Ricinoleic acid, the main constituent of castor oil, has been converted to
γ-decalactone via partial β-oxidation, by yeasts such as Sporidiobolus salmonicolor
and Yarrowia lipolytica. A yield over 10 g/L has been reported along with the
production of undesirable side product hydroxy-γ-decalactone. Saccharomyces
cerevisiae converts hydroxy-γ-decalactone into 3, 4 unsaturated γ-decalactone,
which is then stereoselectively reduced into the desirable γ-decalactone by the
yeast (Vandamme 2003).
7.3.2.6 Phenolic Aldehydes
Phenolic aldehydes which constitute nice flavours are anisaldehyde and some
derivatives of protocatechualdehyde (3, 4-dihydroxybenzaldehyde), such as vanillin,
veratraldehyde and heliotropin (Braga et al. 2018). Vanilla flavour is due to the
phenolic aldehyde vanillin, is widely used for its pleasant, sweet and intense aroma
in ice creams, cookies, cakes, in soft beverages and cosmetics. About 6000 tonnes of
vanilla is consumed worldwide each year (Priefert et al. 2001). Natural vanilla is a
complex mixture of flavours which is obtained from cured vanilla pods belonging to
Vanilla orchids, Vanilla planifolia, Vanilla tahitensis or Vanilla pompona, where it
contributes to about 2% (w/w) of the dry matter (Green Protocols n.d.). Although
flavour and fragrance profile of the vanilla extracts shows more than
200 components, Vanillin (4-hydroxy-3-methoxybenzaldehyde) is the characteristic
key component of vanilla flavour comprising of various functional groups like
aldehyde, ether and phenol (Green Protocols n.d.). It is also used as a precursor for
various pharmaceutical formulations and finds application as a food preservative
(Hassan et al. 2016). Also, synthetic vanillin is used in the production of deodorants,
air fresheners, cleaning products, antifoaming agents or herbicides. In the green
beans, vanillin is present in the conjugated, β-D-glucoside form, which has no trace
of the characteristic vanilla flavour (Green Protocols n.d.). The flavour develops
during the 6 months long fermentation or curing process of green pods. During
curing, vanillin β-D-glucoside and related β-D-glucosides are acted upon by
enzymes β-D-glucosidases releasing vanillin (1–3%) and related phenolics (Walton
et al. 2003). The annual global sales of vanillin were reported to be more than
15,000,000 kg in 2010. It has been reported that less than 1% is obtained from
vanilla pods, while remaining is obtained by the chemical methods (Green Protocols
n.d.). The cultivation of vanilla beans and the isolation of vanillin from vanilla pods
is a laborious and costly process. About 500 kg of vanilla pods have to be processed
to produce 1 kg of vanillin, for which approximately 40,000 vanilla orchid flowers
have to be hand-pollinated. The cost of natural vanillin is quite high due to the
limited availability of vanilla pods, fluctuations in harvest yields, labour intensive
cultivation and curing of vanilla pods (Sinha et al. 2008).
Vanillin was first isolated by evaporation of vanilla extract so as to obtain it in a
dry and crystallized form by Gobley (1858). In 1874, Tiemann and Haarmann,
synthesized vanillin from coniferin present in tissues of pine tree. A company
named ‘Haarmann’s Vanillinfabrik’ was founded for its production, which was
later joined by Reimer. The first chemical method of synthesis of vanillin was
using guaiacol as the substrate (Ciriminna et al. 2019). Guaiacol (a petrochemical
7 Biotechnological Interventions for Production of Flavour and Fragrance. . .
143
γ-decalactone via partial β-oxidation, by yeasts such as Sporidiobolus salmonicolor
and Yarrowia lipolytica. A yield over 10 g/L has been reported along with the
production of undesirable side product hydroxy-γ-decalactone. Saccharomyces
cerevisiae converts hydroxy-γ-decalactone into 3, 4 unsaturated γ-decalactone,
which is then stereoselectively reduced into the desirable γ-decalactone by the
yeast (Vandamme 2003).
7.3.2.6 Phenolic Aldehydes
Phenolic aldehydes which constitute nice flavours are anisaldehyde and some
derivatives of protocatechualdehyde (3, 4-dihydroxybenzaldehyde), such as vanillin,
veratraldehyde and heliotropin (Braga et al. 2018). Vanilla flavour is due to the
phenolic aldehyde vanillin, is widely used for its pleasant, sweet and intense aroma
in ice creams, cookies, cakes, in soft beverages and cosmetics. About 6000 tonnes of
vanilla is consumed worldwide each year (Priefert et al. 2001). Natural vanilla is a
complex mixture of flavours which is obtained from cured vanilla pods belonging to
Vanilla orchids, Vanilla planifolia, Vanilla tahitensis or Vanilla pompona, where it
contributes to about 2% (w/w) of the dry matter (Green Protocols n.d.). Although
flavour and fragrance profile of the vanilla extracts shows more than
200 components, Vanillin (4-hydroxy-3-methoxybenzaldehyde) is the characteristic
key component of vanilla flavour comprising of various functional groups like
aldehyde, ether and phenol (Green Protocols n.d.). It is also used as a precursor for
various pharmaceutical formulations and finds application as a food preservative
(Hassan et al. 2016). Also, synthetic vanillin is used in the production of deodorants,
air fresheners, cleaning products, antifoaming agents or herbicides. In the green
beans, vanillin is present in the conjugated, β-D-glucoside form, which has no trace
of the characteristic vanilla flavour (Green Protocols n.d.). The flavour develops
during the 6 months long fermentation or curing process of green pods. During
curing, vanillin β-D-glucoside and related β-D-glucosides are acted upon by
enzymes β-D-glucosidases releasing vanillin (1–3%) and related phenolics (Walton
et al. 2003). The annual global sales of vanillin were reported to be more than
15,000,000 kg in 2010. It has been reported that less than 1% is obtained from
vanilla pods, while remaining is obtained by the chemical methods (Green Protocols
n.d.). The cultivation of vanilla beans and the isolation of vanillin from vanilla pods
is a laborious and costly process. About 500 kg of vanilla pods have to be processed
to produce 1 kg of vanillin, for which approximately 40,000 vanilla orchid flowers
have to be hand-pollinated. The cost of natural vanillin is quite high due to the
limited availability of vanilla pods, fluctuations in harvest yields, labour intensive
cultivation and curing of vanilla pods (Sinha et al. 2008).
Vanillin was first isolated by evaporation of vanilla extract so as to obtain it in a
dry and crystallized form by Gobley (1858). In 1874, Tiemann and Haarmann,
synthesized vanillin from coniferin present in tissues of pine tree. A company
named ‘Haarmann’s Vanillinfabrik’ was founded for its production, which was
later joined by Reimer. The first chemical method of synthesis of vanillin was
using guaiacol as the substrate (Ciriminna et al. 2019). Guaiacol (a petrochemical
7 Biotechnological Interventions for Production of Flavour and Fragrance. . .
143