The multiple role of polyphenol chemistry in coffee associated with quality attributes

Transcription

1 The multiple role of polyphenol chemistry in coffee associated with quality attributes 24 th ASIC Conference, Costa Rica, Arne Glabasnia, Imre Blank, Federico Mora, Valérie Leloup, Josef Kerler Nestlé PTC rbe

2 AGENDA Introduction Coffee polyphenols as quality markers for green coffee Coffee Polyphenols and aroma Coffee Polyphenols and taste Coffee Polyphenols and health Conclusion PTC rbe-science&nutrition / AGL /

3 The family tree of (poly)phenols Antioxidants Phenolic acids (e.g ferulic acid, caffeic acid, chlorogenic acids) Ellagic acid/ellagitannins (Poly)phenols Flavonoids thers (BHT, Vit C) Isoflavones (genistein, daidzein) Flavonols (e.g. quercetin) Flavanones e.g. hesperidin Flavanols Anthocyanins Catechins Pro(antho)cyanidins PTC rbe-science&nutrition / AGL /

4 Chlorogenic acids are the major phenols in coffee H H H H R H R Quinic acid Intermediate from the shikimic acid cycle H H H R H R H R Cinnamic acids Common metabolites in plants Chlorogenic acids Esters of quinic acid with hydroxycinnamic acids PTC rbe-science&nutrition / AGL /

5 Diversity of chlorogenic acids in coffee H H H H H H 3-caffeoyl quinic acid 4-caffeoyl quinic acid 5-caffeoyl quinic acid H H H CH 3 H CH 3 H 3 C H 3-feruoyl quinic acid 4-feruoyl quinic acid 5-feruoyl quinic acid R R CH 3 R CH 3 R CH 3 CH 3 CH 3 CH 3 CH 3 coumaric acid dimethoxycaffeic acid trimethoxycaffeic acid sinapic acid PTC rbe-science&nutrition / AGL /

6 Diversity further increased by presence of diesters H H H H H 3,4-dicaffeoyl quinic acid 3,5-dicaffeoyl quinic acid 4,5-dicaffeoyl quinic acid Di-Caffeoylquinic acids 1C,3CQA 1C,4CQA 1C,5CQA 1F,3FQA 1F,4FQA 1F,5FQA 3F,4FQA 3F,5FQA 4F,5FQA 1C,3FQA 1C,4FQA 1C,5FQA 3C,4FQA 3C,5FQA 4C,5FQA 1F,3CQA 1F,4CQA 1F,5CQA 3F,4CQA 3F,5CQA 4F,5CQA + all homo- and heterodiesters containing - coumaric acid - dimethoxycaffeic acid - trimethoxycaffeic acid - sinapic acid More than 100 different Di-Chlorogenic acid PTC rbe-science&nutrition / AGL /

7 Coffee phenols as quality markers for green coffee PTC rbe-science&nutrition / AGL /

8 Chlorogenic acids as quality markers for blend To differentiate between Robusta and Arabica To calculate blend of unknown samples LC-DAD (Mullen et al. 2011) by NIR (Haiduc et al.) by NMR (Wei et al. 2010) by LC/MS direct infusion (Garrett et al. 2012) Arabica Robusta PTC rbe-science&nutrition / AGL / Haiduc et al, unpublished Garrett et al, 2012

9 Chlorogenic acids as markers for coffee origin CGA used in as indicator of origin (Alonso-Salces et al, 2009) - to classify Robusta coffees from Cameroon, Indonesia, Vietnam - to classify Arabicas from America and Africa Robusta Arabica Alonso-Salces, 2009 Alonso-Salces, 2009 No effect for origin for Robusta from Africa (Ky et al 2001) PTC rbe-science&nutrition / AGL /

10 Differentiation of cultivar by CGA content Differentiation of cultivars by CGA profile sometimes possible Crop to crop variety for one cultivar bigger than from cultivar to cultivar Monteiro et al (2012) PTC rbe-science&nutrition / AGL /

11 5-CQA [mg/100g] Chlorogenic acids as quality markers for post-harvest treatment 17 brazilians cultivars analysed for CGAs, trigonelline, caffeine and sucrose In average higher CGA content in wet-processed coffee compared to semi-dry Trigonelline higher as well, sucrose lower, no effect on caffeine semi-dry wet (adapted from Duarte et al, 2010) PTC rbe-science&nutrition / AGL /

