Unit 11: Chapter 15 Summary
15.1 What is Sensory Evaluation?
Sensory evaluation is the judgment of food quality as perceived by the human senses
This does not just mean tasting… Implies all senses (texture, aroma, flavor, aftertaste,
Sensory analysis means the same thing as sensory evaluation. Although it should be used
for statistical methods of sensory data
A Scientific Method
Sensory evaluation uses the scientific method
One uses the scientific method to identify problems, hypothesize the problem, and
experimentally strategizes a way to fix them. Data is collected from every experiment and
a conclusion is reached, either verifying the hypothesis or disproving it.
A Quantitative Science
Sensory evaluation is a quantitative science in which numerical data is collected
Human response stimuli are quantifiable
Sensory Science in the Food Industry
The main applications of sensory evaluation in the food industry are quality assurance
and product development
Companies have teams which interact with other departments to make sure the their
product is quality assured
15.2 Sensory Odor, Flavor, and Mouthfeel Perception
Two types of senses involved in sensory perception:
1. Chemical taste and odor
2. Physical sight, sound, and touch
Character notes sensory attributes that define a foods appearance, flavor, texture, and
Taste occurs on the tongue
Taste the sensation derived from food as interpreted though the tonguetobrain sensory
4 primary tastes:
There is a fifth one, umami. This means delicious, meaty and savory.
There are receptor areas on the tongue which express maximum sensitivity to each of the
4 primary tastes.
Taste involves detection of tastants by the taste buds (located on the surface of the
Tastants are food molecules that are perceived to have taste. They could be sour, sweet,
bitter, and/or salty.
When tastants come in contact with a taste bud, it causes the release of neurotransmitters
Taste buds epithelial receptor cells organized into clusters of 50150, which are a part of
structures called papillae.
There are several different types of papillae: foliate, circumvallate, fungiform, and
Taste receptor cells act to detect taste stimuli and send messages to the brain. Newborn
babies have 800010000, and adults have 40006000. This later declines to 20003000.
In taste experiments PROP is used. Everyone has different taste levels. The three levels
are: “supertasters”, “medium tasters”, and “nontasters”
Transduction and Sensitivity
The tongue is linked to the brain through the central nervous system (CNS).
Taste transduction the brains response to taste stimuli Tastants cause a depolarization. A depolarization is when positively charged ions
accumulate in the cell, making the membrane potential less negative. This causes a neural
signal the release of neurotransmitters to the brain.
Smell plays a major role in the enjoyment of food.
Odor, fragrance and aroma are used interchangeably, although when describing an
undesirable smell, “odor” should be used.
Components of aroma include olfactory sensation (rancid or fruity) and nasal feelings
(hot or cold).
The throat, oral cavity and nasal chambers are all connected.
Olfaction only refers to the perception of odors by nerve cells in the nasal area.
Odorants are sensed by the olfactory epithelium, the outer layer of receptor cells on the
roof of the nasal cavity.
Odorant molecules are sensed by millions of cilia that cover the epithelium.
The interaction between odorant and receptor cell initiates a cascade of events that
produce an electrical signal (similar to taste transduction).
Optimal contact time between odorant and receptor cell is 12 seconds. It takes 20
seconds for the receptor cell to fully recharge.
There are two types of sensitivities:
1) the ability to detect something at low concentrations
2) the ability to differentiate between two odorants
Flavor is caused by chemical stimulation of the taste buds, olfactory apparatus and organs
of feeling present within the mouth, throat, and nose. Therefore food flavor is the overall impression combining taste, odor, mouthfeel factors,
and trigeminal perception.
Trigeminal nerve a nerve which runs through the entire facial area. The nerve endings
are located in the nasal and oral cavities and are responsible for “trigeminal perception”
Aftertase is different than actual taste sensation. It is residual taste sensations that linger
on your tongue after swallowing.
Odor contributes to flavor
Retroinhalation plays a major role in flavor. It is the passage of flavor stimuli from the
mouth to the nose.
Is the perceived sensation of food (tactile and thermal sensation) by the epithelial lining
of your mouth.
15.3 Sensory Texture and Colour Perception
Sensory texture deals with the structure and composition of food. The mechanism of
sensory texture isn’t completely understood due to the fact that other attributes such as
memory, sight, hearing and touch, effect it.
Texture perception occurs whenever a food is chewed or a drink is swallowed. We
measure this by describing physical characteristics of the food.
Sensory texture includes different types of sensations: mechanical, geometrical, an