Coffee roasted, acid

Citric acid yields itaconic, citraconic, and mesaconic acids during coffee roasting.3... 

Amino Acids Obtained From Green and Roasted Coffee, by Acidic Hydrolysis, as Percentages of the Total Amino Acid Content3... 

Amino acid Green coffee (%) Roasted coffee (%) (17.6% roast)... 

It should be noted that this mechanism involves a final oxidation. The need for this is avoided when amino acids with an a-hydroxy group in the sidechain (serine, threonine) are involved, as pointed out by Shibamoto and Bernhard234 (see Scheme 5.9). Baltes and Bochmann235 obtained as many as 123 pyrazines, both mono- and bicyclic, by interacting sucrose with serine and threonine under coffee-roasting conditions. 

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

Organic acids contribute to both the taste and flavor of coffee, specifically the acidic taste sensation, because of their volatility. In roasted coffee organic acids are classified into four groups aliphatic, chlorogenic, alicy-clic, and phenolic (Galli and Barbas, 2004). 

DHS applications have been developed, for example, for the determination of aroma-active compounds in bamboo shoots (83), styrene in yoghurt (8- ) and volatile acids in tobacco, tea, and coffee (88), volatile compounds of strawberries (89) and odor-active compounds of hams (90). The applications of DTD-GC include, for example, in the determination of volatile components of Lavandula luisieri (85), in the analysis of volatile components of oak wood (87) and volatiles in various solid-food products such as spices and herbs (black pepper, oregano, basil, garlic), coffee, roasted peanuts, candy and mushrooms (82). 

Gorter (1910) observed the formation of lactic acid in the fermentation of a Liberia coffee. The acid was identified by Schormuller et al. (1961) in a commercial coffee extract (0.45%, 9% of the acid content), and the presence confirmed by Woodman et al. (1968). Feldman et al. (1969) mentioned a content of 0.055-0.09% based on the dry coffee basis, for medium to dark roast arabica and robusta coffees. Blanc (1979) considered that the content of this acid, low in green beans (0.08-0.09% of the dry material), only slowly increased to 0.10-0.16% during roasting for Tanzania and Kenya arabicas. Van der Stegen and van Duijn (1988) could measure the content of lactic acid only in roasted coffee (0.0-0.18%d.m.) with an increase if a brew was maintained at high temperature. Maier (1987) similarly... 

Baltes and Bochmann (1987a) identified it in their model reactions (above) as well as in coffee. According to Winter et al. (1976e), at a concentration of 50 ppm in a syrup base, it has a weak furanic note a bitter, roasted, acid and flowery note being perceived when tasted in a neutral, soluble coffee base at a concentration of 10 ppm. 

Pyridines have been identified among the pyrolysis products of model reactions involving amino acids and sugars, for instance by Ledl and Severin (1973), Mussinan and Katz (1973), and Baltes and Bochmann (1987d). The latter authors identified 15 pyridines present in coffee flavor, 13 of them also being present in reactions of serine and/or threonine, with or without sucrose, under coffee-roasting conditions. Pyridines can also be formed by thermal degradation of Amadori intermediates (van den... 

For Viani and Horman (1974), pyridine represents 25% of the pyrolysis products of a trigonelline monohydrate sample. Pyridine has been found in model reactions between glucose and amino acids (Kato et al., 1973b), when heating serine and/or threonine with or without sucrose under coffee-roasting conditions (Baltes and Bochmann, 1987d who found it also in coffee). Mottram (1991) explained the possible formation of pyridine by reaction of ammonia on 2,4-pentadienal. 

Identified by Andrade-Aispuro and Crouzet (1983) using original laboratory and pilot units allowing recovery of the volatiles produced during coffee roasting, with a system based on an absorption column equipped with Raschig rings and a countercurrent flow of water. The condensate was fractionated by chemical extraction into basic, acid, neutral and phenolic fractions. The constituents were separated and... 

Shikimic acid derivatives are formally obtained from quinic acid derivatives by dehydration at the C1-C2 position of the cyclohexane. Cinnamoyl shiki-mic acids occur naturally in several plants such as date or mate [20], In addition, they are formed at elevated temperatures from CGAs through loss of water, for example, in coffee roasting. 

Protein is subjected to extensive changes when heated in the presence of carbohydrates. There is a shift of the amino acid composition of coffee protein acid hydrolysates before and after bean roasting (Table 21.4). The total amino acid content of the hydrolysate drops by about 30% because of considerable degradation. 

Volatile components constitute about 0.1% of roasted coffee by weight Cojfea species, Rubiaceae), and more than 200 substances have been shown in green coffee. More than 800 compounds are known to make up the aroma of roasted coffee. Of these, only about 60 compounds have a significant role in the coffee aroma. Especially typical are a large number of heterocyclic compounds, mainly furans, pyrroles, indoles, pyridines, quinolines, pyrazines, quinoxalines, thiophenes, thiazoles and oxazoles, which arise in caramehsation and the MaiUard reaction during coffee roasting. In addition to heterocyclic products, other important volatiles are also some aliphatic compounds (hydrocarbons, alcohols, carbonyl compounds, carboxylic acids, esters, aliphatic sulfur and nitrogen compounds), alicyclic compounds (especially ketones) and aromatic compounds (hydrocarbons, alcohols, phenols, carbonyl compounds and esters). 

When roasting coffee, the caffeine content is virtually unchanged. TrigoneUine that accompanies coffee alkaloids decomposes to nicotinic acid and volatile sensorially active pyridines, therefore the trigonelline and caffeine contents ratio is used as an indicator of coffee roasting intensity. 

Additionally, Villanueva et al. studied die eo-extraction of other valuable eom-pounds of coffee, such as phenolic compounds (mainly chlorogenic acids) and oils. These substances have an important role during coffee roasting as preeursors of key eompounds of coffee flavor and aroma and thus, their removal from natural matter during extraction should be minimized. 

Lactisole [13794-15-5] the sodium salt of racemic 2(4-methoxyphenoxy)propionic acid, is a sweet-taste inhibitor marketed by Domino Sugar. It was affirmed as a GRAS flavor (FEMA no. 3773). At a concentration of 100 to 150 ppm, lactisole strongly reduces or eliminates the sweet taste of a 10% sugar solution. This inhibition appears to be receptor-related because lactisole also inhibits the sweet taste of aspartame. The 5 -( —)-enantiomer [4276-74-8] (38), isolated from roasted coffee beans, is the active isomer the i -(+)-enantiomer is inert (127). 

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