color variation in standard virgin-olive-oil tasting glasses

Color Variation in standardColor Variation in standardVirgin-Olive-Oil Tasting Glasses Virgin-Olive-Oil Tasting Glasses

L. Gómez-Robledoa, M. Melgosaa, F.J. Herediab, M.J. Moyanoc, R. Roaa, R. Huertasa

a Basic and App. Colorimetry Lab.Departamento de Óptica, Facultad de Ciencias, Universidad de Granada, Spain, b Laboratorio de Bromatología , Facultad de Farmacia, Universidad de Sevilla,, Spainc Almazara Experimental del Instituto de la Grasa, CSIC, Sevilla, Spain

Universidad de Granada Universidad de Sevilla Instituto de la Grasa 1/18

Introduction

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J. Alba et al. Aceite de oliva virgen. Análisis Sensorial, 1997

Introduction 3/18

Quality Control of Oils

Chemical Analysis

Sensorial Analysis

J. Alba et al. Aceite de oliva virgen. Análisis Sensorial, 1997

Introduction 3/18

(1) It describes the features of glasses that are used in Olive Oil tasting.(2) Stability to avoid spillage.(3) The bottom of the glass must be prepared to homogenize the

temperature of the oil.(4) The geometry of the glass must preserve the bouquet of the oil.(5)The glass must be dark to block the color of the oil.

Standard COI/T.20/Doc.nº 5/18 June 1987

Agustí Romero, Joan Tous. Percepnet. 2005

Introduction 3/18

Introduction 4/18

Introduction

To check if the tasting glasses that are used in the official tasting (COI/T.20 rule) are able to avoid the taster to distinguish the color of the extra virgin olive oils.

Objective

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Introduction

To check if the tasting glasses that are used in the official tasting (COI/T.20 rule) are able to avoid the taster to distinguish the color of the extra virgin olive oils.

Is very different the color of different oils in different glasses?

Does the color of one oil change when we change the glass?

Is very different the color of two oils in the same glass?

Objective

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Material and method

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Number of the glass Capacity (ml)

Height(mm)

Rim’s diameter (mm)

Greater diameter

(mm)

Diameter at bottom (mm)

Thickness of glass at

bottom(mm)

Thickness of the glass at side (mm)

1 128,00 61,00 *45,82 *68,24 *40,00 *6,70 *2,682 136,00 *61,18 50,00 71,06 *24,00 *6,24 *2,603 *142,00 *63,54 51,00 *68,74 *25,14 *6,54 1,664 *142,00 *59,82 50,28 70,88 *25,06 *6,12 *2,865 140,00 *61,20 *45,90 *68,76 *40,58 5,40 *1,906 *144,00 60,50 *46,10 69,20 34,00 *4,38 1,707 *160,00 60,40 49,28 71,10 *21,68 *3,82 *2,408 140,00 *61,82 *45,20 *68,84 *31,58 *6,22 *2,009 138,00 59,72 49,60 70,40 *27,66 5,72 *2,62

10 *144,00 59,74 49,82 *71,08 *26,70 *7,36 *2,6611 *148,00 59,44 49,74 70,92 *27,66 *6,54 *2,6612 *156,00 *61,08 49,40 70,74 *28,22 *7,38 *2,4013 *148,00 60,50 49,96 *71,16 *26,48 *7,36 *2,2214 *150,00 60,38 *48,04 *71,04 *28,00 *6,30 *2,6815 *154,00 59,32 49,42 70,50 *30,78 4,70 *1,1816 *142,00 60,10 49,68 70,90 *25,80 *7,16 *2,7817 132,00 60,98 *43,10 70,50 *23,25 *8,58 *2,6018 *154,00 *63,14 *47,10 70,90 *30,20 *7,84 *2,14

Mean 144,33 60,77 48,30 70,28 28,71 6,35 2,32Standard deviation 8,44 1,16 2,21 1,01 5,20 1,23 0,47

Material and method

18 standard tasting glasses

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Standard glass 130±10 60±1 50±1 70±1 35±1 5±1 1,5±0,2

*Values out of the rule

Material and method

SpectraScan PR-704

GretagMacbeth Spectralight III Cabinet

Light source simulator D65

3 measures of each glass

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Spectrum of the 18 glasses

Material and method 8/18

Color of the 18 glasses assuming:

•D65 Illuminant•CIE64 Standard Observer

Material and method 9/18

Material and method

Sample L*ab,10 a*10 b*10

1 76,97 14,35 117,44

2 74,85 15,66 112,97

3 78,87 17,30 120,56

4 64,26 13,18 100,93

5 69,28 11,42 106,00

6 71,52 10,90 107,93

7 68,87 12,04 105,68

8 70,45 12,27 107,58

9 62,62 12,56 95,53

10 69,31 11,21 105,32

10 Spanish commercial extra-virgin olive oils.

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Material and method

1. 18 Standard tasting glasses.2. 10 Spanish extra-virgin olive oils.3. 3 different geometries.

