Texture Measurement

1
Texture Measurement

• Principles

2
Which test to use?

• Many food texture measurement techniques are
  available
• Many are empirical. They are not based on a
  theoretical approach rather, they have been
  tested and seem to correlate with a useful
  property

3
Classifications

• Many food systems and texture measurements exist
• Different classification schemes have been
  proposed

4
1. Type of Commodity Tested

• Cereal, meat, fish, poultry, vegetables, fruit,
  dairy, beverages, juices, nuts, legumes,
  oilseeds, etc
• Different industries have tended to develop their
  own unique methods for testing products

5
2. Food Type (Matz, 1962)

• Liquids
• Gels
• Fibrous foods
• Turgid cell clusters

• Unctuous foods
• Friable structures
• Glassy foods
• Gas-filled vesicles

6
Food Type (Amerine, 1965)

• Liquids
• Fruits and vegetables
• Meats
• Other foods

7
Food Type (Sone, 1972)

• Liquid foods
• Gel-like foods
• Fibriform foods
• Cellular-form foods
• Edible oils and fats
• Powdered foods

8
3. Type of Test Used
9
OBJECTIVE TESTS

• Well-defined, repeatable, physical
  interpretations
• May or may not correlate with sensor texture
• Tests at small deformations
• Mastication involves combinations of compression,
  shearing, tension
• Chewing involves transient temperatures
• Mastication introduces saliva and enzymes
• Sensory texture evaluation may involve a
  combination of sensory data

10

• However, perceived texture properties are rooted
  in objective properties of food
• A thin beverage will have a small Newtonian
  viscosity
• A viscoelastic solid with high ductility may be
  perceived as chewy
• Objective tests may also provide information
  about molecular structure and effects of
  processing

11
Fundamental Tests

• Measure specific rheological properties
• Shear modulus Viscosity
• Poissons ratio Storage modulus
• Complex viscosity Loss modulus
• Shear rate dependency
• Creep Stress
  relaxation
• As measured by viscometry, DMA, force/distance
  curves

12
Empirical Tests

• Measure properties that are hard to define, but
  correlate with sensory, quality, or processing
  parameters
• Advantages
• Correlate with texture parameter
• Quick and easy
• Inexpensive
• Disadvantages
• Poor defintion of property
• Limited standards
• Limited to particular commodities

13
Imitative Tests

• Mimic conditions uner which food is used
• Texturometer, TPA simulate chewing
• Farinograph imitates working of bread dough

14
Objective TestsFurther Breakdown

• Which variables are measured
• Force
• Distance
• Time
• Energy
• Ratios of these

15
(No Transcript)