I N G R E D I E N T S
A team of Italian investigators
has found that commercial
starter culture produces sausages
with higher acidity and inferior
taste, compared with those made
through spontaneous fermentation,
which is primed by bacteria endemic
to the sausage. University of Turin
professor of food microbiology and
report author Luca Cocolin says fermentation
is usually started by good
microbiota, but it is hard to control
spontaneous fermentation because
of uncertainty of what those bacteria
will do. “More rigorous controls
have to be implemented in order to
guarantee the product’s safety, and
all of this is why the use of starter
cultures makes fermentation much
easier,” he says. The study’s purpose
is to gain a better knowledge of the
microorganisms, metabolic pathways
and biochemical reactions in each
30 APRIL 2018
process — knowledge that might be
used to mitigate their shortcomings
and improve the sensory qualities
of the final product — taste, smell
and mouth feel, for example. Using
next-generation sequencing techniques,
the investigators identified
the relevant microbes and mapped
the metabolic pathways, Cocolin
says. Additionally, they used another
methodology that couples gas chromatography
with mass spectrometry
(GC-MS) to determine and quantify
the metabolites produced during
fermentation. “Next-generation
sequencing makes it possible to determine
which microbes are present
in complex ecosystems and what
they are doing,” Cocolin says. For
example, the investigators found an
increase in the density of lactic acid
bacteria and Staphylococcaceae in
the inoculated meat samples, compared
to the meat that fermented
spontaneously. In the latter, Lactobacillus
sakei and Lactobacillus
curvatus were the most abundant
microbes. The KEGG analysis (Kyoto
Encyclopedia of Genes & Genomes)
that the investigators performed
mapped 1,774 genes within 21
metabolic pathways. “The over-activity
of the starter culture-inoculated
sausages resulted in increased acetic
acid and short-chain fatty acids,” Cocolin
says. These compounds added
notes that he described as “pungent,
vinegar, cheesy and weedy,” and
resulted in a final product that was
less than salutary. Conversely, “the
greater presence of medium- and
long-chain fatty esters enhanced the
sensory profile of these sausages”
by imparting a scent incorporating
notes of fruity wine, waxy sweet
apricot and banana brandy. “My
laboratory has been involved in meat
fermentation since the 1990s, and
considering the importance of the
fermented sausage in Italy at gastronomic,
traditional and economic
levels, we wanted to investigate better
the role of spontaneous biota and
inoculated starters in the fermentation
process. A deeper knowledge
of the fermentation process allows
food producers to control better the
microbiota, generating final products
with high quality and safety,” he
says. “By modulating the activity of
the microorganisms, it will be possible
to produce fermented products
with different sensory profiles, which
will enable production of a larger
diversity of products.”
The research was published in Applied
& Environmental Microbiology,
a journal of the American Society for
Microbiology.
LAMENTING
FERMENTING
Fermented sausages such as salami and chorizo
can vary in taste quality, depending on whether the
fermentation begins ‘spontaneously’ or by using a
commercial starter culture.
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