Biotechnological natural flavours

To cater for the large demand for vanillin, besides different synthetic methods also biotechnological processes have been developed. Synthetic vanillin has a major drawback that products containing this compound cannot be labelled as containing a natural flavour. On the other hand, biotechnological products can be labelled as natural. 

In the context of EU food law, fruit juices must be genuine in view of their aroma, only aroma concentrates of the fruit concerned are suitable for fruit juices from concentrates. Other natural flavourings (from other fruits or biotechnology) are not allowed. 

Decanolide (y-decalactone), which imparts a powerful fruity, especially peach-like aroma has a market volume of several hundred tons per year. In the early 1980s, natural 4-decanolide was an extremely expensive, rare natural flavour (price in excess of US 10,000 per kilogram). The subsequent introduction and optimisation of its biotechnological production has resulted in a steady decrease of the price to approximately US 300 per kilogram and an increase of the market volume to several tons per year [8]. 

Since not only the isolation from nature but also biotechnological processes (the use of microorganisms and enzymes) are a source of natural flavours [5], the term bioflavours will be used. 

Table 2.10 shows that the isolation and purification of naturally occurring flavour chemicals and extracts from animal and plant raw materials is most important for the preparation of natural flavours. About 75% of the commercially used flavours come from such natural sources. Physico-chemical reactions of typical flavour precursors may also lead to natural flavouring substances when mild conditions ( kitchen technology ) are applied. In addition, natural flavour chemicals may be prepared by biotechnological processes. This chapter outlines the most important biotechnical manufacturing techniques. 

Natural flavouring substances may be obtained by physical, enzymatic, or microbial processes from materials as defined in Tab. 3.3. Enzymatic and microbial processes are also known as biotechnological processes. 

Natural Flavouring Substances Manufactured by Biotechnological Processes... 

A selection of biotechnological processes that are used to produce natural flavouring substances is shown in Fig. 3.1 (see also chapter 2.2). Note that physical processes (see 2.1) are always involved in isolating the products from the fermentation broth. 

Fig. 3.1 Selection of biotechnological processes for the production of natural flavouring substances...

With most biotechnologically produced flavour extracts the taste quality of natural fermentation processes can be reached and even surpassed. Normally the taste intensity is significantly higher compared to the usual fermentation process in the raw food material. Even completely new taste types may be accessible biotechnologically. The time necessary for the development of the desired taste in most cases may be signifi-... 

In addition to the raw materials commonly used for the production of flavours, such as synthetic flavouring substances, uniform natural flavouring substances (gained by fermentation respectively biotechnological methods), essential oils, absolutes, essences etc., aqueous alcoholic distillation and extraction are processes which are specifically used today for the production of raw materials for the sector of alcoholic beverages, just as they have been for many years in the spirits industry. 

In the past only citrus and cough drops tastes could be based on natural flavourings. Thanks to biotechnology it is now also possible to create natural flavourings in other tonalities for hard candy, although the price is rather high. 

Today natural flavourings can be used without technical restrictions since in the nineties biotechnology and generally improved technologies provide a much wider, better and more economical range of natural flavouring substances. 

Morrissey, J.P., Etschmann, M.M.W, Schrader, J., and de Billerbeck, G.M, (2015) Cell factory applications of the yeast Kluyveromyces marxianus for the biotechnological production of natural flavour and fragrance molecules. Yeast, 32, 3-16. 

Kim, A. Y. (2005). Application of biotechnology to the production of natural flavour and fragrance chemicals In Natural Flavors and fragrances chemistry, analysis, and production, Frey, C, and Rouseff, R. L. Eds., ACS symposium series 908, ACS, 60-75. 

Gubicza, L., Kabiri-Badr, A., Keoves, E., Belafi-Bako, K. (2000). Large-scale enzymatic production of natural flavour esters in organic solvent with continuous water removal. Journal of Biotechnology, 84, 193—196. 

There are about 25,000 enzymes present in nature and about 400 have been commercialised mainly for stereoselective organic synthesis and also for the biotechnological production of flavour compounds. The worldwide market for enzymes is more than US 1 billion. 

Owing to very low thresholds, volatile sulfur compounds (VSCs) usually have prime impact on food aromas they are found in lots of natural sources, including fermented foods (e.g. wine, beer, cheese), and act as both flavours and off-flavours [249, 250]. Although their biogenetic formation has been elucidated in detail, only few biotechnological processes with potential for commercial application have been reported. The sulfur-containing amino acids L-methionine and L-cysteine are the natural precursors of a wide variety of VSCs. Methanethiol is the most frequently found VSC in cheese and can be readily oxidised to other VSCs, such as dimethyl suMde and dimethyl disulfide, or... 

BMP may become a savoury peptide and a flavour modifier of the future [26]. It occurs naturally in beef. One method of production of BMP already initiated by several concerns is biotechnology [28[. The taste threshold of BMP has been reported to be 1.600 ppm [28[. There are also reports in the literature claiming that BMP cannot be considered as a flavour modifier and that its occurrence in beef is highly unlikely [30, 31 [. 

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 ... 

H.G. Cutler, R.A. Hill, B.G. Ward, B.H. Rowitha and A. Stewart, Antimicrobial, Insecticidal and Medicinal Properties of Natural Product Flavours and Fragrances in Biotechnology for Improved Foods and Flavors ACS Symposium Series 637, G.R. Takeoka, R.Teranishi,... 

Liu, S.-Q., Crow, V. L. (2010). Production of dairy-based, natural sulphur flavour con-cenlrate by yeast fermentation. Food Biotechnology, 24, 62-77. http //dx.doi.org/ 10.1080/08905430903562724. 

Abraham, W.-R., H.-A. Arfmann, B. Stumpf, P. Washausen, and K. Kieslich, 1988. Microbial transformations of some terpenoids and natural compounds. In Bio flavour 87. Analysis—Biochemistry— Biotechnology, P. Schreier, ed., pp. 399-414. Berlin, Germany Walter de Gruyter and Co. 

Lomascolo, A., Stentelaire, C., Asther, M., and Lesage-Meessen, L. (1999) Basidiomycetes as new biotechnological tools to generate natural aromatic flavours for the food industry. Trends Biotechnol, 17, 282—289. 

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