Cocoa - chemistry processing and technology


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How it is made - Chocolate.
Chemistry, processing and technology.

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Cocoa - chemistry processing and technology

  1. 1. CHEMISTRY OF COCOA And cocoA products… -11FET100( 9 -16).
  2. 2. COCOA TREE The Swedish botanist Linnaeus gave cacao tree the name Theobroma cacao or The food of Gods . The cacao tree has distinctive gray – brown bark and grows to a height from 15 – 25 ft. The flowers are about 0.5 inch in diameter. Many are produced but relatively few are pollinated ,apparently by a small midge .Flowers are produced all year long so that the flowers and the resulting cocoa pods are found on the same tree . A single tree produce 20-50 fruits per year
  3. 3. FAVOURABLE CONDITIONS The tree must have right conditions for good growth. It needs a warm and humid environment . Temperatures of 18-35 degrees are adequate ,but the tree does very well at temperatures of 40 degrees and at relative humidities approaching 100%. Good growth requires shade and annual rainfall of at least 50 in. More is desirable , too much can result in water logging and the development of fungal diseases . VARIETIES OF COCOA TREE i) Criollo ii)Forastero iii) Trinitario
  4. 4. Criollo Cocoa tree The criollo has white cotyledons. The colour is given by anthocyanins the group of chemicals which gives most blue and red flowers their colours .they are present in pigment cells. In criollo cocoas ,the coloured anthocyanins are replaced by leucoforms. Criollo without these anthocyanins is another milder cocoa. Criollo cocoa used to be regarded as superior quality and was much in demand .However it is a less vigorous plant and is more vulnerable to diseases.
  5. 5. Forastero Cocoa tree The forastero has purple cotyledons. Anthocyanins are involved in unique flavour of cocoa. The purple anthocyanins are associated with the stronger ,more astringent and robust flavours. Development in processing and of new products both enabled the less desirable features of the forastero to be minimized and use made of their stronger chocolate flavour,so that the tendency to replace criollo by higher yielding forastero has been encouraged . Since forasteros are robust and higher yielding there is a popularity with the growers of forastero, with their suitability for some products they are now being consumed in great quantity has resulted in becoming by far the larger proportion of the cocoa crop.
  6. 6. TRINITARIO Trinitario is the cross between the two criollo and the forastero.It appears to have originated by the hybridization between criollo and forastero. It is now the important type commerciallly. Trinitarios include pale beans within their pods produse larger proportion of beans with purple colour . However they are grown in some areas their popularity is not as much as forasteros.
  7. 7. Criollo Forastero Colour White Purple Anthocyanins Less since they are present in Leuco form More Cocoa flavour Mild Stronger due to presence of anthocyanins Cocoa production 10-20% 70-80% Cocoa quality Superior More robust Yield Less since it is susceptible to disease More production Countries Found only in Venezuela,central america.madagascar,sri lanka and samoa.
  8. 8. Cocoa has a long supply chain extending from smallholders often in remote, less developed tropical regions of world ,to factories and consumers mainly in developed industrial countries. like any crop, it is susceptible to changes in the weather ,to pests and diseases and to social and economic factors. WHERE COCOA IS GROWN…??? • Cocoa is grown commercially between 20degree north and south of the Equator,in areas with a suitable environment for cocoa. • Main growing areas are: west africa,south east asia and south america. • 7 largest cocoa producing countries are Ivory coast , ghana,Indonesia,nigeria,cameroon,brazil and ecuador. • Between them they account for90% of the world crop. • Huge concentration (around 70%) within west africa. • Ivory coast produces 40%of the world crop. • About 90% of the world’s cocoa is grown by small holders. More than 3,000,000 tonnes (3,000,000 long tons; 3,300,000 short tons) of cocoa are produced each year. The global production was 1974: 1,556,484 tons, 1984: 1,810,611 tons, 1994: 2,672,173 tons, 2004: 3,607,052 tons.
