Strawberry, as a fruit of high economic value, is highly susceptible to postharvest spoilage and quality deterioration due to pathogen infection, primarily attributed to its high moisture content and thin peel. While current cold storage methods can delay spoilage to some extent, they fail to effectively monitor the progression of spoilage, resulting in persistently high loss rates. Furthermore, most existing market solutions rely on chemical-based control methods, which pose potential risks to both the environment and consumer health. Consequently, there is a pressing need for an efficient, environmentally friendly, and safe solution to monitor and control strawberry spoilage. This project aims to develop an integrated technical system for monitoring strawberry spoilage and implementing green sterilization control. The system utilizes biosensor technology to detect volatile organic compounds (VOCs) released during the strawberry spoilage process in real-time, and employs chitinase and glucanase preparations for antifungal control. This approach provides a low-cost, user-friendly, and efficient solution, significantly reducing the risk of strawberry spoilage, improving preservation and distribution efficiency, and laying the foundation for subsequent research and industrial application.

In daily life, we frequently encounter a persistent phenomenon: strawberries remain expensive yet their freshness is often compromised. This issue is particularly pronounced in cities distant from production areas, where consumers pay premium prices only to find the strawberries spoil within days. Multiple team members have personally experienced this frustrating scenario during routine shopping, prompting us to question: Why are strawberries consistently expensive while having such a short shelf life? Through investigation of news reports and market surveys, we identified the key contributing factor: strawberries are extremely vulnerable to damage during transportation and storage, with loss rates reaching 20-30%. To mitigate these losses, suppliers often harvest unripe strawberries prematurely, resulting in compromised flavor and texture while maintaining high prices - ultimately disappointing both consumers' palates and wallets. This observation inspired our team to explore whether synthetic biology could offer solutions to extend strawberry freshness while reducing supply chain losses. We consequently developed a dual-strategy approach: first, creating an "early warning system" to detect spoilage signals in the supply chain; second, designing an "invisible protective layer" using enzyme preparations to delay fungal invasion during transportation and storage. Through this innovative framework, we aim to enhance consumer experience while reducing economic and resource waste caused by strawberry perishability, ultimately safeguarding the "sweet journey of strawberries" from farm to table.

The Phenomenon and Consequences of Strawberry Spoilage

The strawberry (Fragaria × ananassa Duch.), belonging to the Rosaceae family, is a widely cultivated fruit with high economic value, cherished by consumers for its vibrant color, distinctive flavor, and richness in vitamin C, anthocyanins, and polyphenols. Strawberry cultivation in China is expanding, setting new global records. According to Li Tianhong, Vice President of the Chinese Society for Horticultural Science, China's strawberry cultivation area now spans nearly 200,000 hectares, ranking first globally. However, strawberries are highly susceptible to postharvest softening, mechanical damage, and microbial infection due to their delicate skin, high moisture content, rapid respiration rate, and non-climacteric ripening characteristics, leading to significant quality deterioration and spoilage. Throughout the supply chain—including harvesting, sorting, packaging, transportation, and retail—external stresses such as mechanical vibration, impact, and compression damage the cellular structure of the fruit, increasing the risk of microbial invasion and resulting in substantial losses [1, 2].

Statistics indicate that the average loss rate of strawberries during the entire distribution process from harvest to retail can reach 30–40%, with transportation and storage being particularly critical stages [3]. Studies have shown that in interprovincial transportation without cold chain facilities, the commercial loss rate of strawberries can exceed 25% within 48 hours [4]. In daily life, our team members have frequently observed that in regions distant from production areas, strawberries, despite their high prices, commonly exhibit reduced freshness, softening, juice leakage, and mold growth. This not only diminishes consumer purchasing intent but also causes economic losses for retailers and leads to resource wastage across the supply chain. Strawberry spoilage contributes not only to economic losses but also to food waste and food security challenges, hindering the achievement of Sustainable Development Goals (SDGs).

