Previous - Next
Appendix A: Triangle test for difference:
critical number (minimum) of correct answers
Appendix B: Simple triangular test
Appendix C: Guide to eec freshness grades
Appendix D: Evaluation form for raw cod
Apppendix E: Evaluation of cooked fish
Appendix F: Quality test using structured
scaling
Appendix A: Triangle test for difference: critical number (minimum) of correct answers
Entries are the minimum number of correct responses required for significance at the stated significance level (i.e., column) for the corresponding number of respondents "n" (i.e., row). Reject the assumption of "no difference" if the number of correct responses is greater than or equal to the tabled value.
Significance level (%) |
Significance level (%) |
||||||||
| n | 10 | 5 | 1 | 0.1 | N | 10 | 6 | 1 | 0.1 |
| 3 | 3 | 3 | - | - | 26 | 13 | 14 | 15 | 17 |
| 4 | 4 | 4 | - | - | 27 | 13 | 14 | 16 | 18 |
| 6 | 4 | 4 | 5 | - | 28 | 14 | 15 | 16 | 18 |
| 29 | 14 | 15 | 17 | 19 | |||||
| 30 | 14 | 15 | 17 | 19 | |||||
| 6 | 5 | 5 | 6. | - | 31 | 15 | 16 | 18 | 20 |
| 7 | 5 | 5 | 6 | 7 | 32 | 15 | 16 | 18 | 20 |
| 8 | 5 | 6 | 7 | 8 | 33 | 15 | 17 | 18 | 21 |
| 9 | 6 | 6 | 7 | 8 | 34 | 16 | 17 | 19 | 21 |
| 10 | 6 | 7 | 8 | 9 | 35 | 16 | 17 | 19 | 22 |
| 11 | 7 | 7 | 8 | 10 | 36 | 17 | 18 | 20 | 22 |
| 12 | 7 | 8 | 9 | 10 | 42 | 19 | 20 | 22 | 25 |
| 13 | 8 | 8 | 9 | 11 | 48 | 21 | 22 | 25 | 27 |
| 14 | 8 | 9 | 10 | 11 | 54 | 23 | 25 | 27 | 30 |
| 15 | 8 | 9 | 10 | 12 | 60 | 26 | 27 | 30 | 33 |
| 16 | 9 | 9 | 11 | 12 | 66 | 28 | 29 | 32 | 35 |
| 17 | 9 | 10 | 11 | 13 | 72 | 30 | 32 | 34 | 38 |
| 18 | 10 | 10 | 12 | 13 | 78 | 32 | 34 | 37 | 40 |
| 19 | 10 | 11 | 12 | 14 | 84 | 35 | 36 | 39 | 43 |
| 20 | 10 | 11 | 13 | 14 | 90 | 37 | 38 | 42 | 45 |
| 96 | 39 | 41 | 44 | 48 | |||||
| 21 | 11 | 12 | 13 | 15 | |||||
| 22 | 11 | 12 | 14 | 15 | |||||
| 23 | 12 | 12 | 14 | 16 | |||||
| 24 | 12 | 13 | 15 | 16 | |||||
| 25 | 12 | 13 | 15 | 17 | |||||
Note: For values of n not in the table compute
where k is the number of correct answers.
Appendix B: Simple triangular test
Practical example of the application of the simple triangular test ("forced choice" option)*
A manufacturer who changes the formulation of his product wishes to know whether the new product will be similar to the old from the sensory point of view.
He has at his disposal 12 assessors.
Two batches are prepared, one representing the old formulation (A) and one the new formulation (B).
Presuming that each assessor makes only one assessment, it will be necessary to prepare 18 test samples of A and 18 test samples of B in two series of six sets, as follows:
- two sets ABB
- two sets AAB
- two sets ABA
- two sets BAA
- two sets BBA
- two sets BAB
These sets are distributed at random among the assessors.
The test supervisor chooses a significance level of 5%, i.e., he accepts a risk of 5% of concluding that the test will reveal a difference when there is none.
The number of correct answers (8) is referred to the table.
With 12 replies, it is concluded that the two products are different at the 5% significance level.
Appendix C: Guide to EEC freshness grades
In order to be placed in grade E, A, B or Unfit (C) the fish should possess the following characteristics. The descriptive terms are meant to be guides and not all the characteristics described will necessarily occur together in every fish. Gill odours are particularly discriminatory.
