Lecture Two: Sensory Evaluation

Question 1

What is sensory evaluation?

Answer 1

• Subjective sensory evaluation - human analysis of the taste, smell, sound, feel, and appearance of the food
• Want to know whether or not a product will be successful in the market; sell or not
• “This product seems to be preferred over the product already in market”

Question 2

Generally speaking, what types of characters of foods will be evaluated in a sensory test?

Answer 2

• Appearance - Shape, size, condition, color
• Taste
• Smell
• Sound
• Feel
• Texture - chewiness, graininess, brittleness, firmness, and consistency

Question 3

Name some physical influences and describe how they affect people’s food preferences?

Answer 3

• Genetic makeup - number of taste buds on tongue (super tasters, medium tasters, and non-tasters)
• Gender - females can be influenced by hormones cycles (eg: cravings during pregnancy)
• Age - Age and health status affect function of taste buds
• Health
• Weight? - No clear linkage between BMI and tasting, but non-tasters tend to prefer higher fat-content food

Question 4

Name some psychological influences and describe how they affect people’s food preferences?

Answer 4

Much stronger influence on taste preference than physical

• When a food is linked to certain events (illness, vacations, etc)
• Biases from label and brand - because you pick the brand you already think that you like the product

Question 5

Name some cultural influences and describe how they affect people’s food preferences?

Answer 5

How you grew up, area you grew up

• Holidays your family and friends celebrate
• Eg: Halloween with candy; Thanksgiving eating turkey
• Comfort food - the food your caregiver gave you as a young kid

Question 6

Name some environmental influences and describe how they affect people’s food preferences?

Answer 6

• Climate
• Geography - people in Alaska will have more exposure to seafood
• Fuel availability - eg. scarcity of coal/gas in Japan influences popularity of sushi; in US fuel is cheap, stews are popular
• Your immediate surroundings - what you eat in your home; what your caregiver is cooking the most

Question 7

What are the sensory characters that can be evaluated objectively?

Answer 7

• Color - by colorimeter

• Hue (red, yellow, blue), value (shade of hue), chroma (intensity of color from high to low)
• Affects perception (eg: think darker chocolate cake has richer flavor)

• Texture - by texture analyzer

Question 8

Can objective evaluations of food characteristics replace sensory evaluation?

Answer 8

No. Texture and color preferences are still subjective; people can prefer one over the other for many reasons

Eg: with texture - still need a sensory panel to determine ideal texture, just use texture analyzer to make sure texture is consistent

Question 9

What are the 5 basic tastes?

Answer 9

salty, bitter, sour, sweet, and savory (umami)

Question 10

How are tastes determined?

Answer 10

Each one has respective receptor on tongue; why there are only 5 tastes (only these five receptors have been found)

Question 11

Describe sour

Answer 11

All sour compounds trigger both sourness and astringency

Astringency is a drawing up of the muscle in the back of the mouth; determined by puckering power of food

Question 12

How does the length of a sugar molecule affect sweetness?

Answer 12

Shorter length sugar molecule is sweeter

so if see a bunch of molecules you should be able to see which will be sweeter

Question 13

How is aroma detected?

Answer 13

Aroma is a factor of flavor (Flavor = taste + aroma)

Detected in nasal cavity by olfactory bulb (bunch of nerve fibers located at the base of the brain, right behind bridge of nose)

Aroma is triggered by volatile particles released by food

Travel through nose cavity and reach receptors on olfactory bulb

Different types of odors will trigger different types of receptors

Question 14

What are the two pathways aromas can reach the nasal canal? How does this effect sensory evaluations?

Answer 14

1. Directly evaporated from food (while cooking)
2. During chewing - more aroma particles are released during chewing; nasal cavity is connected to the back of the throat

That’s why in sensory evaluation all judges are encouraged to thoroughly chew their food to release the aromas

Question 15

How do you control influence from other testers in a sensory evaluation?

Answer 15

• Isolated booth - not be able to see others’ facial expressions
• Make no sounds or comments - includes non-verbal gestures
• Arrange tasting stations in circle with members facing outward

Question 16

How do you control environmental factors in a sensory evaluation?

Answer 16

• Lighting/ masking color/ blindfold - color strongly influences food perception; try to mask colors so every sample looks the same
• Aromas from the room - samples have to all be prepared one day ahead of time and then kept in fridge; brought up to room temp or heated in separate room and then brought to room
• Temperature of sample - all sample temps have to be the same and served at optimal conditions
• Instruct testers to rinse mouth btwn samples - products with high fat content will have lingering taste; plain soda cracker and warm water will be provided to clear flavor resides in mouth

Question 17

How do you control psychological factors in a sensory evaluation?

Answer 17

• Brand - mask brand
• Label code - people tend to choose samples with lower number rather than higher; choose samples with letters closer to the beginning of the alphabet
- When labels reach three digits these biases disappear, so labels use randomly generated 3-digit numbers (the higher the number the less bias)
• Number of samples provided - if judge is asked to review more than five samples they start to lose reliability, becomes inaccurate
- Max number of samples a taster can accurately judge is four or less
• Present order - Judges tend to choose first presented sample, so need to present in balanced order (Half try sample A first, half try sample B first)

Question 18

When do you use trained judges in a sensory evaluation?

Describe what they do.

Answer 18

Used in beginning and middle stage of product development using trained judges

• Judges are trained to be familiar with the type of produce being evaluated and know vocabulary around that product
• Know principles behind each test and can put biases aside
- Can focus on measurable characteristics (eg: how creamy a product is)
• Evaluate on measurable characteristics

Question 19

When would you use a consumer taste panel?

Answer 19

Used in late stage of product development for marketing

Want people who represent buying public (ordinary people)

Questions will be whether you like the product

Question 20

What do difference tests look for?

Answer 20

Are products perceptibly different in any way?

Question 21

Describe a Paired Comparison test.

What are the odds by guess?

Answer 21

Sample A & Sample B: “Which sample is sweeter?”

50% odd by guess

Question 22

Describe a Triangle test.

What are the odds by guess?

Answer 22

Sample A, Sample B, & Sample A’: “Choose the sample most different”

33% odd by guess (so if get more than this you know there’s a significant difference between samples)

So more powerful/sensitive than comparison test

Question 23

Describe a Duo-Trio test.

What are the odds by guess?

Answer 23

Sample A, Sample B, & Sample A’: “Choose the sample that matches the reference”

50% odd by guess