisely controlled but requires closed storage rooms and is relatively costly [68]. Therefore, active preservation technology is more suitable for commercial and large-scale cherry storage.

Maintaining a relatively constant gas composition throughout the storage period is necessary. The adaptation of cherries to oxygen and carbon dioxide concentrations varies between varieties and harvest periods, and therefore, the CO₂/O₂ ratio needs to be optimized. Studies have shown that sweet cherries are highly resistant to high CO₂ concentrations [69]. It is generally considered that a CO₂ concentration in the range of 5–15% is appropriate. Other studies have shown that maintaining the CO₂ concentration at 10–30% is effective in maintaining the cherry firmness and the ascorbic acid and titratable acid levels without negatively affecting the quality [70]. At O₂ concentrations as low as 5%, microbial growth was effectively inhibited. Some varieties of sweet cherries can be preserved for several weeks (21–25 days) at very low O₂ (0.02%) and low temperatures (0–5 °C) [71].

CA and low-temperature conditions can be used to control fungal growth. Studies have shown that molds and Gram-negative aerobic bacteria are sensitive to CO₂, and that low O₂ levels inhibit the growth of most aerobic microorganisms. However, the inhibitory effect of low O₂ environments seems to be limited and not as effective as increasing the CO₂ concentration [72]. Serradilla et al. [15] discussed the effect of adjustable gases on the microbial changes in Ambrunés cherries and showed that the growth of thermophilic aerobic bacteria, Pseudomonas spp., yeasts and molds could be effectively controlled after 15 days of storage under gas compositions of 5% O₂ + 10% CO₂ and 8% O₂ + 10% CO₂. For yeasts and molds, the counts were controlled in the range of 1 to 1.75 log CFU/g. Sun et al. [73] found that controlled-release chlorine dioxide (ClO₂) was effective in inhibiting Salmonella, with a minimum effective concentration of 4 ppm. Although Salmonella is not common in fruits, using this method can not only slow down the weight loss and texture softening of cherries but also inhibit the growth of microorganisms. With the increasing use of pesticides, it is expected that the use of modified atmosphere technology combined with biodegradation will become a promising strategy in the future. However, there is currently no in-depth research in this field.

We hypothesize that CO₂ treatment significantly impacts cherry fruit respiration by regulating key metabolic pathways (Figure 2). CO₂ treatment enhances the Embden–Meyerhof–Parnas (EMP) pathway, facilitating the conversion of glucose to glucose-6-phosphate and boosting the production of ATP and NADPH, which provide energy and reducing power to cells. Additionally, CO₂ treatment increases the activity of pyruvate kinase (PK) and phosphofructokinase (PFK), key enzymes in the EMP pathway, thereby enhancing the conversion of glucose to pyruvate, which may directly influence cherry respiration rates by altering pyruvate metabolism. CO₂ treatment may also modify pyruvate metabolic pathways, affecting the production of aldehydes and ethanol, while modulating pyruvate decarboxylase (PDC) activity [74]. Furthermore, CO₂ treatment could influence the ion balance and signal transduction at the cell membrane by regulating H ± ATPase and Ca²⁺-ATPase activity. Importantly, CO₂ treatment may suppress the activity of cytochrome c oxidase (CCCO) and pyruvate oxidase (PFO), both of which are closely associated with reductions in the respiration rates in cherry fruit.

CA preservation technology significantly extends the shelf life of fruits and vegetables by precisely regulating the gas concentrations, temperature, and pressure in the storage environment, making it particularly suitable for commercial and large-scale cherry storage [75]. By maintaining low oxygen and high carbon dioxide levels, CA technology effectively inhibits microbial growth and respiration, ensuring the stability and quality of cherries. However, the high cost and complexity of CA operations limit its practicality for small-scale and low-cost storage. Additionally, the specific O₂ and CO₂ concentration requirements for different cherry varieties and ripeness stages add to the difficulty of gas regulation. While high CO₂ and low O₂ levels can inhibit certain microbes, they are not universally effective. Future development should focus on creating cost-effective solutions to meet diverse storage needs, using big data and AI to customize storage conditions, integrating biodegradable materials to enhance environmental sustainability, and introducing controlled-release chlorine dioxide for improved safety and quality. Ongoing technological innovation and interdisciplinary applications are expected to significantly enhance the role of CA technology in fruit and vegetable preservation, particularly in terms of improving storage effectiveness and sustainability. As pesticide use increases, integrating biodegradable controlled atmosphere technology is anticipated to become a promising future strategy, despite the lack of extensive research in this field currently.

