The document discusses the senses of sound, sight, and touch. It describes how sound is detected by the ear and interpreted by the brain. Vision is described as detecting light that interacts with objects and is focused on the retina, generating signals to the brain. Tactile texture is evaluated both orally and through touch, with descriptions of characteristics like viscosity, moisture, temperature, and mechanical properties.

1. CHAPTER 3
Texture, colour and appearance
evaluation

2. Sense of sound perception
Sound is vibrations propagating through a medium
(e.g. air)
Detection of these vibrations is a mechanical sense
similar to ‘touch’ but much more specialized
The EAR is really TWO Sense Organs in ONE. It not
only detects Sound Waves, it also senses the
Position of the HEAD, whether it is STILL, MOVING
IN A STRAIGHT LINE, OR ROTATING.
THE SENSE OF SOUND

4. The cochlea.
 This structure is a spiral canal covered
with hair cells. This motion agitates the
hair cells which in turn stimulates nearby
neurons that give rise to impulses that
travel to the brain. This results is the
brains interpretation and thus you can
hear(Marieb, E.N.)

5. Auditory texture
 Sounds are produced by mechanical
disturbances that generate sound waves
that are propagated through the air or
other media.
 Crisp and crunchy
Wet foods
Dry foods

6. Wet crisp foods
 Eg; fruits & vegetables
When the structure is destroyed, by
breaking/chewing, the cells pop and
prodice noise.
The amount of noise produced is less
when the surface tension of the liquid is
high.

7. Dry crisp foods
 Eg;cookies, crackers, chips and toast
Exposing to moisture decreases the
perceived crispness of the food.
The snapping back of the walls cause
vibrations that generate sound waves.
When the moisture content , walls are
less likely to snap back, sound less.

8.  Sounds negatively impact the hedonic
responses associated with the product.
Examples>>>>>Gritty sound of sand when
eating vegetables
 Sounds can add enjoyment.
Examples>>>>crispy sound of breakfast
cereals, crunchy juicy apple.

9. Sight or vision:
Ability of the brain and eye to detect electromagnetic waves
within the visible range (light) and interpret the image
1. The Sense Organ we use to sense Light is the EYES.
(Figure 1)
2. The EYE is composed of THREE LAYERS:
A. The OUTER Layer consists of the SCLERA AND
CORNEA.
B. The MIDDLE Layer contains the CHOROID, CILIARY
BODY, AND IRIS.
C. The INNER Layer consists of the RETINA.
SENSE OF SIGHT

11. A stimulus, light, from an external source interacts with
the object and is brought to focus on the retina of the
eye.
The retina is the receptor of vision and contains two
types of cells.
Light incident on these cells causes a photochemical
reaction that generates an electrical impulse which is
transmitted to the brain via the optic nerve.

12. The appearance of a food item is the first attribute humans tend to
perceive
Color perception in sensory evaluation is important and some
concerns are:
o Perception of color is influenced by
background and relative sizes of contrasting
color.
o The texture and gloss of a surface can
also affect perception of color in sensory
testing.
o The eveness of color as opposed to an
uneven or blotchy appearance can affect
sensory perception

13. Color
Is the perception results from detection of light after it has
interacted with an object.
Importance of color
1. As a cue for doneness of foods and is correlated
with changes in aroma and flavor.Eg; browning of
baked & fried foods.
2. Identity & grading. Eg; lightness of canned tuna fish.
Effect of color on taste
1. The perceived intensity of appropriate coloured
product was perceived higher than unappropriate
coloured product.
2. Panelists scored sweetness of dark colored sugar
solutions higher than lighter colored eventhough the
darker solutions contain less sucrose.

14. Visual Color measurement
Factors influencing appearance:
 Background color should be neutral.
 Light source.
 Panelist viewing angle (45 degrees) &
angle of light on sample.
 Distance from light source & product.

15. Physical form
 physical form that can be subdivided into three
parts:
1. Shape - Sliced, diced, pieces whole
- Length of frozen French fries
- Cut of beans
- Extrusions
2. Surface texture - Open dry structure of meat
- Wrinkling of peas
- Wilting of lettuce
3. Visual consistency -Setting of a jelly
- Syrups of different concentrations
- Pastes and purees

16. Visual Texture
 Visual moistness in a cake
Evaluating differing pore sizes and sheen
of the cut surface.
 Surface roughness in cookies
 Viscosity of fluid
By pouring the fluid from container, tilting,
spreading the fluid.

19. Tactile texture
1. Oral tactile texture-size and shape
2. Mouthfeel characteristics
a) Viscosity (thin,thick)
b) Feel of soft tissue surfaces (smooth,pulpy)
c) Carbonation(tingly,foamy,bubbly)
d) Chemical (astringent, numbing, cooling)
e) Coating of oral cavity (fatty,oily)
f) Resistance to tongue movement
(slimy,sticky,pasty, syrupy)
g) Temperature (hot,cold)
h) Wetness (wet/dry)

20. 3. Tactile handfeel – touching or manipulating the
material with fingers.
a) Mechanical characteristics (force to compress,
resilience, stiffness)
b) Geometrical characteristics (fuzzy, gritty)
c) Moisture (oily, wet)
d) Thermal charateristics (warmth)

21. Sensory texture measurements
 Standard sensory techniques
Discrimination,ranking, descriptive
techniques.