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Presented by:
Deepika Kathuria
ID No. 41813
M.Sc. Food Technology
Department of Food Science and
Technology
After this seminar audience is
expected to have
better insight into purpose and
techniques of non-destructive
quality evaluation of foods
understanding of basic
concepts, methods and
apparatus used
enhance exposure as to how
these techniques may be used
in research
Background
X-ray
(1st
NDT)
1940 - 1944 Ultrasonic test method developed in USA by Dr.
Floyd Firestone
To detect the presence of inhomogeneities of density or elasticity
in materials
In 1932, the first European who was an Italian built a magnetic
particle crack detector: Giraudi. His machine was named
"Metalloscopio".
Penetrant Testing started in second half of 19th century
People who applied the "Oil and Whiting"-process for crack
detection to railway-components are unknown. Now, called as
Morden Liquid Penetration technique.
1935 - 1940s Eddy current instruments developed
Background Continued…
Protect food from
distortion
Non destructive technique
Determination of
surface and internal defect
Concept
Definition
Source: Adapted from Anonymous (2016)
Non destructive technique (NDT) is the non
invasive technique used for inspecting,
testing, or evaluating materials, components
or assemblies for discontinuities, or
differences in characteristics without
destroying the serviceability of the part or
system. It helps in determining the surface or
internal defects without interfering the
material and its suitability for services
Limitations of traditional methods
of food quality evaluation
Significant distortion or damage to the product
Higher requirement of time and man power
Economic losses due to product destruction
Measure quality in batches
Determines only one or a few properties of the
material
Advantages of non-destructive
techniques
Limitations of NDT
Expensive installation
Requires experts to work
with instruments
Proper maintenance of
equipment is required
Applications of NDT in food
industry
Plate 1: Sorting of apples using NDT
Source: Anonymous
(2016)
Sorting of apple using non destructive technique
Plate 2: Online near infrared analyzer Corona to perform compositional analysis
in food production (Carl Zeiss GmbH, Jena).
Source: Irudayaraj and Reh
(2008)
Online compositional analysis of food using near
infrared analyzer
S.N
o. Methodology Technique
being used
Components
1. Optics Image analysis Size, shape, colour, outward defects
Spectroscopy
(NIR)
Sugar, acidity, soluble solid content, colour,
internal and external defects, stiffness
2. X-ray X-ray image
and CT
The inner cavity structure, the degree of
maturity
3. Mechanics Ultrasound Stiffness, viscoelasticity, internal cavity,
density, sugar
Acoustic Stiffness, viscoelasticity, internal cavity,
density, sugar, texture
4. Electromagnetic NMR/MRI Sugar, moisture content, the inner cavity
5. Chemical E-nose and E-
tongue
Acidity, sugar, odour, flavour
Non-destructive methods to evaluate the quality
characteristics of agricultural and food products
Source: Aboonajmi and Faridi (2016)
1. Optics
1.1 Imaging analysis
Imaging techniques
Provide spatial information from electromagnetic spectrum
Determine quality and detect safety
Classification and sorting of agricultural produces
Human eye sees visible light in three bands, i.e. red, green and blue
whereas spectral imaging divides the spectrum into many bands
Plate 3: Bands obtained during imaging analysis
1.1.1 Hyper spectral imaging system
Principle
Difference in the chemical composition and inherent physical
structure, reflect, scatter, absorb and emit electromagnetic
energy in distinctive patterns at specific wavelengths
Fig. 1: Hyperspectral spatial and spectral information
Spectral signature of pizza components
This characteristic is called spectral signature or spectral
fingerprint, or simply the spectrum
• Similar spectral patterns will indicates similarity in chemical
composition
• Different concentrations of the major chemical compositions make
the difference in reflectance (absorbance) values at some key
wavelengths.
Fig. 2: Spectral signature of pizza components
1.1.2 Multispectral imaging system
Langreo et al. (2014) determine
the efficiency of MRI by
detecting the foreign material
present in powdered food by
incorporating peanut powder
into wheat flour. Plate 4: Segmented images for 10 %
adulteration (left) and 0.01 % (right)
Factor Hyperspectral Multispectral
Number of spectral band More than 10 Less than 10
Wavelength range
required
More Less
Spaced bands pattern Regular Not regular
Pixel image Full spectrum No real spectrum
Eight sample of peanut adulterated in flour were prepared ranging
from 10 to 0.01 % by weight
Fig. 3: The average absorbance spectra of the reference samples of pure peanut and wheat
flour.