  9. 9. Top Cocoa Beans Producers in 2010 (million metric tons) Ivory Coast 1.242 Indonesia 0.844 Ghana 0.632 Nigeria 0.360 Cameroon 0.264 Brazil 0.235 Ecuador 0.132 Togo 0.102 Dominican Republic 0.058 Peru 0.047 World Total 4.082
  10. 10. • trinitario cocoa • forastero cocoa
  11. 11. • Criollo cocoa
  12. 12. Composition of cocoa
  13. 13. Lipids o Cocoa beans contain about 54% fat. o The naturally occurring lipid within the cocoa bean is referred to as cocoa butter. o The three primary fatty acids that make up cocoa butter are oleic acid (C18:1), stearic acid (C18:0), and palmitic acid (C16:0). o In general, about 37.5% of the fat within cocoa butter is unsaturated fat and about 61.4% is saturated fat. o The triglyceride composition of the fat in cocoa butter is primarily in the configuration of saturated fat (sn1), unsaturated fat (sn-2), and saturated fat (sn3), with oleic acid being the primary fatty acid in the sn-2 position of the triglyceride.
  14. 14. Carbohydrates o Cocoa bean contain a fairly large amount of carbohydrates, contributing about 31% of dry weight of the beans. o Most of the carbohydrates are starch, soluble dietary fibers, and insoluble dietary fibers. A very small proportion is simple sugar (~1%). o The various sugars present are glucose, fructose , sucrose, raffinose, stachyose verbascose and many others. o The concentrations of glucose and fructose decreased after roasting but levels of the non-reducing sugars, sucrose, raffinose, stachyose and verbascose, were not markedly affected. o Approximately 10% of the arabinose content of the polysaccharides was degraded but, overall, the pectic and hemicellulosic polymers remained intact after roasting..
  15. 15. Proteins o Cocoa beans contain 10–15% protein, based on the origin. o In most seeds, 95% of the protein is comprised of four main fractions: albumins (water-soluble), globulins (salt-soluble), prolamins (alcoholsoluble), and glutelins (soluble in dilute acids and alkali). o During fermentation, proteins are degraded by enzymes to polypeptides and amino acids which are the chocolate flavor precursors. o Thus during fermentation ,the protein content decreases. Minerals o Cocoa beans are rich in a number of essential minerals, including magnesium, sulfur, calcium, iron, zinc, copper, potassium and manganese. Vitamins o Cocoa beans contain vitamin A, B1, B2, B3, C, E and pantothenic acid.
  16. 16. Polyphenols o Polyphenols constitute one of the most numerous and widely distributed groups of substances in the plant kingdom. o Dietary polyphenols have received extensive attention in recent years because of their potential health benefits such as anti-inflammatory, anti-carcinogenic , antiatherogenic , etc. o Cocoa beans contain three major groups of polyphenols: catechins or flavan-3-ol monomers (~37% of total polyphenols content), proanthocyanidins or flavan-3-ol polymers (~58% of total polyphenols content) and anthocyanin (~4% of total polyphenols content). 1. Catechins 2. Proanthocyanidines 3. Anthocyanins
  17. 17. 1.Catechins o Catechin is a flavan-3-ol, a type of natural phenol and antioxidant. It is a plant secondary metabolite. It is part of the chemical family of flavonoids. oThe two stereoisomers found in cocoa are Catechin and Epicatechin. o The different other enantiomers can as well be found in chocolate where the different processes of fabrication can lead to epimerisation by heating. o The main catechin is (-)-epicatechin with up to 35% of total polyphenol content o When beans are fermented there is a large loss of both (-)-epicatechin and (+)-catechin, but also the formation of (-)-catechin. The heat of fermentation may, in part, be responsible for the formation of this enantiomer. o When beans are progressively roasted at conditions described as low, medium and high roast conditions, there is a progressive loss of (-)epicatechin and (+)-catechin and an increase in (-)-catechin with the higher roast levels.
  18. 18. 2. Proanthocyanidins o Proanthocyanidins , refer to a larger class of polyphenols, called flavanols. o These are also called condensed tannins, which are oligomers and polymers of monomeric flavans linked through specific single (B linkages) and double (A linkages) bonds o These secondary plant metabolites have substantial antioxidant activity. 3. Anthocyanins o It is a flavonoid and imparts the purple colour to fresh forastero cocoa beans o It is a water soluble glycosidic compound made up of a glycone (the sugar portion) and an aglycone (the non sugar portion) o During fermentation, it is enzymatically transformed to become an anthocyanidin aglycone.
