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Barry Arnold: The story of Chocolate: Science and serendipity
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Barry Arnold: The story of Chocolate: Science and serendipity

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Barry worked as head of cocoa R&D at the Mars Confectionery Company for many years, both in cocoa plantations and here in the UK. ...

Barry worked as head of cocoa R&D at the Mars Confectionery Company for many years, both in cocoa plantations and here in the UK.

He has a detailed knowledge of why so many of us like chocolate and of the scientific approach to understanding its appeal!

This presentation gives the history of Chocolate's discovery and understanding the attempts of the industry to scientifically analyse what makes chocolate so desirable - both in scent and taste.

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Transcript

  • 1. The Chocolate Story – Science and Serendipity
  • 2. Chocolate-scented Daisy Berlandiera lyrata
  • 3. Cosmos
  • 4. Theobroma Cacao
  • 5. Tropical Rain Forest
  • 6. Rain 1500-3000mm/year
  • 7. Tropical zone – temp. 20deg C +
  • 8. Cocoa Flowers • ~ 10,000 flowers per tree • Natural pollination by midges • Very poor success rate : ~ 1-10% • No. of pods which mature also poor ~1-10% (diseases, animals, wilt) • Approx. 6 months from pollination until mature pods ripen • (Some artificial pollination e.g. Malaysia)
  • 9. Cocoa Propagation • “Indehiscent droop” • Needs animal to gnaw into pod and remove seeds, or for whole pod to be cut or bitten from tree • Seeds are coated with germination inhibitor • Seeds will not root in close proximity to parent • Seeds viable for ~ 7 days, will not survive desiccation
  • 10. Original centre of diversity
  • 11. Cocoa – History Lesson • Original trees – upper Amazon and tributaries • Valued by native Amazonians for its sweet, aromatic pulp • Brought over many generations by canoe and overland to Central America – transported short distances as pods/seeds, more likely as saplings • Evidence of domestication by Maya ~ 400BC (Costa Rica) • Highly prized and consumed as a drink by Aztecs (15-16th century) “XOCOLATL”
  • 12. Beans used as currency by Aztecs (need to have dried beans) • 4 beans to purchase a pumpkin • 10 beans for a rabbit • 12 beans for services of a prostitute! • 100 beans to buy a slave
  • 13. “Santa Maria” 1492
  • 14. XOCOLATL • Hernan Cortes (1519) at court of Montezuma • Ground cocoa beans mixed with spices (chilli) and water – drunk COLD • Stimulant and (probably) aphrodisiac • Prepared in vast quantities for “Gods” e.g.Quetzalcoatl • Often drunk from golden goblets • Spanish wanted gold rather than cocoa! • Xocolatl Tree was classified by Linnaeus (1734) as “Theobroma cacao” – the food of the Gods
  • 15. Cocoa in the Caribbean 16-17th Century
  • 16. Why Cocoa in Trinidad?
  • 17. Drinking Chocolate • Xocolatl received unenthusiastically back in Spain until….. • Combining the advantages of colonisation : sugar was added! - Spanish court in 17th century • Became the delight of the wealthy in Europe as a drink in “cocoa houses” (alongside coffee) e.g. London 1700-1750 • Probably still rather unpalatable by our standards – bitter, raw and astringent • However clearly a stimulant and probably still regarded as aphrodisiac
  • 18. MolinetCocoa Pot
  • 19. Spanish Recipe for Hot Chocolate • Roasted, fermented cocoa beans • Sugar • Cinnamon • Vanilla • Hot water • Variants included honey, cloves, aniseed, maize to thicken
  • 20. Sir Hans Sloane – English physician and botanist 1660-1753 • Collected specimens in Jamaica - including cocoa • Credited with adding milk to drinking chocolate!
  • 21. • Only possible when means of extracting cocoa butter was invented • Chocolate needs more fat than is present in beans alone (especially for moulding and coatings) • Dutch invention of the cocoa press (Van Houten 1825) – efficient way to make powder and butter • First chocolate will have been dark chocolate • Peters invented milk chocolate (Switzerland 1875) The first bar of chocolate?
