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5.5 Símbolos
The affective, acceptance, or hedonic tests are the most common and frequently used tests to determine the sen-sory properties of foods. These tests are used for product development purposes, product improvement, or optimi-zation especially in terms of new additives and to assess the market potential of new products. The questionnaires for affective testing should be short, easy to understand, and simple to follow and contain clear questions and score sheets. Each questionnaire should be tailor-made according to the number of products to be compared and the desired test attributes (appearance, flavor, texture, viscosity, crisp-ness, color, sweetcrisp-ness, odor/aroma, aftertaste, etc.). The questionnaire should avoid asking irrelevant or unneces-sary questions.
There are many hedonic scales. The scale should be cho-sen according to the type of panelist and degree of accuracy.
The most common scales are category scales (9, 7, or 5-point), line scale, and facial hedonic. The 9-point scale consists of like extremely, like very much, like moderately, like slightly, neither like nor dislike, dislike slightly, dislike moderately, dislike very much, and dislike extremely (Figure 3.9). There are also score sheets containing 7-point or 5-point scales.
The evaluation on the line hedonic scale (Figure 3.10) is done by simply marking the degree of product likeness on the line labeled on each side with two contrasting product attributes,
whereas the facial hedonic scale is generally used to conduct sensory tests for children. The advantage of line scales is that the intensity can be more accurately graded because there are no numbers, whereas the main disadvantage is that the panelist is usually less consistent because sometimes he or she cannot remember the position on the line.
The data generated by hedonic tests is almost always statistically evaluated using t test or analysis of variance (ANOVA) test. The t test is used when comparing two treat-ments, whereas the ANOVA test is used when comparing more than two treatments. The means of the rank sums are usually compared with least significant differences, Duncan, or Tukey tests at a level of significance of 5% or 1%.
3.4.3 researCh suggestions
1. Prepare five loaves of table bread with hydrogenated shortening or fractionated palm stearin (free of trans fatty acids) according to the procedure in Section 9.2.6.1. Slice the bread into 1-in.-thick slices, pack the bread in sealed polyethylene bags and store it at room temperature.
a. Determine subjective and objective crumb color with the Hunter Lab colorimeter (L, a, b, chroma, hue and color index E).
b. Determine crumb texture with the universal testing machine or TA.XT2 texture analyzer using the double compression test at days 0, 1, 2, 5, and 7.
Name Date Type of sample
Type attribute
Instructions
1. Taste the coded five samples from left to right and note the degree of . Wait at least 30 seconds between samples and rinse the palate as required.
2. Write “1” in the coded sample which you find with more , “2”
for the next and so on. If two samples appear the same, make a best guess as to their rank order.
Code
Rank
Comments:
FIGurE 3.8 Example of score sheet for simple ranking test.
103 Determination of Color, Texture, and Sensory Properties of Cereal Grain Products
c. Design a triangular test to determine if the use of the palm stearin significantly affects the sen-sory properties of the bread (color, texture, fla-vor, and aroma).
2. Prepare five different types of corn tortillas following the dry masa flour procedure (procedure in Section 7.2.4.2). The control dry masa will be supplemented
with (1) 0.2% fumaric acid/0.2% calcium propionate, (2) 0.5% lecithin/0.1% Sodium Stearoyl Lactylate (SSL), (3) 0.2% carboxymethyl cellulose, (4) 0.2%
fumaric acid/0.2% calcium propionate, 0.5% leci-thin/0.1% SSL, and 0.2% carboxymethyl cellulose.
Pack the resulting tortillas in sealed polyethylene bags and store bags at room temperature.
Name Date Age Sex: Male Female
Evaluate the TEXTuRE, ColoR, and FlAvoR of the five coded bread samples marking with an “X” the degree of preference. Please rinse your palate after evaluating each sample.
Sample Code 356 906 488 106 092
TEXTuRE like extremely
like very much like moderately like slightly
Neither like nor dislike Dislike slightly Dislike moderately Dislike very much Dislike extremely
ColoR like extremely
like very much like moderately like slightly
Neither like nor dislike Dislike slightly Dislike moderately Dislike very much Dislike extremely
FlAvoR like extremely
like very much like moderately like slightly
Neither like nor dislike Dislike slightly Dislike moderately Dislike very much Dislike extremely
Comments
FIGurE 3.9 Example of score sheet for 9-point hedonic test.