12 Chlorogenic acids in correlation with cup quality Correlation of CGA content with cup quality (Farah et al, 2006) The higher the CGA content the lower the cup quality Cup quality PTC rbe-science&nutrition / AGL / Farah et al (2006)

13 Coffee phenols and their role in coffee aroma PTC rbe-science&nutrition / AGL /

14 Chlorogenic acids as aroma precursors upon roasting PTC rbe-science&nutrition / AGL /

15 Important aroma compounds in roasted coffee Dose-over threshold Compound Arabica Robusta (E)-beta-damescenone furfurylthiol MMBF MBT isobutyl-2-methoxypyrazin homofuraneol furaneol ,3-butandione vinylguaiacol guaiacol ,3-pentandione methional vanillin ethyl-3,5-dimethylpyrazin ,3-diethyl-5-methylpyrazin sotolon ethylguaiacol abhexon Semmelroch et al. (1995) Phenolic impact compounds guaiacol CH 2 CH 3 4-vinylguaiacol CH 3 CH 3 CH 3 CH 3 4-ethylguaiacol vanillin PTC rbe-science&nutrition / AGL /

16 Relative headspace concentration (%) Role of chlorogenic acids in aroma staling Significant losses in headspace concentration of e.g. thiols, pyrroles occur within hours Losses in headspace concentration of FFT occur within minutes DMS Ethanethiol FFT MMBF N-Methylpyrrole 2,3-Pentanedione Time (hours) Mueller et al, 2007 Are chlorogenic acids involved in that degradation? PTC rbe-science&nutrition / AGL /

17 Trapping of key odorants (thiols) by polyphenols via oxidative coupling hydroxyhydroquinone (HHQ) (Müller et al, 2007) The loss of 2-furfurylthiol during coffee storage is mainly due to the oxidative coupling of the odorant to hydroxyhydroquinone (2), giving rise to the conjugates 9 and 10. PTC rbe-science&nutrition / AGL /

18 Reaction possible for intact CGAs but not found in coffee Formed in model experiments Found in coffee brew H S H S catechol adduct H 3 C S caffeic acid adduct H S H S CQA adduct PTC rbe-science&nutrition / AGL / (Mueller et al, 2007)

19 Chlorogenic acids involved in coffee staling but not exclusively Munro et al. (2003) R SH oxidation - direct or radical induced (S-radical) S S R N S Milo et al. (unpublished ) radical induced oxidation (C-radical) reaction with aldehydes/ heterocycles? Müller & Hofmann (2005) H H S S H H nucleophilic addition at chlorogenic acid derivatives SH nucleophilic addition at melanoidins R N +. N R S R N N R R N N R + + S Hofmann & Schieberle (2002) PTC rbe-science&nutrition / AGL /

20 Coffee phenols and their role in coffee taste PTC rbe-science&nutrition / AGL /

21 CGAs as precursors for tastants: lactones Lactone formation well known (Farah et al, 2005) Lactones have been identified as bitter compounds in coffee (Frank et al. 2006) giving pleasant coffee-like bitter taste Bitter threshold Compound mg/l umol/l 3--caffeoyl-γ-quinide (2a) caffeoyl-γ- quinide (3a) caffeoyl-epi-δ-qunide (4a) caffeoyl-muco-γ- quinide (5a) caffeoyl-muco-γ- quinide (6a) feruoyl-γ-quinide (2b) feruoyl-γ- quinide (3b) ,4--dicaffeoyl-γ-quinide ,5--dicaffeoyl-epi-δ-quinide ,5--dicaffeoyl-muco-γ- quinide (3a) Frank et al., 2006 PTC rbe-science&nutrition / AGL / Frank et al., 2006