White fish: cod, saithe, haddock, whiting, plaice, redfish, ring, hake
| E | A | B | Unit(C) | ||
| Skin | bright; shining; iridescent (not redfish) or opalescent; no bleaching |
waxy; slight
1088 of bloom; very slight bleaching |
dull; some bleaching |
dull; gritty; marked bleaching and shrinkage |
|
| Outer slime | transparent; water white |
milky | yellowish-gray; some clotting |
yellow-brown;
very clotted and thick |
|
| Eyes | convex; black
pupil; translucent cornea slightly opalescent |
plane; slightly opaque pupil; opaque cornea |
slightly
concave; grey pupil; discoloured cornea |
completely
sunken; grey pupil opaque |
|
| Gills | dark red or
bright red; mucus translucent |
red or pink;
mucus slightly opaque |
brown/gray and bleached; mucus opaque and thick |
brown or
bleached; mucus yellowish grey and clotted |
|
| Peritoneum (in gutted fish) |
glossy;
brilliant; difficult to tear from flesh |
slightly dull; difficult to tear from flesh |
gritty; faily
easy to tear from flesh |
gritty; easily
torn from flesh |
|
| all except plaice |
fresh; seaweedy; shellfishy |
no odour;
neutral odour; trace musty, mousy, milky, capryllic, garlic or peppery |
definite musty, mousy, milky, capryllic, garlic or peppery; bready; malty; beery; lactic; slightly sour |
acetic: butyric; fruity; turnipy; amines; sulphide; faecal |
|
| plaice | |||||
Dogfish
| E | A | B | Unfit(C) | |
| Eyes | convex; very
bright and iridescent; narrow pupils |
convex to net; green; clear but some loss of brightness and irridescence; oval pupils |
flat to sunken;
some yellowing; slithgly cloudy |
sunken; yellow; cloudy |
| Appearance | in or partly in rigor; small amount of clear slime on skin |
loss of rigor;
no slime on skin and particularly no slime in mouth or at gill openings |
sticky slime in mouth and at gill openings; some flattening of snout |
copious slime in mouth and gill openings; obvious flattering of snout |
| Odour | fresh marine musty; not ammoniacal |
ordourless or slightly | ammoniacal, sour very sour |
very ammoniacal, |
Herring
| E | A | B | Unfit(C) | |
| Skin | full bloom;
bright; shining; iridescent; clean |
slight dullness
and loss of bloom |
difinite
dullness and loss of bloom |
dull; no bloom |
| Outer slime | transparent or
water white |
milky; slight browning |
brownish | brown |
| Gill covers | silvery | silvery; slight browning; slight bright red blood stain |
some browning
and blood staining |
very brown and blood stained |
| Eyes | convex | plane | slightly concave | concave; sunken |
| Firmness | very stiff and firm | fairly stiff and
firm absent, fairly soft |
stiffness nearly | soft or very soft |
| Gill odours | fresh seaweedy | less fresh
seaweedy, slight oily |
slight stale seaweedy; definite oily; trace or slight H2S (sulphide), "salt cured" or rancid oil |
definite H2S (sulphide); rancid oil; amines; faecal; sour |
Mackerel
| E | A | B | Unfit(C) | |
| Skin | strong blue and turquoise colours; iridescence over all body; well defined lateral line; reticulations on upper surface; clear distinction between upper and lower surfaces |
loss of bright
colours with fading of reticulations; pale golden tinge on lower surface patchy iridescence |
golden tinge
over all body; akin wrinkles on flexing; washed- out appearance of colours; |
yellow slime;
little distinction between upper and lower surfaces |
| Texture of body | stiff | firm | some softening | limp and floppy |
| Eyes | bulging with protruding lens; shiny jet black/blue pupil with metallic brown iris; transparent eye cap |
convex; slight clouding of lens and wrinkling of iris; clouding of eye cap |
plane; cloudy
lens with black specks in iris; pale golden eye cap |
sunken eye
covered with yellow slime |
| Gill appearance | uniformly dark red/purple with free blood and water clear slime |
loss of colour
with red/brown slime; pale margins to gills |
further JOBS of
colour with patchy bleaching; increase in red/brown slime |
bleached; thick yellow slime |
| Gill odour | fresh seaweed; sharp; halogens; pepper; fresh-cut grass; metallic; blood; fresh, sweet oil |
dull; muddy;
musty; mousy; cardboard; fish oil strong oily |
yeast; sour
rotten fruit; "wet dogs"; old grass cuttings; sulphides; rancid oil |
compost heap; rotten turnips; sour cheese; ammonia; |
Appendix D: Evaluation form for raw cod
Quality assessment of cod - Raw fish
Name:
Date:
| Quality parameter | Characteristics | Grading | |
| Skin | Surface appearance | 0 1 2 3 |
Bright shining Waxy, slight loss of bloom Dull, some bleaching Dull, gritty |
| Slime | 0 1 2 3 |
Transparent or
water white Milky Yellow-grey Yellow-brown |
|
| Stiffness | 0 1 |
Firm Soft |
|
| Flesh | Stiffness | 0 1 |
Rigor Post-rigor |
| Eyes | Clarity | 0 1 2 |
Translucent
cornea Opalescent cornea Opaque cornea |
| Shape of Pupil | 0 1 2 |
Convex Plane Sunken |
|
| Colour | 0 1 2 |
Bright red Pink Faded/discoloured |
|
| Odour | 0 1 2 3 |
Fresh/seaweed Fishy Stale Spoilt |
|
| Mucus | 0 1 2 |
Absent Moderate Excessive |
|
| Flesh colour | In open surfaces | 0 1 2 |
Translucent Grey Yellow-brown |
| Blood | In throat cut | 0 1 2 |
Red Dark red Brown |
| Character sum | |||
Instruction: Please assess the fish using the list of descriptive terms provided above. Rate the fish on each of the quality parameters and circle the corresponding score on the scale.
