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Simple Texture Devices

Simple Texture Devices. Puncture Testers/Penetrometers. Devices used to measure the force required for a probe to penetrate the food Magness Taylor “Pressure testers” UC Fruit Firmness testers Ballauf, Chatillon, Effi-Gi

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Simple Texture Devices

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  1. Simple Texture Devices

  2. Puncture Testers/Penetrometers • Devices used to measure the force required for a probe to penetrate the food • Magness Taylor “Pressure testers” • UC Fruit Firmness testers • Ballauf, Chatillon, Effi-Gi • Maximum force is measured at which material yields (the material gives and exhibits irreversible damage)

  3. Dial stays at maximum force reached • Firmness of fruits related to ripeness or process • Firmness of vegetables due to maturity or processing

  4. Probes may be attached to TXAT2 or Instron

  5. The force changes in different ways after penetration A: Force increases after yield point B: Force levels off after yield point C: Force decreases after yield point D: Gradual increase in force after yield point E: Increasing force; no yield point observed

  6. The distribution in stress before puncture is uneven over the area of the probe

  7. The force-distance curves are determined both by compression and shearing

  8. Force on the punch is given by • F = KcA + KsP + C • where Kc is the compression coefficient (N mm-2), A the area of the punch (mm2), Ks is the shear coefficient (N mm-1), P is the perimeter of the punch (mm), and C is a constant. Note!! The skin greatly influences the results Typically it is first removed.

  9. Cone Penetrometer • Measure firmness/yield point of butter, margarines, solid fats • Allow cone to fall into sample by gravity after specific time (e.g. 5 secs)

  10. For fats, Haighton (1959) showed that the yield value C is related to the weight of the cone (W), the penetration depth (P), and a cone constant (K): • Dixon and Parekh (1979) describe butter firmness by:

  11. Distance Measuring Devices • Bostwick Consistometer • consistency of applesauce, catsup, baby food, carrot puree • distance (in cm) sample travels in 30 sec

  12. For curved surface, measure front edge 24 23 22 21 20 1 1 1 1 1 1 1 Ignore clear separated liquid

  13. Hilker-Guthrie Plummet: consistency of cream, yogurt. Graduated scale measures how for it Penetrates (read after 5 s)

  14. For cultured cream Very thin 0 - 2 Thin 2 - 4 Medium 4 - 6 Good 6 - 7.5 Slightly heavy 7.5 - 8.5 Heavy 8.5 - 10 Very heavy > 10

  15. Ridgelimeter: measures rigidity of pectin jellies • Jelly mad in proscribed conditions • At 24 hrs inverted on stage • Pointer tip lowered and zeroed true grade = assumed grade (2.0 - %sag/23.5)

  16. Ball Indenter: test hardness of fats and waxes

  17. Brinell Tester

  18. Haugh Meter: used to measure egg quality. Thick yolks that do not run indicate fresh, high quality eggs.

  19. Weigh egg, break shell • Spread on glass plate • Put center pin ~10 mm from edge of yolk • Turn to just touch albumen

  20. One measure of egg quality • Grade AA or Fancy Haugh units > 72 • Grade A Haugh units > 60

  21. USDA Consistometer: sample of defined dimensions placed in center of sheet containing concentric circles. • Distance of flow in 4 quadrants measured after 1 minute • Consistency of applesauce

  22. Take average of 4 quadrants

  23. USDA grades for apple sauce • Grade A Regular Flow < 6.5 cm • Grade A Chunky Flow < 7.5 cm • Grade B Regular Flow < 8.5 cm • Grade B Chunky Flow < 9.5 cm

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