Luminescence characteristics for identifying irradiated black soybeans

Area of Science:

• Food science and technology
• Analytical chemistry
• Radiation physics

Background:

• Food irradiation is a globally accepted method for extending shelf life and ensuring food safety.
• International trade of irradiated food necessitates reliable methods for authenticity verification.
• Black soybeans are a valuable agricultural commodity susceptible to irradiation for preservation.

Purpose of the Study:

• To evaluate the efficacy of Photostimulated Luminescence (PSL) and Thermoluminescence (TL) in identifying irradiated black soybeans.
• To differentiate between irradiated and non-irradiated black soybean samples originating from China or Korea.
• To establish reliable analytical techniques for verifying food irradiation in black soybeans.

Main Methods:

• Black soybean samples were subjected to gamma irradiation (Co-60) or electron beam irradiation at doses ranging from 0 to 5 kGy.
• Photostimulated Luminescence (PSL) analysis was performed to measure photon counts.
• Thermoluminescence (TL) analysis was conducted, including measurement of initial (TL₁) and re-irradiated (TL₂) glow curves.

Main Results:

• PSL photon counts were significantly higher in irradiated samples and increased proportionally with irradiation dose.
• TL analysis revealed distinct glow curves with higher intensity at approximately 200°C for irradiated samples compared to non-irradiated ones.
• TL ratios (TL₁/TL₂) and the shape of TL₁ glow curves provided clear differentiation between irradiated and non-irradiated black soybeans.

Conclusions:

• PSL and TL are highly effective methods for screening and confirming the irradiation of black soybeans.
• These luminescence-based techniques can reliably distinguish between gamma ray or electron beam irradiated and non-irradiated black soybeans.
• The study validates PSL and TL as essential tools for regulatory control and consumer protection in the irradiated food market.