22 CGAs as precursors for tastants: phenylindanes Phenylindanes another class of bitter compounds formed from CQA degradation H R 1 H C H phenylbutanes phenylbutanes H H quinic acid H H H + Interm. R 1 H phenylbutenes phenylbutenes HC H 3 C H phenylindanes phenylindanes 5-Chlorogenic acid 4-vinyl 5-CQA caffeic acid vinylcatechol R 1 Bitter threshold Compound mg/l µmol/l H H H H Phenylbutanes 6 23 Phenylbutenes Phenylindanes H 3 C H H H 3 C Diphenylindanes Frank et al., 2007 PTC rbe-science&nutrition / AGL / R 1 diphenylindanes diphenylindanes R 1 Frank et al., 2007

23 CGA as precursors for tastants: furan benzene diols Benzene diols are formed from catechols and furan derivatives in model roast experiments (Kreppenhofer et al. 2010) furfuryl alcohol H H+ - H 2 0 H H + CH 2 R + CH 2 + R H 4-(furan-2-ylmethyl)benzene-1,2-diol 4-CQA catechol H H CH 3 TC: 9.6 mg/l TC: 6.5 mg/l H H H CH 3 PTC rbe-science&nutrition / AGL / TC: 5.7 mg/l Kreppenhofer et al, 2007 TC: 7.5 mg/l

24 Rel% Formation of bitter tastants upon roasting Roasting Caffeine CQL DKP Phenylindane Bitter precursor content depends on blend caffeine-like 80 coffee-like Bitter compound formation depends on roasting degree metallic harsh Kinetics are different for different chemical classes 20 Bitter quality also different 0 green Roast degree Compound class Threshold for bitterness (umol/l) Caffeine 750 Lactones DKPs Phenylindanes Benzenediols PTC rbe-science&nutrition / AGL /

25 Sensory analytical correlation Profiling was carried out with an expert panel (n=12) The basic attributes... roasty bitter acid... describe the basic properties of an Espresso coffee The subtle aroma descriptors... fruity-floral red fruits, lemon, jasmine green-vegetal herbs, fresh vegetables dry-vegetal wood, malt, cereal vegetal-humus earthy, mushroom cacao roasted, cacao, dark chocolate sweet vanilla, caramel, honey... describe the signature aroma of an Espresso coffee... are grouped based on olfactive similarity PTC rbe-science&nutrition / AGL / Baggenstoss et al, ASIC 2010

26 54 aroma and taste compounds were analyzed for the present study substance flavor quality substance flavor quality 1 methanethiol sulfur, garlic 28 2-acetylthiazole roasty, popcorn 2 dimethyl sulfide cabbage, sulfur 29 furfural grass, almond 3 dimethyl trisulfide sulfur, cabbage 30 furfuryl acetate - 4 furfurylthiol sulfur, roast 31 2,3,5-trimethylpyrazine roasty 5 3-mercapto-3-methylbutylformate catty 32 2-ethyl-3,6-dimethylpyrazine roasty, earthy 6 methional potato 33 2-ethyl-3,5-dimethylpyrazine roasty, earthy 7 3-methyl-2-butenethiol sulfur, amine 34 2-ethenyl-3,5-dimethylpyrazine roasty, earthy 8 2-methyl-3-furanthiol meat 35 2,3-diethyl-5-methylpyrazine roasty, earthy 9 acetaldehyde pungent, fruity 36 2-acetylpyrazine roasty 10 propanal solvent, pungent, fruity 37 2-isopropyl-3-methoxypyrazine pea, earthy 11 2-methylpropanal fruity, pungent 38 2-isobutyl-3-methoxypyrazine pea, earthy 12 2-methylbutanal fruity, cocoa 39 β-damascenone rose, honey 13 3-methylbutanal malty 40 sotolon maggi, curry 14 phenylacetaldehyde honey 41 furaneol caramel 15 hexanal grass 42 maltol caramel 16 2,3-butanedione buttery 43 3-CQA ,3-pentanedione buttery 44 5-CQA - 18 vanilline vanilla 45 4-CQA - 19 ethyl 2-methylbutanoate fruity 46 5-CQL bitter 20 ethyl 3-methylbutanoate fruity 47 4-CQL bitter 21 p-cresol medicinal, phenolic, smoke 48 5-FQA - 22 guaiacol smoke, medicine 49 4-FQA ethylguaiacol spice, clove 50 cyclo-val-pro bitter 24 4-vinylguaiacol spice, clove 51 cyclo-ala-pro bitter 25 N-methylpyrrole - 52 cyclo-pro-leu bitter 26 pyridine - 53 cyclo-phe-pro bitter 27 2-acetylpyridine popcorn 54 caffeine bitter PTC rbe-science&nutrition / AGL / Baggenstoss et al, ASIC 2010

