Five changes occur during the roasting of cocoa beans • Development of flavouring components which enhance both cocoa taste and aroma. • Textural changes in the shell. • Development of colour • Removal of moisture • Chemical changes in the bean constituents Winnowing The purpose of winnowing is to separate the shell and germ and to split the cocoa bean into its natural segments (cocoa nibs)Cocoa beans are first cracked. Then air is passed to blow away the lighter shell. The velocity of this air stream is critical. It should be sufficient to remove the undesirable shell but not too high to blow off the costly cocoa nibs and must be varied to suit the changing size of cocoa bean from the differing sources. The de-shelled beans (now mostly broken) are referred to as nibs. The nib and remaining shell fragments should be passed through the germ separator. Here vibratory perforated screen cylinders or sieves can be used to separate the germ from the nib. Alkalization This is the stage which further develops the flavor and colour. The nib should be soaked in a alkaline solution which is held in suitable non corrosive vats and then dried. The alkaline chemicals used are ammonia, potassium and sodium bicarbonate. Grinding May be carried out using granite rolls, roll refiners or rotating and fixed steel disc pulverizers. The nibs are ground into very small particles, a process which releases a large amount of fat and results in the mass becoming a thick syrup. Extraction of Cocoa butter The cocoa fluid or mass is then fed into felt-lined steel pans fitted with a movable perforated lid. When subjected to hydraulic pressure some of the fat is forced through the filter leaving behind a solid residue known as press cake. The press cake is used for producing cocoa powder. This is removed from the pan, cooled to set the colour, pulverized and sieved. To this very fine powder a small quantity of salt and flavouring (vanilla) is usually added before it is marketed as the familiar cocoa powder. 07
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