raman spectroscopy

2. Application of raman
spectroscopy in food analysis

3. Contents:
 Introducton.
 Why Raman is used in Food analysis.
 Technique used in Food analysis.
 Application of RS in Food analysis.
 Conclusion.

4. Sir Chandrasekhara Venkata Raman
 November 7, 1888-
November 21, 1970
 work in the field of light
scattering.
 Nobel prize for physics in
1930.
 Discovered the “Raman
effect.”

5. Raman spectroscopy
 Raman spectroscopy is a non-destructive.
 Highly versatile technique.
 Perform both the qualitative and quantitative analysis for a
wide range of samples.

6. Why Raman is used in food
anailysis?
 Non-destructive technique
 High Specificity.
 Good compatibility for aqueous system.
 No special sample preparation.
 Short timescale.

7. Raman Techniques used in Food
Analysis
 Dispersive Raman spectroscopy.
 Fourier transform Raman spectroscopy.
 Surface-enhanced Raman spectroscopy.
 Spatially offset Raman spectroscopy.

8. Dispersive Raman Spectroscopy
 Common and basic
technique.
 Gas laser such as argon,
krypton ions or diodes.
 Combined with a CCD array
detector with a single-grating
detector.

9. Advantages of Dispersive
Raman spectroscopy
 Very suitable for aqueous- phase samples.
 Used for sample with elevated temperatures, above 100°C.
 black samples.
 It can suppress the flourescence of samples.

10. Fourier Transform Raman
Spectroscopy
 Available since 1987.
 Systems have a
YAG;Nd3+laser is used to
excited the sample.
 Flourescence is then
minimized.
 Instruments may be
combined with a microscope
or optical fibre.

11. Advantages of Fourier Transform
Raman Spectroscopy
 Reduces flourescene.
 Possesses high spectral resolution.

12. Surface-Enhanced Raman
Spectroscopy
 Two Enhancinng media.
i-Solid substrates.
ii-Colloidal nano-particles.
 Enhancedment of Raman
scattering by nanoparticles
adsorbed on sample surfaces.
 The total enhancement of
1014 times.

13. Advantages Surface-Enhanced
Raman Spectroscopy
 High molecule specificity.
 High sensitivity.
 High resolution.
 Perform for single molecule detection due to high signal
amplification.

14. Spatially Offset Raman
Spectroscopy
 Chemical analysis of objects
beneath obscuring surfaces.
 Example ,analysis of
tablets inside plastics bottles
or cold drinks inside bottles.

15. Advantages Spatially Offset
Raman Spectroscopy
 More effective illumination.
 Suppress flourescene.
 Facilitates analysis of a variety of samples.

17. Application of RS in Food
Analysis
Fruits and vegetables:
 Structural Analysis.
biomechanical behavior analysis of isolated tomato
 Safety Control.
FT-Raman approach to detect and classify food borne
microorganisms on the whole apple surface or on the citrus
fruit surface.
 Classification.
Classification of olive oli on the bases of fatty acid content.

19. Application of RS in Food
Analysis
Meat and Dairy Products:
 Determination of fat in milk powder.
 Conjugated linoleic acids (CLA) determination in cow’s
milk by FT-Raman spectroscopy.
 Determination of meat and fish quality parameters,
including protein, fat, and so on.
 The effect of external condition changes on meat and fish
structure.

21. Application of RS in Food
Analysis
Crops:
 Cacao:
determination of the chemical components in cacao.
 Raw cotton:
FT-Raman spectroscopy also determine the acetylation level of
natural cellulose fibers.
 Rice:
Raman spectroscopy used for differentiation of rice of two
geographical origins.

22. Application of RS in Food
Analysis
Oil:
 Adulteration of food.
 Raman spectroscopy used for classification of different
vegetable oils and quantification of adulteration of virgin olive
oils.

24. Application of RS in Food
Analysis
 Beverages:
 Raman spectroscopy can be used in quality and security control
of beverages.
 For pesticides or fungicides:
 SERS technology combined with gold-coated SERS-active nano-
substrates.
 To detect and characterize pesticides that extracted from the surfaces
of fruits.
 For bacterial identification:
 SERS coupled with silver nanosubstrates to detect the presence
of bacteria.

25. Conclusion
 Raman spectroscopy is a powerful tool to assess internal
quality and safety, due to many advantages such as
nondestructive detection, no sample preparation, and fast
measurement. Due to its narrow and sharply resolved bands,
Raman spectroscopy shows great potential in qualitative,
structural, and quantitative analysis. The industrial application
of this technology may be a realistic option in the near future.