  • 22. Countries where cocoa is grown today
  • 23. Source: UNCTAD based on the data from International Cocoa Organization, quaterly bulletin of cocoa statistics Share of countries in total cocoa beans production (2005/06 crop year forecasts)
  • 24. World Cocoa Production (tonnes) Cote D’Ivoire : 1,300,000 Ghana : 720,000 Nigeria : 160,000 Indonesia : 450,000 Brazil : 150,000 Ecuador : 115,000 Malaysia : 30,000 Dominican Rep : 45,000 Others : 200,000
  • 25. • 1 Million + farmers in Cote D’Ivoire • Each farm ~ 2-3hectares • 600-1000kg per farm per year! • 1 pod = ~ 50g dried beans • 20,000 pods per farm per year • BUT – only 10 pods (average) per tree The Real World!
  • 26. Cocoa Fermentation – Why? • Convenient way to dry beans (historic) • No chocolate flavour without fermentation! • Farmers get better price for fermented beans
  • 27. Cocoa Fermentation – How? • Split pods to separate beans from husk • Heap beans (+ pulp) on plantain leaves • Cover with more leaves and wait! • Turn heap with shovel after 2-3 days (maybe) • Put beans out to dry in the sun after 7 days • (Can be piled in a box or deep trays – some limited attempts to industrialise)
  • 28. The Biochemistry of Cocoa Fermentation • Yeasts ferment pulp sugars to ethanol • Acetobacter convert ethanol to acetic acid • Temperature of mass rises to ca. 50 deg C • Acetic acid level rises • Beans “die” and cell walls breakdown • Pre-germinative enzymes begin autolysis of bean components • Flavour precursors are formed
  • 29. What can go wrong? • Underripe pods – pulp slow to ferment • Over aeration disrupts process and changes microflora – e.g. lactic acid bacteria • Low temperatures allows beans to germinate prematurely • Putrefaction – especially from contaminated boxes and during drying • Flavour taints – wood smoke, moulds …..
  • 30. 0 1 2 3 4 5 6 Day1 Day2 Day3 Day4 Day5 Day6 Day7 pH pH pH
  • 31. Other Factors • Variation among cocoa genotypes • Effects of microbial metabolites (+ or -) • Opportunity to generate/preserve health benefits
  • 32. Drying beans on platforms
  • 33. Beans dry after 5-10 days • Ready to be bagged for sale and shipment • Farmers generally have no transport – rely on chain of “middle men” • Price paid increases down chain to port • Usually does not reflect world traded price • By the way – beans still have NO chocolate flavour!
  • 34. Chemistry of Drying Process • Enzymes are inactivated, autolysis ceases • Oxidation of precursor components • Dehydration “locks” and preserves flavour potential • NB – Beans still need roasting to develop cocoa flavour!!!
