4
Sensory Properties of Food
Exercises and Experiments
Exercise 1: Are You A Supertaster?
Using regular (water-soluble) food-grade blue food coloring, a cotton swab, and a magnifying mirror, apply food coloring to the front half-inch of your tongue. Rinse your mouth with water to remove excess food coloring (spit out or swallow the rinse water). Look in the mirror at the appearance of the tip of your tongue. If necessary, use a flashlight to better see details. Is your tongue mostly blue with a few pink spots, or is it mostly pink with very little blue? The pink spots are the fungiform papillae on your tongue. Fungiform papillae are the only papillae on the front of the tongue where taste buds reside. The smaller bumps on your tongue that dye blue are also papillae, but they are not associated with taste buds. The more pink papillae on your tongue, the more taste buds there are.
To estimate the number of taste buds in a given area on your tongue, place a paper reinforcement sticker on the tip of your tongue or use a hole puncher to punch a hole in a small piece of paper and place the paper on the tip of your tongue. Count the number of pink papillae within the hole. On average, nontasters have fewer than fifteen fungiform papillae in this area; normal tasters have from fifteen to thirty; supertasters have over thirty pink papillae crowded into this small space. Compare the appearance of your tongue with those of your classmates. Can you predict who might be a supertaster and who might be a nontaster?
Exercise 2: Ice Cream Storage and Texture
Compare the texture of properly stored (or freshly made) ice cream and ice cream that has been poorly stored (same flavor ice cream, but thawed slightly and refrozen one or more times over the course of several days). Record your evaluations by filling in the Results Table, which follows. Use information from Table 4.4 to help you with texture terms.
Results Table A Comparison of the Texture of Properly and Improperly Stored Ice Cream
Ice Cream Sample / Visual Evaluation of Smoothness (Scale of 1–5, 1 being not very smooth; icy) / Softness When Scooped (Scale of 1–5, 1 being soft, easy to scoop) / Creaminess When Eaten (Scale of 1–5, 1 being not very smooth and creamy; icy) / Additional CommentsProperly stored
Improperly stored
Summarize in one sentence the overall texture differences in the ice cream samples:
Answer:
Exercise 3: Texture
Compare the texture of two products of your choice. Examples include butter and margarine, fresh and stale bread, two different chocolate couvertures, two different types of cake, two pie fillings, two types of dried fruit, ginger snaps and marshmallows, and so forth. Record the names of the two products in the row headings in the following blank Results Table. Decide on the proper sensory characteristics to evaluate and write these in the column headings of the Results Table. Also write a title for your Results Table. Use information from Table 4.4 to help you with texture terms.
Results Table
ProductSummarize in one sentence the overall texture differences between your two samples.
Answer:
Experiment 4: Apple Juice Flavor
Apple juice is a relatively mild-tasting juice, which will be made even milder by diluting with water. Next, ingredients will be added to the diluted juice for you to taste. Some samples might taste very strong to you, others might be difficult for you to perceive. This varies from person to person since we live in different taste worlds. If necessary, make up a stronger sample of any ingredient that you cannot taste.
Work slowly through this experiment. You will find that your ability to identify and describe differences between samples will progress as you proceed. Taste samples several times, going back and forth from one to the next as many times as you need.
While diluted apple juice is used to complete this experiment, as you progress through it, think about how the lessons learned using apple juice can be applied to real pastry products such as pie fillings, coulis, ice cream, even chocolate brownies and cheesecake.
Objectives
• Identify and describe differences between sourness, astringency, and bitterness
• Demonstrate how sugar affects perception of sourness
• Demonstrate how acid affects perception of sweetness
• Demonstrate the importance of basic tastes and astringency in overall flavor perception
• Create a good-tasting apple beverage that has a pleasing balance of sweetness, sourness, and astringency
Products Prepared
Diluted apple juice with
• No additions (control product)
• Sugar
• Acid
• Tannin powder
• Caffeine
• Sugar and acid
• Other (sugar and tannin powder, sugar and caffeine, different acid or different sugar, etc.)
• Your choice of additions
Materials and Equipment
• Apple juice, 6 quarts (6 liters) or more
• Water, 2 quarts (2 liters), bottled or tap
• Large bowl or pan, to hold 11 quarts (liters)
• Pitchers, to hold 1 quart (1 liter) of liquid, one per test product
• Scale
• Measuring spoons
• Sugar, regular granulated
• Malic or other acid (citric acid, tartaric acid, or cream of tartar)
• Tannin powder (from wine-making store). If unavailable, use alum (sometimes found in supermarkets, with spices or canning supplies).
• Caffeine tablets, 200 mg, any brand, such as Vivarin or NoDoz Maximum Strength
• Sample tasting cups (1 fl. oz./30 ml soufflé cups or larger)
• Plain unsalted crackers
Procedure
1 Set aside 1 quart (1 liter) apple juice.
2 Dilute 5 quarts (5 liters) apple juice by adding 2 quarts (2 liters) water to it in a large pan or bowl. Add more water if apple juice is very sweet or strong tasting. Set aside 1 quart (1 liter) and label sample “diluted apple juice.”
3 Measure out 1 quart (1 liter) diluted apple juice into each of 5 separate containers and prepare samples as described below. (You will have some excess diluted juice.) Note: for very small quantities of ingredients, measurements are given in both weight and volumetric measurements. Use measuring spoons with these ingredients, if necessary.
• Add 1 ounce (30 grams) granulated sugar to 1 quart (1 liter) diluted apple juice. Label sample “with sugar.”
