Flavour coffee

Semmelroch, P., Laskawy, G., Blank, I., Grosch, W., Determination of potent odorants in roasted coffee by stable isotope dilution assays, Flavour Fragrance J. 10(1), 1, 1995. 

Cappuccino coffee is named after Marco d Aviano, a Capuchin monk who was recently made a saint. He entered a looted Turkish army camp, and found sacks of roasted coffee beans. He mixed it with milk and honey to moderate its bitter flavour. 

In principle, we could remove the water from the coffee by just boiling it off, to leave a solid residue as a form of instant coffee . In fact, some early varieties of instant coffee were made in just this way, but the flavour was generally unpleasant as... 

The modem method of removing I from coffee resembles the operation of a coffee percolator, in which the water-soluble chemicals giving flavour, colour and aroma are leached from the ground-up coffee during constant irrigation with a stream of boiling water. 

Water is a good choice of solvent in a standard kitchen percolator because it removes all the water-soluble components from the coffee - hence the flavour. Clearly, however, a different solvent is required if only the caffeine is to be removed. Such a solvent must be cheap, have a low boiling point to prevent charring of the coffee and, most importantly, should leave no toxic residues. The presence of any residue would be unsatisfactory to a customer, since it would almost certainly leave a taste and there are also health and safety implications when residues persist. 

The preferred solvent is supercritical CO2. The reasons for this choice are many and various. Firstly, the CO2 is not hot (CO2 first becomes critical at 31 °C and 73 atm pressure see Figure 5.5), so no charring of the coffee occurs during decaffeination. Furthermore, at such a low temperature, all the components within the coffee that impart the flavour and aroma remain within the solid coffee - try soaking coffee beans in cold water and see how the water tastes afterwards Caffeine is removed while retaining a full flavour. 

But why are NP-rich plants more expensive than commodity or crops Simply because, in contrast to the easily substitutable staple foods, the plants that produce highly attractive NPs usually have a much more limited geographical distribution. Consequently, there is less competition in the market place and substitution remains very difficult in most cases (e.g., there is no satisfactory synthetic coffee, tea or chocolate). Some of the NPs used in scents and flavours have been substituted with synthetic chemicals but even then many consumers were prepared to pay a premium for plant-derived flavouring (e.g., natural vs. synthetic vanilla). 

Some representatives of y-lactones are y-valerolactone 150, y-decalactone 151 with peach-like flavour, (Z)-6-dodecen-4-olide 152, 3-methyl-4-octanolide (whiskey lactone) 153 and 3-hydroxy-4,5-dimethyl-2(51T)-furanone (sotolone) 154 (Structure 4.46), found in fenugreek, coffee and sake [1-4, 21-23, 62]. 

Oxazoles have been found in relatively few cooked foods, although over 30 have been reported in coffee and cocoa, and 9 in cooked meat. Oxazolines have been found in cooked meat and roast peanuts, but not to any extent in other foods. 2,4,5-Trimethyl-3-oxazoline has been regularly detected in cooked meat [26], and when it was first identified in boiled beef [27] it was thought that the compound possessed the characteristic meat aroma however, on synthesis it was shown to have a woody, musty, green flavour with a threshold value of 1 mg/kg [28]. Other 3-oxazolines have nutty, sweet or vegetable-like aromas and the oxazoles also appear to be green and vegetable-like [28]. The contribution of these compounds to the overall aroma of heated foods is probably not as important as the closely related thiazoles and thiazolines. 

Furfural comes from pentose sugars in cereal straws and brans. Furfural is the precursor of furfuryl mercaptan and its disulfide, difurfuryl disulfide, which are both important chemicals for coffee, meat and roasted flavours. They are prepared by the reaction of furfural and hydrogen sulfide (Scheme 13.15). 

In order to illustrate the potential of MDGC when dealing with complex mixtures, an application to determine off-flavour compounds in defective coffee beans is given byway of example (Fig. 15.3)... 

A typical REMPl at 266 nm mass spectrum is shown Fig. 15.22, obtained by roasting 80 g of Arabica coffee at 225 °C. The laserpower density was adjusted to 10 -10 W/cm in order to avoid non-resonant ionisation processes. The spectrum contains predominantly molecular ions. Chemical assignment of the ion peaks was based on three distinct pieces of information the literature on coffee flavour compounds [204], the mass as observed in TOFMS and optical absorption properties. With this information, many volatiles observed in Fig. 15.22 were unambiguously identified. 