  • 35. Chocolate Story - what’s next? • Beans shipped half way round the world • Usually in sacks in holds – containers only very recently, first bulk shipments in 1996 • Held in dockside warehouses at destination • Traders buy and sell both “futures” and real beans! • Chocolate manufacturers check quality • Finally beans reach chocolate factory
  • 36. 1980 - 2010 US$
  • 37. US$
  • 38. Beans enter the 21st century! • Beans are roasted in rotating ovens or fluidised bed • Shells are removed • Flesh of beans (nib) is ground to produce COCOA LIQUOR • Liquor may be separated into BUTTER + POWDER (approx. 50:50) • Typical manufacturer may process 30,000 tonnes of beans each year
  • 39. Menthol Vanillin (ethyl vanillin) Limonene C H2 5 ( ) Examples of Food Flavour Chemistry
  • 40. Table 1. Aroma components of chocolate produced from heap- and tray-fermented cocoa beans. Compound Identificationa Description of odour Peak areab x103 ‘heap’ ‘tray’ 2/3-Methylbutanal MS, GC-O, S cocoa, chocolate 438 512 2,3-Butanedione MS, GC-O, S caramel, sweet 327 201 Hexanal MS, S 59 86 Isoamylacetate MS 388* 95* 2-Pentanol MS, S 107 79 2-Heptanone MS, S 88 64 Heptanal MS, S 17 18 2/3-Methyl butanol MS, S 45 26 2-Pentyl furan MS, S 82 95 1-Pentanol MS, S 94 53 Methylpyrazine MS 48 35 3-Hydroxy-2-butanone MS, GC-O fruity 365 220 2-Octanone MS 60 58 Octanal MS, GC-O, S orange, soapy 30 22 2,5-Dimethylpyrazined MS, GC-O, S earthy, mushroom 104 76 2,6-Dimethylpyrazine MS 64 54 2-Decanol MS 51 24
  • 41. Benzaldehyded MS, GC-O, S vegetable, grass 359 267 2,3,5-Trimethyl-6- ethylpyrazinec MS, GC-O grass, paprika 39 14 Propanoic acid MS, S 31 21 Linaloold MS, GC-O flowery, fruity 16* 47* Ethylpyrazined MS, GC-O popcorn 22 16 2-Acetylcyclopentanone MS 43 - 2,3-Dimethylpyrazinec MS, GC-O popcorn, potato 61 37 Dimethyl trisulphide MS, GC-O, S unpleasant, sharp 12 10 2-Ethyl-6-methylpyrazine MS 37 25 2-Nonanone MS, GC-O, S alcohol 72 43 Nonanal MS, GC-O, S fresh, fruity 120 113 2,3,5-Trimethylpyrazine MS, GC-O earthy, grass 388 166 Unknown 1 GC-O sharp, liquorice n.d. n.d. Unknown 2 GC-O grass, lettuce n.d. n.d. Ethyl octanoate MS, S 29 26 Acetic acid MS, GC-O, S vinegar, sharp 3596 4686 Furfural MS, S 37 - 2,5(or 6)-Dimethyl-3- ethylpyrazine MS, GC-O, S potato, earthy 35 21 Linalool oxide MS, S 34 20 Tetramethylpyrazine MS, GC-O potato, earthy 2393 1042 2-AcetylfuranMS, GC-O, S MS sharp, rubber
  • 42. 2-Methyl propanoic acid MS 1135 518 1,3/2,3-Butanediol MS 1945 1746 Dihydro-2(3H)-furanone MS 79 55 Butanoic acid MS, S 68 47 Phenylacetaldehyded MS, GC-O cocoa 132 121 1-Phenyl ethanone MS, GC-O flowery, sweet 137 70 Furfuryl alcoholc MS, GC-O, S oat 14 - 3-Methyl butanoic acid MS, GC-O, S unpleasant, blue cheese 1453 912 3-Methyl-2-heptanone MS - 10 Benzyl acetated MS, GC-O, S liquorice 14 9 Methyl phenylacetate MS 29* 8* Epoxylinalol MS, GC-O sweet, flowery 34 18 Ethyl phenylacetate MS, GC-O, S flowery, rose 133 255 1-(2-Hydroxyphenyl)- ethanone MS 16 - 1-Phenylethanol MS 44 19 Phenethyl acetate MS, GC-O, S 775 667 1-Butanol-3-methyl benzoate MS 214 93 Hexanoic acidd MS, GC-O, S sharp, spicy 131 108 Butoxyethoxy ethylacetate MS 31 32 o-Methoxyphenol MS, S 53 - Benzyl alcoholc MS 61 214 Unknown 3 GC-O sweet, vanilla n.d. n.d. 2-Phenethyl alcohol MS, GC-O, S flowery, rose 881 324 2-Phenyl-2-butenal MS 30 16 Heptanoic acid MS, S 131 108 2-Acetylpyrrole MS 63 59 Phenol MS 71 28
  • 43. Colour & Flavour Maillard Reaction Chemistry
  • 44. Roasting Chemistry • “Maillard” reactions between peptides, amino acids and reducing sugars • Maillard products rearrange and fragment • Volatile aroma chemicals generated • Oxidation of polyphenols • Unique oligopeptides are (probably) the key components
  • 45. Quest for the key peptides • Bean storage proteins identified and sequenced • Protease enzymes extracted • Complex mix of potential reactants • Attempts to link precursors to aroma chemical analysis (GC/MS/OD,etc.)
