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TEXTURE PROFILE ANALYSIS . Instrumental Method. 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

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texture profile analysis

TEXTURE PROFILE ANALYSIS

Instrumental Method

slide2

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
slide3

Texture

Technologies

Shimadzu

Instron

Gardco

these carefully measure force and work to cause some action on the food
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

texture profile analysis1
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
slide6
~1 cm3 (bite size pieces) compressed (and decompressed) 2 times
  • Deformation typically 75-90% of height
  • Follow force-time curve
slide18

Down

Down

Up

Up

Force

Time

definitions
Definitions
  • Fractuability

force required to produce first significant break in the curve on the first bite.

  • Popular terms: crumbly, crunchy, brittle
slide20

Second bite

First bite

Down

Down

Up

Up

Fracturability

Force

Time

slide21
Hardness

force exhibited in first bite at maximum compression

  • Popular terms: soft, firm, hard
slide22

Down

Down

Up

Up

Fracturability

Hardness

Force

Time

slide23
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.

slide24

Down

Down

Up

Up

Fracturability

Hardness

A2

Cohesiveness =

A1

A1

Force

A2

Time

slide25
Adhesiveness

work to pull the plunger away from the sample after the first compression (A3)

  • Popular terms: sticky, tacky, gooey
slide26

Down

Down

Up

Up

Fracturability

Hardness

A1

Force

A2

A3

Adhesiveness = A3

Time

slide27
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
slide28

Down

Down

Up

Up

A1

Force

A2

A3

Springiness

Time

slide30

Down

Down

Up

Up

A1

Force

A2

A3

L1

L2

Time

slide31
Gumminess

hardness X cohesiveness

  • Popular terms: short, mealy, pasty, gummy
slide32
Chewiness
  • gumminess X springiness

Don’t report both gumminess and chewiness for the same food!

a few terms have been recently added
A few terms have been recently added . . .
  • Stringiness: the distance that the product is extended during decompression before separating from the probe.
slide34

Down

Down

Up

Up

Stringiness

A1

Force

A2

A3

Time

slide35

Resilience: A measurement of how the sample recovers from deformation.

  • Ratio of the first UP ( decompression) stroke to the first DOWN ( compression) stroke
slide36

Down

Down

Up

Up

A5

A1

Force

A2

Time

slide37

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
slide38

A1

Force

F1.5

1.5

Time (s)

gf texture profile analyzer
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
slide41

Studies by the General Foods Group showed good correlations with sensory ratings.

For example, A. S. Szczesniaket al. Classification of textural characteristics. J. Food Sci. 28: 385-389

slide42
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?