Calibration and testing of a Raman hyperspectral imaging system to reveal powdered food adulteration

PLoS One. 2018 Apr 30;13(4):e0195253. doi: 10.1371/journal.pone.0195253. eCollection 2018.

Abstract

The potential adulteration of foodstuffs has led to increasing concern regarding food safety and security, in particular for powdered food products where cheap ground materials or hazardous chemicals can be added to increase the quantity of powder or to obtain the desired aesthetic quality. Due to the resulting potential health threat to consumers, the development of a fast, label-free, and non-invasive technique for the detection of adulteration over a wide range of food products is necessary. We therefore report the development of a rapid Raman hyperspectral imaging technique for the detection of food adulteration and for authenticity analysis. The Raman hyperspectral imaging system comprises of a custom designed laser illumination system, sensing module, and a software interface. Laser illumination system generates a 785 nm laser line of high power, and the Gaussian like intensity distribution of laser beam is shaped by incorporating an engineered diffuser. The sensing module utilize Rayleigh filters, imaging spectrometer, and detector for collection of the Raman scattering signals along the laser line. A custom-built software to acquire Raman hyperspectral images which also facilitate the real time visualization of Raman chemical images of scanned samples. The developed system was employed for the simultaneous detection of Sudan dye and Congo red dye adulteration in paprika powder, and benzoyl peroxide and alloxan monohydrate adulteration in wheat flour at six different concentrations (w/w) from 0.05 to 1%. The collected Raman imaging data of the adulterated samples were analyzed to visualize and detect the adulterant concentrations by generating a binary image for each individual adulterant material. The results obtained based on the Raman chemical images of adulterants showed a strong correlation (R>0.98) between added and pixel based calculated concentration of adulterant materials. This developed Raman imaging system thus, can be considered as a powerful analytical technique for the quality and authenticity analysis of food products.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzoyl Peroxide / analysis
  • Calibration
  • Capsicum / chemistry
  • Congo Red / analysis
  • Equipment Design
  • Flour / analysis
  • Food Contamination / analysis*
  • Lasers
  • Powders / chemistry*
  • Spectrum Analysis, Raman / instrumentation*
  • Spectrum Analysis, Raman / methods
  • Triticum / chemistry
  • User-Computer Interface

Substances

  • Powders
  • Congo Red
  • Benzoyl Peroxide

Grants and funding

This work was supported by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries(IPET) through Agriculture, Food and Rural Affairs Research Center Support Program, funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA), Republic of Korea (No. 717001071WT111) and partly by research funds from the Golden Seed Project, Ministry of Ocean and Fisheries, Rural Development Administration, and Korea Forest Services.