27 Comp2 Around 30 compounds exhibit strong correlation to aroma quality mL (Ristretto) 40mL (Espresso) 110mL (Lungo) E1 dimethyl sulfide sotolon furaneol CTn methional furfural E6 E2 acetaldehyde 2,3-pentanedione 2,3-butanedione methanethiol fruity-flowery acid green-vegetal E3 L1 2,3,5-trimethylpyrazine furfurylthiol pyridine furfuryl acetate 2-acetylpyridine E4 E5 R2 R1 3-methyl-2- butene-1-thiol N-methylpyrrole 2-isopropyl-3- methoxypyrazine L2 2-methyl-3-furanthiol 2-methylbutanal 4-vinylguaiacol 4-ethylguaiacol dimethyl trisulfide guaiacol 2-acetylthiazole vanilline 2,3-diethyl-5-methylpyrazine 2-isobutyl-3-methoxypyrazine 2-methylpropanal hexanal R3 p-cresol L3 vegetal-humus sweet phenylacetaldehyde roasty dry-vegetal cocoa bitter No correlation with lactones found for bitterness perception PTC rbe-science&nutrition / AGL / Comp1 Baggenstoss et al, ASIC 2010

28 Around 30 compounds exhibit strong correlation to the sensory descriptors 2,3,5-trimethylpyrazine 2-furfurylthiol acetaldehyde methanethiol 2,3-butanedione 2,3-pentanedione dimethyl sulfide sotolon furaneol 2-acetylpyridine pyridine sweet furfuryl acetate phenylacetaldehyde roasty dry vegetal vegetalhumus fruityflowery 3-methyl-2-butenethiol N-methylpyrrole methional furfural 2-methylbutanal acid green vegetal vanilline 2-acetylthiazole hexanal 2-isobutyl-3-methoxypyrazine 2-methylpropanal PTC rbe-science&nutrition / AGL / p-cresol bitter cocoa 2-isopropyl-3-methoxypyrazine 2-methyl-3-furanthiol 4-ethylguaiacol guaiacol 4-vinylguaiacol dimethyl trisulfide 2,3-diethyl-5-methylpyrazine Correlation found for aroma compounds derived from CQA breakdown with bitterness perception Baggenstoss et al, ASIC 2010

29 Bitterness prediction model from aroma compounds including those derived from CQA is very good Baggenstoss et al, ASIC 2010 PTC rbe-science&nutrition / AGL /

30 Coffee phenols and their role for health PTC rbe-science&nutrition / AGL /

31 Polyphenols/flavonoids have been considered to have an effect on health for many years 1936 Albert von Szent- Györgyi Nobel Prize in Physiology or Medicine (1937) 1957 PTC rbe-science&nutrition / AGL /

32 The importance of coffee polyphenols in human diet pear black tea apricot pecan black grape nectarine red wine dessert apple broad bean peach raspberry grapefruit strawberry green tea infusion orange juice cider apple plum highbush blueberry blackberry dark chocolate (mg/100g fresh weight) epicatechin catechin procyanidin B2 procyanidin B3 procyanidin B1 procyanidin C1 procyanidin EEC EGC EGCG cyanidin delphinidin malvidin pelargonidin petunidin quercetin hesperidin naringenin Coffee 36. place in mg/100g 6. place per serving 1. place for daily consumption (3-4 cups per day) PTC rbe-science&nutrition / AGL / Scalbert et al, 2010

33 CQAs most contributors to polyphenol intake in French adults Scalbert et al, 2011 PTC rbe-science&nutrition / AGL /

34 More and more reports on positive effects on health for a moderate coffee consumption Robust inverse relation between regular coffee consumption, including decaffeinated, and risk of type 2 diabetes based on meta-analyses of epidemiological studies (van Dam 2006; van Dam and Hu 2005) Coffee, decaffeinated coffee, and tea consumption in relation to incident type 2 diabetes mellitus: a systematic review with meta-analysis. (Huxley et al 2009) The use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trials. (nakpoya et al 2011) Lipophilic antioxidants more neuroprotective than hydrophilic (e.g. lactones (Chu et al 2009) High CQA coffees prevent oxidative damage (Hoelzl et al 2010) Antioxidant rich coffee reduces DNA damage (Bakuradze et al, 2011) CGA rich coffee induce chemopreventive phase II enzymes (Boettler et al. 2011) Coffee has positive effects to reduce cognitive decline (Abreu et al, 2011) ASIC session yesterday PTC rbe-science&nutrition / AGL /