  19. 19. Caffeine o It is a xanthine alkaloid substance found in cocoa beans and many other plants. o The cocoa bean contains between 0.10.7% caffeine, 0.2% being the most common amount found. o Caffeine is also present in lesser amounts in the husk that surrounds the cocoa beans, usually from 0.05% -0.3%. o The amount of caffeine in the beans varies with the type of beans and the degree of fermentation o Caffeine is consumed for both its stimulatory and psychological effects.
  20. 20. Theobromine o The cocoa bean is nature’s most concentrated source of theobromine, a compound closely related to caffeine. o Theobromine (theobromide), also known as xantheose, is a bitter alkaloid of the cacao plant, with the chemical formula C7H8N4O2. o It is in the methylxanthine class of chemical compounds, which also includes the similar compounds theophylline and caffeine o But unlike caffeine, Theobromine has only a mild stimulatory effect on the central nervous system, but it has a slight diuretic action similar to caffeine. o Despite its name, the compound contains no bromine—theobromine is derived from Theobroma
  21. 21. Theophylline o It is also known as dimethylxanthine, is a methylxanthine drug used in therapy for respiratory diseases such as COPD and asthma under a variety of brand names. o Because of its numerous side-effects, the drug is now rarely administered for clinical use. o Along with cocoa beans,it is also found in tea but in trace amounts. o Amounts as high as 3.7 mg/g have been reported in Criollo cocoa beans.
  22. 22. Aromatic compounds in fermented cocoa beans o The most important aromatic compounds in fermented cocoa are the following classes: • Pyrazines (20%) • Aldehydes • Alcohols • Ketones • Esters o Some of these compounds are influenced by fermentation time, others are not. o All are affected by the temperature and time of the roasting protocol.
  23. 23. POST-HARVESTING PROCESSES Fermenting &curing Drying Roasting
  24. 24. FERMENTATION AND CURING The process has to be carried out within 24-48 hours after breaking the cocoa pod.  It takes about 5-7 days on average and varies according to the species. Forastero- 5-7 days Criollo- 1-3 days  It is responsible for the chocolate flavor and aroma in cocoa and also external browning of beans. 
  25. 25. FERMENTATION AND CURING •Coca beans do not themselves undergo a fermentation at all •It is pulp surrounding the beans which is fermented, while an almost simultaneous ‘curing’ process takes place within the beans Fermentation Site: In the pulp  Carried out by microorganisms Immediate and initial process after breaking of pods Purpose: removal of pulp out of the pod Curing Site: inside the beans Carried out by enzymes Occurs after fermentation Purpose: flavor development & partially responsible for the brown colour
  26. 26. MICROBIAL ASPECTS OF FERMENTATION Micro-organisms are responsible for the breakdown of the pulp that surrounds the beans.  Their activities result in the death of the beans and they create the environment that enables the formation of cocoa flavor precursors  The pulp is an excellent medium for the growth of micro-organisms since it contains 10-15% of sugars.  When the beans are removed from the pods, the pulp is inoculated naturally with a variety of micro-organisms from the environment. 
  27. 27. There are 3 stages of fermentation: Stage 1Anaerobic yeasts  Sugar  Alcohol + CO₂  24-36 hrs  Rise in temperature  pH < 4 acidic  Low oxygen  Bean death on second day occurs due to acetic acid and alcohol
  28. 28. Stage 2: Lactic acid bacteria  Sugar & organic acids  Lactic acid  LAB are present from start but only become dominant in 48-96 hrs Pulp composition Components Percentage Water 82-87 Sugar 10-15 Pentosans 2-3 Citric acid 1-2 Salts 8-10
  29. 29. Stage 3: Acetic acid bacteria  Also present from start but become significant at the end when the aeration increases  Alcohol  acetic acid  Exothermic reaction  Increases temperature to 50˚C
  30. 30. Pulp sugars Respiration aeration yeasts CO₂ + H₂O Fermentation yeasts Ethanol + CO₂ Aeration Acetic acid bacteria Lactic acid bacteria Lactic acid (non volatile) Acetic acid (volatile)
  31. 31. METHODS OF FERMENTATION 1. 2. 3. 4. Heap Baskets Boxes Batch processes
  32. 32. FERMENTATION The pulp around the beans is sticky and needs to be separated.  The pulp starts loosening from the bean in the 1st microbial stage.  Turning of the beans aids to the fermentation process  In 1st 2 processes the temperature rises due to the exothermic reactions to almost 49-54˚C  By the end of 3rd stage, the temperature drops rapidly and most of the pulp has drained away as a liquid. 
