THE KINETICS OF COFFEE AROMA EXTRACTION - Imre Blank · THE KINETICS OF COFFEE AROMA EXTRACTION...
Transcript of THE KINETICS OF COFFEE AROMA EXTRACTION - Imre Blank · THE KINETICS OF COFFEE AROMA EXTRACTION...
23/11/2014
THE KINETICS OF COFFEE AROMA EXTRACTION
Frédéric Mestdagh, Britta Folmer, Tomas Davidek, Imre Blank
P2
Outline
INTRODUCTION Experimental setup
Quantitative aroma analysis in-cup
EXTRACTION KINETICS Role of odorant polarity and volatility
Impact of granulometry
CONCLUSIONS
01
02
03
From blend creation to the cup. But how about the extraction kinetics?
BLEND CREATION
Selection
Roast degree
Grind size
Capsule load
P3
EXTRACTION
Temperature
Flowtime
Water quality
Pressure
IN CUP QUALITY
Sensory attributes
Aroma composition
Non-volatile analysis
Extraction kinetics:
How are coffee odorants extracted?
Experimental setup
Modified extraction machine With pressure-programmable pump
Operating at constant pressure (20 bar)
Two Nespresso grand crus (proposed extraction volume – mean granulometry) Lungo (110mL – 365 µm)
Espresso (40mL – 275 µm)
Extraction and quantitative aroma measurement in-cup 10-20-40-80-110-150mL
Using Aqua Panna water
Each analysis point is an average of 3 extractions
P4
20 bar
Pre
ssu
re
Time
Quantitative measurement of 22 key coffee odorants in-cup
22 aroma compounds
• Isotope dilution assay
• SPME-GC-MS and SPME-GC-QQQ
P5
Quantitative measurement of 22 key coffee odorants in-cup: Varying volatility and polarity
Volatility Polarity Compound Aroma quality
High High 2,3-butanedione Buttery
Medium High 2,3-pentanedione Buttery
Low High 2-acetylpyrazine Popcorn
Low High Furfural Bready
Medium High Pyridine Fishy
Very high High Methanethiol Sulfury, cabbage, gassy
Low High 2-acetylpyridine Popcorn
Very high High Dimethylsulfide cabbage, sulfury
High Medium 2-methylbutanal malty, cocoa
High Medium 3-methylbutanal Malty
Low Medium Guaiacol Smoky, phenolic
Medium Medium N-methylpyrrole Roasty
Low Medium 2-ethyl-3,5-dimethylpyrazine Earthy
Low Medium 3-mercapto-3-methylbutylformate Roasted, sweaty
Medium Medium 2-furfurylthiol Roasty
Low Medium Phenylacetaldehyde Floral, honey
Medium Low Hexanal Green/grassy
Low Low 4-vinylguaiacol Spicy, medicinal
Medium Low Ethyl-2-methylbutanoate Fruity
Low Low 4-ethylguaiacol Smoky, medicinal
Low Low Skatol animal
Low Low Beta-damascenone Cooked apple
roasty
malty
fruity
buttery
earthy
floral,
honey
Cabbage,
sulfury
popcorn
grassy
smoky
animal
apple
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160
No
rmal
ized
in-c
up
aro
ma
qu
anti
ty
Extraction volume (mL)
High volatile High polar
Extraction kinetics differ among odorants
Extraction equation
Y =
P7
a x
b + x
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160
No
rmal
ize
d in
-cu
p a
rom
a q
uan
tity
Extraction volume (mL)
High volatile High polar
Low volatile Low polar
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160
No
rmal
ized
in-c
up
aro
ma
qu
anti
ty
Extraction volume (mL)
High volatile High polar
High volatile Medium polar
Low volatile Low polar
a / b
Volatility does not determine extraction behaviour
P8
0.00
0.05
0.10
0.15
0.20
0.25
0.30
-2.0 -1.0 0.0 1.0 2.0 3.0 4.0
Slo
pe
at o
rigi
n (
a/b
)
Volatility (Log [vapour pressure])
Lungo 20 bar
2-methylbutanal
2-acetylpyrazine
2,3-butanedione Low volatile High volatile
β-damascenone
Instead, polarity does impact the extraction behaviour
P9
High polar Low polar
y = -0.0464x + 0.1426R² = 0.6077
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
-1.5 -0.5 0.5 1.5 2.5 3.5
Slo
pe
at o
rigi
n (
a/b
)
Polarity (logP o/w)
Lungo 20 bar
2-methylbutanal
2,3-butanedione
2-acetylpyrazine
β-damascenone
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160
No
rmal
ize
d in
-cu
p a
rom
a q
uan
tity
Extraction volume (mL)
High volatile High polar
High volatile Medium polar
Low volatile Low polar
Aroma balance changes during extraction
P10
Lungo
! Based on normalized in-cup quantitative data,
Aroma values not taken into account !
13mL
High polar
Medium Polar
Low polar
144mL
High polar
Medium Polar
Low polar
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 20 40 60 80 100 120 140 160
No
rmal
ize
d in
-cu
p a
rom
a q
uan
tity
Extraction volume (mL)
365nm
275nm
Extraction of high polar compounds is affected by granulometry
P11
Finer granulometry faster extraction
High polar
Extraction kinetics of low polar
odorants is less affected
Granulometry
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 20 40 60 80 100 120 140 160N
orm
aliz
ed in
-cu
p a
rom
a q
uan
tity
Extraction volume (mL)
365nm
275nm
Low polar
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
-1.5 -0.5 0.5 1.5 2.5 3.5
Slo
pe
at o
rigi
n (
a/b
)
Polarity (log P o/w)
365nm
275nm
Finer granulometry faster extraction
P12
Sometimes deviating
extraction behaviour
Extraction profile of
odorants with lower polarity
less affected
Granulometry
High polar Low polar
Granulometry plays a key role for the extraction kinetics of high polar compounds
P13
• Extraction kinetics of coffee odorants
depend on the polarity
• R&G granulometry
• influences the extraction profile of
high polar odorants
• does not influence the extraction
behaviour of low polar odorants
Based on the above we can suggest that granulometry is one of the key
parameters for developing espresso coffees
Non-volatiles are also expected to play a key role and should be further
investigated