Therefore, reducing strawberry spoilage is not only crucial for enhancing economic efficiency but also represents a vital step toward minimizing food waste and promoting sustainable agricultural practices. Based on the aforementioned data, we propose the development of an early-stage strawberry spoilage detection system combined with an enzymatic intervention strategy to inhibit fungal growth, enabling timely spoilage alerts and extending the shelf life of strawberries during transportation and retail.

Figure 1: Strawberry planting area and yield in various countries [5]

Market Characteristics and Application Potential in Europe and America

Figure 2 Proportion of different forms of global strawberry trade in 2019 [6]

The structure of strawberry supply and consumer habits in European and American markets differ significantly from those in China. The utilization of strawberries in these regions is highly diverse. Beyond fresh consumption, frozen strawberries and processed strawberry products (such as jams, canned strawberries) constitute a substantial portion of market circulation. A significant volume of strawberries is used for producing jam, serving as ingredients in yogurt, being added to ice cream, or used in baked goods. Many are also frozen to extend their availability. This situation results in a relatively limited total volume of fresh strawberries reaching supermarkets, where they command higher prices.

Consequently, the retail sector is extremely sensitive to strawberry freshness and highly concerned about spoilage. Global trade statistics from 2019 illustrate this clearly: fresh fruit accounted for only about 53.9% of global strawberry trade, while frozen products represented 37.6%, and processed products made up 8.5%. This data underscores that fresh strawberries are often treated as high-value, short-shelf-life commodities in European and American markets (Figure 2).

However, postharvest and distribution losses within the European and American strawberry supply chain are substantial. During sorting, packaging, and retail stages, loss rates typically range from 20% to 40%. Interruptions in the cold chain, mechanical damage, and prolonged display times in stores are primary contributors to this waste. Research on supply chains in regions like the Pacific West Coast identifies retail shelves and distribution centers as major hotspots for strawberry waste [7].

Regarding disease, fungi such as Botrytis cinerea (gray mold) cause massive losses in the postharvest phase. Studies estimate that gray mold alone can account for losses ranging from 25% to 55% at certain stages, particularly under suboptimal temperature and humidity conditions, inappropriate packaging choices, and extended transportation times [8].

Our project focuses on the early detection of strawberry spoilage and preventive intervention through fungal eradication. Given the market realities in Europe and America, the application of our project's outcomes in these regions holds significant potential. Since the nutritional value of fresh fruit far exceeds that of jams or canned products, our results could contribute to increasing the availability of affordable, high-quality fresh strawberries in these markets. This would aid local populations in achieving dietary balance. Furthermore, it would reduce fresh fruit waste in supermarkets, enabling broader access to fresh strawberries for households, especially those with lower incomes, thereby enhancing overall societal nutritional status and quality of life.

As a high-value berry crop, strawberries are highly susceptible to postharvest spoilage, primarily resulting from the combined effects of pathogen infection, unfavorable environmental conditions, and the inherent vulnerability of the fruit itself.

Firstly, anthracnose (Colletotrichum spp.) and soft rot (Rhizopus stolonifer, Mucor spp.) represent the most prevalent and destructive diseases. Anthracnose typically infiltrates through micro-cracks or mechanical injuries in the fruit skin, forming dark brown, sunken lesions that can cause over 30% yield loss in severe cases. Soft rot frequently erupts rapidly during transportation and retail phases, leading to tissue maceration, skin rupture, and distinct spoilage odors [9, 10].

Secondly, adverse environmental factors significantly exacerbate disease progression. High humidity not only facilitates pathogen spore germination and adhesion but also creates aqueous films on fruit surfaces that enable fungal penetration. Inadequate ventilation or fluctuations in temperature and humidity can cause accumulation of metabolic gases including carbon dioxide and ethylene, compromising the fruit's defense mechanisms and triggering chain-reaction disease spread [11].