• Add 0.15 ounce or 1 teaspoon (4 grams or 5 milliliters) malic acid to 1 quart (1 liter) diluted apple juice. Label sample “with acid.”
• Add 0.1 ounce or 1/2 teaspoon (2.5 grams or 2.5 milliliters) tannin powder to 1 quart (1 liter) diluted apple juice. Label sample “with tannin.”
• Add 4 caffeine tablets, finely crushed, to 1 quart (1 liter) diluted apple juice. Label sample “with caffeine.” Note: this is about the same amount of caffeine as in coffee.
• Add 1 ounce (30 grams) granulated sugar and 0.15 ounce or 1 teaspoon (4 grams or 5 milliliters) malic acid to 1 quart (1 liter) diluted apple juice. Label sample “with sugar and acid.”
4 Set samples aside at room temperature for about 30 minutes, to allow powders to dissolve completely. Caffeine, in particular, needs time to dissolve.
Results
1 Evaluate the flavor of diluted apple juice samples with added acid, tannin, and caffeine and record results in Results Table 1. Be sure to taste each in turn against the control product (diluted apple juice) and against each other. Block your nose, to focus your attention on sensations throughout the mouth, and cleanse your palate between samples using water and unsalted crackers. Go back and retaste samples as often as needed, and focus on the following:
• What is perceived (puckering, salivating, drying, general unpleasantness, etc.) other than sweetness and aroma.
• When (how quickly) sensation is perceived (immediately, slowly, as an aftertaste, etc.).
• Name other foods with this sensation (unsweetened chocolate, Sour Patch Kids candy, strong black tea, etc.).
Results Table 1 Sourness, Bitterness, and Astringency in Apple Juice
Apple Juice / What Is Perceived / When Sensation Is Perceived / Foods with Similar Sensation / Additional CommentsDiluted
Diluted, with acid
Diluted, with tannin
Diluted, with caffeine
2 Evaluate the flavor of diluted apple juice samples with added sugar, added acid, and added sugar and acid and record evaluations in Results Table 2, which follows.
a Be sure to compare each in turn with the control product (diluted apple juice, rated as 3 on a scale of 1 to 5) and with each other. Cleanse your palate between samples using water and unsalted crackers. Go back and retaste samples as often as needed, and evaluate the following:
• Fullness of flavor (a full flavor is one that does not taste watered down or thin)
• Sweetness
• Sourness
b Next, compare each of these products with undiluted apple juice, to evaluate for acceptability. Record your results in Results Table 2, as you complete the following:
• Rate each sample as acceptable or unacceptable, and describe what makes it acceptable or unacceptable.
• Add any additional comments, as necessary.
c Reevaluate the undiluted apple juice, and record results in bottom row of Results Table 2. Be as complete as you can in your evaluation of overall fullness of flavor, sweetness, and sourness. Also evaluate for astringency. If necessary, retaste the diluted apple juice with added tannin powder, if you forget what astringency tastes like.
Results Table 2 How a Combination of Ingredients Affects Flavor Perception in Apple Juice
Apple Juice / Fullness of Flavor (Scale of 1–5, 1 being very low) / Sweetness (Scale of 1–5, 1 being very low) / Sourness (Scale of 1–5, 1 being very low) / Overall Acceptability / Additional CommentsDiluted apple juice (control product) / 3 / 3 / 3
With sugar
With acid
With sugar and acid
Undiluted apple juice
3 Based on your evaluations above, combine the diluted juice samples or add additional ingredients to either match the undiluted apple juice as closely as possible, or to create a good-tasting apple beverage that balances sweetness, sourness, and astringency.
• Keep track of the samples combined and ingredients added. Label each sample and list them in the first column of Results Table 3.
• Describe the flavor and overall acceptability of each of your apple beverages compared with undiluted apple juice. Record in next two columns in Results Table 3.
• Add any additional comments, as necessary.
Results Table 3 Comparison of Flavor and Overall Acceptability of Apple Beverages with Undiluted Apple Juice
Apple Beverage / Description of Apple Beverage Flavor / Overall Acceptability (Compared with Undiluted Apple Juice) / Additional CommentsSources of Error
List any sources of error that might make it difficult to draw the proper conclusions from your experiment. Consider, in particular, whether samples were all at the same temperature when evaluated; whether powdered ingredients were fully dissolved; whether a large number of samples made evaluations difficult or confusing for you.
Answer:
State what you could do differently next time to minimize or eliminate each source of error.
Answer:
Conclusions
Select one from the choices in bold or fill in the blanks.
1 One difference between sourness and bitterness is that sourness bitterness causes you to salivate. Another difference is that sourness bitterness lingers much longer as an aftertaste. An example of a food product that is sour is An example of a food product that is bitter is
2 One difference between sourness and astringency is that sourness astringency makes your mouth dry and your tongue feel rough. An example of a food product that is astringent is
3 Sugar increased decreased did not change the sourness of the diluted apple juice.
4 Acid increased decreased did not change the sweetness of the diluted apple juice.
5 Sugar increased decreased the fullness of flavor of the diluted apple juice. What else affected fullness of flavor?
Answer:
6 Other noticeable differences between the products were as follows:
Answer:
7 Describe the strategy you used to create a pleasing apple beverage.
Answer:
8 You make a strawberry coulis (fruit sauce) from fresh pureed strawberries. You taste the coulis and find that it lacks a full, rich, fruity flavor. Based on the results of this experiment, what can you add to improve its flavor?
Answer: