Natural flavourings from biotechnology for foods and beverages - Natural Food Additives, Ingredients and Flavourings - page 230

'nature-identical' rather than natural, which means that they are the chemical
equivalent of natural fl avors but are chemically synthesized (Schwab et al. 2008).
However, chemical synthesis is often an environmentally unfriendly production
process and results in the production of an undesirable racemic mixture of
compounds. In addition, due to increasingly health- and nutrition-conscious
lifestyles, consumers have developed a 'chemophobia' attitude towards synthetic
compounds (Cheetham 1993, 1997; Krings and Berger 1998). There is, therefore,
growing demand for natural fl avors and fragrances, and novel strategies for aroma
chemical production are required (Krings and Berger 1998). A rapid switch
towards the bioproduction and use of fl avor compounds from biotechnological
origin (biofl avors) has been observed.
The production of biofl avors has usually been undertaken by direct recovery
from nature, although many disadvantages are encountered, such as (i) low
concentrations of the product of interest, which increases the extraction and
purifi cation procedures; (ii) dependency on seasonal, climatic and political
features; and (iii) possible ecological problems involved with the extraction
(Bicas et al. 2009). Biotechnological production is an attractive alternative for the
production of fl avors, since it occurs at mild conditions, yields desirable regiomeric
and enantiomeric fl avor compounds, involves process conditions that are less
damaging for the environment and does not generate toxic waste. Biotechnology
is also an interesting approach for the production of biofl avors, since the
compounds produced by this method are defi ned as 'natural' or 'naturally
produced' fl avors (Demyttenaere et al. 2001; Bicas et al. 2009). Thus, biofl avors
appeal to many sectors and represent products of high market value (Gatfi eld
1997; Krings and Berger 1998).
The bio-route for fl avor synthesis is based on either de novo microbial
processes (fermentation) or on bioconversions of natural precursors with
microbial cells or enzymes (biotransformation). In general, microorganisms are
capable of producing an amazingly broad array of fl avor compounds by de novo
synthesis. However, production levels are very poor and thus constitute a limit for
industrial exploitation. For this reason, biotechnologists have focused on
bioconversion processes that offer more economic advantages (Feron and
Waché 2006). Several studies have been conducted to make bio-processes
more economically viable. Berger (2009) discussed the latest advances in the
bioproduction of fl avor compounds; for the author, progress is expected from
the toolbox of genetic engineering which is likely to help in identifying
metabolic bottlenecks and in creating novel high-yielding strains. Bioengineering,
in a complementary way, provides promising technical options, such as
improved substrate dosage, gas-phase or two-phase reactions, and in situ product
recovery. The use of agro-industrial residues as substrates for biotechnological
processes (e.g. cassava bagasse, cassava wastewater and coffee husk) has also
been proposed and studied by some research groups (Bicas et al. 2009). This
chapter focuses on the current state-of-the-art of biofl avor synthesis, with an
emphasis on de novo synthesis and biotransformation to produce fl avor
compounds.

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