104 Cereal Grains: Laboratory Reference and Procedures Manual
a. Determine the TPA of the different types of masas and the folding and firmness of the torti-llas at days 0, 1, 2, and 5.
b. Design a hedonic test to determine if the vari-ous types of additives negatively or positively affect the consumer preference of these tortillas (color, texture, flavor, and overall acceptability).
3. Prepare two different types of wheat flour tortillas following the same formulation and the hot-press procedure (procedure in Section 10.5.1.1). One torti-lla will be prepared with whole wheat flour whereas the other with whole grain flour. Pack the resulting tortillas in sealed polyethylene bags and store bags at room temperature.
a. Determine and compare the Agtron color of the two different flours.
b. Determine and compare the rheological proper-ties of the two flours using the farinograph.
c. Determine subjectively and objectively the tor-tilla color with the Hunter Lab colorimeter (L, a, b, chroma, hue, and color index E).
d. Determine and compare tortilla firmness and bending with the TA.XT2 texture analyzer at days 0, 1, 2, 3, and 6.
e. Design a triangular test to determine which of the two tortillas (color, texture, flavor, and overall acceptability) is preferred by panelists.
4. Prepare two different types of lager beers following procedure in Section 14.2.2.1. One beer will be pro-duced using barley malt and refined sorghum grits whereas the other will use sorghum malt and refined sorghum grits.
a. Determine and compare the color of the two different beers.
b. Determine and compare the Brookfield viscos-ity of the two beers.
c. Determine the alcohol content of the two beers.
d. Design a triangular test with adult panelists to determine which of the two beers (color, body texture, flavor, and aroma) is preferred by panelists.
Name Date Age Sex: Male Female
Evaluate the TEXTuRE, ColoR, FlAvoR and ovERAll ACCEPTABIlITY of the two coded cracker samples by placing a mark on each line below. Please rinse your palate after evaluating each sample.
Texture
Code 732 Hard Soft Code 175 Hard Soft Color
Code 732 light Dark Code 175 light Dark Flavor
Code 732 None Strong
like extremely Dislike extremely Code 175 None Strong
like extremely Dislike extremely Overall Acceptability
Code 732 like extremely Dislike extremely Code 175 like extremely Dislike extremely
Comments:
FIGurE 3.10 Example of score sheet with line hedonic scale.
105 Determination of Color, Texture, and Sensory Properties of Cereal Grain Products
3.4.4 researCh Questions
1. Select the most appropriate test for evaluating the production of beer with a new lot of diastatic malt.
The sensory analyst wishes to know if the consumer can distinguish from the control beer.
2. A new lot of pan bread is produced using dry yeast instead of fresh compressed yeast. The sensory ana-lyst wishes to know if breads can be distinguished. A 1% risk factor (α = 0.01) is accepted and 20 assessors evaluated the two breads in a triangular test. Fourteen out of the 20 panelists identified the odd sample. What can you conclude from this sensory evaluation test?
3. Design a sensory evaluation test aimed toward the determination of the overall acceptability of two commercially produced beers. One beer was treated with a new hop extract whereas the other was pro-duced with hop pellets. The two lots of beers were held for 1, 2, 4, 6, and 8 weeks under two conditions:
refrigeration temperature (1–5°C) and ambient tem-perature (20°C/70% relative humidity (RH)). Define the minimum number of panelist, score sheets, the sensory evaluation method, and the statistical anal-ysis of the data.
4. What are the advantages and disadvantages of using untrained or trained panelists?
rEFErEncES
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Editorial Acribia, S.A.
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Blackie Academic & Professional.
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Rasper, V. F., and C. E. Walker. 2000. “Quality Evaluation of Cereals and Cereal Products.” In Handbook of Cereal Science and Technology, edited by K. Kulp and J. G. Ponte. New York:
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Symons, S. J., and J. E. Dexter. 1991. “Computer Analysis of Fluorescence for the Measurement of Flour Refinement as Determined by Flour Ash Content, Flour Grade Color and Tristimulus Color Measurements.” Cereal Chemistry 68:454–460.
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