TEXTURE PROFILE ANALYSIS

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TEXTURE PROFILE ANALYSIS

• Instrumental Method

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Texture Analyzers

• Module based instruments
• different load cells
• different probes/attachments/fixtures
• Crosshead moves at constant speed giving linear
  deformation
• Forces vary from 2N to 5kN
• Overhead load cell eliminates crumbs and force
  due to sample weight

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Texture Technologies
Shimadzu
Instron
Gardco
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These carefully measure force and work to cause
some action on the food

-Compressive force shown directly vs time (speed
4 mm/s) -The work done on the sample up to 3mm is
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Texture Profile Analysis

• Attempt to correlate instrumental measurements
  with sensory descriptions
• First developed by Friedman Szczesniak (1963) at
  the General Foods Corporation General Foods
  Texturometer
• Modified by Malcolm Bourne for the Instron
• Bite-sized food compressed 2 times to simulate
  chewing

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• 1 cm3 (bite size pieces) compressed (and
  decompressed) 2 times
• Deformation typically 75-90 of height
• Follow force-time curve

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Down
Down
Up
Up

Force
Time
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Definitions

• Fractuability
• force required to produce first significant
  break in the curve on the first bite.
• Popular terms crumbly, crunchy, brittle

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Second bite
First bite
Down
Up
Down
Up
Fracturability

Force
Time
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• Hardness
• force exhibited in first bite at maximum
  compression
• Popular terms soft, firm, hard

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Down
Up
Down
Up
Fracturability

Hardness
Force
Time
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• Cohesiveness
• ratio of the positive force areas under first
  and second compressions (A2/A1) Usually use only
  areas under the compression part of curve (not
  decompression), i.e. up to the dotted lines in
  the figures.

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Down
Up
Down
Up
Fracturability

Hardness
A2
Cohesiveness
A1
A1
Force
A2
Time
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• Adhesiveness
• work to pull the plunger away from the sample
  after the first compression (A3)
• Popular terms sticky, tacky, gooey

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Down
Up
Down
Up
Fracturability

Hardness
A1
Force
A2
A3
Adhesiveness A3
Time
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• Springiness
• Distance over which the material recovers its
  height between the end of the first bite and the
  start of the second bite (BC)
• Popular terms plastic, elastic

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Down
Up
Down
Up

A1
Force
A2
A3
Springiness
Time
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• Springiness sometimes defined differently, such
  as by a ratio

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Down
Up
Down
Up
A1
Force
A2
A3
L1
L2
Time
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• Gumminess
• hardness X cohesiveness
• Popular terms short, mealy, pasty, gummy

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• Chewiness
• gumminess X springiness

Dont report both gumminess and chewiness for the
same food!
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A few terms have been recently added . . .

• Stringiness the distance that the product is
  extended during decompression before separating
  from the probe.

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Down
Up
Down
Up
Stringiness
A1
Force
A2
A3
Time
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• Resilience A measurement of how the sample
  recovers from deformation.
• Ratio of the first UP ( decompression) stroke to
  the first DOWN ( compression) stroke

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Down
Up
Down
Up
A5
A1
Force
A2
Time
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• Initial Modulus Initial Stress/Initial Strain
• Initial Stress taken as mean force from 0.5 -1.5
  secs and then dividing by the contact Area
• Initial Strain calculated at the 1.5 second
  point

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Force
F1.5
1.5
Time (s)
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GF Texture Profile Analyzer

• Similar to Instron but smaller scale and adapted
  to food use only
• Instron vs Texturometer
• Texturometer speed is sinusoidal, Instron speed
  is constant
• Instron has sharper peaks
• Instron force-time curve can be related to
  force-distance

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Studies by the General Foods Group showed good
correlations with sensory ratings. For
example, A. S. Szczesniak et al. Classification
of textural characteristics. J. Food
Sci. 28 385-389
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• TPA has been used on a wide variety of foods
• Review by W. M. Breene (1975). Application of
  texture profile analysis to instrumental food
  texture evaluation. J. Texture Studies 6 53-82
• Do correlations with sensory evaluations exist
  for all products?