Food Texture

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Food Texture

• What is It?

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TEXTURE IS A QUALITY FACTOR

• Nutrition protein, carbohydrate, vitamins
  minerals
• Appearance color, shape, size, etc (visual)
• Flavor taste(tongue), odor (nose)
• Texture tactile contact with some part of body
  and food

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What is Food Texture?
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• Physical properties derived from food structure
• Mechanical or rheological science
• Group of properties
• Sensed by touch, usually in mouth
• Not a chemical senses (taste/odor)
• Objective measurement through M, L, T
• Force MLT-2, work ML2T-2, flow L3T-1
• Texture usually applies to solids Viscosity
  to liquids. Distinction sometimes difficult.

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Structure matters
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Sensed by touch
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Texture is the composite of attributes which
arise from the structural elements of foods and
the manner in which it registers with the
physiological senses
(Philip
Sherman, 1970)
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Texture is the attribute of a substance resulting
from a combination of physical properties and
perceived by the senses of touch, sight, and
hearing. Physical properties may include size,
shape, number, nature, and conformation of
constituent structural elements

(Jowitt, 1974)
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Texture is the human physiological-psychological
perception of a number of rheological and other
properties of foods and their interactions
(McCarthy, 1987)
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Texture comprises those properties of a
foodstuff, apprehended by the eyes and by the and
muscle senses in the mouth, including roughness,
smoothness, graininess, etc. (Anonymous,
1964)
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How do we measure or sense texture?
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• Food rheology the study of the deformation and
  flow of raw materials, intermediate , and final
  products of the food industry
• Psychophysics relationship between measurable
  stimuli and corresponding human response
• Psychorheology deals with the sensory perception
  of rheological properties of foods

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rheology
Solids deform spring back when pushed
Liquids flow when pushed
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psychophysics
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psychorheology
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DISCIPLINES RELATED TO FOOD TEXTURE

• Food rheology
• Other physical properties wettability, phase
  changes, surface tension
• Psychophysics, psychorheology/sensory science
• Mastication/anatomy/physiology
• Microscopy, x-ray diffraction, NMR

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• But rheology and mechanical properties are not
  texture
• Empirical tests may do a better job of predicting
  texture as perceived by panelists

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• The fact that fundamental rheological
  measurements may not correlate as well with
  sensory measurements of texture as do empirical
  tests may result from the incompleteness of the
  science of rheology to describe all the changes
  that are actually sensed in the mouth
• Malcolm Bourne (1982)

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TEXTURE IMPORTANCE TO CONSUMERS

• Critical food in which texture is the dominant
  quality characteristic (meat, celery, chips)
• Important foods in which texture is significant
  but not dominant (fruit, bread, candy)
• Minor foods in which texture makes a negligible
  contribution (beverages, thin soups)

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Critical
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Important
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Minor
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• If texture of a food is the way people have
  learned to expect it to be, and if it is
  psychologically and physiologically acceptable,
  then it will scarcely be noticed. If, however,
  the texture is not as expected... it becomes a
  focal point for criticism and rejection of the
  food. Care must be taken not to underestimate
  the importance of texture just because it is
  taken for granted when all is as it should be.
  -Szczesniak and Kahn (1971)

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Importance of Rheology

• Rheology is the study of how materials flow or
  deform when subject to various forces
• Rheological and mechanical properties are related
  to how we perceive food. Body, mouthfeel,
  chewiness, etc. related to how material deforms
  and flows
• Rheological properties of food materials
  determine how they are processed (pump sizing,
  time in heating tube, extrudability)

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• Processing may be used to change food texture
• flour grinding
• fermentation of milk
• freezing of ice cream
• forming chicken pieces
• Mechanical and rheological properties determine
  how food is handled
• Sometimes changes are inadvertent and undesirable
• Changes in frozen strawberries
• Mushiness in overcooked products

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• Native foods original structure of agricultural
  commodity determines texture. Is modified by
  drying, canning, size reduction, etc
• Formulated foods processed from a number of
  ingredients whose native structure is lost. More
  options for final texture. Jellies, sausage,
  sauces, candies, etc.

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Types of Foods

• Fluids a substance that deforms continuously
  when acted on by a shearing force.
• Elastic Solid a material that deforms by a
  finite amount when a force is applied, but
  returns instantaneously to its original form when
  the force is removed
• Semi-solids solid foods that exhibit some
  properties of liquid (or vice versa)

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Physical Versus Sensory Properties

• Physical properties are measured by mechanical
  instruments, are quantitative, and reproducible
• Sensory properties relate to how people collect
  data about the outside world, and develop a
  perception about the world in their mind.
  Measured using human beings as the measuring
  instrument.

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• Sensory Property
• Color
• Brightness
• Pitch
• Loudness
• Aroma
• Hot/cold

• Physical Property
• Wavelength
• Intensity
• Frequency
• Volume
• Chemical composition
• Temperature

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• Sensory properties are difficult to quantify
• Humans are inherently non-linear instruments,
  with limited reproducibility
• a sound with twice the air pressure will not be
  twice as loud
• adding 3 times as much sugar to a drink will not
  cause it to be 3 times as sweet
• materials with twice the elastic modulus may
  not be perceived as twice as hard or springy

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Mullers Description

• Texture often used to describe both physical
  and sensory properties.
• Texture is
• Rheology branch of physics that describes
  physical/mechanical properties of food
• Haptaesthesis branch of psychology that deals
  with perception of the mechanical properties of
  materials

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TEXTURE
Rheology Haptaesthesis

• Youngs modulus
• Shear modulus
• Poissons ratio
• Viscosity
• Loss compliance

• Mouthfeel
• Hardness
• Chewiness
• Gumminess
• Adhesiveness

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Textural Parameters/Popular Nomenclature
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Texture Do We Need It?

• The identification of a food may rely a great
  deal on its texture characteristics.
• However, while we are usually fairly conscious of
  flavor or appearance, texture may be evaluated at
  a more sub-conscious level

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Many factors may influence our perception of
texture
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Correct Identification of Pureed Foods
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Other Tidbits

• Relative importance of texture and words used to
  describe it vary with culture
• Texture is readily discernible and an important
  food attribute
• Texture awareness more subconscious than flavor.
  Awareness increases when textural expectations
  not met

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• Time of day exerts influence on texture awareness
• Breakfast prefer restricted range of textures
  that lubricate mouth, remove dryness
• Evening texture most appreciated and enjoyed
• appetizers non-demanding textures/stimulate
  saliva
• main meal wide variety, some chewy
• dessert require low energy for chewing
• Children and teenagers rate texture as a more
  important attribute

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