Flavour materials

K. Bauer, D. Garbe, and H. Surburg, in Common Fragrance and Flavours Materials, Wiley-VCH, New York, 1997. 

These are materials that are synthetic but are the same compound as is present in a natural flavouring material. From time to time it emerges that one substance produces a given flavour. Most chemists know that benzaldehyde has a smell of almonds. Some chemists know that hydrogen cyanide smells of bitter almonds. If a natural flavouring can be represented by a single substance and that substance can be synthesised then the flavour is likely to be available as a nature identical flavour. Vanilla flavour is a good example. Vanilla flavour can be all natural and derived from vanilla pods or nature identical or artificial. The nature identical product would be based on vanillin, which is in vanilla pods and has a flavour of vanilla. An artificial vanilla flavour would be ethyl vanillin, which is not present in vanilla pods but has a flavour two and a... 

These are flavours that are produced synthetically but are not present in a natural flavouring material. The chemistry of flavours is a complex topic that has been the subject of many books, for example ref. 3. Synthetic flavours are made from a mix of flavouring substances that have been found to produce a given flavour note . Those who develop flavours are referred to as flavourists. Flavourists take the musical analogy of notes further by referring to the top notes and the bottom notes of a flavour. 

Part III extraction solvents that may be used for the preparation of flavourings from natural flavouring materials diethyl ether, hexane, methyl acetate, butan-l-ol, butan-2-ol, ethylmethyl ketone, dichloromethane,... 

Such figures indicate the necessity for a global regulatory approach for flavouring material. 

About two thirds of the citrus produced worldwide is consumed as fresh fruit. Unfortunately, citrus utilised as fresh fruit cannot constitute a source of commercial flavours. However, in certain high-production countries such as the USA (Florida) and Brazil, the majority of the citrus crop is processed. In Florida over 90% of the orange crop is processed and is a major source for citrus flavouring material. Citrus fruits are processed primarily into juice, but oil from the outer layer of the peel, flavedo, and the condensate from making concentrated juice are also major sources of flavour products from citrus fruit. 

It should be no surprise that the methods used to produce most flavourings from plant sources are based on similar principles as those used in the isolation of aroma compounds from foods. However, economics and scale play major roles in dictating methods. Additionally, the physical characteristics of the plant material, and concentrations and properties of flavouring materials also... 

Isolation of Flavouring Materials from Waste Streams... 

Besides the well-known Maillard reaction, additional reactions like sugar degradation, fat oxidation and interaction of Maillard intermediates are major sources for powerful flavour materials. 

Hydroxypyran-4-ones are potent flavouring materials of which maltol (427), present in roasted malt, is particularly well known. Amongst other features, it imparts a newly baked odour to bread. Kojic acid (712) is produced in an aerobic process by a range of microorganisms, notably Aspergillus oryzae, from a variety of carbohydrate sources and is used as a source of maltol. 

The exact quantities of flavouring materials can be determined from the ingredient formulae in Table 5.9. 

The radical reductive cyclisation of diesters to acyloins (see also Section 5.9.1, p. 628) is an important method of synthesis for ring sizes from four-membered upwards. The example selected here is 2-hydroxy-3-methylcyclopent-2-enone ( corylone ) (29) (Expt 7.10), which is an important perfumery and flavouring material.53 In the first step (i), methyl acrylate is converted into its dimer with tris(cyclohexyl)phosphine in pyridine solution.5b Step (ii) is the protection of the double bond by conversion into the dimethylamino adduct. The acyloin reaction is step (iii), and the product is trapped as its bis(trimethylsilyl)ether. Finally, in step (iv), the protecting dimethylamino and trimethylsilyl groups are removed by passage down a column of silica gel. 

Bauer K, Garbe D, Surburg H (2001) Common fragrance and flavour materials. Wiley, Weinheim... 

Additionally the conversion of the Amadori Rearrangement Product is enhanced, resulting in the increased formation of reaction products, which are the actual flavour materials. The highest yields of ARP based on the starting materials were therefore obtained in the absence of phosphate. 

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... 

Arctander, S. (1 960) Perfume and Flavour Materials of Natural Origin. Mrs. G. Arctander, 6665 Valley View Boulevard, Las Vegas, Nevada. 

In the twentieth century oil overtook coal as the main source of bulk organic compounds so that simple hydrocarbons like methane (CH4, natural gas ) and propane (CH3CH2CHV calor gas ) became available for fuel. At the same time chemists began the search for new molecules from new sources such as fungi, corals, and bacteria and two organic chemical industries developed in parallel— bulk and fine chemicals. Bulk chemicals like paints and plastics are usually based on simple molecules produced in multitonne quantities while fine chemicals such as drugs, perfumes, and flavouring materials are produced in smaller quantities but much more profitably. 

Terpenes were originally named after turpentine, the volatile oil from pine trees used in oil painting, whose major constituent is a-pinene. The term was rather vaguely used for all the volatile oily compounds, insoluble in water and usually with resiny smells from plants. The oils distilled from plants, which often contain perfumery or flavouring materials, are called essential oils and these too contain terpenes. Examples include camphor from the camphor tree, used to preserve clothes from moths, humulene from hops, which helps to give beer its flavour, and phytol, found in many plants. 

Linalool and linalyl acetate are the intensively studied chiral monoterpenoids. Their enantiomeric ratio had been investigated in the precious bergamot oil [36-38], lavender oils [39], and many other plants used as fragrance and flavour materials mainly fi-om Labiatae and Rutaceae families [40-42]. 

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