Sensory Evaluation CDE Preparation

Jeffri BohlscheidSchool of Food Science

University of Idaho

Objectives

• After this session the student will be able to – Apply techniques of orthonasal evaluation of

unknown aromas

– Apply multiple techniques to differentiate common food products

Food Sensory Evaluation

• One does not necessarily have to have a “special gift”

• Most professional sensory evaluators are trained

• Specific techniques are used for different products

FFA Sensory CDE

• Two parts– Aroma Recognition• Pool of samples from 31 possible common aromas

– Triangle test• Choosing which one sample of the three presented is

different

Aroma Recognition Possibilities

1. Peanut Butter2. Chocolate 3. Maple4. Molasses 5. Vanilla6. Almond 7. Oregano 8. Basil9. Licorice (anise)10. Clove11. Nutmeg12. Cinnamon

13. Ginger 14. Lemon 15. Lime

16. Orange 17. Banana18. Coconut19. Raspberry20. Strawberry21. Cherry 22. Grape

23. Onion 24. Garlic25. Butter26. Smoke (liquid)27. Lilac (Floral) 28. Wintergreen29. Peppermint30. Menthol31. Pine

Aroma Recognition

• Training– Group similar aromas• What are the similarities and differences between

groups?• What are the similarities and differences within groups?

– Develop “Sense Memory”• You want to try to link a visual memory with the aroma• “See aroma in your head”• Improved recognition

How to Smell• Don’t wash for a month (just a joke)• Remove interferences to what you are evaluating – Don’t chew gum– Don’t were perfume, cologne, strongly scented

deodorant, hair products, or other personal care products

– Don’t smoke or use smokeless tobacco products– Stay away from strong bleach or other caustic fumes– Wash your hands, and use a neutral smelling soap– Close the windows and doors

How to Smell

• Things to remember:– Our sense of smell habituates quickly.• We get “used to” an aroma rapidly and lose the ability

for fine discriminations.• Caused by “over sniffing”.

– Need to take a 30-60 second break to allow receptors to “recharge”.

– Sniff water between samples to moisten nasal passages and flush aroma molecules out.

How to smell• When you have the sample (most likely in a

bottle):– Uncap and hold about ½ in. below your nose– Close your eyes– Take two short strong sniffs then one longer one

where you can feel the air at the back of your throat

– Move the bottle away and visualize the smell– Cap the bottle.– If you “re-sniff”, sniff some water in between

Set up for training

• A pitcher or bottle of neutral smelling water• Small cups (wax Dixie)• Labeled samples– Usually small dark colored glass vials or medication

bottles (2-4 oz).– Small wad of cotton (increases surface area and

allows for more volatilization of the aroma molecules)– A few drops of the sample is generally sufficient

• Unlabeled samples– Actually use a random 3 digit codes to differentiate– Use a different code each time

Aroma Training• Start out with one aroma from each group with

labeled bottles

• Sniff and visualize

• Mix up and try again with unlabeled bottles

• Evaluated until 100% correct

• Try with another set and repeat process

Aroma Training -Continued• Now try 3 or 4 from the same aroma group– Developing finer discrimination skills

• Sniff and visualize

• Remember to take a break between each sample

• Now try with randomized, unlabeled bottles

Aroma Training -Continued• When you have reached a high level of accuracy:– Begin random selections of 12 unlabeled samples

– If you miss one, go back and try to figure out what you were missing – do you have a strong mental picture of the smell?

– Repeat with different set of 12

– Continue until you have gone through all of the sample

– Keep randomizing and sniffing!

Training Schedule• Mastery of the aromas will take a number of sessions

• Sensory fatigue will generally occur after 30-45 minutes

• Mix this activity up with other classroom activities

• The senses are generally most acute around 10 am and worst right after lunch or at the end of the day. – Training in the morning and testing your skill later in the

day

Homework

• Get in the habit of evaluating all of the foods and smell you run across each day.

• You will be surprised how quickly you will begin to develop your skills– Imagine only practicing a musical instrument or

sport 30 minutes a day, once a week vs. 1-2 hours and everyday

Sources of Aroma• Many of the aroma manufacturers will provide sample free of

charge. See the appendix at the end of the slides.

• You can also purchase a number of essences and extracts from grocery (see the spice aisle) and health food stores.

• You may need to dilute with water.

• Be aware that many of these products are sensitive to heat, light, and oxygen.

• They will start losing there strength after a few months.

• Store in a cool dark place.

Triangle Test

• Sing with me!– “One of these things is not like the other one, one

of these things is not the same…”

• The object of this activity is to differentiate between different food products. Examples:– Diet vs. Regular soda– Different brands of corn flakes– Different types of yogurt (low fat vs. fat free)

Triangle Test

• You will be presented with three samples • Use all of your sensory skills to determine

which is different– Vision– Touch– Smell– Taste

Visual Evaluation

• Look for differences in color, shape, size of product, texture, or components (chunks of fruit in yogurt)– Different shades of brown in toasted oat cereal?

• For gels or thick products:– Do they break or smear the same– Do they both stick or drip for a spoon the same

way?

Touch Evaluation

• For dry items– Are they the same texture?– Do they crumble the same way?– Do they “smoosh” the same way between your

fingers?

• Moist items– Smooth vs. grainy– Sticky, gummy, tacky or slimy

Smell Evaluation

• Use the techniques we discussed earlier

“Taste” evaluation

• Combination of four aspects– Taste– Sensation– Aroma/Flavor– Mouthfeel

“Taste” evaluation

• Taste– Sweet – sugar, honey– Salty – table salt–Bitter – quinine, caffeine, strong cold coffee– Sour – vinegar, lemon juice, citric acid–Umami – meaty or brothy, bullion cubes

“Taste” evaluation

• Sensation– Drying – astringency• Strong cold black tea

– Cooling – “minty”• Breath mints• Chewing gum with xylitol

– “Hot” – spicy, piquant• Jalapeño pepper, cayenne peppers, cinnamon candies

– Temperature – how cold or hot

“Taste” evaluation

• Aroma– Retronasal evaluation

– Chew, inhale through your mouth, and exhale through your nose

– Use your smell evaluation skills

“Taste” evaluation

• Mouthfeel– How does the product feel in your mouth?– Crunchy– Sticky– Slimy– Hard– Grainy– Does the item dissolve quickly or coat your mouth?– Rub the food with your tongue across the roof of your

mouth

Triangle test

• Try to find one aspect that stands out for different types of food products– Look for obvious differences, but be aware of

subtleties

Triangle test• When setting up samples always use the same

sizes, shapes, and amount/volume.

• Also use the same plates or cups.

• Do not let the evaluator see or smell anything until the time for evaluation

• Limit the time to no more than 3 minutes per sample

How do you improve your skills

• Practice, practice, practice!

• Concentration on task

• Find your weak points and work on them

Aroma Standard Sources

• You may be able to obtain free samples of aromas from the following manufacturers– http://www.ottensflavors.com/company.asp– http://www.virginiadare.com/– http://www.bellff.com/?id=&lng=eng– http://www.dmflavors.com/index.cfm/fuseaction/

dmflavors.home/index.cfm– http://www.givaudan.com/givcom/– http://www.firmenich.com/m/flavors/solutions/overview/

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