prefer the consumption of products which are being flavoured by the artificial
chemicals. The flavours with greener image are now becoming a preferential choice.
The increasing demand for natural flavours has led to a significant shortage of
several plant materials. Essential oils and isolated aroma compounds are currently
available at prices of more than 5000 US$/kg. Moreover, the production processes of
chemically synthesized compounds are not eco-friendly and produce undesirable
by-products resulting into environmental pollution. The production cost of these
synthetic ingredients is also high (Willaert et al. 2005; Poornima and Preetha 2017).
Further, nowadays, many researchers and industries have switched to biocatalytic
flavour synthesis due to consumer’s inclination towards natural flavours (Longo and
Sanromán 2006). Due to disadvantages of both nature-identical and artificial flavour
compound and more interest in natural products, newer strategies are being explored
for the production of natural flavours.
The biotechnological methods are better alternative methods for the flavour
production. These methods are sustainable and eco-friendly unlike the global
warming and pollution issues associated with chemical industries. White biotechnology can also be used for the production in flavour and fragrance industry. The
biotechnological approach for production of aroma compounds includes (1) Enzymatic methods, (2) Microbial methods-de novo synthesis and biotransformation,
(3) Plant tissue culture methods.
7.3
Biotechnological Methods for Production of Flavours
7.3.1 Enzymatic Methods
A significant amount of enzymes are able to directly produce flavour molecules by
hydrolysis of larger precursors with higher productivity than direct extraction from
plants (Ben Akacha and Gargouri 2015). The enzyme catalysed reactions involve the
use of lipases, proteases, glucosidases, hydroxylases, etc. Chang et al. (2001)
reported the use of lipases from Staphylococcus epidermidis in the synthesis of
various flavour esters in aqueous media. Lipase produced by Mucor miehei has been
found to be highly selective towards flavour active short-chain fatty acids. Butanoic,
hexanoic, octanoic and decanoic acid are produced which can be used as flavouring
agents as they have cream-like/butter-like flavour (Chen and Yang 1992).
Mesifurane [2,5-dimethyl-4-methoxy-3(2H)-furanone], an important flavour compound in arctic bramble, strawberry and pineapple, is produced by Candida
antarctica (Nozaki et al. 2000). Proteases were used for obtaining the flavour
concentrates in the processing of crayfish as the concentration of benzaldehyde
and pyrazines were increased (Baek and Cadwallader 1996). Advances in technology have also led to the use of immobilized enzymes in flavour production. de
Temiño et al. (2005) used immobilized alcohol dehydrogenase from Lactobacillus
kefir to synthesize (R)-phenylethanol from acetophenone in an organic solvent
(hexane). The enzyme and its cofactor were entrapped in polyvinyl alcohol gel
beads so as to enhance their stability in organic solvents, which enabled both
7 Biotechnological Interventions for Production of Flavour and Fragrance. . .
135
chemicals. The flavours with greener image are now becoming a preferential choice.
The increasing demand for natural flavours has led to a significant shortage of
several plant materials. Essential oils and isolated aroma compounds are currently
available at prices of more than 5000 US$/kg. Moreover, the production processes of
chemically synthesized compounds are not eco-friendly and produce undesirable
by-products resulting into environmental pollution. The production cost of these
synthetic ingredients is also high (Willaert et al. 2005; Poornima and Preetha 2017).
Further, nowadays, many researchers and industries have switched to biocatalytic
flavour synthesis due to consumer’s inclination towards natural flavours (Longo and
Sanromán 2006). Due to disadvantages of both nature-identical and artificial flavour
compound and more interest in natural products, newer strategies are being explored
for the production of natural flavours.
The biotechnological methods are better alternative methods for the flavour
production. These methods are sustainable and eco-friendly unlike the global
warming and pollution issues associated with chemical industries. White biotechnology can also be used for the production in flavour and fragrance industry. The
biotechnological approach for production of aroma compounds includes (1) Enzymatic methods, (2) Microbial methods-de novo synthesis and biotransformation,
(3) Plant tissue culture methods.
7.3
Biotechnological Methods for Production of Flavours
7.3.1 Enzymatic Methods
A significant amount of enzymes are able to directly produce flavour molecules by
hydrolysis of larger precursors with higher productivity than direct extraction from
plants (Ben Akacha and Gargouri 2015). The enzyme catalysed reactions involve the
use of lipases, proteases, glucosidases, hydroxylases, etc. Chang et al. (2001)
reported the use of lipases from Staphylococcus epidermidis in the synthesis of
various flavour esters in aqueous media. Lipase produced by Mucor miehei has been
found to be highly selective towards flavour active short-chain fatty acids. Butanoic,
hexanoic, octanoic and decanoic acid are produced which can be used as flavouring
agents as they have cream-like/butter-like flavour (Chen and Yang 1992).
Mesifurane [2,5-dimethyl-4-methoxy-3(2H)-furanone], an important flavour compound in arctic bramble, strawberry and pineapple, is produced by Candida
antarctica (Nozaki et al. 2000). Proteases were used for obtaining the flavour
concentrates in the processing of crayfish as the concentration of benzaldehyde
and pyrazines were increased (Baek and Cadwallader 1996). Advances in technology have also led to the use of immobilized enzymes in flavour production. de
Temiño et al. (2005) used immobilized alcohol dehydrogenase from Lactobacillus
kefir to synthesize (R)-phenylethanol from acetophenone in an organic solvent
(hexane). The enzyme and its cofactor were entrapped in polyvinyl alcohol gel
beads so as to enhance their stability in organic solvents, which enabled both
7 Biotechnological Interventions for Production of Flavour and Fragrance. . .
135