3.3. Gas-Conditioning Composite Preservation Technology

The limitations of single modified atmosphere preservation for cherries have prompted researchers to explore the combination of MAP with other preservation techniques to enhance their shelf life. Various technologies, such as ultraviolet irradiation (UV), dipping, edible coatings, and pressurization, have been developed (Table 1). While fungicides remain the most effective method for controlling postharvest fungal diseases in perishable fruits, the use of microbial antagonists as biological control agents presents a promising alternative. This approach aims to reduce chemical fungicide usage, addressing concerns about food safety, environmental impacts, and pathogen resistance. Current research focuses on yeasts, which exhibit many ideal characteristics for antagonists. The combination of biocidal agents and modified atmosphere storage effectively prevents postharvest diseases in cherries. Studies indicate that MAP has minimal effects on yeast growth, allowing the antagonist yeasts HO-L479 and MP-L672 to colonize and thrive on wounded cherries during cold storage [24]. Notably, MP-L672 showed better adaptation to sweet cherries under all the MAP conditions, with counts 1 log CFU/g higher than HO-L479, indicating effective control of Penicillium in MAP.

Acidic electrolyzed water (EW) demonstrates sterilizing effects prior to immersion. Hayta et al. [76] studied the combined effects of EW and MAP at varying free chlorine concentrations on postharvest quality. Cherries treated with low concentrations of EW (25 and 50 mg/L) exhibited lower pH levels, reduced total soluble solids content, and decreased decay rates compared to the controls and other treatments. However, when the EW concentrations exceeded 200 mg/L, the oxygen content in the packaging decreased sharply, negatively affecting the sensory quality of the cherries. Colgecen et al. [77] investigated the quality changes in cherries pre-treated with ClO₂ in MAP, finding that treatments with 16 and 20 mg/L of ClO₂ helped maintain the pH, total soluble solids content, and firmness, with no mold growth observed during the first two weeks of storage. Additionally, compounds such as eugenol, thymol, and menthol found in clove oil enhance MAP’s effectiveness by delaying stem browning, reducing titratable acid loss, and inhibiting the colonization of aerobic thermophilic bacteria [78].

Coating preservation technology creates a semi-permeable barrier on fruit surfaces, regulating water vapor and gas exchange. Natural edible coatings—such as aloe vera gel, alginate, chitosan, gum arabic, and beeswax—have shown promise in extending cherries’ shelf life and maintaining their quality [79]. However, studies that combine bio-coatings with MAP remain limited. Aglar et al. [80] examined a composite MAP coating made from stearic acid, cellulose, and calcium ions, which effectively preserved the cherry firmness and reduced the spoilage, although it had minimal impact on the moisture, vitamin C, and total phenolic content.

Inert gas pressurization is an emerging storage method that forms structured water compounds by bonding inert gases with water molecules in fruit and vegetable cells at specific pressures [81]. These compounds limit molecular and enzymatic activity, inhibiting physiological and metabolic processes, thereby delaying browning and ripening while preserving quality. This non-toxic, user-friendly technology has garnered significant attention in recent years. Currently, air-conditioning storage is often combined with inert gas pressurization to enhance the preservation of fruits and vegetables. While research highlights the potential of this method, most studies focus on optimizing its application in pressurization and air-conditioning storage [82]. For instance, treating fruit with argon gas (Ar) at 0.5 MPa for one hour under conditions of 5% O₂, 10% CO₂, and 85% Ar significantly delayed flesh browning, resulting in a 94.81% reduction in the browning indices and an 82.93% decrease in the decay indices compared to single-condition treatments [9]. This approach also effectively prevented the degradation of phenolic compounds and suppressed increases in the activity of PPO and phenylalanine ammonia lyase.

Table 1. Comparison of different types of composite controlled atmosphere technology.

Variety	Gas-Conditioning Method	Component Parameters	Storage Time	Storage Temperature	References
Van sweet cherry	ClO2 + MAP	O2: 13–16%; CO2: 3–8% ClO2: 4–25 mg/mL	35 d	4.00 ± 0.50 ℃	[78]
Lycopersicon esculentum L.	MAP + UV-exposure	10% CO2 + 5% O2 UV-C: 2–10 kJ/m2	9 d	4.00 ± 1.00 °C; 20.00 ± 1.00 °C	[75]
Bing, Lapins, and Sweetheart	Ultrasound-Assisted + CaCl2 + MAP	Ca2+: 9–90 mM; 40 kHz	28 d	0.00 ± 0.50 °C	[83]
Lapins	Argon + CA	5% O2, 10% CO2 85% Ar (0.5 MPa)	63 d	0.00 ± 1.00 °C	[9]
Prunus avium L.	EW + MAP	25–100 mg/L EW 21% O2 + 0.03% CO2 + 79% N2	30 d	4.00 ± 1.00 °C	[77]
Ambrunés	Antagonistic Yeasts + MAP	Strain: HO-L479 and MP-L672 (20 μL) CO2/O2:NA	35 d	1.00 ± 0.50 °C	[46]
Prunus avium L. “0900 Ziraat”	Ethylene Inhibitor + MAP	225 mg·L–1 AVG CO2/O2:NA	21 d	0.00 ± 0.50 °C	[8]
Prunus avium L. “0900 Ziraat”	Coating + MAP	1% Stearic Acid/Cellulose/Calcium-based Biofilm Coating CO2/O2:NA	21 d	0.00 ± 0.50 °C	[80]

Note: NA: no data source available.

