A 1064 nm Dispersive Raman Spectral Imaging System for Food Safety and Quality Evaluation

Abstract

Raman spectral imaging is an effective method to analyze and evaluate the chemical composition and structure of a sample, and has many applications for food safety and quality research. This study developed a 1064 nm dispersive Raman spectral imaging system for surface and subsurface analysis of food samples. A 1064 nm laser module is used for sample excitation. A bifurcated optical fiber coupled with Raman probe is used to focus excitation laser on the sample and carry scattering signal to the spectrograph. A high throughput volume phase grating disperses the incoming Raman signal. A 512 pixels Indium-Gallium-Arsenide (InGaAs) detector receives the dispersed light signal. A motorized positioning table moves the sample in two-axis directions, accumulating hyperspectral image of the sample by the point-scan method. An interface software was developed in-house for parameterization, data acquisition, and data transfer. The system was spectrally calibrated using naphthalene and polystyrene. It has the Raman shift range of 142 to 1820 cm −1 , the spectral resolution of 12 cm −1 at full width half maximum (FWHM). The spatial resolution of the system was evaluated using a standard resolution glass test chart. It has the spatial resolution of 0.1 mm. The application of the system was demonstrated by surface and subsurface detection of metanil yellow contamination in turmeric powder. Results indicate that the 1064 nm dispersive Raman spectral imaging system is a useful tool for food safety and quality evaluation.

Detection of Azo Dyes in Curry Powder Using a 1064-nm Dispersive Point-Scan Raman System

“…The Raman spectrograph uses a high throughput volume phase grating (VPG) (BaySpec, Inc., San Jose, CA, USA) optimized for 1064 nm laser excitation [28]. The scattering Raman signal from the sample is directed to the VPG through a concave mirror in the spectrograph.…”

“…This study used a newly developed 1064 nm dispersive Raman system [28] to measure curry powder mixed with Sudan-I and (separately) with metanil yellow at different concentrations for detection of Sudan-I and metanil yellow contamination in curry powder. This study further demonstrates the use of the 1064 nm Raman system for simultaneous detection of multiple contaminants (Sudan-I and metanil yellow) in curry powder.…”

Quantum Calibration of Photon-Number-Resolving Detectors Based on Multi-Pixel Photon Counters

“…Traditional single-photon detectors such as Si-APD and InGaAs APD are unable to resolve the number of incident photons, though they are fully developed and applied in various fields [20]. In order to obtain the information of the incident photon statistics, considerable progress has been made in the development of PNRDs, including direct PNRDs [21] and multiplexed PNRDs [22].…”

Inspection of maleic anhydride in starch powder using line-scan hyperspectral Raman chemical imaging technique

“…Our group has developed macro-scale Raman chemical imaging techniques for direct inspection of various food powders and ingredients. Two point-scan hyperspectral Raman imaging systems were developed using 785 nm [10] and 1064 nm [11] point lasers, respectively. The point-scan systems have been used to detect chemical adulterants mixed in the food powders, such as melamine in milk powder [12] and metanil yellow in turmeric powder [11] .…”

“…Two point-scan hyperspectral Raman imaging systems were developed using 785 nm [10] and 1064 nm [11] point lasers, respectively. The point-scan systems have been used to detect chemical adulterants mixed in the food powders, such as melamine in milk powder [12] and metanil yellow in turmeric powder [11] . A more efficient line-scan hyperspectral Raman imaging system using a 785 nm line laser was also developed to implement high-throughput chemical imaging for food safety research [13,14] .…”