35 Antioxidant activity of green coffee comes mainly from CGAs 80% of the total antioxidant activity in green coffee comes from the 9 main chlorogenic acid H H H Total Antioxidant Activity by folin in% H CH 3 H CQA FQA di-cqa More than 100 coffee polyphenols have been already reported in the literature by the scientific community (Clifford & Kuhnert ) PTC rbe-science&nutrition / AGL /

36 Antioxidant activity in roasted coffee stays at high level but is less explained by CGAs Total polyphenols (µmol 3CQA /g green coffee d.b.) Antioxidant capacity (µmol 3CQA /g green coffee d.b.) Total polyphenols (µmol 3CQA /g green coffee d.b.) Antioxidant capacity (µmol 3CQA /g green coffee d.b.) a)total polyphenols by FLIN From 9 CGAs 0 GC Light Medium Dark 0 GC From melanoidins b) Antioxidant capacity by ABTS GC Light Medium Dark 0 GC Leloup et al, ASIC 2010 PTC rbe-science&nutrition / AGL /

37 Antioxidant activity of roasted coffee derives from small new peaks but mainly from a unresolved hump Absorption Absorption mg/mL 325nm ABTS CQAs FQAs dicqas retention time (min) mg/mL 325nm ABTS retention time (min) Leloup et al, ASIC 2010 PTC rbe-science&nutrition / AGL /

38 Intensity * * * Precursor ion scan by LC/MS of a roasted coffee to detect precursors of caffeic acid moiety CQA CafTrp * Lactones * Caffeic acid moiety di-cqa Leloup et al, ASIC 2010 Retention time (min) Caffeic acid moiety largely present in unresolved hump PTC rbe-science&nutrition / AGL /

39 Incorporation of chlorogenic acids into coffee melanoidins PTC rbe-science&nutrition / AGL / Bekedam et al, 2007

40 g/100g Model roasting of 5-CQA at 200 C in dry state U n 8 Degradation of 5-CQA and Folin of reaction mixture HPLC chromatogram from final reaction mixture CQA content Folin response lactones RT: MA: N 2 C U n heating time in minutes Time (min) 5-CQA is rapidly degraded in model roast mix at 200 C TPP by Folin of reaction mixture remains almost constant Lactones are formed but cannot explain loss of 5-CQA and Folin values A lot of minor peaks are detectable Chromatographic tools suitable? PTC rbe-science&nutrition / AGL /

41 C:\Xcalibur\data\Kaffee\111208c :05:03 CQA + Sucrose 30 min c #10 RT: 0.27 AV: 1 NL: 4.23E7 T: - c ESI Full ms [ ] Direct infusion into LC/MS of model roast of 5-CQA Polymerization of CQA can be observed QA-H2 H H H H H H CQA CQL DiCQA Di-CQL CA-H QA-H CA-H m/z PTC rbe-science&nutrition / AGL / QA-H2 H H H H H H H H polymers

42 H Possible transformations of CGA and the effect on AX properties H AX property H H C H 2 x 2 Chlorogenic acid Polymerization CH 3 Nucl. H H H H H H H H H H H H S PTC rbe-science&nutrition / AGL /

43 Conclusions Chlorogenic acids can be used to evaluate green coffee quality with regards to variety, origin and post-harvest treatment Chlorogenic acids play a crucial role in the formation and degradation of important coffee aroma compounds Chlorogenic acids are the main precursors of several bitter compounds in coffee Chlorogenic acids are converted into various compounds upon thermal treatment whilst maintaining the antioxidant activity PTC rbe-science&nutrition / AGL /

44 But one thing is sure... Coffee is the most pleasurable hot beverage in the world PTC rbe-science&nutrition / AGL /