Finally, the physiological and structural characteristics of strawberries determine their innate vulnerability. The extremely thin epidermis with insufficient wax layer, combined with high tissue moisture content and fragile cell walls, makes the fruit particularly prone to damage during harvesting, packaging, and transportation [12]. This damage results in juice exudation that provides nutrient substrates for pathogens [9]. Concurrently, high respiration rates and rapid reactive oxygen species accumulation accelerate membrane lipid peroxidation and tissue softening. Crucially, strawberries exhibit high ethylene sensitivity, where even low concentrations can activate cell wall-degrading enzymes, substantially reducing shelf life [13].

During spoilage progression, strawberries emit characteristic volatile organic compounds (VOCs)—including alcohols, aldehydes, and esters—which serve as early indicators of quality deterioration and may influence pathogen growth and colonization [14]. In summary, the convergence of pathogen invasion, environmental triggers, and intrinsic fruit vulnerability creates conditions for rapid spoilage and substantial losses throughout the postharvest supply chain.

Figure 3: Schematic diagram of strawberry infection

The challenge of strawberry spoilage has long attracted significant attention from both the research community and industry. To extend shelf life and reduce supply chain losses, researchers and producers have primarily employed physical methods (such as cold chain transportation, modified atmosphere packaging, heat treatment, and UV-C irradiation) and chemical methods (including fungicide applications and gas fumigation), while also exploring emerging technologies (such as edible coatings, nanomaterials, and intelligent monitoring systems). While these measures have improved strawberry preservation to some extent, they generally present limitations: physical and chemical approaches often involve high costs, potential quality degradation, or safety concerns, whereas emerging technologies remain predominantly at the laboratory or demonstration stages, lacking maturity for large-scale implementation. To systematically illustrate the characteristics and shortcomings of existing management strategies, we provide a comprehensive summary in the following section [15-16].

Table 1: Current Storage Methods and Advantages and Disadvantages of Strawberries

Although existing physical methods, chemical control strategies, and emerging technologies have alleviated strawberry postharvest decay to some extent, they generally suffer from several limitations, including high cost, safety concerns, unstable effectiveness, and restricted applicability. For instance, cold chain systems are highly dependent on infrastructure; chemical fungicides can lead to residues and resistance development; and emerging technologies remain mostly at the laboratory or pilot demonstration stage, far from industrial-scale application. Consequently, identifying a safe, eco-friendly, sustainable, and consistently effective approach has become a central demand in both strawberry postharvest preservation research and industrial practice. This necessity serves as the entry point for our innovative exploration of biological approaches, particularly the application of chitinase and other biogenic agents.

Strawberry Spoilage Monitoring System

Overall Design

During the spoilage process, strawberries release a series of characteristic volatile organic compounds (VOCs), such as alcohols, esters, aldehydes, and ethylene. The composition and concentration of these VOCs vary with the progression of spoilage, making them reliable biomarkers of deterioration【17】. By screening bacterial promoters sensitive to these environmental signals (e.g., recA, grpE, soxS, and lasI) and coupling them with the vioABCDE gene cluster responsible for violacein biosynthesis, the engineered bacteria can activate vio cluster expression upon detection of spoilage-associated VOCs, thereby producing the intensely purple pigment violacein. This strategy effectively transforms spoilage gas signals into an intuitive colorimetric change, enabling low-cost and instrument-free early spoilage warning【18,19】.

It should be noted that once strawberries exhibit visible signs of spoilage, they are no longer edible and must be discarded, resulting in direct economic loss. In contrast, this early-warning system provides alerts prior to visible spoilage, allowing timely application of temporary preservation or intervention measures. Such an approach can reduce fruit wastage, minimize supply chain losses, and improve overall economic efficiency.

