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TEXTURE PROFILE ANALYSIS

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

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  1. TEXTURE PROFILE ANALYSIS Instrumental Method

  2. 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

  3. Texture Technologies Shimadzu Instron Gardco

  4. 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

  5. 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

  6. ~1 cm3 (bite size pieces) compressed (and decompressed) 2 times • Deformation typically 75-90% of height • Follow force-time curve

  7. INSTRON

  8. INSTRON

  9. INSTRON

  10. INSTRON

  11. INSTRON

  12. INSTRON

  13. INSTRON

  14. INSTRON

  15. INSTRON

  16. INSTRON

  17. INSTRON

  18. Down Down Up Up Force Time

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

  20. Second bite First bite Down Down Up Up Fracturability Force Time

  21. Hardness force exhibited in first bite at maximum compression • Popular terms: soft, firm, hard

  22. Down Down Up Up Fracturability Hardness Force Time

  23. 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.

  24. Down Down Up Up Fracturability Hardness A2 Cohesiveness = A1 A1 Force A2 Time

  25. Adhesiveness work to pull the plunger away from the sample after the first compression (A3) • Popular terms: sticky, tacky, gooey

  26. Down Down Up Up Fracturability Hardness A1 Force A2 A3 Adhesiveness = A3 Time

  27. 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

  28. Down Down Up Up A1 Force A2 A3 Springiness Time

  29. Springiness sometimes defined differently, such as by a ratio

  30. Down Down Up Up A1 Force A2 A3 L1 L2 Time

  31. Gumminess hardness X cohesiveness • Popular terms: short, mealy, pasty, gummy

  32. Chewiness • gumminess X springiness Don’t report both gumminess and chewiness for the same food!

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

  34. Down Down Up Up Stringiness A1 Force A2 A3 Time

  35. Resilience: A measurement of how the sample recovers from deformation. • Ratio of the first UP ( decompression) stroke to the first DOWN ( compression) stroke

  36. Down Down Up Up A5 A1 Force A2 Time

  37. 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

  38. A1 Force F1.5 1.5 Time (s)

  39. 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

  40. 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

  41. 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?

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