As mentioned in the introduction to this section, there is the opportunity to recover aroma compounds from baking or roasting exhaust gases. The patent literature contains numerous references to the recovery of aroma compounds using this approach, most commonly from cocoa, coffee, or tea processing. Aroma compounds from the roaster exhaust gases are either condensed in cryogenic traps [29-32] or collected on absorbents (e.g. charcoal [33]) and then solvent-extracted to obtain a concentrated aroma extract. The concentrated extract may be used to aromatise a similar product (e.g. soluble coffee) or may be used to flavour other products (e.g. coffee-flavoured ice creams). 

A successful flavour is based on different elements. A very important part is the selection of the most potent volatile aroma compounds. All we eat, every fruit, every meal, every drink, every cup of fresh coffee contains a combination of various volatile flavour ingredients. 

Juice and/or Coffee-type Wine coolers Flavoured teas... 

Phenylethanol has a rose-like odour and makes the chemically produced compound the most used fragrance chemical in perfume and cosmetics, with a world market of about 7,000 t year [107, 108]. 2-Phenylethanol is also found in many foods as a characteristic flavour compound rounding off the overall aroma, especially in foods obtained by fermentation, such as wine, beer, cheese, tea leaves, cocoa, coffee, bread, cider and soy sauce [109]. In food applications, natural 2-phenylethanol is preferred rather than its nature-identical counterpart from chemical synthesis and it has a market volume of 0.5-11 year . This product is sold at market prices of up to US 1,000 per kiklogram and is mainly produced by yeast-based bioprocesses since its isolation from natural sources, e.g. rose oil, would be too costly [109]. 

Furfiirylthiol is a key flavour especially for coffee, beef and roast-like food aromas. It was synthesised in concentrations of up to 1 g L using /1-lyase activity of whole bacterial cells, e.g. Enterobacter cloacae or Eubacterium limosum [256] (Scheme 23.21). Resting cells were used to cleave the sulfur-carbon bond of a furfural-cysteine conjugate and an XAD-4 resin connected to the gas outlet... 

Amongst furans are several compounds of great importance in fragrances and flavours. The rose owes some of its odour to a terpenoid furan, rosefuran, coffee some of its characteristics to furylmethanethiol and related compounds. Compounds like the 3-furanone derivative furaneol (10) are particularly interesting for their odours depend upon concentration— furaneol can seem to resemble pineapple, caramel, burnt toast etc. Furaneol is a dihydrofuran-3-one dihydrofuran-2-ones are obviously lactones and are usually dealt with as such. 

Coffee Carbonated drink Flavoured milk Wine... 

Soft drinks and fruit juices compete with many other beverages - water, milk (natural or flavoured), tea, coffee and so on - for our attention and the % share of throat . Whether they are still, carbonated, sweetened, unsweetened, eneigy-boosting or complement diets, all will claim to be needed in our hectic lifestyles. 

Extracts of coffee bean and cocoa bean have been produced experimentally that contained about 3% of caffeine and 3% theobromine respectively without the disadvantage of flavour concentration typically associated with those raw materials. These are potentially alternative natural sources of effective stimulants to guarana and kola. Other supplementary herbs that have a place in energy... 

Flament, I. Coffee, Cocoa and Tea Flavors A Review of Present Knowledge, Int. Symp. on Food Flavours (Paris 1982), Adda, J. and Richard, H., Ed. Tec-Doc, Paris, 1983 p. 32... 

Being volatile, the aldehydes formed in the Strecker degradation have often been thought to be important contributors to the aroma of foodstuffs and many patents have been granted which use the Strecker degradation to produce flavouring materials of various types, such as, maple, chocolate, coffee, tea, honey, mushroom, and bread.66... 

Cardamom seeds are used widely for flavouring purposes in food and as a carminative. Despite their numerous applications in the cooking styles of Sri Lanka, India and Iran, 60% of the world production is exported to Arab countries (South-west Asia, North Africa), where the largest percentage is used to prepare coffee. 

The spice is used throughout Europe and Asia and is smoked in a type of cigarette, known locally as kretek, in Indonesia and in occasional coffee bars in the West, mixed with marijuana to create marijuana spliffs. Clove cigarettes (Indonesian kretek) are cigarettes made with a complex blend of tobacco, cloves and a flavouring sauce . Cloves are also an important incense material in Chinese and Japanese culture. 

Chemists produce synthetic flavourings such as smoky bacon and even chocolate . Meaty flavours come from simple heterocycles such as alkyl pyrazines (present in coffee as well as roast meat) and furonol, originally found in pineapples. Compounds such as corylone and maltol give caramel and meaty flavours. Mixtures of these and other synthetic compounds can be tuned to taste like many roasted foods from fresh bread to coffee and barbecued meat. 

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