  35. 35. CURING Acetic acid penetrates into testa (husk) of cocoa beans.  High temperature and influx of acid:  1. 2. Kill the bean Disrupt the internal structure Cocoa beans are composed of white cells (fats, proteins) and purple cells (polyphenols)  Due to the disruption compounds in the beans mix and interact within themselves.  Reactions between storage proteins, enzymes (proteolytic, polyphenol oxidase, invertase) and polyphenols result in formation of the crucial chocolate flavor precursors 
  36. 36. Chocolate flavor precursors •Proteins are degraded by enzymes to polypeptides and amino acids •Reducing sugars (glucose/ fructose) are released. Reduction of astringent and bitter taste •Part of polyphenols oxidized into large tannin molecules •Part of polyphenols and theobromine/caffeine (20%) diffused and exudated from the bean Components Percentage Water Cellulose Starch 32-39 2-3 4-6 Pentosans Sucrose Fat Protein Theobromine Caffeine Polyphenols Acids Salts 4-6 2-3 30-32 8-10 2-3 1 5-6 1 2-3
  37. 37. IMPORTANCE OF FERMENTATION & CURING There is no chocolate flavor in cocoa bean without fermentation  Chocolate flavor precursors are formed during fermentation which help in further flavor development 
  38. 38. IMPORATANCE OF FERMENATTION & CURING Fermentation helps in the separation of pulp and beans  Omission of fermentation prevents the possiblity of ever developing a true chocolate flavor and defect cannot be removed by later attempts of fermenting  With lower temperatures the putrefaction bacteria will start to proliferate and longer fermentation would cause hammy off-flavors typical for over fermented cocoa beans 
  39. 39. FACTORS AFFECTING FERMENTATION Extent of ripeness of pod  Pod storage  Quantity of beans  Quantity of pulp  Type of cocoa  Duration of fermentation  Turning  Seasonal/ climatic effects  Pod’s disease 
  40. 40. BY PRODUCTS Shell In African countries, it is used as manure due to its fibrous content  Fermented pulp Use of liquid fermented pulp for manufacturing of vinegar has been proposed by many. But practical application has not been tried yet. 
  41. 41. DRYING Extended process of fermentation  Superficial browning in cocoa beans continues to deepen  Slow but progressive loss of moisture  Loss of astringency & bitter tasteloosening of the shell from the bean  Shrinking of furrowed cotyledons into 2 almost separate halves  Moisture content reduced to 6%  The enzymatic action as evidenced by colour changes in the bean should be allowed to proceed to conclusion 
  42. 42. DRYING If the beans are dried too quickly some of the chemical reactions started in the fermentation process are not allowed to complete their work and the beans are acidic with a bitter flavor.  If the drying is too slow moulds and off flavors can develop.  Temperature should not exceed 65˚C  Types of drying: sun-drying mechanical drying 
  44. 44. SUN-DRYING Fermented beans are spread in a thin layer (1-2 inch deep  Exposed to sun until dry  Beans are occasionally turned for uniformity  Sundrying can be carried out on small as well as on large scale basis  Traditionally there is also a method call dancing the beans which serves the purpose of drying and removal of shell 
  45. 45. Large scale sun drying Dancing sun drying Small scale sun drying
  46. 46. Sun-drying ADVANTAGES    Maximum quality development Economically cheaper Enough time for properly started curing to run to completion hardly any danger of premature death of beans from elevated temperatures DISADVANTAGES     Length of time involved Labour required Uncertain weather Possibility of moth formation Though the advantages are not numerically great, they are important enough as to be overriding
  47. 47. MECHANICAL DRYING  They can be roughly divided into 2 types: using rotating drums using trays, platforms or endless belts
  48. 48. MECHANICAL DRYING ADVANTAGES      Freedom from dependence on weather In shorter time (14-48 hrs) Saving in labor No contamination by foreign matter (sticks, stines, etc.) Less posibility of mold growth DISADVANTAGES       Shortens the drying to the extent that drying enzymatic action is not completed Might increase bitterness Makes cotyledons fragile and thus uniform roasting impossible High acidity retained More expensive Danger of smoke contamination
  49. 49. IMPORTANCE OF DRYING Sun-drying is best for good quality  Significant lowering of strong acid/sour flavor: volatile acetic acid evaporates through husk during slow drying non-volatile lactic acid is partly transported by water from the bean to the husk  Strong oxidation browning of polyphenols leading to reduced astringency and bitterness  Flavor forming reactions occur 
  50. 50. ROASTING Dried beans are artfully roasted at 200˚F to 250˚F for one to two hours in order to develop the flavor of the beans.  The beans become brown in color and friable (brittle). 