Appendix E: Evaluation of cooked fish
NAME:_____________________DATE:__________________SPECIES:__________________
INSTRUCTION: Choose the best description to characterize the
code.
Write the corresponding value in the column to the right for the
description under the right code.
Please note the choice between two sets of description for each
of the three parameters:
Uppermost: Fat species (e.g., herring, sardine, anchovy, sardine,
mackerel, trout, salmon ,etc.).
Lowermost: Lean species (e.g., cod, haddock, saithe, plaice,
hake, etc.).
WHOLE FISH
FILLET
CODE INDICATION
| 10 | 8 | 6 | 4 | 2 | 0 | |
| FAT | Fresh oil,
marine creamy. weak odour |
Oily, rancid. musty. Burnt. slightly brown oil |
Rancid, cheesy, slightly sour |
Very rancid, sweaty, cheesy, sour, stale meat |
Very rancid sour |
spoilt, rotten |
| SMELL | ||||||
| Species-specific. |
Fresh fish, Seaweed |
Condensed milk, slightly fishy, slightly sour |
Sour, stale, cabbage, sulphide |
Rotten, spoilt, strong ammonia |
||
| LEAN | ||||||
| FAT | Fresh oil.
sweet. meaty. creamy |
Oily. sweet, meaty, creamy, burnt, neutral |
Oily, sweet, stale meat, creamy, rancid, sour |
Rancid, sweet, cheesy, slightly biker, sour fruit |
Very rancid, bitter | |
| TASTE | ||||||
| LEAN | Meaty flavour. sweet, watery, initially no sweetness |
Sweet and Characteristic but reduces in intensity |
Insipid -
neutral, slightly fishy |
Musty, fishy, slight sour, some off- flavours |
Slight rotten, sour, sulphide |
Rotten, spoilt |
| FAT | Firm, elastic, springy, flaky, juicy |
Firm, springy, juicy, slightly dry, a bit stringy/fibrous |
Less firm, less juicy, a bit stringy/fibrous |
Dry and fibrous | Dry end sough | |
| TEXTURE | ||||||
| LEAN | Firm, elastic springy, flaky, juicy |
Firm, springy, Juicy |
Less firm, less juicy |
Softer, gritty | Very soft | Slippery, sloppy, greasy |
| 10 | 8 | 6 | 4 | 2 | 0 | |
Rejection level |
||||||
OVER ALL QUALITY SCORE |
||||||
Appendix F: Quality test using structured scaling
Two samples (A and B) of cooked fish were evaluated by 10 assessors using the scheme fig. 8.3. The following overall quality score was obtained.
| Assessor | Treatments |
Difference A - B |
|
| A | B | ||
| 1 | 7 | 7 | 0 |
| 3 | 6 | 5 | 1 |
| 4 | 7 | 5 | 2 |
| 5 | 7 | 5 | 2 |
| 6 | 8 | 6 | 2 |
| 8 | 8 | 6 | 2 |
| 9 | 7 | 5 | 2 |
| 10 | 8 | 7 | 1 |
| Total | 74 | 59 | 15 |
| Mean | 7.4 | 5.9 | 1.5 |
Standard deviation 
n is number of assessor
t = Mean difference/ (s/
)
t = 1.5/(1.643/3.165) = 2.889
From Table with n - 1 degree of freedom (probability 0.05%) t is 2.622.
Sample A is significantly different as t(2.889) > t table(2.622).