LED treatment effectively maintains the postharvest quality of blueberries

Fungal infection remains the primary cause of postharvest blueberry decay.

As a non-thermal technology, light-emitting diode (LED) offers a promising approach to preservation by inhibiting fungal activity.

This study investigated the antifungal effects and mechanisms of LED against the main spoilage fungi (Penicillium sclerotiorum and Cladosporium cladosporioides) in blueberries and its application potential for preservation.

Under optimal conditions (410–420 nm LED, 25°C, 12 h), LED treatment achieved spore inhibition rates of 99.46–99.52 % in vitro.

The in vivo study using inoculated blueberries, under the same conditions (extended to 36 h), demonstrated maximum log reductions of 4.11 and 2.50 CFU/g for the two fungi, respectively.

Based on these, the antifungal mechanism was further elucidated through cellular and molecular analyses. 

At the cellular level, results indicated that cellular membrane damage (lipid peroxidation and intracellular leakage), oxidative stress (ROS accumulation and diminished antioxidant enzyme activities), and mitochondrial dysfunction (ΔΨm dysregulation and ATP depletion) are the main causes of cell damage.

Molecular analysis revealed that LED disrupted structural integrity by suppressing cell wall/membrane biosynthesis genes, impaired antioxidant defense by inhibiting peroxisome biogenesis (P. sclerotiorum) and GSH synthesis genes (C. cladosporioides), and dysregulated energy metabolism by altering key genes in glycolysis, TCA cycle, and oxidative phosphorylation.

Furthermore, compared with the untreated control, the LED treatment had no significant effect on the blueberries' color, soluble solids, and pH, though it increased weight loss and reduced firmness.

These findings suggest a novel LED-based preservation strategy for blueberries and provide a theoretical basis for its application.

Introduction

Blueberry (Vaccinium spp.), a representative berry of the genus Vaccinium, is acclaimed as the "King of Fruits" due to its delicate texture and balanced sweet-tart flavor (Sharma et al., 2024).

Blueberries contain abundant bioactive constituents such as anthocyanins, flavonoids, and vitamins, which confer antioxidant, anti-inflammatory, and anticancer activities, thus attracting significant attention in the functional food industry with a continuously growing market demand (Jung et al., 2021, Mustafa et al., 2022, Wu et al., 2022).

However, postharvest preservation of blueberries faces severe challenges. First of all, blueberries have active physiological metabolism and are highly prone to softening, water loss, shrinkage, and nutrient loss after harvest (Rivera et al., 2021).

Secondly, they have thin and soft skin, making them susceptible to mechanical damage during harvesting, storage, and transportation, which provides pathways for infection by spoilage fungi (Paniagua et al., 2014).

Penicillium sclerotiorum and Cladosporium cladosporioides, main fungi causing rot

Penicillium sclerotiorum and Cladosporium cladosporioides are the primary fungi responsible for blueberry decay.

Upon infection, these fungi grow rapidly, with their mycelia accelerating tissue breakdown, often leading to soft rot accompanied by lesions and, in severe cases, extensive fruit decay, thereby significantly compromising fruit quality and storage stability (Bell et al., 2021, Pérez-Lavalle et al., 2020).

Common postharvest control methods

Chemical fungicides and low-temperature storage are two common methods used to control postharvest fungal diseases in blueberries; however, both exhibit significant limitations (Hu et al., 2021). 

Chemical treatments may leave harmful residues, raising food safety concerns (Iñiguez-Moreno et al., 2023).

Low-temperature storage is associated with high energy consumption and cost, and it is ineffective against psychrotrophic bacteria. Furthermore, low-temperature storage may induce chilling injury in the fruit.

Studies have shown that blueberries stored at 0°C for 30 days develop symptoms of chilling injury, such as pedicel pitting, with the incidence increasing significantly with prolonged storage (Zhang et al., 2020).

Notably, when fruits are transferred from cold storage to ambient shelf conditions, rapid softening, browning, and reddening often occur within a short period, leading to substantial economic losses (Wang et al., 2019).

LED, an answer to the need to develop non-chemical and highly effective postharvest preservation technologies

Therefore, there is an urgent need to develop non-chemical and highly effective postharvest preservation technologies to address these challenges.

