[4-1600-C] Postharvest/Food Technology and Process Engineering (4)

[4-1600-C-08] Measurement of Chicken Eggshell Optical Properties Using Terahertz Spectroscopy

*Alin Khaliduzzaman^1,3, Keiji Konagaya¹, Tetsuhito Suzuki¹, Ayuko Kashimori², Naoshi Kondo¹, Yuichi Ogawa¹ (1. Graduate School of Agriculture, Kyoto University(Japan), 2. NABEL Co., LTd.(Japan), 3. Department of Food Engineering and Technology, Sylhet Agricultural University(Bangladesh))

キーワード：Eggshell, Optical properties, Refractive index, Dielectric constant, Extinction co-efficient, Terahertz spectroscopy

Terahertz (THz) is a relatively new and under explored part of the electromagnetic spectrum that promises to be an extremely useful tool for research in the agricultural sciences. One such under explored area is how it interacts with biological objects like avian eggs. In this respect, chicken eggs are considered an ideal representative for avian studies. Eggshell plays various important roles such as protecting the internal contents and embryo of these eggs from ultraviolet (UV) rays, predators and contaminants. In addition, it provides major minerals for embryo development and facilitates embryonic respiration (i.e. gas exchange) during incubation. Electromagnetic waves below the THz range are limited in their ability to probe eggshell properties due to high absorbance and scattering effects in the UV, Visible and even NIR regions. Moreover, eggshell color pigment, called protoporphyrin, masks measurements in the Visible region. Therefore, we aim to measure the optical properties of the chicken eggshell using THz waves to obtain foundational data for researchers working on avian and reptile eggs. Moreover, this dataset could help to inform scientists regarding eggshell factors relevant to their research protocols. Optical properties of chicken (layer) eggshell, such as refractive index, dielectric constant and extinction co-efficient, were measured using Terahertz Time domain Spectroscopy (0.2 to 3.0 Terahertz). THz transmission and THz reflection were measured for broken eggshell and intact eggshell respectively. The refractive index of the eggshell increased slightly with increasing THz frequency; varying from 2.7 to 3.3. Whereas the extinction co-efficient sharply increased from 0.2 to 2.0 THz. The dielectric constant of the eggshell increased slightly from 7.0 to 10.2 in the 0.2 to 2.0 THz range. This research has shown that when probing the optical properties of crystalline structures with very low water content, such as eggshells, THz waves are an appropriate tool. The foundational properties documented in this research can be used in various applied research fields (e.g. applied optics, ecology, ornithology, evolutionary biology) in the future.