Paper No.: 09 Paper Title: BAKERY AND CONFECTIONERY TECHNOLOGY Module 29: General aspects of cocoa bean processing: cocoa mass, cocoa butter and cocoa powder Paper Coordinator: Dr. P. Narender Raju, Scientist, ICAR-NDRI, Karnal Content Writer: Ms. Deepika Goswami, Scientist, ICAR-CIPHET, Ludhiana
General aspects of cocoa bean processing: cocoa mass, cocoa butter and cocoa powder
Cocoa tree (Theobroma cocoa L.) For chocolate manufacture four types of cacao trees are cultivated: 1) Forastero 2) Criollo 3) Trinitario 4) Nacional Cocoa bean (6.5% m.c.) Testa/Shell (12%) Cocoa nibs (87.1%) Germ (0.9%)
Processing of cocoa beans Removal of cocoa beans from cocoa pods Fermentation Drying Cleaning of nib Roasting Winnowing (cracking and fanning) Grinding of nib to produce cocoa mass (liquor) Expelling of cocoa butter from the liquor Grinding of cocoa cake to cocoa powder
Fermentation of cocoa beans The cocoa beans along with adhering pulp is fermented by making heap, on platform, baskets or boxes. The process takes 6-8 days to complete. Sugars in pulp break down to ethanol and lactic acid and temperature raise to about 45 o C during first two days of fermentation. During the remaining period of fermentation temperature remains between 45-50 o C. The ph rises to 5.0. The mass is turned every day to aerate it that causes oxidization of alcohol to acetic acid.
Drying The raw cocoa bean (6.5% moisture) contains 87.1% nib (cotyledon), 12% shell and 0.9% germ of which cocoa bean is the valuable part. Sun drying and artificial drying is used for drying. The moisture content of the fermented cocoa beans is reduced to a safe storage level (6-8%). During drying, the fermentation process is completed. The drying is gradual and uniform. Dried cocoa beans must be stored in suitable environment so that they do not pick up moisture during storage.
Roasting Development of the true chocolate flavour. The moisture of raw nib and the shell reduced from 4-5% and 8-10% to 1.5-3% and 4%, respectively. Loosening of the shell. Enhanced friability and darkening of colour of the nibs (cotyledon). Maillard reaction or non-enzymatic browning for color and flavor development. The time and temperature of roasting and the rate of moisture loss greatly effects these changes.
Roasting An alternative heat treatment to roasting is given in two stage- Low-temperature heating (<100 o C) to dry and loosen the shell only High temperature heating (125 to 130 o C) for roasting effect. Temperature in this stage is chosen depending on the requirement of manufacture (chocolate or cocoa powder cocoa butter expression)
Winnowing (cracking and fanning) The shell and some of the germ are separated from the rest of the beans so as to reduce the shell content of nibs below 1.5%. Separation is based on the difference in apparent density of the nib and shell. Winnowing machine takes combined action of sieving and air elutriation. For the winnowing process it is desirable to have 85-90% of the nib pieces over 3 mm in size because particles of smaller size may not be separated from the shells in air separation.
Micronization pre-treatment reduces the amount of fine particles at the cracking stage and transfers cocoa butter from the nib to the shell. For micronization pre-treatment, the cocoa beans are subjected to radiant heat for 60-120 sec. The differential heating and drying of shells and nibs results into detachment of the shells from the nib. The cocoa nib thus obtained is either ground to produce cocoa liquor (cocoa mass) or subjected to expelling to obtain cocoa cake.
Grinding of nib to produce cocoa mass (cocoa liquor) Grinding releases the fat of cocoa nib termed as cocoa butter (approximately 55%) by rupturing the cell wall and the fat melts due to the frictional and applied heat. The particle size of non fat constituent is reduced. A paste with enhanced fluidity is formed. The following are the main aims of grinding the cocoa nib: To make the cocoa particles small enough (30 microns to 0.5 cm) so that they can be made into chocolate To remove as much fat as possible from the cells within nib (cotyledons)
There are many machines for grinding cocoa nib to liquor (cocoa mass) Impact mills Disc Mills Pin or hammer mills Ball or bead mills The cocoa liquor is treated for flavour development and removal of unwanted flavours by using the following methods: Simple heating of thin films Thin film roasting and air scrubbing Thin film roasting with vacuum
Expelling of cocoa butter from the liquor Cocoa butter is obtained by the following methods- Hydraulic pressing of finely ground cocoa mass Extruder, expeller or screw press Cocoa liquor Expelling Hydraulic press Expeller Cocoa butter Cocoa press cake Solvent extraction Cocoa butter
Optimum temperature of the liquor (95-105 o C) Moisture content (0.8 to 1.8 percent) Degree of roast (high roast beans) Homogenization Particle size (98-99% particles passing through a 200 mesh sieve) Hydraulic pressing of cocoa butter In hydraulic pressing, to obtain an optimum yield the following points needs to be considered Pressure (40-50 Mpa)
Solvent extraction of cocoa cake Solvent extraction is also employed for extracting cocoa butter from the cocoa cake, obtained from expelling of whole beans and blends of winnowing products consisting of shell. As per PFA Standard: Recommended solvent : n-hexane (Food Grade) Maximum tolerance limit: 5.0 ppm in the refined extracted cocoa butter
Cocoa butter (FSSR Standards) Cocoa butter means the fat obtained by expression from the nibs of the beans of Theobroma cocoa L. Press, expeller or refined cocoa butter may also be referred as cocoa butter. It shall be free from other oils and fats, mineral oil and added colours. It shall conform to the following standards: Particulars FSSR limit Percentage of free fatty acids (calculated as oleic acid) Not more than 1.5 Iodine value 32 to 42 Melting point 29 o C to 34 o C Butyro-refractometer reading at 40 o C OR 40.9 to 48.0 Refractive Index at 40 o C 1.4530 to 1.4580 Saponification value 188 to 200
Grinding of cocoa cake to cocoa powder Grinding is done using cooled pin mill or hammer mill Cooling and feed rate adjusted so as to attain a powder temperature of 21-24 o C at the exit of the mill Cooling done using dry air (RH 50-60%) to avoid increase in moisture content of cocoa powder
Cocoa powder (FSSR Standards) As per the PFA Standards, cocoa powder may be subjected to treatments during manufacture with alkali and/or magnesium carbonate, bicarbonate, and with tartaric, citric or phosphoric acids. It shall be free from rancidity, dirt, filth, insects and insect fragments or fungus infestations. It shall conform to the following PFA Standards: Particulars Total ash (on moisture and fat free basis) Ash insoluble in dilute HCI (on moisture and fat free basis) Alkalinity of total ash (on moisture and fat free basis) Cocoa butter in low fat cocoa powder free basis) (on moisture Cocoa butter in high fat cocoa powder (on moisture free basis) FSSR limit Not more than 14.0 per cent Not more than 1.0 per cent Not more than 6.0 per cent as K 2 O Not less than 10.0 per cent Not less than 20 per cent
Suggested reading Minifie BM (1997). Chocolate, cocoa and confectionery. CBS Publishers and Distributors, New Delhi. Beckett ST (2008). The Science of Chocolate (2 nd Publication, UK. Edition). RSC Talbot G (2009). Science and Technology of enrobed and filled chocolate and confectionary and bakery products. Woodhead Publication, UK.
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