The light-emitting diode (LED) is a semiconductor device that converts electrical energy into light, emitting monochromatic visible light within the wavelength range of 400–780 nm (Finardi et al., 2021).

Based on photodynamic principles, LED technology has been developed as a novel non-thermal physical sterilization method (Yu et al., 2022).

Its core antimicrobial mechanism involves the use of specific wavelengths of light to excite endogenous photosensitizers (PS) within microbial cells, thereby inducing a photodynamic effect and generating reactive oxygen species (ROS) (Cossu et al., 2021, Ghate et al., 2019).

Antimicrobial efficacy, wavelength dependent

Notably, the antimicrobial efficacy of LED is highly wavelength-dependent. Violet (400–450 nm) and blue (450–500 nm) light bands exhibit strong antimicrobial potential due to their higher photon energy and better match with the absorption spectra of endogenous microbial photosensitizers (Angarano et al., 2020, Kumar et al., 2016, Yu et al., 2023a).

Previous studies have found that 410 nm LED light is significantly more effective in suppressing postharvest decay fungi in litchi and citrus than 460–470 nm and 520–530 nm LED light (Wu et al., 2025, Yu et al., 2023a). These findings provide a direct rationale for the selection of specific wavelengths in this study for systematic comparison.

Violet and blue light bands, excelent antifungal potential

Given the excellent antifungal potential demonstrated by the violet and blue light bands, LED technology has been extensively explored for controlling postharvest fungal diseases in a variety of fruits and vegetables. 

For instance, blue LED light at different intensities effectively inhibited the growth of Penicillium italicum, a major spoilage fungus in citrus (Yamaga et al., 2015).

Another study showed that 405 nm LED treatment reduced the colony counts of Botrytis cinerea and Rhizopus stolonifer on tomatoes and strawberries by over 94 % (Ghate et al., 2021).

Moreover, a 10-hour exposure to 410–420 nm LED light completely suppressed spore germination in Geotrichum candidum and Fusarium spp., inhibited mycelial growth by approximately 65–79 %, and reduced fungal populations on litchi surfaces (Yu et al., 2023a).

Other benefits of the LED technology

Driven by these antifungal effects, LED technology has further demonstrated comprehensive value in postharvest preservation practices. 

Studies on strawberries, litchi, citrus, and tomatoes have consistently shown that LED treatments not only delay postharvest decay but also maintain or even enhance the sensory quality and nutritional components of the fruits (Chong et al., 2021, Chua et al., 2021, D'Souza et al., 2015, Yu et al., 2023a).

These findings demonstrate that LED technology has a unique "dual-effect synergy of sterilization and freshness preservation" advantage in postharvest fruit preservation.

The need of systematic research for controlling fungal spoilage

However, systematic research on its application for controlling fungal spoilage in blueberries remains limited.

The unique cuticular structure of blueberries and their associated pathogen communities may necessitate distinct response mechanisms to LED light. 

Furthermore, existing research on the antifungal mechanisms of LED remains limited, often confined to phenotypic observations.

Thus, this study systematically evaluates the antifungal effects of LED treatment against major postharvest spoilage fungi in blueberries (P. sclerotiorum and C. cladosporioides) through in vitro and in vivo assessments under multiple wavelengths (410–420 nm, 460–470 nm and 520–530 nm) and temperatures (4°C, 10°C, 25°C), while simultaneously examining its impact on blueberry quality.

By integrating systematic analyses spanning from cellular damage to transcriptional regulation, we comprehensively elucidate the multi-target antifungal mechanisms of LED and their species-specific differences.

These findings provide crucial theoretical support and practical guidance for advancing LED technology into a mechanism-guided, precise, and efficient strategy for postharvest blueberry preservation.

Source

Antifungal mechanisms and preservation applications of LED technology against postharvest spoilage fungi in blueberries
Jialing Li, Ziqian Zhang, Yingyin Wu, Zhiwei Ye, Yuan Zou,
Hyun-Gyun Yuk, Qianwang Zheng
Postharvest Biology and Technology Volume 234, April 2026, 114128
https://doi.org/10.1016/j.postharvbio.2025.114128
https://www.sciencedirect.com/science/article/abs/pii/S0925521425007409