H4-DH7-B Corrosion category C or C Medium or high salin Helical speed reduction gearbox H4

Flender/Flender Gear Units/Helical speed reduction gearbox H4

ig. 1 Degradation of caffeine. (From Ref. 2.) nin amides. The level of trigonelline (Fig. present in coffee depends on the species: . arabica coffee contains about 1% and . robusta about 0.7%. 4.1.3.3 Chlorogenic Acid Chlorogenic acid is another compound present in coffee; it is considered the second most important component and its level is generally analyzed. Levels of chlorogenic acid appear to be dependent on species and are unaffected by differences in agronomic practice or Fig. 1 Trigonelline. (From Ref. 2.) Coffee Processing 7 Fig. 2 Chlorogenic acids. (From Ref. 2.) method of processing. The level of chlorogenic acid in Coffea arabica varies from 5% to 7.5% and in . robusta from 7.0% to 1.5%. Chlorogenic acid (Fig. comprises group of compounds: () caffeoyl quinic acid, () dicaffeoyl quinic acids, () coumaroyl quinic acid, () feruloyl quinic acids, () caffeoyl feruloyl quinic acids, ( ) feruloyl caf-feoyl quinic acids. The astringency of coffee is contributed by chlorogenic acid. It isgenerally agreed that high chlorogenic acid level indicates lower quality. These com-pounds suffer heavy losses during roasting; the degree of loss depends on the type ofroasting (. Analytical methods can broadly be grouped into two kinds: spectrometric (colori- metric) methods, which determine total chlorogenic acid content, and chromatographicmethods, which allow separation and quantication of individual isomers. typical colori-metric method is based on the formation of molybdenum-dihydroxy phenol complex(, but quantication is complicated by the different molar absorbances of the complexesformed from various chlorogenic acids. In another method, chlorogenic acid is estimatedby UV spectrometry before and after lead acetate treatment of coffee extract, followed by measurement of the absorbance at 3 nm (. The preferred chromatographic method is based on HPLC (, wherein good degree of selectivity of detection is achieved byusing UV absorption at 3 nm. 4.1.3.4 Cof