Agriculture Reference
In-Depth Information
was reported that
Acetobacter
strains are able to synthesize methylbutyric acid.
Besides its industrial relevance as a fl avor, this acid can be a valuable precursor of
common fl avor esters (Vandamme and Soetart 2002).
11.2.4
Other compounds
Terpenes
Terpenes are the most abundant group in nature responsible for the characteristic
odors of essential oils and are a preferable substrate for bioconversion studies
(Janssens
et al.
1992). In studies involving
de novo
synthesis, terpenes are present
only in a few works.
Drawert and Barton (1978) related the use by
Kluyveromyces lactis
in the
production of citronellol, linalool and geraniol. Bluemke and Schrader (2001)
reported a production of citronellol and geraniol by
Ceratocystis moniliformis
in
a fi ve-liter bioreactor.
Sulfur compounds
Methional is important for the typical taste of cheeses, especially cheddar
(Spinnler
et al.
2002). Another example is methylthioacetate, which has been used
in baked goods, imitation dairy, chewing gum, meat products, condiments,
relishes, non-alcoholic beverages, frozen dairy, snack foods, soft candy, hard
candy and soups (Burdock and Fenaroli 2010) and lager beer at a concentration
between 4 and 31 ppb (Spinnler
et al.
2002). Strains of
Hanseniaspora uvarum,
Hanseniaspora guilliermondii
and
Saccharomyces cerevisiae
are capable of
producing sulfur compounds such as methional and 2-methyltetrahydrothiophen-
3-one, 2-mercaptoethanol,
cis
-2-methyltetrahydro-thiophen-3-ol,
trans
-2-
methyltetrahydro-thiophen-3-ol and 3-mercapto-1-propanol (Moreira
et al.
2005,
2008). Other volatile thiols, in particular 4-mercapto-4-methylpentan-2-one,
3-mercaptohexan-1-ol and 3-mercaptohexyl acetate, are some of the most potent
aroma compounds of wine. At optimal concentrations in wine, these compounds
impart fl avors of passionfruit, grapefruit, gooseberry, blackcurrant, lychee and
guava (Swiegers
et al.
2007).
Pyrazines
Tetramethylpyrazine has a musty, fermented, coffee odor and is present in several
cheeses (Swiss, camembert, gruyère), roasted peanuts, soy products, beans,
mushroom, cocoa and coffee products. This compound has an aroma threshold
varying from 1 to 10 ppm and is of great industrial importance in beverages,
baked goods, meat products and frozen dairy products (Burdock and Fenaroli
2010). A few microorganisms are also able to produce this pyrazine, e.g.
Bacillus
subtilis
grown on a sucrose asparagine medium (Kosuge and Kamiya 1962). The
same compound was also evidenced during the fermentation of cocoa beans
by the action of microorganisms (Reineccius
et al.
1972). One strain of
Corynebacterium glutamicum
was able to produce 3 g L
−1
of tetramethypyrazine
Search WWH ::
Custom Search