Absorbance spectra of wheat and peanut flour
A positive correlation was found between actual and predicted value with
r²=0.956. Results show the feasibility of the proposed index to detect peanut
adulteration up to 0.01%.
Fig. 4: Correlation plot between actual vs. predicted percentage of peanut adulteration in
wheat flour samples.
Precision of multispectral system to detect peanut flour
1.2 Spectroscopy
1.2.1 NIR (Near Infrared Resonance)
Principle
Based on optical properties that respond of matter to
near-infrared (0.7-25 μm) where the light either get
absorbed, reflected or transmitted
• Simple, accurate and expeditiousness
• Require minimum sample preparation
Concept of NIR
Thin skin and homogenous pulp
Thick skin and high water content
Penetration power of NIR
• Restricted to fruits with homogeneous pulp and thin skin
• Assess soluble solid content (SSC), titratable acidity and/or
other physiological properties in intact fruits such as in prune,
stonefruit and apricot
• High penetration in range of 0.7-0.9 μm.
Full transmittance
measuring system
Half transmittance
measuring system
Reflectance measuring system
NIR spectrometer measuring method
Plate 5: Different NIR spectrometer measuring methods
Source: Chio et al. (2006)
Precision of NIR
Fig. 5: Soluble solid contents of tomatoes
Slaughter et al. (1996) determine the soluble solid content of tomatoes of 30
popular varieties including Arletta, Better Bush, Celebrity, Early girl, Heat
wave, Jackpot, Sunny, Tango, etc were harvested in stage of maturity from
green to ripe red fruit.
The optical absorption spectrum from 400 to 110 nm was measured at five
different location in a sequential manner (first four at equator and fifth at
blossom end)
Calibrated result of fructose and glucose in
kiwifruit
Slaughter and Crisosto, 1998 determining the intemal quality of
intact kiwifruit by measuring fructose content (r = 0.96, SEC =
1.96%), glucose content (r = 0.97, SEC = 1.68%), soluble solids
content (r = 0.99, SEC = 0.78"Brix), and dry weight (r = 0.97, SEC =
0.61%) of kiwifruit.
Fig.6: Calibrated result of fructose and glucose using NIR
2. X ray and
Computed
tomography
Principle
Uses and application
Fig. 7: X-ray CT images showing the radial and longitudinal internal sections of
peaches; (a) fresh; (b) ripened for one week; (c) ripened for two weeks
Source: Barcelon et al. (1999)
X-ray image of peaches
3. Mechanics
Ultrasonic waves (above the range of human hearing i.e. 20 KHz to 1
MHz) and acoustic sound waves (in the range of human hearing i.e. 20
Hz to 20 KHz) are used to evaluate the quality of fresh vegetables non-
destructively
3.1 Ultrasonic waves
Principle
Ultrasound is generated by a transducer containing a ceramic
crystal which is excited by a short electrical pulse having
several sine cycles is converted into mechanical wave that
propagate as a short sonic pulse
Used to quantify relation with the ripening, maturity, firmness
and other internal quality of fruit and vegetables
Meftah and Azimin (2012) demonstrate the potential of
ultrasonic for detecting foreign bodies in canned products by
mounting a transducer to the side of can
Plate 6: Working model of ultrasonic wave
Transduc
er
Sound wave
specimen
Uses and application
Fig. 8: Can attached with transducer
Three types of foreign bodies were deliberately introduced
i.e.
1.FB1: a rock of dimension 62 x 38 mm,
2.FB2: an aluminium plate of dimension 30 x 23 x 4 mm
3.FB3: an aluminium plate of dimension 122 x 21 x 1 mm.
Oil was used to couple the
ultrasonic pulse to the specimen.
A TD Scan Advanced
Ultrasonic Inspection System
was used to drive the transducer
and to receive the echo signal.
The result was displayed on the
TD Scan monitor in real time
Ultrasonic inspection of cans
FB2
CONTROL
FB1 FB3
Fig. 9: Ultrasonic image of canned products indicating presence of foreign material
Ultrasonic image of canned products
3.2 Acoustic
Principle
In acoustic sound, a device used to lightly tap or thump the
commodity to create a sound wave that pass through the
product tissue which is then scattered, transmitted or reflected
from the object
Acoustic emission (AE) is an important attributed quality of
food texture specially snack type food
Crunchiness and crispness, which are noticed as signs of
freshness, are other aspects of acoustic properties.