Figure 4: Diagram of Strawberry Decay Detection

SystemVOC-Responsive Promoter Screening

To achieve rapid early-warning of strawberry spoilage, this study aims to exploit the characteristic volatile organic compounds (VOCs) released during the initial stages of decay, such as alcohols, esters, aldehydes, and ketones, as detection signals. Our team will systematically screen a set of natural promoters known to be sensitive to environmental stresses or specific signal molecules (e.g., recA, grpE, soxS, and lasI) and evaluate their response profiles. From this screening, we intend to identify candidate elements with the highest sensitivity and specificity toward spoilage-related VOCs. Ultimately, these promoters will be employed to drive downstream chromogenic pathways, thereby converting spoilage signals into visible color changes. This approach enables a low-cost, intuitive, and quantifiable strategy for early spoilage detection.

Table 2: Source species, induction signals, and functional overview of different promoters

Violacein Biosynthesis System

To achieve intuitive detection of early strawberry spoilage signals, this study moves beyond traditional approaches that rely on fluorescent proteins. Conventional fluorescent protein–based detection requires expensive instrumentation, making it unsuitable for the practical and convenient use required by farmers. Therefore, we explored the use of visible pigment molecules as an alternative.

Specifically, we designed a violacein biosynthesis system based on the vioABCDE gene cluster derived from Chromobacterium violaceum. The vioABCDE pathway represents a classic metabolic route: VioA converts tryptophan into an indole-3-pyruvic acid imine (IPA imine); VioB and VioE act sequentially to generate the intermediate prodeoxyviolacein; and VioC and VioD catalyze hydroxylation and oxidation reactions, respectively, ultimately yielding the purple pigment violacein. When this entire pathway is introduced into Escherichia coli, it can, in principle, exploit host metabolic intermediates to achieve stable violacein production without the need for exogenous substrate supplementation【20】.

Figure 5: The synthetic mechanism of violacein [20]

In the design of the detection system, a violacein standard will be employed to determine its absorption spectrum, identify characteristic absorption peaks, and construct a concentration–absorbance calibration curve, thereby establishing a reliable quantitative method. By measuring the absorbance of engineered bacterial cultures or extracts at the characteristic wavelength and converting values through the standard curve, it is theoretically possible to achieve precise evaluation of violacein yield. This system is intended to compare the response strength of different promoter–vioABCDE combinations and dynamically monitor the temporal changes in violacein biosynthesis, thus providing a quantitative basis for evaluating the performance of the early spoilage warning system.

The rationale for selecting violacein as the reporter molecule is threefold:

1. Violacein is a water-soluble pigment with strong absorption peaks in the visible spectrum, exhibiting a vivid blue–purple color that contrasts directly with the natural red of strawberries, enabling intuitive recognition by the naked eye and supporting low-cost, equipment-free detection.
2. The biosynthetic mechanism of violacein is well-characterized, and the pigment itself exhibits high stability, allowing production under ideal conditions without additional substrates or complex requirements.
3. Violacein possesses a dual functionality, being both amenable to spectrophotometric quantification and serving as a visible colorimetric signal, thereby significantly lowering the technical barriers for strawberry early spoilage monitoring【21】.

Figure 6: Strawberry spoilage monitoring system using violacein as a reporter molecule

Enzyme-Based Antifungal System

Overall Strategy

The major postharvest fungal pathogens of strawberries rely on chitin and β-glucan as the primary components of their cell walls, which ensure structural stability and defense capacity. In addition, the presence of extracellular polysaccharide (EPS) matrices enhances fungal adhesion and biofilm formation. Chitinases and glucanases can specifically target and degrade chitin and β-glucan, respectively, while synergistically disrupting EPS. This process compromises the integrity of fungal cell walls and reduces their infectivity, ultimately inhibiting the onset and spread of gray mold and soft rot【22,23】.