  51. 51. CHANGES OCCURRING IN ROASTING Development of pleasant aromatic complex (chocolate flavor)  Evaporation of organic acids and astringents of volatile nature  Chemical modification of tannins and other non-volatile that remain, with consequent reduction of bitterness  Darkening of cotyledon color to deep attractive brown  Elimination of excess moisture  Loosening the shell from cotyledon 
  52. 52. RXNS INVOLVING FLAVOUR DURING ROASTING PROCESS • One of the important reaction for flavor development is the Maillard reaction or carbonyl-amine reaction. • The reactions may be conveniently seperated into three stages -initiation -intermediate -final • INITIATION: FORMATION OF ADDITION COMPOUNDS Reducing sugars + amino acids glucoslyamines or fructoslyamines (depending upon initial reducing sugars) ISOMERISATION The isomerizaion product formed during the initial phase are primarily addition compounds formed from amino acids and sugars • INTERMEDIATE
  53. 53. moisture is evaluated by hygrometer probe. ERH > 40% - very light roast ERH = 28-30% - average roast ERH < 20% - very dark roast
  54. 54. COMPOSITION OF ROASTED COCOA BEAN Components Percentage moisture 1-4 Organic acid 5 Nib/shell 8-14
  55. 55. IMPORTANCE OF ROASTING Non uniformity in moisture content, age, ripeness, fermentation and curing  To convert flavor precursors into the type and intensity of chocolate flavor desired  Roasting duration and temperature varies for different species as well as for different products 
  56. 56. Cocoa products Main products obtained from Cocoa beans are -Cocoa butter also called theobroma oil, is a pale-yellow, pure, edible vegetable fat. -Cocoa powder End product of cocoa solids which are lowfat components and are rich in flavonoids -Chocolate A food preparation in the form of a paste or solid block made from roasted and ground cacao seeds, typically sweetened.
  58. 58. Cocoa products 1)Cocoa liquor : After roasting and drying , the cocoa nib is disintegrated and milled in order to rupture the cell walls of aggregates and expose the cocoa butter. The resultant product is a homogeneous mobile paste, a flowing cocoa mass or cocoa liquor COCOA BUTTER Pressing Press cocoa cake (COCOA POWDER) COCOA LIQUOR Mixing with sugar, fat and milk powder Grinding and refining
  59. 59. COCOA BUTTER     Cocoa butter is the natural fat of the cocoa bean .Cocoa butter (hydraulic expression of cocoa nib) is a light yellow fat, exhibiting a distinct brittle fracture >20°C, a fairly sharp complete melting point about 35°C, with an incipient fusion or softening around 30-32°C. The completely liquid fat displays mark tendency to super cool,(which means that the liquid fat in an undisturbed condition will remain in the liquid state well below its melting point.) which must be taken into account during chocolate enrobing and molding Cocoa butter is composed of number of glycerides of stearic, palmatic and oleic fatty acids with a small proportion of linoleic. The cocoa butter has important functions. It not only forms part of every recipe, but it also later gives the chocolate its fine structure, beautiful lustre and delicate, attractive glaze.
