Industrial Process Flavourings

4 Industrial Process Flavourings 3.2.3.4.1 Savoury Process Flavourings 

Savoury process flavourings are widely used in culinary products to boost meat flavour (beef, chicken, pork, lamb, veal) or other notes (fish, seafood, vegetable). The development of meat-like process flavours started in the 1950s and the first patents were published in 1960. To date meat-like and other savoury flavours still represent the largest volumes of all process flavourings produced. 

Thiamine is another key sulphur precursor used for meat-like process flavours. Bid-mead and co-workers [95] used thiamine as precursor in combination with an aliphatic carboxylic acid to obtain roasted meat flavours. The reaction can be carried out in presence or absence of a carbohydrate. For example, refluxing thiamine, cysteine hydrochloride and a carbohydrate-free HVP (hydrolysed vegetable protein) for 4 hours results in a product with beef flavour. Giacino [69] proposes the reaction of thiamine with a cysteine-containing peptide, e.g. glutathione or an amino acid mixture containing cysteine, and adding aldehydes and ketones after the reaction. The reaction is preferably carried out in fat. 

Animal phospholipids, especially egg phospholipids or egg yolk, are the key precursors for a patent application, which claims the reaction with a sulphur-containing compound like cysteine to produce meaty flavours ]102], Phospholipids and monoglycerides can play a fundamental role in the physical structure of a process flavour. Vauthey and co-workers ]103] use these emulsifiers in water to generate nanostmctured mesophases or microemulsions at the reaction temperature. Better aroma yields and different aroma compounds were obtained in these nanostmctured reaction media compared to aqueous solutions. 

Process flavourings for application in sweet and bakery goods (e.g. flavourings with chocolate, malt, caramel, egg, coffee or biscuit tonality) have been known for an even longer time than their savoury counterparts. Sulphur-containing aroma precursors such a cysteine are not the main concern of sweet process flavourings, and in many cases they even have to be avoided in order to prevent the formation of off-flavours. 

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So far none of the industrial processes recycle the catalyst. Yet the number of ways to do this has grown far beyond simple immobilization. Two-phase catalysis now comes in many flavours. 

Romagnoli LG, Knorr D (1988) Effects of ferulic acid treatment on growth and flavor development of cultured Vanilla planifolia cells. Food Biotechnol 2 93-104 Schrader J, Etschmann MMW, Sell D, Hilmer J-M, Rabenhorst J (2004) Applied biocatalysis for the synthesis of natural flavour compounds—current industrial processes and future prospects. Biotechnol Lett 26 463-472... 

Ajowan oleoresin prepared from seeds gives a warm, aromatic and pleasing flavour to food products and is used in processed foods, snacks, sauces and various vegetable preparations. Ajowan oil can be treated with aqueous alkaline solution to extract thymol (Pruthi, 2001). Fatty oils produced from ajowan seed have their use in various pharmaceutical and cosmetic industries, are used in the soap industry for flavouring and as a deodorant. They are also used for perfuming disinfectant soaps and as an insecticide. A thymol-free fraction of the oil, known as thymene , finds application in soap perfumes (Malhotra and Vijay, 2004). 

International Organisation of the Flavour Industry. lOFI Guidelines for the production and labelling of process flavourings. In Code of practice for the flavour industry, including replacement sheets January 1997, lOFI, Geneva, 1997, F1-F4. 

Fermentation plays an important role in the development of specific, characteristic flavourings. Natural fermentation is used since thousands of years to get wine, beer or cheese. Modem biotechnological processes have been developed to produce flavourings and flavouring building blocks based on natural processes. There are many important fermented products on the markets, produced by traditional and industrial processes ... 

These interface techniques for connecting the HPLC with the MS-system are very sensitive for most of the substances of interest to the flavour industry. Therefore, HPLC-MS coupling techniques have become an increasingly powerful tool for quality control of flavourings, especially for the analysis of complex mixtures like process flavourings or contaminants present in such complex mixtures. New developments in the area of mass detection systems, such as time-of-flight (ToF) mass analysers and tandem mass spectrometry systems or the features of matrix-assisted laser desorption ionization (MALDI) techniques, may enhance the analytical capabilities of these systems in the near future [16, 17, 28-31 ]. 

The restrictive list of natural and nature-identical flavouring substances of the lOFI Code of Practice for the Flavour Industry applies also to process flavourings. 

If you think these rearrangements sound like academic reactions and too refined for the rough and tumble of industry, you re in for a surprise. The Carroll rearrangement, a [3,3) sigmatropic shift, is an important industrial process used to make vitamin A and some perfumery and flavouring compounds at BASF in Germany. 

Replacement of organic solvents by water may be done for environmental, cost e.g. reduction in raw materials and VOC containment costs) or technical reasons. In the flavour and fragrance industry, where the presence of even trace amounts of volatile impurities can be detected by the expert nose , significant process costs are entailed in ensuring complete removal of solvent. If reactions can be carried out in water then these additional costs can be saved. As an example geraniol can be isomerized to the important fragrance intermediates a-terpinol and linalol in water at 220 °C (Scheme 5.9). 

Alkylcatechols are important as chemicals and chemical intermediates in the fine chemistry industry for the synthesis of flavouring agents, agricultural chemicals and pharmaceuticals [1]. 3-methyl catechol has a special value from the industrial point of view. Previously y-alumina was found to be an effective catalyst for the gas-phase methylation of catechol with methanol [2]. The process can be schematically presented as ... 

Obviously, in a relatively small work such as this it is not possible to be comprehensive. Preparations of bulk, achiral materials (e.g. simple oxiranes such as ethylene oxide) involving key catalytic processes will not be featured. Only a handful of representative examples of preparations of optically inactive compounds will be given, since the emphasis in the main body of this book, i.e. the experimental section, is on the preparation of chiral compounds. The focus on the preparation of compounds in single enantiomer form reflects the much increased importance of these compounds in the fine chemical industry (e.g. for pharmaceuticals, agrichemicals, fragrances, flavours and the suppliers of intermediates for these products). 

The aroma compounds from the tropical fruits described in this chapter can be very important for consumers and industry as they are exotic and extremely pleasant however, the production of these compounds by biotechnological processes should be emphasised since the extraction from the fruits is a hard task. Many tropical soils contain less nitrogen and phosphorus, have lower capacity to absorb fertilisers, and therefore have lower conventional productive capacity, but some tropical soils have been very intensively farmed and further intensification is possible in other areas. Thus, the evaluation of a sustainable agriculture in tropical regions requires a sophisticated approach including the estimation of the risk of microbial or insect infestations. As many fruits go directly to fresh markets or to immediate processing, a continuing supply of the flavour manufacturers in the future is not completely assured. 

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