At the application level, this study proposes to formulate these two enzymes into a sprayable aqueous solution for postharvest strawberry treatment. The antifungal effectiveness will be evaluated by comparing single-enzyme applications with combined formulations, under identical storage conditions. Key indicators such as lesion appearance time, decay rate, and fruit quality changes will be monitored to verify the effectiveness of this strategy in delaying spoilage and reducing disease incidence. This mechanism, together with the proposed implementation strategy, offers a green, safe, and efficient biological solution for postharvest control of strawberry diseases【24,25】.

Figure 7: Construction of chitinase and glucanase expression vectors

Functional Overview and Mechanism of Chitinase and Glucanase

Chitinase and glucanase are two key hydrolytic enzymes that act on fungal cell walls and hold significant potential in food safety and plant disease management. Chitinase, a member of the glycoside hydrolase family, specifically cleaves the β-1,4-glycosidic bonds in chitin, thereby disrupting the chitin backbone of the cell wall and reducing its mechanical strength and stability. Glucanase, in contrast, hydrolyzes β-1,3 and β-1,6-glycosidic bonds, targeting the degradation of glucan components in both the fungal cell wall and the extracellular polysaccharide (EPS) matrix, which further compromises the barrier function of the cell wall and reduces fungal adhesion capacity on host surfaces【26–28】.

During postharvest storage and transportation of strawberries, Botrytis cinerea (gray mold) and Rhizopus spp. (soft rot pathogens) rely on robust cell walls and EPS to withstand environmental stresses and host defense responses, thereby maintaining their ability to colonize and infect fruit surfaces【29】. This project proposes the combined application of chitinase and glucanase to achieve dual-targeted synergistic action: chitinase degrades the core chitin scaffold of the fungal cell wall, while glucanase further cleaves glucans and EPS, resulting in systemic disintegration of the cell wall at the molecular level. Their combined effects significantly weaken fungal infectivity, delay the progression of gray mold and soft rot, and effectively reduce the postharvest decay rate of strawberries【30】.

Importantly, the cell wall composition of strawberries is primarily composed of cellulose, pectin, and hemicellulose, and does not contain chitin or β-1,3/β-1,6-glucans. As a result, these two enzymes do not damage strawberry cell walls or significantly affect fruit tissue integrity, ensuring a high degree of selectivity against fungi. This property guarantees the safety of chitinase and glucanase in application, making them a green, efficient, and quality-preserving strategy for postharvest disease control.

Figure 8: Mechanism of action of chitinase and glucanase

In the postharvest strawberry protection system, the chitinase and glucanase utilized in this study, after heterologous expression in E. coli and subsequent purification, can be formulated into sprayable enzyme preparations for surface treatment of harvested fruits. Operationally, the enzyme preparations can be applied immediately after harvesting through spraying onto strawberry surfaces, covering areas potentially exposed to pathogens and ensuring sufficient contact between the enzymes and fruit surfaces. To enhance treatment uniformity and persistence, operators may perform a secondary application before packaging or pre-cooling, maintaining enzyme activity and protective efficacy during storage and transportation. Depending on specific protection requirements, users can employ either single-enzyme applications (chitinase or glucanase alone) or combined applications (both enzymes formulated together), allowing flexible adjustment of dosage and combination strategies [31].

The enzyme preparations demonstrate adaptability to various storage conditions and operational scales, enabling direct application in standard refrigeration units or circulation packaging through either spraying or immersion methods to achieve uniform coverage. During implementation, treatment dosage and application frequency can be optimized according to fruit quantity, surface coverage area, and storage conditions to meet practical postharvest management needs [32]. Through this approach, the enzyme preparations serve as preventive protective measures on host surfaces, forming a continuously active protective layer that provides an operable green treatment solution for strawberries during storage and transportation phases.

Chassis Microorganism

In this project, to achieve rapid monitoring and control of postharvest strawberry spoilage, we selected Escherichia coli BL21(DE3) as the core chassis organism. The BL21(DE3) strain is an ideal choice due to its high protein expression capacity and rapid metabolic response, enabling it to generate visible fluorescent signals in response to target VOCs within a short time frame, thereby meeting the requirements of real-time monitoring. Moreover, BL21(DE3) exhibits strong genetic tractability, allowing it to accommodate VOC-recognition elements and fluorescent reporter genes, which further improves the efficiency of spoilage signal detection.