  60. 60. COCOA BUTTER COCOA BUTTER PRIME PRESSED COCOA BUTTER • It is the fat obtained from good quality cocoa nib by means of mechanical (hydraulic) pressing • No refining other than filtration is done EXPELLER PRESSED COCOA BUTTER • Cacao nib is steamed and expeller pressed to remove cocoa butter • Flavor obtained is very mild and floral, if raw beans used. • If substandard raw material is used then resultant cocoa butter has to be subjected to a refining process SOLVENT EXTRACTED COCOA BUTTER- • extracted from the cake residue after expeller pressing. • It is always subjected to refining (de-odorization, de-gumming)
  61. 61. COCOA POWDER • The cocoa mass/liquor is converted into cocoa powder , the cocoa fat is reduced by pressing, by means of hydraulic, mechanical pressing or preferentially , horizontally- run expeller press at a pressure of 400- 500 bar and temperature of 90-100 degree C • The cocoa powders are divided according to the extent of defatting Extent of defatting Cocoa butter content Lightly defatted powder 20-22% residual cocoa butter Extensively defatted powder Less than 20% but more than 10% butter • Cocoa powder is widely used in the manufacture of other products e.g. cake fillings, icings, pudding powders , ice creams, and cocoa beverages • Cocoa powder can be made by two main processes:-Natural process -Dutch process
  62. 62. Natural Process Dutch Process The process involves use of simply unsweetened cocoa powder. The process involves use of alkalized unsweetened cocoa powder. No treatment given. Cocoa beans are directly pulverized into fine powder. Cocoa bean Treated with potassium solution to neutralize acidity Cocoa powder reacts with baking powder used in recipes Doesn’t react with baking powder So not used in recipes Lighter in colour than dutch process powder. Neutralization of acidity makes it dark in colour Strong cocoa beans taste Milder taste compared to Natural process cocoa powder Flavonols content greater than that in dutch processed powder. Lower amounts of flavonols
  63. 63. Natural process cocoa powder Dutch process cocoa powder
  64. 64. CHOCOLATE • • • Chocolates were originally made directly from cocoa nibs by grinding them in presence of sugar Chocolates is now made from nonalkalized cocoa liquor by incorporating sucrose, cocoa butter , aroma or flavouring substances and occasionally, other constituents (milk ingredients , nuts , coffee paste , etc.) The ingredients are mixed , refined , thoroughly conched and finally , the chocolate mass is molded. Product Cocoa mass(%) Skim milk powder(% ) Cocoa butter(%) Total fat(%) Butter fat (milk)(%) Sugar (%) Baking chocolate 33-50 - 5-7 22-30 - 50-60 Milk cream 10-20 chocolate 8-16 10-22 33-36 5.5-10 35-60 Whole milk 10-30 chocolate 9.3-23 12-20 28-32 3.2-7.5 32-60 Skim milk chocolate 10-35 12.5-25 15-25 22-30 0-2 30-60 icings 33-65 5-25 35-46 25-50
  65. 65. CONCHING           It can be described as the working of chocolate flake and crumb into a fluid paste. The process improves the texture and mouthfeel by reducing the particle size. The bitterness is further reduced and flavours are more pronounced. It was suggested that Strecker degradation was not complete at the end of roasting process and suggested it continued during conching. Water content is lowered from 1.6% to 0.6-0.8% due to this unwanted flavour component is removed 30% of acetic acid and 50% of low boiling point aldehydes are volatilize which gives chocolate a better flavour There is development of amino acid ( 33-50% ) to that of formed during roasting which contributes to flavour PROCESS Cyclic meachanical and shearing forces are exerted in order to separate the agglomerates formed during grinding, to coat the particles with fat and to disperse the cocoa butter phase. Types are longitudinal , rotatory etc
  66. 66. STORAGE OF COCOA PRODUCTS • All products , from the raw cacao to chocolate, demand careful storage – dry, cool, well aerated space , protected from light and sources of other odours. A temperature of 10-12 degree C and a relative humidity of 55-65% are suitable • Chocolate products are readily attacked by pests, particularly cacao moths , the flour moth and beetles , cockroaches and ants • Chocolates not properly stored are recognized by a greyish matte surface. Sugar bloom is caused by storage of chocolate in moist conditions(relative humidity above 75-80%) or by deposition of dew, causing the tiny sugar particles on the surface of the chocolate to solubilize and then , after evaporation , to form larger crystals. • A fat bloom arises from chocolate fat at temperatures above 30 degree C . At these temperatures the liquid fat is separated and , after repeated congealing, forms a white and larger spot • This may also occur as a result of improper precrystllisation or tempering during chocolate production. the defect may be prevented or rectified by posttempering at 30 degree C for 6 h