Non-destructive inspection of food and technical oils by terahertz spectroscopy

Abstract

Quality control and non-destructive monitoring are of notable interest of food and pharmaceutical industries. It relies on the ability of non-invasive inspection which can be employed for manufacturing process control. We hereby apply terahertz (THz) time-domain spectroscopy as non-destructive technique to monitor pure and degraded oils as well as hydrocarbon chemicals. Significant differences in the spectra of refractive index (RI) and absorption coefficient arising from the presence of ester linkages in the edible and technical oils were obtained. Explicit increase from 1.38 to 1.5 of the RI in all THz spectrum range was observed in hydrocarbons and mono-functional esters with the increase of molar mass. This fact is in contrast of RI dependence on molar mass in multi-functional esters, such as Adipate or vegetable oils, where it is around 1.54. Degradation products, Oleic Acid (OA) and water in particular, lead only to some changes in absorption coefficient and RI spectra of vegetable oils. We demonstrate that complex colloidal and supramolecular processes, such as dynamics of inverse micelles and oil hydrolysis, take part during oil degradation and are responsible for non-uniform dependence of optical properties on extent of degradation.

Antenna-Coupled Titanium Microbolometers: Application for Precise Control of Radiation Patterns in Terahertz Time-Domain Systems

“…Terahertz time-domain spectroscopy (THz-TDS) is a distinctive example of a wideband electromagnetic radiation system invented more than three decades ago [ 1 ]. The THz spectroscopy is very powerful technique for the test and discrimination of different kind of materials [ 2 , 3 , 4 ]; it can successfully serve for a medical inspection [ 5 , 6 ], security aims [ 7 , 8 ], photovoltaics industry [ 9 , 10 ] as well as food control purposes [ 11 , 12 ].…”

Spurious Absorption Frequency Appearance Due to Frequency Conversion Processes in Pulsed THz TDS Problems

“…Is well known that the THz pulsed TDS is traditionally used for the detection and identification of explosive and illicit drug [1][2][3][4][5][6][7][8][9][10]. Moreover, it is currently considered to be a new powerful tool for application in the chemical sciences and molecular structure investigations [11][12][13][14], nondestructive inspections [15][16][17][18], thickness measurements [19,20], art investigations [21,22], pharmaceutical and biomedical applications [23][24][25][26], and food quality control [27][28][29]. In [30], a comprehensive review of the history and state of the art of the GaN-based devices for THz applications is provided.…”

Insights into the water status in hydrous minerals using terahertz time-domain spectroscopy

“…The exploitation of a novel technique allowing to circumvent many of the challenges thus becomes highly crucial for the fundamental understanding of water content in minerals. Terahertz time-domain spectroscopy (THz-TDS), as a state-of-the-art spectra technique over the past decade, has prevailed in biology 10–14 ; oils 15,16 ; and medical 17–19 because it can provide sufficient optical information of molecular level interactions by obtaining amplitude and phase data simultaneously 20,21 . THz-TDS adopts the terahertz-wave detection with higher signal-to-noise ratio (SNR) locating in frequencies (0.1–10 THz) between the far infrared and microwave 22,23 .…”