Author: Site Editor Publish Time: 31-10-2025 Origin: Site
In an era where consumer demands for food safety and quality continue to rise, alongside an urgent need to reduce chemical preservatives, physical preservation technologies are entering a golden period of development. Among these, ultraviolet C-band (UV-C, wavelength 200-280 nm) irradiation stands out as a non-thermal, residue-free sterilization method that has matured over decades of research. In recent years, breakthroughs in semiconductor technology have optimized UV-C light-emitting diode (UV-C LED) technology, which offers significant advantages over traditional mercury lamps and is gradually replacing them. This positions UV-C LED as a technology with immense industrialization potential in fruit and vegetable preservation. This article systematically reviews research from authoritative academic databases such as CNKI, PubMed, Google Scholar, and Wanfang Data, analyzing the core value and development path of UV-C LED in fruit and vegetable preservation across four dimensions: technological evolution, preservation mechanisms, application efficacy, and future trends.
Traditional UV-C sterilization relies on low-pressure mercury lamps with a primary emission wavelength of 254 nm. Extensive studies confirm their strong microbial inactivation effects, but inherent flaws severely limit widespread adoption in the food industry. Specifically, low-pressure mercury lamps contain heavy metal mercury, posing environmental pollution and food safety risks if damaged; they require several minutes to start, failing to meet instant on/off needs in production lines; they consume 30%-50% more power than newer sources, conflicting with low-carbon principles; and they are bulky with poor installation flexibility. Additionally, they generate ozone during use, necessitating extra ozone treatment devices.
The advent of UV-C LED technology has transformed this landscape. Studies show UV-C LEDs offer instant switching (response time <1 ms), compact size (enabling modular integration), low energy consumption (over 40% savings compared to mercury lamps), long lifespan (10,000-30,000 hours, 3-5 times that of mercury lamps), mercury-free environmental compliance (meeting RoHS standards), and precise wavelength tunability (200-280 nm as needed). These features allow flexible integration into fruit and vegetable production lines, smart cold storage, automated packaging machines, and even household refrigerators, enabling precise, dynamic, low-energy preservation across the entire post-harvest to terminal storage chain—providing core support for innovating fruit and vegetable preservation technology.
UV-C LED's preservation effects on fruits and vegetables go beyond surface sterilization, achieving a multidimensional system through the dual mechanisms of "direct inactivation" and "induced resistance." The specific pathways are as follows:
UV-C photons possess extremely high energy, strongly absorbed by DNA and RNA in microbial cells (including bacteria, molds, and yeasts), particularly pyrimidine bases (e.g., thymine, cytosine) with absorption efficiency far exceeding other bases. Upon absorption, adjacent pyrimidine bases undergo cross-linking to form dimers (e.g., thymine dimers). This severely impedes DNA replication and RNA transcription, preventing synthesis of essential proteins and enzymes, ultimately leading to loss of metabolic activity and cell death.
Notably, inactivation efficiency varies significantly by UV-C wavelength. For instance, 265 nm UV-C excels against Gram-negative bacteria like Escherichia coli and Salmonella, while 275 nm UV-C is more effective against molds like Botrytis cinerea and Penicillium. UV-C LED's wavelength selectivity enables customized sterilization schemes targeting primary spoilage microbes in different produce, achieving "precision inactivation" and greatly enhancing preservation efficiency.
Low-dose UV-C irradiation is perceived by fruits and vegetables as a "mild stress signal," activating defense signaling pathways (e.g., MAPK pathways) in plant tissues, inducing synthesis and accumulation of stress-resistant compounds—a process known as the "elicitor effect" or "hormesis effect." Specifically, UV-C-induced resistance manifests in two key aspects:
Accumulation of Antioxidants: UV-C promotes synthesis of phenolic compounds (e.g., chlorogenic acid, anthocyanins) and flavonoids, while enhancing antioxidant enzyme systems (e.g., superoxide dismutase SOD, peroxidase POD, catalase CAT). These clear reactive oxygen species (ROS), reducing oxidative damage to cell membranes, proteins, and vitamins, thereby delaying browning and quality deterioration. In fresh-cut apples treated with 0.6 kJ/m² of 265 nm UV-C LED, total phenolic content increased 23.5% over controls, DPPH radical scavenging rate rose 18.2%, and browning index dropped 35.7%.
