Natural flavourings from biotechnology for foods and beverages - Natural Food Additives, Ingredients and Flavourings - page 231

11.2 Production of natural fl avors by de novo synthesis
As mentioned before, de novo synthesis comprises the production of complex
substances from simple molecules through complex metabolic pathways (Bicas
et al. 2009). Chemically quite different volatile fl avors, such as short-chain
alcohols, esters, aldehydes, ketones, methylketones and acids as well as pyrazines
and lactones can potentially be produced concurrently (Krings and Berger 1998).
The main groups of biofl avor compounds obtained by means of de novo synthesis
are discussed below. Some examples of processes to obtain aroma compounds are
detailed in Table 11.1.

11.2.1 Esters
Ethyl acetate is a fruity smelling liquid with a brandy note and is the most common
ester in fruits (Bauer et al. 2001). This ester, for example, has a signifi cant effect
on the organoleptic characteristics of distillates. It can be produced by different
microorganisms, including:
•

Staphylococcus (Talon et al. 1998)

•

Saccharomyces cerevisiae (Valero et al. 2002; Brown and Hammond 2003;
Kobayashi et al. 2008; Carrau et al. 2010; Sumby et al. 2010)

•

Geotrichum fragans (Damasceno et al. 2003)

• Kluyveromyces marxianus (Medeiros et al. 2000, 2001; Dragone et al. 2009)

•

Ceratocystis fi mbriata (Soares et al. 2000)

•

Ceratocysis moniliformis (Bluemke and Schrader 2001)

•

Neurospora sp. (Brigido 2000)

•

Hanseniaspora guilliermondii 11104 (Rojas et al. 2003)

• Pichia anomala (Rojas et al. 2003).

Butyl acetate has a strong, fruity odor and a burning, then sweet taste reminiscent
of pineapple. It occurs in many fruits and is a constituent of apple (Bauer et al.
2001). Its bioproduction was reported by Medeiros and co-workers (2000) using
Kluyveromyces marxianus in cassava bagasse.
Another important compound is isoamyl acetate. This compound has a fruity,
banana, sweet, fragrant, powerful odor with a bittersweet taste reminiscent of pear
with an aroma threshold of 2-43 parts per billion (ppb). Its uses comprise alcoholic
beverages, gelatins, puddings, baked goods, hard candy, chewing gum, non-
alcoholic beverages, confectionary, frosting, soft candy, frozen dairy and sweet
sauce in a range of 19-112 parts per million (ppm). It occurs naturally in some
fruits like apple, apricot, banana, grape, berries, melon, papaya, peach, pear and
pineapple, and products such as vinegar, wheat and rye bread, cheeses, butter,
alcoholic and non-alcoholic beverages (Burdock and Fenaroli 2010).
Biotechnological production was reported using Saccharomyces cerevisiae
(Brown and Hammond 2003; Kłosowski and Czuprynyski 2006; Kobayashi et al.
2008), Staphylococcus (Talon et al. 1998), Ceratocystis fi mbriata (Soares et al.
2000) and Ceratocysis moniliformis (Bluemke and Schrader 2001).

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