Table 1. Comparison of different types of composite controlled atmosphere technology.

Variety	Gas-Conditioning Method	Component Parameters	Storage Time	Storage Temperature	References
Van sweet cherry	ClO2 + MAP	O2: 13–16%; CO2: 3–8% ClO2: 4–25 mg/mL	35 d	4.00 ± 0.50 ℃	[78]
Lycopersicon esculentum L.	MAP + UV-exposure	10% CO2 + 5% O2 UV-C: 2–10 kJ/m2	9 d	4.00 ± 1.00 °C; 20.00 ± 1.00 °C	[75]
Bing, Lapins, and Sweetheart	Ultrasound-Assisted + CaCl2 + MAP	Ca2+: 9–90 mM; 40 kHz	28 d	0.00 ± 0.50 °C	[83]
Lapins	Argon + CA	5% O2, 10% CO2 85% Ar (0.5 MPa)	63 d	0.00 ± 1.00 °C	[9]
Prunus avium L.	EW + MAP	25–100 mg/L EW 21% O2 + 0.03% CO2 + 79% N2	30 d	4.00 ± 1.00 °C	[77]
Ambrunés	Antagonistic Yeasts + MAP	Strain: HO-L479 and MP-L672 (20 μL) CO2/O2:NA	35 d	1.00 ± 0.50 °C	[46]
Prunus avium L. “0900 Ziraat”	Ethylene Inhibitor + MAP	225 mg·L–1 AVG CO2/O2:NA	21 d	0.00 ± 0.50 °C	[8]
Prunus avium L. “0900 Ziraat”	Coating + MAP	1% Stearic Acid/Cellulose/Calcium-based Biofilm Coating CO2/O2:NA	21 d	0.00 ± 0.50 °C	[80]

Note: NA: no data source available.

In terms of enhancing the storage quality of cherries, single modified atmosphere preservation technology has its limitations, prompting researchers to explore combinations with other preservation methods, such as ultraviolet irradiation, soaking, edible coatings, and pressurization [83]. Microbial antagonists show great potential as a biological alternative to chemical fungicides, being particularly effective in suppressing postharvest diseases. Treatments with acidic electrolyzed water and the application of ClO₂ and plant essential oils also enhance the efficacy of modified atmosphere techniques [84]. However, these combined methods face challenges such as the operational complexity, limited research, and varying effectiveness [85]. Future development should focus on integrating multiple technologies, optimizing the development of natural materials, advancing mechanization and automation, deeply studying the synergistic effects of combined technologies, and promoting interdisciplinary innovation. Through these efforts, cherry preservation techniques can achieve higher efficiency and broader application, offering consumers higher-quality fruit.

3.4. Differences Between MAP and Other Preservation Technologies

The effectiveness of MAP in extending the shelf life of cherries is influenced by several key factors, including the gas composition ratios, temperature control, humidity management, packaging material design, initial fruit conditions, and handling processes [86]. Appropriate low O₂ (5%) and high CO₂ (5%) concentrations effectively suppress respiration and microbial growth, while suitable low-temperature (0–2 °C) conditions reduce both the respiration rates and microbial proliferation, thereby extending the storage time [87]. Proper humidity levels (85–90%) help maintain the moisture content of cherries, preventing water loss and texture deterioration. High-quality packaging materials should exhibit good breathability and barrier properties to ensure a stable internal gas environment [88]. Furthermore, the ripeness, quality, and health of cherries directly affect MAP’s effectiveness; fruits in optimal condition significantly enhance the preservation results. Additionally, the postharvest handling, washing, sterilization, and effective packaging and transportation management are crucial determinants of the final shelf life. Optimizing these conditions can significantly enhance the preservation capabilities of MAP, thereby better maintaining cherries’ quality and flavor.

Under MAP storage, cherries undergo physiological and biochemical changes that effectively prolong their shelf life. Firstly, MAP significantly slows down the respiration rate and metabolic activities of cherries by lowering the oxygen levels and increasing the carbon dioxide concentrations, thus delaying aging and spoilage [74]. Moreover, MAP inhibits ethylene production and action, further postponing the ripening process. The low oxygen and high carbon dioxide environment effectively suppresses the growth of various spoilage microorganisms, reducing the risk of decay [71]. Sealed packaging minimizes the moisture evaporation, helping to maintain the juiciness and texture of cherries while slowing the oxidation reactions in a low-oxygen environment, thereby preserving the active components and nutritional value of the fruit. Additionally, MAP maintains pigment stability, preserving the vibrant color of cherries and enhancing their market appeal [89]. These physiological and biochemical changes enable MAP to significantly extend the shelf life and overall quality of cherries.

