Shielding Your Snacks: The Crucial Role of UV-Blocking Food Packaging

Importance of the Topic

Ultraviolet (UV) radiation can accelerate degradation of food products via photo-oxidation and other light-catalyzed reactions, reducing shelf life and compromising safety. At the same time, visible light transparency is often required for consumer appeal. Assessing the UV-visible light transmission properties of packaging materials is therefore critical for ensuring both functional protection and aesthetic quality in the food industry.

Objectives and Overview of the Study

This application note reports a systematic evaluation of the total transmission of UV (200–400 nm) and visible (400–900 nm) light through various plastic food packaging samples. The study employs the Agilent Cary 60 UV-Visible spectrophotometer equipped with an internal diffuse reflectance accessory (DRA) to provide accurate, reproducible measurements of both specular and diffuse transmission in solid films.

Methodology

Sample Preparation:

• Cut 4 × 4 cm pieces from five packaging types: candied ginger packet, gummy bear wrapper, sesame seed bar wrapper, rice package film, and milk and water bottles.
• Clean each piece with distilled water and laboratory tissue to remove residues and fingerprints.

Measurement Procedure:

• Mount samples in the DRA’s solid film holder, using a 6 mm aperture insert and a PTFE plug to cover the reflection port.
• Collect a 100 % transmittance baseline without a sample in the port.
• Acquire five repeat spectra per sample over 200–900 nm with 1 nm data interval and 0.1 s averaging time, rotating and repositioning each sample between scans to account for surface inhomogeneity.

Used Instrumentation

• Agilent Cary 60 UV-Visible Spectrophotometer
• Internal Diffuse Reflectance Accessory (DRA) with solid film sample holder
• Cary WinUV Software for spectrum acquisition

Main Results and Discussion

The transmission profiles reveal that most packaging films exhibit a sharp absorption edge in the UVB/UVA transition region and high transparency in the visible range:

• Candied ginger and rice packages show an absorption edge around 330 nm, blocking most UVB while transmitting >85 % of visible light.
• Gummy bear and sesame wrappers absorb strongly below 305 nm and transmit >90 % above this threshold.
• Milk bottle material transmits only ~70 % of visible light and permits some UV transmission, indicating lower opacity.
• Water bottle exhibits the lowest UV transmittance (~29 %) and high visible transparency (~89 %).

The mean transmittance over 200–400 nm ranged from 28.9 % to 50.0 %, and over 400–900 nm from 70.6 % to 92.2 %. Average standard deviations were below 0.6 %T, demonstrating excellent measurement precision.

Benefits and Practical Applications of the Method

The combination of the Cary 60 spectrophotometer and internal DRA provides a rapid, user-friendly workflow for quality control of food packaging. It enables manufacturers to:

• Verify UV barrier performance to extend product shelf life.
• Ensure visual clarity meets brand and consumer expectations.
• Detect film inhomogeneities through reproducible diffuse and specular transmission measurements.

Future Trends and Possibilities for Application

Advances in packaging technology may focus on:

• Novel UV-absorbing polymer additives and nanocomposite films with tunable transmission properties.
• Integration of inline UV-Vis transmission testing in manufacturing lines for real-time quality control.
• Development of smart packaging materials combining UV protection with indicators for food freshness.

Conclusion

The Agilent Cary 60 UV-Vis spectrophotometer with internal DRA delivers reliable, high-precision measurements of UV and visible light transmission in diverse food packaging films. This approach supports rapid QC workflows, helping producers ensure packaging efficacy and product safety.

References

1. Roy S., Ramakrishnan R., Goksen G., Sunita Singh, Łopusiewicz L. Recent Progress on UV-light Barrier Food Packaging Films – A Systematic Review. Innovative Food Science & Emerging Technologies. 2024; 91: 103550. DOI: 10.1016/j.ifset.2023.103550.