  • 46. The first bar of chocolate? • Only possible when means of extracting cocoa butter was invented • Chocolate needs more fat than is present in beans alone (especially for moulding and coatings) • Dutch invention of the cocoa press (Van Houten 1825) – efficient way to make powder and butter • First chocolate will have been dark chocolate • Beans are roasted in hi-tech ovens – flavour develops at last!! • Peters invented milk chocolate (Switzerland 1875)
  • 47. So – What is Chocolate? • Dark chocolate is simply cocoa liquor, sugar and cocoa butter • Milk chocolate is cocoa liquor, sugar, milk powder, cocoa butter and milk fat • White chocolate has no cocoa liquor • All types will have some added flavours – like vanilla, spices or fruit flavours
  • 48. Chocolate Processing • Heavy machinery and high energy needed • Basically 3 steps : mixing, milling and whipping • The best chocolates are very smooth • Mixing and whipping both affect flavours • Special processes like “refining” and “conching” • Overall efficiency (and cost) depends on viscosity and flow properties
  • 49. Tempering • Real chocolate needs to be “tempered” so that it will set properly and not “bloom” • Difficult to do without proper equipment • Need to make fat crystallise in correct form and at right speed! • “Cooking chocolate” doesn’t need tempering – but doesn’t taste so good!
  • 50. Typical Milk Chocolate Recipe • Cocoa liquor : 10 % • Sugar : 45 % • Whole milk powder : 20 % • Cocoa butter : 25 % • Vanilla : 0.05%
  • 51. Xanthine Alkaloids
  • 52. Anthocyanins
  • 53. Tannic Acid (Polyphenol)
  • 54. Mars Symbioscience CocoaPro CocoaVia Cirku
  • 55. The cocoa flavanols in CocoaVia™ - a cocoa extract supplement - help maintain healthy circulation by helping your blood vessels stay flexible and expand as needed, even as you age†. With daily intake, the cocoa flavanols in the CocoaVia™ supplement help oxygen and nutrients reach your organs and tissues, to help you stay on top – today and every day. Contains 250mg per serving vs. less than 5% in regular cocoa beans or 5-20mg in 100g regular dark chocolate
  • 56. Epicatechin Epigallocatechin FLAVAN-3-OLS
  • 57. Theoflavin
  • 58. beta - Sitosterol Benecol etc.
  • 59. Fair Trade Or Sustainablility??
  • 60. A Mars spokesperson says, Certification’s first priority should be to improve farmers' livelihoods, and Mars Chocolate is committed to putting farmers first. Through our work with certification organisations we have seen great progress in farming communities; increasing yields and income while simultaneously protecting the environment and improving social conditions. Mars Chocolate is committed to sourcing 100% certified sustainable cocoa by 2020, helping to reach as many farmers as possible at a scale that creates meaningful change. In the global cocoa sector, traceable supply chains are limited; under 10% of the world’s cocoa crop is currently certified. Limiting purchasing to those farmers involved in physically traceable supply chains would prevent the benefits of certification from reaching farmers that are more remote, less well connected into the supply chain, and most in need of the training and services that certification brings. Current mass balance policies, which include complete document traceability, are absolutely necessary to enable significantly greater numbers of farmers to benefit. Certification is the best tool industry has to support as many of the world’s 5 to 6 million cocoa farmers as possible and provide them with the material support and organisation they need to be successful. In 2012, we will purchase around 90,000 metric tons of certified sustainable cocoa, the largest amount of any manufacturer, as we move towards achieving our 2020 commitment for 100% certified sustainable cocoa in all our products.
  • 61. Famous Names from 19th century • Poulain, Menier, Barry (France) • Lindt, Suchard, Nestle (Switzerland) • Cadbury, Rowntree (UK) • Hershey (USA) • Mars – not until 1932 (USA and UK) (Kraft/Nestlé)