Compared to traditional storage methods, MAP demonstrates significant advantages in maintaining cherry quality and prolonging shelf life. By adjusting the oxygen and carbon dioxide concentrations within the packaging, MAP effectively delays respiration and aging in cherries while inhibiting microbial growth, thereby preserving freshness and flavor [9]. Traditional storage methods typically rely on ambient air, lacking control over the gas composition, which accelerates the aging and spoilage of cherries. In terms of the temperature control, MAP generally operates under low-temperature conditions of 0 °C to 2 °C, whereas traditional methods often lack precise temperature management, adversely affecting fruit quality [73]. Furthermore, the sealed packaging environment of MAP significantly reduces the moisture evaporation, retaining the juiciness and texture of cherries, while traditional methods may lead to fruit dehydration and texture degradation. MAP can extend the shelf life of cherries to several weeks or months, whereas traditional methods often yield a much shorter shelf life of only a few days to a week [46]. Additionally, traditional methods demonstrate weaker microbial control capabilities, resulting in increased spoilage and potential food safety concerns [90]. Therefore, MAP technology, through precise gas environment control, temperature management, moisture retention, and microbial suppression, more effectively extends the quality and shelf life of cherries compared to traditional storage methods, enhancing the stability of the market supply.

3.5. Scalability of MAP in Large-Scale Commercial Applications

The scalability of MAP in large-scale commercial applications is high, primarily reflected in the equipment flexibility, the diversity of packaging technologies, and the integration with automated production lines. Modern MAP systems can be adjusted according to the size and needs of specific businesses, with the options ranging from small-scale equipment to large industrial systems. This allows companies to select appropriate packaging materials and designs based on different product characteristics.

With advancements in automation technology, the integration of MAP with modern production lines has increased the packaging efficiency and reduced the labor costs [91]. Moreover, MAP is not limited to cherries; it can also be extended to other perishable agricultural products, such as fruits, vegetables, and seafood, achieving greater economic benefits [92]. The growing consumer demand for freshness and food safety has accelerated the adoption of MAP in commercial applications. Simultaneously, decreasing technology costs have made it feasible for small and medium-sized enterprises to adopt this technology, further promoting its widespread use. Many equipment suppliers and research institutions are actively engaged in the research and promotion of MAP technology, providing essential technical support and guidance. Therefore, MAP demonstrates excellent scalability, being capable of adapting to enterprises across various industries and sizes, aligning with market development trends.

4. Summary and Outlook

The integration of MAP technology with refrigeration has marked a significant advancement in the preservation of high-value fruits such as cherries, positioning it as a pivotal method for extending the shelf life and enhancing the sensory quality. As global market demands for sustained fruit quality and prolonged supply periods escalate, the potential applications of MAP technology have become increasingly vital. However, scaling this technology for widespread commercial use presents several challenges. Precise control of the gas composition is paramount; even minor deviations can adversely affect the fruit quality, necessitating high-precision monitoring equipment and standardized operational protocols. The selection of packaging materials is equally critical, as they must offer sufficient permeability and environmental stability, driving innovation to improve performance and reduce costs.

Temperature and humidity management are central to the efficacy of MAP. Fluctuations in the temperature during logistics can influence fruit metabolism and microbial growth, while excessive humidity can foster mold development. Therefore, the adoption of intelligent control systems to maintain optimal environmental conditions is a key area for technological enhancement. Additionally, reducing the implementation costs, especially for small-scale producers, is essential for broader adoption.To formulate more scientifically robust and effective preservation strategies, it is imperative to establish a comprehensive theoretical framework that accounts for the varietal characteristics of cherries, postharvest physiological changes, and storage environmental factors. This necessitates interdisciplinary research that integrates insights from molecular biology, physiological ecology, and materials science. Enhancements to precision control and automation are crucial, leveraging advanced sensors and Internet of Things (IoT) technology for real-time monitoring to ensure optimal conditions throughout the storage process. Concurrently, the development of eco-friendly, efficient, and recyclable packaging materials is critical, not only to meet storage requirements but also to minimize environmental impacts.

Furthermore, there should be a transition from single technologies to composite technologies that amalgamate refrigeration, MAP, physical field treatments, and biopreservatives to create robust preservation systems capable of comprehensively inhibiting microbial growth and delaying fruit senescence. Driven by technological innovation and interdisciplinary collaboration, the preservation techniques for high-value fruits like cherries are on the cusp of significant breakthroughs, steering the industry toward standardization, intelligence, and sustainability to better meet global market demands.