The yield was found to be quite low and efficiency was only 10% (Abraham et al.
1988). The excrement of herbivorous animals has been used for the production of
plant polyphenol using the subcritical water. This unusual discovery has been
awarded Nobel Prize. Vanillin, protocatechuic acid, vanillic acid and syringic acid
were produced by the method, which was used as the intermediate materials of the
medicines and vanilla flavourings (Yamamoto et al. 2008).
Vanillin can also be produced by phenolic biotransformation by Aspergillus
luchuensis (a fermentation starter fungus). During the production of ‘awamori’
(a fermented beverage), vanillin was also produced. It involves a two-step process
catalysed by the enzymes, CoA ligases and feruloyl-CoA hydratase followed by a
two-carbon elimination of ferulic acid which produces vanillin and acetyl-CoA. The
production mechanism can be explained as the side chain cleavage of ferulic acid
through Coenzyme A (CoA) and feruloyl-CoA hydratase/lyase, to form vanillin and
acetyl-CoA (Taira et al. 2018).
Furanones comprise the aromatic chemicals present in many fruits such as
pineapple, strawberries, mangoes, raspberries. 2,5-dimethyl-4-hydroxy-3(2H)furanone (DMHF) marketed as Furaneol
® imparts strawberry flavour in dilute
solutions and caramel-like flavour in concentrated form (Vandamme 2003). Soy
sauce yeast Zygosaccharomyces rouxii can also produce DMHF in the medium
supplied with D- fructose-1,6-biphosphate (FBP) and glucose. Since FBP is readily
available, microbial process is a cheaper alternative (Dahlen et al. 2001).
7.3.2.7 Grassy Aroma
The ‘grassy’ aroma found in damaged green tissue (e.g. cut grass) and in aromas of
many fruits and vegetables is formed via the degradation of plant polyunsaturated
fatty acids (PUFA) such as linolenic acid which are acted upon by lipoxygenases and
hydroperoxides. Although, these enzymes have not been detected so far in bacteria
or fungi, but the genes for lipoxygenase and hydroperoxides lyase have been
expressed in yeast cells and green note flavour by fungal fermentation has been
obtained from linolenic acid added in the medium (Gallo et al. 2001).
7.3.2.8 Musk Aroma
Lactones with a musk aroma are found in some plants such as ambrette seed oil,
galbanum, whereas the keto musk aroma is produced by musk deer and civet cats.
Being obtained from animals, these are very expensive and unethical. Mutants of
Torulopsis bombicola were developed which were able to convert palmitic acid into
ω-hydroxypalmitic acid ester, which can then be cyclised into hexadecanolide
lactone musk.
Ambrox, an important ingredient of Ambergris, has a musk like fragrance. It is a
rare product which is produced in the digestive tract of the sperm whale (Physeter
macrocephalus) (Leffingwell and Leffingwell 2011). Chemical synthesis of this
musky compound is carried using a terpene, sclareol (Extracted from the Salvia
sclarea plant) as starting material, which is first converted to sclareolide and then
into Ambrox
® . The fungus Hyphozyma roseoniger and the yeast Cryptococcus
sp. can use sclareol as a sole carbon source and can accumulate sclareolide, which
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T. Malik and S. Rawat
1988). The excrement of herbivorous animals has been used for the production of
plant polyphenol using the subcritical water. This unusual discovery has been
awarded Nobel Prize. Vanillin, protocatechuic acid, vanillic acid and syringic acid
were produced by the method, which was used as the intermediate materials of the
medicines and vanilla flavourings (Yamamoto et al. 2008).
Vanillin can also be produced by phenolic biotransformation by Aspergillus
luchuensis (a fermentation starter fungus). During the production of ‘awamori’
(a fermented beverage), vanillin was also produced. It involves a two-step process
catalysed by the enzymes, CoA ligases and feruloyl-CoA hydratase followed by a
two-carbon elimination of ferulic acid which produces vanillin and acetyl-CoA. The
production mechanism can be explained as the side chain cleavage of ferulic acid
through Coenzyme A (CoA) and feruloyl-CoA hydratase/lyase, to form vanillin and
acetyl-CoA (Taira et al. 2018).
Furanones comprise the aromatic chemicals present in many fruits such as
pineapple, strawberries, mangoes, raspberries. 2,5-dimethyl-4-hydroxy-3(2H)furanone (DMHF) marketed as Furaneol
® imparts strawberry flavour in dilute
solutions and caramel-like flavour in concentrated form (Vandamme 2003). Soy
sauce yeast Zygosaccharomyces rouxii can also produce DMHF in the medium
supplied with D- fructose-1,6-biphosphate (FBP) and glucose. Since FBP is readily
available, microbial process is a cheaper alternative (Dahlen et al. 2001).
7.3.2.7 Grassy Aroma
The ‘grassy’ aroma found in damaged green tissue (e.g. cut grass) and in aromas of
many fruits and vegetables is formed via the degradation of plant polyunsaturated
fatty acids (PUFA) such as linolenic acid which are acted upon by lipoxygenases and
hydroperoxides. Although, these enzymes have not been detected so far in bacteria
or fungi, but the genes for lipoxygenase and hydroperoxides lyase have been
expressed in yeast cells and green note flavour by fungal fermentation has been
obtained from linolenic acid added in the medium (Gallo et al. 2001).
7.3.2.8 Musk Aroma
Lactones with a musk aroma are found in some plants such as ambrette seed oil,
galbanum, whereas the keto musk aroma is produced by musk deer and civet cats.
Being obtained from animals, these are very expensive and unethical. Mutants of
Torulopsis bombicola were developed which were able to convert palmitic acid into
ω-hydroxypalmitic acid ester, which can then be cyclised into hexadecanolide
lactone musk.
Ambrox, an important ingredient of Ambergris, has a musk like fragrance. It is a
rare product which is produced in the digestive tract of the sperm whale (Physeter
macrocephalus) (Leffingwell and Leffingwell 2011). Chemical synthesis of this
musky compound is carried using a terpene, sclareol (Extracted from the Salvia
sclarea plant) as starting material, which is first converted to sclareolide and then
into Ambrox
® . The fungus Hyphozyma roseoniger and the yeast Cryptococcus
sp. can use sclareol as a sole carbon source and can accumulate sclareolide, which
146
T. Malik and S. Rawat