Total: 540 measures.

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Results

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Does the color of one oil change when we change the glass?

Results 13/18

Results 13/18

Does the color of one oil change when we change the glass?

Results

* * *

1 1 1, ,

N N N

i i ii i i

L a bMean

N N N

13/18

Does the color of one oil change when we change the glass?

* * *

1 1 1, ,

N N N

i i ii i i

L a bMean

N N N

Does the color of one oil change when we change the glass?

Results

2 2 2* * * * * *

,ab i i i iE L L a a b b

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Results

1 1 1, ,

N N N

i i ii i i

L a bMean

N N N

2 2 2* * * * * *

,ab i i i iE L L a a b b

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,

*

1ab i

N

i

EMCDM

N

Mean

ColorDifferencerespect to theMean

Does the color of one oil change when we change the glass?

R. Berns. 2000.

Resultados

Color diferencies in CIELAB unitsOil 0° 30° 60°

MCDM SD MCDM SD MCDM SD1 1,96 1,60 3,72 2,51 4,80 3,362 1,83 1,56 3,07 2,23 4,25 3,153 2,12 2,73 3,05 2,04 3,70 2,494 1,18 1,07 3,25 2,12 3,93 3,295 2,03 1,86 3,50 1,87 4,35 3,856 1,73 1,84 3,44 2,04 4,67 3,797 2,67 3,09 3,12 2,75 3,44 2,868 2,08 2,10 3,90 2,19 4,27 2,819 1,38 1,09 3,78 2,26 5,15 3,18

10 2,28 2,23 4,07 1,92 4,41 2,84Mean/SD 1,93 0,43 3,49 0,37 4,30 0,51

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Does the color of one oil change when we change the glass?

MCDM of oils in a 46,4 mm transparent Pyrex Glass*= 6,9 CIELAB units

*L. Gómez-Robledo et al. JAOCS 2008. in press

Is very different the color of two oils in the same glass?

Results 14/18

Is very different the color of two oils in the same glass?

Results

0° 30° 60°

Glass MCDM SD MCDM SD MCDM SD

1 0,39 0,18 1,17 0,79 2,27 1,73

2 1,41 0,89 1,78 0,94 3,36 1,82

3 1,03 0,53 1,36 0,71 3,02 1,18

4 1,02 0,73 2,28 1,28 2,95 2,42

5 0,89 0,42 1,97 1,08 1,86 1,21

6 1,15 0,70 1,85 0,77 1,74 1,31

7 3,66 4,56 3,00 1,92 6,66 1,50

8 0,66 0,43 1,19 0,90 2,62 1,61

9 1,48 1,01 1,18 0,84 2,56 1,47

10 1,34 0,87 1,26 0,93 2,26 1,31

11 1,02 1,01 1,23 0,91 2,29 1,42

12 1,25 0,53 2,42 0,85 2,93 1,93

13 1,37 0,76 1,42 0,61 2,71 0,94

14 0,82 0,46 2,40 1,51 3,02 1,31

15 3,79 1,63 1,84 0,83 3,01 1,50

16 1,63 0,85 1,78 1,16 1,97 1,37

17 1,04 0,39 1,08 0,49 2,01 1,92

18 0,82 0,54 1,53 0,90 2,40 1,91

Mean/SD 1,38 0,91 1,71 0,54 2,76 1,08

MeanColorDifferencesrespect to theMean

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,

*

1ab i

N

i

EMCDM

N

MCDM of oils in Pyrex Glass= 6,9 CIELAB units*L. Gómez-Robledo et al. JAOCS 2008. in press

Is very different the color of different oils in different glasses?

Results 15/18

Is very different the color of different oils in different glasses?

18

2

Results

153

15/18

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153

10

2

18

2

45

Results

Is very different the color of different oils in different glasses?

15/18Results

13770 combinations for each geometry

10

2

18

2

245153

Is very different the color of different oils in different glasses?

Results

ΔE ab,10 SD

0° 3,07 2,87

30° 5,25 3,07

60° 6,89 4,59

13770 combinations for each geometry

16/18

Is very different the color of different oils in different glasses?

0 2 4 6 8 10 12 14 16 18 20 22 24 26 280

10

20

30

40

50

E*ab,10

(CIELAB units)

%

0deg 30deg 60deg

*L. Gómez-Robledo et al. JAOCS 2008 (in press)

Mean of measures in a 46,4 mm transparent Pyrex Glass*

10,96 7,23

Conclusions

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Conclusions

The present tasting glasses obey the International Olive Oil Council rules in an acceptable way. The color differences are perceptible.

Manufactures must follow the dimensions of the standard glasses, adding a fixed color specification with corresponding tolerances.

Improve the sensorial analysis we propose two types: opaque glasses to a taste analysis and transparent glasses to a color sensorial analysis.

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Thanks a lot for your attention

Aknowledments:Research Project P06-AGR-01744, Consejería de Innovación, Ciencia y Empresa; Junta de Andalucía (Spain).