Detection of Foreign Bodies in Foods Using Continuous Wave Terahertz Imaging

Abstract

Foreign bodies (FBs) in food are health hazards and quality issues for many food manufacturers and enforcement authorities. In this study, continuous wave (CW) terahertz (THz) imaging at 0.2 THz with an output power of 10 mW was compared with X-ray imaging as techniques for inspection of food for FBs. High-density FBs, i.e., aluminum and granite pieces of various sizes, were embedded in a powdered instant noodle product and detected using THz and X-ray imaging. All aluminum and granite pieces (regular hexahedrons with an edge length of 1 to 5 mm) were visualized by both CW THz and X-ray imaging. THz imaging also detected maggots (length = 8 to 22 mm) and crickets (length = 35 and 50 mm), which were embedded in samples as low density FBs. However, not all sizes of maggot pieces embedded in powdered instant noodle were detected with X-ray imaging, although larger crickets (length = 50 mm and thickness = 10 mm) were detected. These results suggest that CW THz imaging has potential for detecting both high-density and low-density FBs embedded in food.

Coherent synthesis of terahertz radiation from femtosecond laser filaments in air

“…THz spectroscopy is ideally suited for the identification of biological or complex inorganic molecules [1], the study of collective excitations in condensed media [2][3][4], for plasma diagnostics [5]. Applications of THz radiation range from medicine [6], food industry process control [7], to security concerns [8], telecommunication [9], etc. Impressive progress has been achieved in the last few years in the development of intense THz sources.…”

High-performance sub-terahertz transmission imaging system for food inspection

“…Moreover, according to the previous reports on food quality monitoring by continuous-wave (CW) sub-THz imaging, it has been shown that even low-density organic materials can be well discriminated at these frequencies [4,[11][12][13]. This implies that the sub-THz imaging technique displays distinctive advantages for food quality inspection compared to conventional X-ray imaging systems.…”

“…Even though the X-ray systems are useful for discriminating both metallic and nonmetallic materials in food products, the identification of low-density objects (often organic materials such as insects and plastics) is known to be challenging [2]. Thus, complications caused by the presence of those flaws in food products are still being reported, and this represents a significant concern for many food manufacturers and food retailers [3,4].…”

Effect of X-ray exposure on the pharmaceutical quality of drug tablets using X-ray inspection equipment

“…In addition, X-ray inspection equipment has been used often in the food industry 18 due to its highthroughput (detecting and sorting) and good penetration capabilities, compared with alternative technologies such as terahertz and sub-terahertz imaging 19,20 . These useful technologies have expanded to the pharmaceutical industry, where companies have demonstrated their use for inspecting drug packages to detect foreign matter and wrong or missing contents.…”