Fresh Produce CO2 Laser Labeling: Analysis of Postharvest Quality, Microbial Safety, And Economic Aspects

Researchers from Kansas State University in the United States published an article titled CO2 Laser-labeling on Fresh Produce: Evaluating Postharvest Quality, Microbial Safety, and Economic Analysis in the international journal Journal of Food Protection.

01 Paper Introduction
With the increasing consumption of fresh fruits and vegetables, the incidence of foodborne illnesses has also been rising. Traditional Price Look-Up (PLU) stickers used to label agricultural products pose several problems, such as detachment, lack of traceability, and plastic pollution. Therefore, there is an urgent need for an eco-friendly and efficient alternative labeling method. In recent years, CO₂ laser labeling technology (LLT) has drawn wide attention. This technology directly etches QR codes or alphanumeric codes onto the surface of fruits and vegetables to enable sustainable product traceability. However, systematic studies on the impact of laser labeling on postharvest quality, microbial contamination risks, and economic feasibility remain scarce. This study systematically evaluates the application potential of LLT on three common fruits and vegetables: Red Delicious apples, green bell peppers, and cucumbers.

02 Full Text Overview
This study systematically investigates the application of CO₂ laser labeling technology on three common fresh produce types (Red Delicious apples, bell peppers, and cucumbers), focusing on its effects on postharvest quality, microbial safety, and economic feasibility. Two types of laser etching—QR codes and text codes—were used, and an edible wax coating was applied to the etched areas to simulate commercial processing. In terms of postharvest quality, laser-labeled samples showed slight weight loss, especially for QR codes due to their larger etched area, but visual quality scores remained largely unaffected. QR code readability remained stable in apples but slightly declined in bell peppers and cucumbers over time. In microbial safety tests, after inoculation with rifampicin-resistant E. coli, text-labeled samples exhibited higher bacterial adhesion across all three produce types, while QR code-labeled and unlabeled control groups showed no significant difference, indicating higher safety of QR code labeling. The wax coating had no significant effect on microbial adhesion. The economic analysis simulated labeling of 1 million units and found that although initial equipment costs are high and laser speed is slower than the PLU sticker system, the per-unit cost is lower and the operation is simpler, showing notable economic advantages in large-scale applications.

03 Figures and Analysis
Figure 1 shows Red Delicious apples etched at a 3.8 cm distance from the laser head, using a 2.03 mm diameter lens.

Figure 1. Trotec Speedy 300 laser engraver etching QR code labels on red Delicious fruit

Figure 2 indicates that QR code-labeled apples showed the highest weight loss at all time points, followed by text-labeled samples, with the control group having the lowest loss. Moisture loss in the QR code group remained significantly higher throughout the storage period, indicating that laser labeling, particularly QR codes, accelerates water loss but not to a severe extent.

Figure 2. Percentage loss of fresh weight of red Delicious fruit affected by laser marking and days after treatment

Figure 3 shows the effect of laser labeling on weight loss in cucumbers and bell peppers. In cucumbers, the QR code group (1.56%) and text code group (1.54%) lost more weight than the control group (1.28%), but the difference between QR and text was not significant. In bell peppers, the three groups had similar weight loss, though statistical differences existed between QR and text groups. Overall, laser labeling caused only slight moisture loss in cucumbers and bell peppers, with minimal impact on postharvest quality.

Figure 3. Percentage loss of fresh weight of cucumbers (A) and green peppers (B) affected by laser marking

Figure 4 shows minimal visual differences in the QR label areas over extended periods (8 or 16 days).

Figure 4. Visual quality of horticultural products after QR code labeling

04 Conclusion
This study systematically validates the application potential of CO₂ laser labeling technology on Red Delicious apples, bell peppers, and cucumbers, and concludes the following:

1. Although laser etching may cause some degree of water loss, visual quality and QR code readability remain good. More importantly, QR code labeling does not significantly increase microbial contamination risk, indicating favorable food safety characteristics.

2. Economic analysis also suggests that the technology offers significant cost advantages in large-scale applications. However, current laser processing speed does not yet meet commercial high-throughput requirements, and parameter optimization for different produce types is still needed. Future work should focus on increasing etching speed, improving QR code recognition, and developing laser control algorithms better suited for varying surface characteristics to promote industrial application in produce packaging and traceability.

Paper link : https://doi.org/10.1016/j.jfp.2024.100329

**--Cite the article published by 高能束加工技术 on July 8, 2025, in the WeChat public account "High-Energy Beam Processing Technology and Applications."