NIRS principle and working

1. PREPARED BY: ALOK RANJAN
M. V. Sc. Scholar
ANIMAL NUTRITION DEPTT.

2. INTRODUCTION
Near infrared reflectance spectroscopy
(NIRS) is a nondestructive and rapid
technique applied increasingly for food
quality evaluation in recent years
The most wide spread use of NIRS
has been for determination of protein,
moisture, starch, lipids, ash, oil, and
salts

3. NIR SPECTRA

4. PRINCIPLE OF NIR
 NIR spectroscopy utilizes the spectral range from
780 to 2500 nm and provides much more complex
structural information related to the vibration
behavior of combination of bonds.
 The record of NIR region of the electromagnetic
spectrum involves the response of the molecular
bonds O=H, C=H, C=O, N=H.
 These are subjected to vibrational energy changes
when irradiated by NIR frequencies, and two
vibration patterns exist in these bonds including
stretch vibration and bent vibration.

5. CONT…
 The energy absorption of organic molecules in NIR
region occurs when molecules vibrate or is
translated into an absorption spectrum within the
NIR spectrometer.
 These special bonds also play an important part in
the field of chemical food chemical analysis, and
could extract information to analyze the chemical
structures.
 HORMONIC
OSCILLATION

6. MOLECULES THAT ABSORBS WAVELENGTH
NEAR INFRARED- ENERGY VIBRATE IN 2
MODES:
SRETCHING AND BENDING
 Streching Defines The Continous Change In The
Intratomic Distance Along The Axis Of Bonds
Between The Two Atoms
 Bending Defines Change In Bond Angle

8. THE SKETCH MAP OF NIR SPECTROMETER

9. CONT…
 Beam splitter used to translate multi –color light into
single –color light.
 Liquid sample, such as fruit juice often adopt glass or
quartz chamber with different sizes, while solid samples
use diffuse reflection carrrier accessories.
 Tungsten halogen lamps are used.
 A computer has software for data acquisition, analysis
control communication and numerical analysis within the
spectrometer system.
 The selection of wavelength regions, solution, scan
speed, number ,mode and sampling interval would
influence the precision and repetition of the experiment.

10. CALIBRATION PROCEDURE
 Calibration are based on the statistical analysis, termed
“chemometrics” of the relationship between mathematically
transformed spectra and frequency of chemical bonds in an
organic matrix.
 Quantitative analysis by NIRS is based on the Beer- Lamberts
law (crooks 1978)

11. .

12. SUMMERY
 specific light cause specific molecular vibrations
 wavelength of absorption characterizes molecules
 amount of energy absorption are then quantified

13. QUERIES ?