Compared with other commonly used chassis strains, BL21(DE3) demonstrates significant advantages in both protein expression and metabolic responsiveness, making it capable of efficiently driving a VOC-responsive system under low-risk conditions. Thus, BL21(DE3) was chosen as the final engineering strain for this project【33,34】.

When compared with alternative hosts such as DH5α, K-12, or yeast, the advantages of BL21(DE3) become more evident. DH5α is highly suitable for gene cloning and plasmid amplification but has limited capacity for protein expression. The K-12 strain, while possessing excellent safety characteristics, often forms inclusion bodies during high-level heterologous expression, thereby impairing protein functionality. Yeast and other eukaryotic chassis strains, although advantageous in certain secretory systems, exhibit relatively long growth cycles, making them unsuitable for rapid-response monitoring【35】.

Therefore, BL21(DE3) offers a unique balance of safety, genetic operability, and fast metabolic response, enabling efficient activation of the VOC-responsive system and facilitating rapid, visual detection of strawberry spoilage signals. This makes it the most appropriate microbial chassis for the engineering applications proposed in this study.

In the context of postharvest strawberry storage and transportation, the proposed chitinase and glucanase spray system will serve as a safe, green, and highly operable control strategy. Its primary stakeholders include: strawberry growers and harvesters (for field-level initial treatment), packaging and sorting center operators (for pre-transport treatment), logistics companies (for quality maintenance during transportation), and retail terminals (for short-term preservation before display and sales).

Key Stages of Spoilage Control System Implementation

Production and Purification of Enzyme Preparations

Prior to application for control and prevention, efficient chitinase and glucanase must be prepared in a fermentation facility. Through the cultivation and fermentation of engineered strains, large quantities of antifungal enzyme preparations can be obtained. After the engineered strains grow and (if applicable) secrete the target enzymes in the fermenter, impurities are removed through steps including centrifugation, filtration, and purification, ultimately yielding a mixture of highly purified chitinase and glucanase. This enzyme preparation undergoes activity assays and quality control to ensure it exhibits stable and significant fungal inhibition efficacy in subsequent strawberry protection applications.

Initial Treatment after Harvest

Immediately after harvest, strawberries should undergo an initial treatment. The fruits are placed on a clean handling table or conveyor belt, where a handheld sprayer is used to apply the enzyme formulation containing chitinase and glucanase uniformly over the strawberry surface. Care must be taken to ensure complete coverage of the top, bottom, and lateral sides of each fruit. Following spraying, the strawberries are allowed to air-dry for 2–3 minutes, enabling the enzymes to firmly adhere to the fruit surface. This operation effectively reduces pathogen loads introduced during harvest and establishes a preliminary protective barrier, thereby enhancing fruit safety and quality.

Secondary Spraying before Packaging and Precooling

Before the strawberries enter the cold chain, a secondary spraying treatment is required. The pretreated strawberries are placed in cold-chain packaging boxes, and just before sealing, an additional application is carried out using spraying or immersion methods to ensure every fruit surface is covered with an effective enzyme concentration. After treatment, precooling is performed immediately to preserve enzyme stability. This operation ensures that the antifungal effect of the enzymes can persist during subsequent storage and transportation.

Monitoring and Maintenance during Transportation

During strawberry transportation, typically conducted under cold-chain conditions at 2–4 °C, continuous quality assurance is essential. VOC monitoring devices, such as portable detection kits or cold-chain monitoring modules, are installed in transport vehicles to track the release of volatile organic compounds (VOCs) from the fruit in real time. If the system detects rising VOC concentrations, it sends alerts via sound-light signals or a mobile application, warning of potential spoilage risks. Operators can then respond by applying additional enzyme sprays en route or by adjusting transport conditions (e.g., lowering the temperature). This combined approach of real-time monitoring and intervention allows for dynamic quality management and ensures strawberry freshness and safety during transit.

