ALICYCLOBACILLUS SPP.

ALICYCLOBACILLUS SPP.
Alicyclobacillus is a genus of Gram-positive, rod-shaped, spore-forming, bacteria.
The bacteria are able to grow in acidic conditions, while the spores are able to survive typical
pasteurization procedures. Alicyclobacillus are strictly aerobic, acidophilic, thermophilic,
soil-dwelling organisms, and have been shown to grow at temperatures between 42–60 °C at a
pH of 3.5 – 4.5 (growth range pH 2.2 – 5.8). Their spores survive for long periods in fruit
concentrates and similar environments.
Spoilage of shelf-stable fruit juice products
by Alicyclobacillus bacteria can be very costly.
Indeed, the
fruit
juice
industry
has
acknowledged Alicyclobacillus spp. as a major
quality control target microorganism. However,
these bacteria are not considered a safety
hazard.
Guaiacol and halophenols were identified as the
offensive smelling agent in many Alicyclobacillus
spp. related spoilage. These off-flavors are mainly
described as “Smoky bacon”, “Hammy” or even
“Antiseptic”. Both raw material producers and
finished product packagers need to be aware of this
organism and understand how to control it.
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The spores, often present in fruit concentrates, are
heat resistant and can survive routine pasteurization
techniques (92 °C for 10 seconds). It is therefore
important that concentrates and other raw materials
are screened for spores of these taint producers to
reduce the risk of spoilage of processed products. The
risk of Alicyclobacillus contamination will vary
according to product type and the process used in
their production.
IFU-Method on the Detection of Alicyclobacillus in
Fruit Juices (2003) describes three methods of
detection, depending on the sample composition and
the time passed since processing:
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1. Raw materials (including processed water): A
heat shock treatment is required followed by direct
plating (optional), filtration or enrichment in a
liquid medium of the heated material.
Aliclyclobacillus acidoterrestris
ATCC 27009
ALICYCLOBACILLUS AGAR - Cat. 2002
2. End products: sampled directly after (heat)
processing where an additional heat shock is
unnecessary: Pre-incubation of the sample in a
liquid medium is required.
3. End products taken from the market:
Pre-incubation of the sample and heat shock
treatment are optional. However, if spoilage
is suspected and no Alicyclobacillus are
detected after direct plating, a heat shock and
enrichment is recommended.
In all methodology, incubation for 3-5 days at 45 ±
1ºC is recommended.
Given the need to check for the identification of
these important target bacteria, CONDA S.A. offers
ALICYCLOBACILLUS DETECTION AGAR (Cat. 2002)
and BAT BROTH (Cat. 2053). The Alicyclobacillus
Agar and BAT Broth support the growth of
Alicyclobacillus. The low pH-value in combination
with the high incubation temperature inhibit the
growth of contaminating flora. It is important to
note that the medium has a spontaneous pH of 5.3
± 0.2. Adjustment of the pH to 4.0 ± 0.2 is made after
the autoclaving.
These media do not contain any inhibitors. Its
formulation is characterized by the presence of
many trace elements which supply all of the specific
requirements for these bacteria. However, what
renders the media selective are the pH,
temperature and time of incubation. If these
parameters are not well controlled more flora may
grow in the medium and results may be confusing.
ALICYCLOBACILLUS AGAR and BAT BROTH
support the growth of most Alicyclobacillus
spp. This medium is recommended by the IFU.
Alternative recommended IFU Methods, used in
the past or for broader investigations, are:
POTATO DEXTROSE AGAR (Cat.1022)
ORANGE SERUM AGAR (Cat.1307)
BIBLIOGRAPHY
BAUMGART, J. and MENJE, S.: The Impact of Alicyclobacillus
acidoterrestris on the Quality of Juices and Soft Drinks. Fruit
Processing 7; 251- 254 (2000)
BAUMGART, J. (2003) Media for detection and enumeration of
Alicyclobacillus acidoterrestris and Alicyclobacillus
acidocaldarius in foods. In Handbook of Culture Media for Food
Microbiology. J.E.L. Corry et al. (Eds.) Elsevier Sci
B.V. Amsterdam
IFU Working Group Microbiology: First Standard IFU-Method on the
Detection of Alicyclobacillus in Fruit Juices. (April 2003)
A. acidoterrestris can be differentiated from
A.acidocaldarius by incubating cultures at 30, 45
and 65ºC. A. acidoterrestris does not grow at 65ºC
and A. acidocaldarius does not grow at 30ºC.
www.condalab.com
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.
Jensen Nancy, Evaluation of detection methods for Alicyclobacilli in fuit
juice concentrates in Australia. Food Science, Australia
Akira Yokota, Tateo Fujii, Keiichi Goto, Alicyclobacillus: Thermophilic
Acidophilic Bacilli. Springer (2008)
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28850 - Torrejón de Ardoz, Madrid - Spain
Phone. +34 91 761 02 00
Fax +34 91 656 82 28