Reviewed by Lexie CornerMar 11 2025
In a recent study published in Horticulture Research, researchers from Shenyang Agricultural University and Liaoning Agricultural Vocational and Technical College demonstrated how violet LED light can effectively prevent browning in fresh-cut apples, improving their appearance and shelf life.
Violet LED light increased the antioxidant capacity and decreased oxidative enzyme activities of fresh-cut apple fruit. (a) The Fuji’ apple fruit was harvested in 2020 at 180 DAFB. Apple slices were treated with violet LED light at 700 lx at 10 °C for 4 days, and samples were collected every 2 days. The samples were stored in the dark at 10 °C as a control. Bars: 1 cm. BI (b), total phenolic content (c), DPPH radical scavenging rate (d), PPO activity (e), and POD activity (f) were investigated in the control and violet LED light-treated samples. The samples placed in the dark were used as a control. Data represents the means ± SE. Asterisks indicate significant differences (*P < 0.05; **P < 0.01, Student’s t-test). Image Credit: Horticulture Research
Fresh-cut fruits have become popular in modern diets due to their convenience and nutritional value. However, enzymatic browning, caused by the oxidation of phenolic compounds, continues to be a challenge.
This browning negatively impacts the marketability and visual appeal of the produce, reducing its shelf life. While chemical treatments have been used to address this, they come with disadvantages, including high costs and potential health risks.
Light-based solutions have emerged as a viable alternative, though the specific molecular processes involved have not been fully understood. This study addresses that gap by focusing on how violet LED light can help maintain the quality of fresh-cut fruits.
The research identifies MdHY5 and MdHYH as key transcription factors that regulate genes involved in oxidative enzyme activity and phenolic metabolism. This provides a molecular basis for using light as a natural, non-invasive preservation technique.
The study found that violet LED light treatment increases the accumulation of antioxidant-rich phenolic compounds while suppressing the activity of oxidative enzymes like polyphenol oxidase (PPO) and peroxidase (POD), reducing browning in fresh-cut apples.
Transcriptomic analysis showed that genes involved in phenolic degradation, such as MdPPO and MdPOD, were suppressed, while MdPAL, a key phenolic synthesis gene, was upregulated.
MdHY5 and MdHYH were identified as important regulators of this process, binding to the promoters of MdPPO, MdPOD, and MdPAL to regulate their expression through a positive feedback loop. Silencing these transcription factors eliminated the browning inhibition effect of violet LED light, confirming their crucial role in the process.
This research opens up exciting possibilities for the food industry. By understanding how violet LED light and specific transcription factors work together to prevent browning, we can develop more effective, eco-friendly methods to extend the shelf life of fresh-cut fruits without relying on chemicals.
Dr. Aide Wang, Study Corresponding Author, Shenyang Agricultural University
Dr. Wang's observations suggest that this new method could significantly change fruit preservation.
The study's findings have the potential to impact the fresh-cut fruit industry. Violet LED light provides a low-cost, chemical-free solution to prevent browning, improving the appearance and nutritional value of fresh-cut apples.
By integrating this technology into current postharvest processing systems, food waste could be reduced, and customer satisfaction improved. Moreover, the discovery that MdHY5 and MdHYH are key regulators opens the door for future genetic engineering or breeding efforts to create fruit varieties resistant to browning.
This research promotes greener practices in the food industry and establishes a foundation for more effective and sustainable fruit preservation methods.
Journal Reference:
Jin, J., et al. (2024) Violet LED light-activated MdHY5 positively regulates phenolic accumulation to inhibit fresh-cut apple fruit browning. Horticulture Research. doi.org/10.1093/hr/uhae276.