Expression of Pathogenesis-Related (PR) Proteins: UV-C induces synthesis of PR proteins like chitinase and β-1,3-glucanase, which degrade key microbial cell wall components (chitin, glucan), inhibiting pathogen invasion and proliferation—essentially "vaccinating" produce to boost intrinsic resistance to spoilage.
Numerous studies in leading domestic and international journals empirically confirm UV-C LED's significant effects across berry, solanaceous, leafy, and other produce categories. Key examples include:
Strawberries, with thin skins and high moisture, are highly susceptible to Botrytis cinerea post-harvest, making preservation challenging. Fresh strawberries treated with 275 nm UV-C LED at 1.2 kJ/m² and stored at 4°C showed:
Microbial Control: Treated surfaces had 2.1 log CFU/g fewer Botrytis cinerea colonies than controls; decay rate fell from 38.5% to 23.1% (40.0% reduction).
Quality Retention: Firmness (2.3 kg/m²) exceeded controls (1.8 kg/m²); soluble solids (9.2 Brix) and vitamin C (58.3 mg/100g) were 0.8 Brix and 6.5 mg/100g higher, preserving flavor and nutrition.
Fresh-cut lettuce and spinach suffer cell wall damage during processing, leading to wilting, chlorophyll degradation, and contamination. As a cold light source with no thermal radiation, UV-C LED suits heat-sensitive fresh-cuts. Fresh-cut lettuce treated with 270 nm UV-C LED at 0.8 kJ/m² and stored at 5°C for 7 days showed:
Microbial Safety: Total plate count (4.2 log CFU/g) was 2.3 log CFU/g lower than controls (6.5 log CFU/g); coliforms undetectable (vs. 2.1 log CFU/g in controls), meeting GB 2716-2018 limits for fresh-cut vegetables.
Sensory and Nutrition: Chlorophyll (1.8 mg/g) rose 38.5% over controls (1.3 mg/g); wilting rate (8.5%) was far below controls (23.2%), retaining vibrant green color and crisp texture.
Despite vast potential, scaling UV-C LED from lab to industry requires overcoming technical and cost barriers. Key challenges and strategies:
Establishing Optimal Parameters: UV-C exhibits a "low-dose beneficial, high-dose harmful" duality—insufficient dosing fails to inhibit microbes; excess causes epidermal burns or vitamin C degradation. Unified standards for parameters (wavelength, dose, irradiation mode) across produce types, varieties, and maturities remain absent, necessitating more systematic research.
Wall-Plug Efficiency and Cost Barriers: Commercial UV-C LEDs achieve <10% efficiency (vs. >50% for visible LEDs and >20% for mercury lamps), driving equipment costs 3-5 times higher and hindering adoption in SMEs.
Integration and Uniform Irradiation: Produce shape (e.g., round tomatoes, irregular strawberries) and surface features (e.g., strawberry fuzz) complicate uniform exposure; efficient integration into lines (washing, packaging) without dead zones is a design hurdle.
Material and Process Innovations: Advances in AlGaN epitaxy (e.g., MOCVD optimization) and transparent electrodes (ITO, graphene) could boost efficiency to >20% in 3-5 years; wafer-level packaging will drive costs to mercury lamp parity post-2025.
Intelligent Optimization: Machine learning and computer vision can create "produce type-maturity-parameter" models, auto-adjusting wavelength/dose via real-time quality monitoring for personalized preservation.
Full-Chain Integration: Combine with controlled atmosphere packaging and cold storage for a green system spanning post-harvest to retail. UV-C LED modules in refrigerated trucks enable real-time microbial suppression; household fridge integrations extend shelf life and reduce waste.
UV-C LED technology, with its residue-free, low-energy, and flexible advantages, offers a green, efficient solution for post-harvest fruit and vegetable preservation. Authoritative studies confirm its dual direct inactivation and induced resistance mechanisms effectively curb microbial contamination, delay senescence, and maintain nutritional quality—demonstrating clear benefits in strawberries, tomatoes, fresh-cuts, and more. Though challenges like parameter standardization and costs persist, semiconductor innovations, smart equipment, and scaling will position UV-C LED as a core cold-chain technology in 5-10 years. This will help curb global food waste (FAO: ~1/3 of produce lost annually to spoilage), ensure safety and quality, and drive the food industry toward green sustainability.
