B2-CH-15-D Nominal power ratings PN kW type B continued o n Bevel-helical gear units B2

Flender/Flender Gear Units/Bevel-helical gear units B2

medium roasts: high acidityprovides better quality and more intense aroma to the beverage. It is generally agreed thatpH 4.9 to 5.2 is the ideal range for coffee beverages. Under ideal roasting conditions, Coffee Processing 7 roasted . arabica yields brew of the beverage in that pH range, and . robusta yields less acid brew of pH 5.0.8. 4.1.6.2 Bitterness An element of bitterness is desirable in coffee. Bitterness has been attributed to caffeine, but even decaffeinated coffees have been found to possess profound bitterness. It appears that other heterocyclics also contribute to bitterness. 4.1.6.3 Astringency Astringency is not primary taste. Many astringent molecules are bitter, and these sensa- tions may be confused; they are distinguished by expert tasters. Caffeoyl quinic acids,dicaffeoyl quinic acid, and caffeic acid are the likely astringent components of coffee. 4.1.6.4 Staling Staling refers to the deterioration of taste and odor on storage of coffee powder. The roasted and ground coffee preserves its aroma for up to 6 months under inert conditionsat low temperatures. The entrapped CO 2is instrumental in achieving this storage life. During storage, many volatiles decline in concentration as result of volatility and oxida- tion. Similarly many new compounds are formed as result of oxidation and other interac- tions. 4.2 Soluble Coffee Soluble coffee is an important product, second only to & coffee. It is prepared by dehydrating the coffee brew and is instantly soluble in water (Fig. . The product is inferior in taste and aroma to the freshly prepared brew. As coffee product, this has gained popularity in most countries. The processing for soluble coffee consists mainly of two steps, viz., extraction of Fig. 2 Conversion of green beans into soluble coffee. 7 Ramalakshmi and Raghavan the brew and drying. The extraction of & coffee by using domestic brewing devices yields very dilute solutions with about 1% solids concentration. The solubles represent1%2