Agriculture Reference
In-Depth Information
can be used within the current legislative framework to produce fl avour bases for
use as food fl avourings. In many cases these do not need to be further purifi ed as
they have characteristics such as brown sugar/caramel or smoke that can be used
directly in formulations.
Microwaves can be precisely controlled in power and temperature to give a
reproducible composition and large-scale continuous equipment is already used
widely in the food industry. The most studied applications for microwave are
those molecules that can be derived from carbohydrates or from lignin, since both
represent large volume renewable resources.
Carbohydrates are sources of fl avour molecules such as furans (Underwood
and Stradal 1993) and produce characteristic burnt sugar/caramel/toffee fl avours.
Lignins are polyphenolic structures that produce complex mixtures or aromatics
under microwave conditions (Budarin
et al.
2009) and in most cases co-exist with
cellulose and hemicellulose. Most of the aromatics produced from lignin are
phenol, syringol or guaiacol derivatives and an example of barley straw pyrolysis
is shown in Fig. 12.8. The oils isolated from this pyrolysis have a sweet smoke
character not dissimilar to the characteristics of aged whisky and this can be
attributed to the vanillin and phenolics. If similar treatment was applied to wood
a liquid smoke product is produced. A recent example used this technique followed
by extraction using supercritical CO
2
to produce a liquid smoke product low in
polycyclic aromatic hydrocarbons (Plaschke 2007).
12.4 Future perspectives
To effectively achieve both EU natural status and a greener approach it is desirable
to use only natural and renewable sources of raw material and to extract or modify
fl avour active compounds using processes permitted in Annex II of Regulation
(EC) No. 1334/2008. These processes will preferably use green solvent options
and use physical processes such as low-energy microwave technologies in parallel
with microbial biotransformation and biocatalysis in aqueous media or organic
solvents such as supercritical carbon dioxide.
The continued growth in the market for natural fl avourings and the introduction
of new EU legislation, together with consumer pressure to adopt greener process
technologies, will require the development and commercialisation of alternative
greener approaches to the production of fl avouring substances and fl avour
preparations. The traditional approach is often ineffi cient, energy-intensive and
uses solvents that are becoming undesirable but the investment that has been
made in these existing technologies presents a considerable barrier to the adoption
of cleaner and greener approaches to the preparation of traditional fl avouring
materials.
Future technical developments in some of these greener technologies could
lead to more cost-effective application. These include the development of
continuous extraction with supercritical CO
2
and the demonstration of large-scale
subcritical water extraction and microwave-assisted distillation. Biocatalysts are
Search WWH ::
Custom Search