This document discusses near infrared reflectance spectroscopy (NIRS) and its principles. NIRS is a nondestructive technique used to evaluate food quality by determining components like protein, moisture, starch and lipids. It works by measuring the absorption of near infrared light as it interacts with molecular bonds in organic materials. Different bonds like C=H, C=O and N=H absorb different wavelengths. The absorbed energy is detected to create a spectral profile that can be analyzed using chemometrics to quantify various chemical components through calibration.

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 ?