Coffee lipid aroma

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. 

The major analytes of coffee include caffeine, chlorogenic acids, and flavor and volatile aromatic components. The major analytes in cocoa are me-thylxanthines, mainly theobromine and trace amounts of caffeine, cocoa fat, and lipids. Other analytes of interest in cocoa are tannins, pigments, and aroma components. The major analytes of tea are the methylxanthine alkaloids, including caffeine and theophylline, polyphenols (catechins, tannins, and related flavanols), and volatile and aromatic components. Analysis of black tea would also include theaflavins and thearubigens, which are oxidation and condensation products of polyphenols. 

Some examples of successful commercial selective extractions are the removal of caffeine from coffee or the solubilization of nicotine from tobacco both accomplished on moist matrices to aid in selectively solubilizing the alkaloid component. Selective extraction has been demonstrated for the segregation of essential oil from other lipid components in natural extracts derived from fruits and for the separation of aroma components in cocoa butter from the base oil. Other enrichment SEE schemes that have been reported include the fractionation of carotenoid from leaf protein concentrate [25], the fortification of sterols in seed oils [26], and the isolation of lecithin (phospholipid-containing fraction) from triglycerides [27]. 

The thermal generation of flavor is a very essential process for the "taste" of many different foodstuffs, e.g. cocoa, coffee, bread, meat. The resulting aromas are formed through non-enzymatic reactions mainly with carbohydrates, lipids, amino acids (proteins), and vitamins under the influence of heat. Thiamin (vitamin B ) and the amino acids, cysteine and methionine, belong to those food constituents which act as flavor precursors in thermal reactions. The role of thiamin as a potent flavor precursor is related to its chemical structure which consists of a thiazole as well as a pyrimidine moiety. The thermal degradation of this heterocyclic constituent leads to very reactive intermediates which are able to react directly to highly odoriferous flavor compounds or with degradation products of amino acids or carbohydrates. 

The lipids of coffee play an important part in the store-ability of roasted coffee. During storage the lipids can be oxidized if oxigen is present and it changes the aroma of coffee, too. 

Canolol belongs to a new class of naturally derived compounds that show the antioxidant as promising and implicates disease treatment in the near future. The future scope is supported by the current in vitro research data and there is no doubt that there is lack of data for in vivo research. The accumulated literature of vinyl phenol derivatives including vinyl syringol/canolol indicates the overwhelming role of these compounds in flavour and aroma of beer, wine and coffee (see Chapter 3). It has been already demonstrated to be effective in controlling oxidation in lipid model relevant to food. In vitro and in vivo studies conducted so far come to an agreement that. 

A number of the procedures described in Sec. VI will yield a material that is primarily lipid in nature. In addition, many samples available to the researcher are themselves lipids. A few materials that one may encounter are coffee oil, vegetable and nut oils, cocoa butter, lard, butter oil, lipids used for deep fat frying, and lipids used as the solvent for Maillard reaction systems. Such materials can be a relatively rich source of aromatic compounds because aroma compounds are typically lipid soluble. A number of procedures can be used to prepare a sample. In this section we will cover three useful ones. 

An alternative source of characteristic heated flavor compounds is via the Maillard pathway, the thermally induced reaction between amino acids and reducing sugars. Aroma constituents in chocolate, coffee, toasted bread, and popcorn are products of Maillard reactions, in addition to flavors in roasted nuts and meats, which are discussed in Sec. II.E and 11.E. Guaiacols occur as pyrolysis products of carbohydrates or lipids in smoked or char-broiled meats. 

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