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changes from gray green to light brown, dark brown, or almost black, depending on the type of roast. The pH of the roasted coffee brewfalls down to 5.5.0 from pH 6.0 of the green beans. This reaction is mainly due to theformation of volatile organic acids. In general light roasts produce more acid per cup thandark roasts. Medium roasts have cup pH of 5.0 and darker roasts have pH up to 5.3 (. Sugars and proteins break down to aldehydes, alcohols, and acids. Sucrose is the major sugar that suffers heavy loss during roasting. Proteins are denatured and are brokendown to amino acids. The most signicant change occurring during roasting is the forma-tion of aroma compounds. Roasted whole beans retain the characteristic aroma for about1 week under normal atmospheric conditions. This is mainly due to carbon dioxide buildupinside the bean, which provides an inert atmosphere. 4.1.5 Brewing of Coffee The extraction of soluble solids from roasted and ground (&) coffee by using hot water is called the brewing process . The quality of the beverage depends, to great extent, on the brewing process, viz., the type of equipment used, quality and quantity of water used, yield of soluble solids, and concentration of the brew. There are several brewing practices: steeping, drip lter, vacuum coffee maker, and percolator. In steeping, coffee powder is mixed with boiling water and kept covered with lid for 5 min and the brew is de-canted. The drip lter is the most common method employed for preparing coffee bever-ages, & coffee (coarse powder) is placed in steel vessel with perforated bottom,boiling water is added, and the brew is collected in the vessel below. The efciency of 7 Ramalakshmi and Raghavan Table 1 Chemical Composition per Cup Roasted and Total soluble solids ground coffee in 6.7 oz (1.3 ) Caffeine 0.0 Chlorogenic acid 0.1Reducing sugars 0.0Other carbohydrates 0.2Peptides 0.0 Potassium 0.1 Other minerals 0.1 Acids 0.1Trigonelline 0.0 Volatiles /H1.0 Source : From Ref.