Retail-End Supplemental Control

Before strawberries are displayed in supermarkets or retail outlets, operators may perform light enzyme spraying based on VOC monitoring results. This final step extends the shelf life of strawberries and effectively reduces losses at the retail stage.

User Experience and Division of Labor Diagram

Table 3: Postharvest Staged Treatment and Dynamic Monitoring Plan for Strawberries

The quality control and safety monitoring protocol for strawberries across the supply chain involves multiple stages tailored to different stakeholders. At the grower stage, initial post-harvest treatment is performed using handheld sprayers and workbenches to reduce the initial microbial load. Subsequently, at the packaging centers, strawberries undergo packaging combined with a secondary spray or dip application, utilizing specialized spray or immersion equipment to ensure uniform coverage of preservative agents on the fruit surface. During cold chain logistics, transport companies implement dynamic monitoring using volatile organic compound (VOC) detection hardware to provide timely risk alerts. Finally, retailers perform a supplementary spray application prior to sale using small-scale sprayers to further extend shelf life. This multi-stage collaborative process ensures the maintenance of strawberry quality and safety from harvest to retail.

Figure 9: Overall Flowchart of Strawberry Prevention and Control System

Target User Groups for the Strawberry Spoilage Prevention System

The primary users of this project encompass key stakeholders throughout the strawberry industry chain: growers and cooperatives can apply enzyme preparations immediately after harvest for source-level prevention; distributors and wholesalers can utilize the monitoring module for quality control during sorting and circulation; cold chain logistics and storage enterprises can implement batch monitoring through combined spray prevention and colorimetric alerts; while retailers and platform sellers can rely on visual signal outputs to enhance shelf-life management and consumer experience.

Application Scenarios for the Strawberry Spoilage Prevention System

In practical implementation, this project's solution covers critical nodes in the strawberry supply chain: during postharvest handling, sprayable enzyme preparations are employed to inhibit fungal infection; throughout packaging and transportation, integrated prevention and monitoring ensure quality maintenance during long-distance shipping; in storage and distribution, the monitoring module enables dynamic supervision of large fruit quantities; and at the retail and consumption stage, colorimetric signals provide intuitive warnings to reduce losses and enhance consumer trust.

The dual-strategy approach proposed in this project combines both forward-looking and practical features. On one hand, the VOCs-based engineered bacterial monitoring system enables early detection of strawberry spoilage, providing timely warnings during transportation and retail stages. On the other hand, the application of chitinase and β-1,4-glucanase effectively inhibits the growth of postharvest fungal pathogens, thereby extending both storage life and shelf life of strawberries. Compared with conventional cold storage or chemical treatments, this approach offers a green, safe, and intuitive solution, while also demonstrating scalability for application to other perishable fruits and vegetables. By reducing supply chain losses, prolonging freshness, and enhancing consumer experience, this project not only holds significant economic value but also contributes to food waste reduction and promotes sustainable agriculture.

Key advantages of this system include:

1. Dual-strategy framework: Integrates source-level prevention and process-level monitoring to establish a closed-loop spoilage management system.
2. Intuitive visualization: Early spoilage warnings are rendered visibly through violacein coloration, requiring no specialized equipment.
3. Digitalized management: Signals can be interfaced with hardware devices and mobile applications for automated data collection, remote monitoring, and intelligent management.
4. High scalability: The modular design is adaptable to various perishable fruits and vegetables and can be integrated with smart logistics and cold-chain systems.
5. Industrial and societal impact: Significantly reduces supply chain losses, enhances consumer satisfaction, and aligns with trends in sustainable agricultural development.

Figure 10: Analysis of the Advantages of the Strawberry Control System

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