Alteration of food texture can be measured by analysis of the
emitted sound
4. Electromagnetic
4.1 Nuclear magnetic resonance
Principle
When nuclei with a magnetic moment, like protons, are
placed in an external magnetic field, it align along the
magnetic field direction and rotate about their own axes at a
specific frequency Ѡ and develops a net macroscopic ₀
magnetization M
α
Now, NMR is well known as magnetic resonance imaging
(MRI)
MRI measure the NMR properties of a sample as a function of
spatial position
Pulsed linear magnetic field gradients are used to produce
frequency variations across the sample which are converted into
spatial coordinates
Energy absorbed by
the nuclei
Number of a particular
nucleus in the sample such as
the protons in water or oil
Properties of MRI
Application
(Chen et al., 1993) find a
desirable features for high
speed sorting using a
surface-coil NMR probe
that determine the
oil/water resonance peak
ratio of the signal from one
region in an intact fruit.
Fig. 10: Sorting of cherries using NMR
(Chen et al., 1993) use MRI based sensor for on-line
grading of cherries
A set of 39 cherries were used with spin-echo pulse
sequence was used to acquire one-dimensional
images
The cherries(both whole and pitted) were placed on
the sample holder, the pitting direction must be
perpendicular to the moving direction in order to
detect clear distinctions
Results were classified based on valley to peak ratio
If a valley to peak ratio is greater than or equal to the
threshold value it is classified as a whole cherry.
Results based on NMR
Speed
mm/s
Threshold
value
State Total no. Correctly
classified
no.
Missclassifie
d no.
Error%
0 0.79 Whole 117 115 1 1
Pitted(z) 27 8 19 70
Pitted(y) 90 88 2 2
50 0.79 Whole 117 117 0 0
Pitted(z) 27 6 21 78
Pitted(y) 90 88 2 2
150 0.80 Whole 117 117 0 0
Pitted(z) 27 9 18 67
Pitted(y) 90 88 2 2
250 0.81 Whole 117 117 0 0
Pitted(z) 27 8 19 70
Pitted(y) 90 89 1 1
Classification errors at four different sample speeds.
5. Chemical
5.1 E-nose: A device intended to detect, identify and
quantify specific component of odors and flavors
Principle
Signal
[Analyte]
Feature extraction and
pattern recognition
Raw data
acquisition
Sensor
Array
Sample
Sample delivery
system
Computing systemDetection system
Array-Based E-Noses
Fig. 11: Actual and predicted value of TVC in beef(left) and sheep(right)
Precision using E-nose
5.2 E-tongue: An array of sensors that are immersed in
liquids, in order to identify their different physical-chemical
characteristics, for example, “tastes”.
Principle
Working Electrode: Serves as a surface where electrochemical
redox reaction takes place. Surface area should very less (few mm²)
to limit current flow.
Reference Electrode: Measure the working electrode potential.
Auxiliary electrode: It completes the cell circuit. It is generally
inert conductor. The current flow into the solution via the working
electrode leaves the solution via the counter electrode.
A relay box is used, enabling the working electrodes to be
connected consecutively to form four standard three electrode
configurations giving rise to measured current. The potential
pulses/steps are applied by a potentiostate which is controlled
by a PC. The PC is used to set and control the pulses, measure
and store current responses and to operate the relay box
Figure12: Working model of E-nose
Working model of E-nose
Anonymous. 2016. Industry experience apple sorting.
http://tao.umd.edu/html/industry_exp_.html . Acessed on 28/08/2016.
Anonymous . 2016. introduction to non destructive testing. American
society for non destructive testing.
https://www.asnt.org/MinorSiteSections/AboutASNT/Intro-to-NDT.
Acessed on 8/9/2016.
Chio. 2006. non destructive quality evaluation technology in fruits
and vegetables using near-infrared spectroscopy.
http://ring.ciard.net/node/10603
Irudayaraj, J. and Reh, C. 2008. Nondestructive testing of food
quality. Blackwell Publishing and the Institute of Food Technologists,
USA. pp2-5.
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