Composition of Green Coffee

The composition of green coffee is dependent on variety, origin, processing and climate. A review of the differences between Arabica and Robusta coffee is provided in Table 21.2. The constituents will be covered in more detail in the section dealing with roasted coffee. 

Clifford M.N. (1975b), 4 pp., 73 ref. The composition of green and roasted coffee beans. 

Smith (1963a) and Feldman et al. (1969) underlined the importance of non-volatile compounds to the flavor of coffee. The comparison between the composition of green and of roasted coffee showed an important decrease in the content of proteins, chlorogenic acid and sucrose on roasting. Fractionation and analysis of the aroma precursors in green coffee have also been studied by Russwurm (1970) who considers that the non-volatile constituents of green coffee that may be involved in flavor formation are carbohydrates, proteins, peptides and free amino acids, polyamines and tryptamines, lipids, phenolic acids, trigonelline and various non-volatile acids. 

In 1969, at the 4th ASIC symposium in Amsterdam, Merritt et al. (1970) asserted that the object of research on the composition of the constituents of coffee aroma is not the mere compilation of lists, but the relationship of the compounds to their precursors, in order to establish a mechanism for their formation, and ultimately for controlling the quality of the product. Merritt et al. (1970) tried to correlate the composition of green and roasted coffees and gave a list of some pyrolysis products of various amino acids, observing that proteins containing the same amino acids produce the same pyrolysates. After having identified 16 other constituents, the authors hoped that new techniques will lead to more direct correlations between the aroma and their precursors, providing a more secure basis to evaluate and control the quality of coffee. 

In an attempt to correlate the chemical changes that occur during roasting with the formation of nonvolatile flavors, Feldman et al. (1969) reviewed the chemical composition of green and roasted coffee. Generally, all acids decreased with increased roasting time. The differences in concentration of volatile acids were relatively low and the differences between varieties were slight. In any case, these lower acids are not the major contributors to the acidity in the coffee brew. Their total represents only 0.39-0.45 % of the dry roasted coffee beans. 

Identified in green coffee by Vitzthum et al. (1976). In their study on the influence of brewing time on the composition of brewed coffee, Lee et al. (1992) qualified aniline of fast extractor (70-80% extracted after 5 min). 

Table 21.2. Composition of green Arabica and Robusta coffee s ...

Rahn, W., Meyer, H. W., Koenig, W.A., Effect of steam treatment on the composition of phenolic components of green and roasted coffee, Z. Lebensm.-Unters. Forsch. 169, 346, 1979. (CA92 40077m)... 

Composition of Amino Acids in Green and Roasted Coffee (After Acid Hydrolysis),%... 

The composition of the aroma of coffee is extremely complex with more than 900 compounds determined146,147 (see Chapter 3.25). The aroma of tea is greatly influenced by the degree of fermentation (green tea148 and black tea149 to mention a representative example) (see Chapter 3.23). Research of cacao mass volatiles using AEDA was also conducted (Table 16).150... 

Very recently, Cantergiani et al. (2001) (Figure 2,11) investigated the composition of the volatile fraction of a Mexican green coffee with a pronounced earthy/mouldy off-flavor. The three components responsible were determined by GC-olfactometry, isolated, concentrated and finally characterized by GC/MS as geosmin (Section 5,B.46), 2-methylisoborneol (Section 5,B.44) and 2,4,6-trichloroanisole (Section 5,H.82), The concentrations were lower in the reference than in the defective samples. The... 

Folstar P. (1976) The composition of wax and oil in green coffee beans. Thesis, Wageningen University, The Netherlands. 

Full G., Lonzarich V. and Suggi-Liverani F. (2000)) Differences in chemical composition of electronically sorted green coffee beans. 18th Int. Colloq. Chem. Coffee (Helsinki, 2-6.8.1999) (ASIC, 2000), 35-42. 

Ohveira, L. S., Franca, A. S., Mendon9a, J. C. R, Barros-Junior, M. C. (2006). Proximate composition and fatty acids profile of green and roasted defective coffee beans. LWT -Food Science and Technology, 39, 235-239. 

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