Dark Chocolate… The Real Dark Secret
Mark Pieterse LECO South Africa 2015
Presentation Outline : • General facts • Method of Extraction • GC-TOFMS Methodology • Results • Conclusion
Where is Cocoa Grown ?
Global Production :
Bean to Bar : • Pods are collected and split open • A farmer can expect 20-50 beans per pod,
depending upon variety • Takes approximately 400 beans to produce 500g of
Chocolate • Harvested beans are fermented for 3-7 days • Fermented beans are then dried, sold, packed and
transported • Roasting and Grinding- Cocoa liquor produced • Cocoa liquor pressed ready for Chocolate
manufacture
Dark Chocolate…
• More cocoa solids than sugar • Greater health benefits • More intense flavours
LECO GC-TOFMS : Fastest Type of Mass Analyzer • Requires fast data acquisition system • Leco Pegasus HT: Capable of 500 Full Mass Range
Spectra/s • Ability to properly define narrow chromatographic peaks
(Hi Speed GC) • Delivers the data density needed for True Signal
Deconvolution® • Full range mass spectrum is collected at all times without
sacrificing speed or sensitivity….no need for SIM for best sensitivity
• Spectral Continuity, no spectral skewing
Method of Extraction : • 2 grams of each sample weighed out into headspace vial • Each sample incubated at 37ºC for 15 minutes • Fibre used for SPME was PDMS-DVB-Carboxen • Sampled with SPME for 20 minutes • Thereafter sample was desorbed in GC inlet and
analysed
GC-TOFMS Method : GC: Agilent 7890 Gas Chromatograph Column: 30m x 0.25mm x 0.25µm Restek Stabilwax Inlet: Splitless @ 220°C Carrier Gas: 1.50 mL/min, Constant Flow GC Oven: 40°C (5 min hold), 7°C/min to 220°C, (5 min hold) MS Transfer Line: 200°C MS: LECO Pegasus HT Ion Source: EI at -70 eV Ion Source Temperature: 220°C Spectral Acquisition Rate: 20 spectra/s Acquired Mass Range: 30-550 m/z Instrument Control and Data Review: ChromaTOF Instrument Control and Data Review: ChromaTOF
Typical Dark Chocolate Chromatogram:
200 400 600 800 1000 1200 1400 1600 18000
5e+006
1e+007
1.5e+007
2e+007
2.5e+007
3e+007
3.5e+007
4e+007
Time (s)TIC
Does Chromatographic Peak Size Count ?
400 600 800 1000 1200 1400 1600 18000
1e+006
2e+006
3e+006
4e+006
5e+006
6e+006
Time (s)TIC
Marks & Spencer Dark Chocolate 72% : Mix of Flavours
• Aldehydes impart chocolate flavour : 2-Methylbutanal and 3-Methylbutanal • Furanoid : Flowery, fruity taste, : trans-Linalool
oxide • Pyrazines generally a roasted odour or flavour : Methylpyrazine
Aldehydes impart chocolate flavour : 2-Methylbutanal and 3-Methylbutanal
150 152.5 155 157.5 160 162.5 165 167.5 170
1e+006
2e+006
3e+006
4e+006
5e+006
Time (s)
Buta
nal,
2-m
ethy
l-
Buta
nal,
3-m
ethy
l-
TIC
Furanoid Flowery, fruity taste: trans-Linalool oxide
937.5 940 942.5 945 947.5 950 952.5 955 957.5 960
-0
20000
40000
60000
80000
100000
120000
140000
160000
Time (s)
3-Fu
rald
ehyd
e
2-Fu
ranm
etha
nol,
5-et
heny
ltetra
hydr
o-à,
à,5-
trim
ethy
l-, c
is-
Pyra
zine,
tetra
met
hyl-
59
Pyrazines Roasted : Methylpyrazine
681 682 683 684 685 6860
10000
20000
30000
40000
50000
60000
70000
80000
Time (s)
Pyra
zine
, m
ethy
l-
2-H
epta
nol,
acet
ate
94
Willie’s Cacao Madagascan Gold, 71% - Notes of Summer fruits :
• Alcohols – Flowery, Floral and Fruity: 1-Pentanol
• Esters – Honey, Sweet, Fruity and Floral : Acetic acid, 2-phenylethyl ester
Alcohols – Flowery, Floral and Fruity: 1-Pentanol
663 664 665 666 667 668 669 670-0
5000
10000
15000
20000
25000
30000
35000
40000
Time (s)
1-Pe
ntan
ol
55
Esters – Honey, Sweet, Fruity and Floral : 2-phenylethyl ester Acetic acid
1299 1300 1301 1302 1303 1304 1305 1306
-0
200000
400000
600000
800000
1e+006
1.2e+006
Time (s)
Acet
ic ac
id, 2
-phe
nyle
thyl
est
er
104
Visual Difference :
200 400 600 800 1000 1200 1400 1600 1800 20000
500000
1e+006
1.5e+006
2e+006
2.5e+006
3e+006
Time (s)TIC Madagascar 71%:1 TIC Marks Spencer 72%:1
Aldehydes : 2-Methyl Butanal
155 156 157 158 159 160
-0
20000
40000
60000
80000
100000
120000
140000
160000
180000
Time (s)
Buta
nal,
2-m
ethy
l-
Buta
nal,
2-m
ethy
l-
57 Marks Spencer 72%:1 57 Madagascar 71%:1
Alcohols: 1- Pentanol
663 664 665 666 667 668 669 670 671 672
-0
5000
10000
15000
20000
25000
30000
35000
40000
45000
Time (s)
1-Pe
ntan
ol
55 Marks Spencer 72%:1 55 Madagascar 71%:1
Pyrazines: Methyl-Pyrazine
681 682 683 684 685
10000
20000
30000
40000
50000
60000
Time (s)
Pyra
zine,
met
hyl-
2-He
ptan
ol, a
ceta
te
Pyra
zine,
met
hyl-
94 Marks Spencer 72%:1 94 Madagascar 71%:1
The Difference : Linalool Oxide, Marks Spencer
945 946 947 948 949
5e+006
1e+007
1.5e+007
2e+007
2.5e+007
3e+007
3.5e+007
Time (s)
Pyra
zine,
tetra
met
hyl-
Linalo
ol Ox
ide
Pyra
zine,
tetra
met
hyl-
TIC Madagascar 71%:1 TIC Marks Spencer 72%:1
Conclusion : • Chocolate is a very complex sample, not as simple
as it tastes • SPME provides a snapshot • GC-TOFMS can find a multitude of components • We have only seen the tip of the iceberg • Due to mass spectra produced fingerprinting of
compounds is even more beneficial • Provides more accurate results
Acknowledgements : • SENSORY FX • KERRY Flavours • SAAFoST
Thank you!