Microbiological Aspects of Dairy Ingredients 91germination and outgrowth of spores. Rapid
growth of these organisms could occur in
reconstituted milks stored at ambient tem-
peratures. Investigations into the Croatian
outbreak revealed that both Bacillus strains
were able to enter the log phase of growth
within two hours of storage of the reconsti-
tuted milk at room temperature. Therefore
the application of Hazard Analysis and
Critical Control Point (HACCP) principles,
particularly in relation to reconstitution and
consumption of such products, is recom-
mended. Various levels of B. cereus contami-
nation in dried whole milk and non - fat dry
milk have been reported: United States,
62.5% (Rodriguez and Barrett, 1986 );
Germany, 13% to 43% (Becker et al., 1994 );
Germany, 10.1% (Hammer et al., 2001 ); UK,
17% (Rowan et al., 1997 ); Brazil, 28% (Costa
et al., 2004 ).
Infant botulism results from the ingestion
of spores of Cl. botulinum , which germinate,
colonize the intestine, and produce neuro-
toxin in vivo. This intoxication is rare;
however, an epidemiological investigation of
one such case in the UK has advocated a
possible link to infant formula milk powder
(Brett et al., 2005 ). Clostridium botulinum
type B was isolated from an opened container
of infant formula from the patient ’ s home and
an unopened container of the same batch
obtained prior to distribution and retail sale.Ice Cream
Ice cream can be chemically defi ned as ice
crystals and solidifi ed fat globules embedded
in a continuous unfrozen liquid phase com-
prised of proteins, carbohydrates, salts, and
gums. It must contain at least 5% fat and
2.5% milk protein and, in the case of dairy
ice cream, the fat component must be exclu-
sively milk fat. One of the main microbio-
logical factors is that ice cream usually
contains eggs and ice cream therefore carries
the attendant food poisoning risks associated
with eggs (e.g., Salmonella spp.). Therefore,Asia (Mi - Kyoung and Jong - Hyun, 2006 ) and
25% in the Middle East (Shaker et al., 2007 ).
Antibiotic - resistant isolates of Cron. saka-
sakii have been detected in dried milk and
related products from Egypt (El - Sharoud et
al., 2009 ). These strains could be transmitted
from skim milk powder to its related product,
imitation recombined cheese, and survive
within this product (El - Sharoud et al., 2008 ).
Iversen and Forsythe (2003) have indicated
that where Cron. sakasakii has been linked to
outbreaks, the infection levels have been
attained through gross temperature abuse or
poor hygiene in the manufacturing process or
during preparation of the formula. The prin-
cipal control measures relevant to Cron.
sakasakii in infant formula milk powder
are control of initial levels in raw milk,
reduction of levels during heat treatment of
raw milk, prevention of an increase in levels
by avoiding post - processing contamination,
and provision of appropriate information and
preparation instructions to users.
Powdered milk - based infant formulas are
heat - treated during preparation but are not
commercially sterile. Some reports have sug-
gested relatively high thermal resistance, with
this organism surviving pasteurization, while
other studies doubt this phenomenon (see
Gurtler et al., 2005 for review). The organism
appears to have a high tolerance for dessica-
tion and can form biofi lms, which may help
protect it from commercial disinfectants.
Some concerns have been raised about the
presence of B. cereus , other Bacillus spp.,
and Cl. botulinum in dried milk products,
especially infant formula. Spores can survive
in powders for at least 6 months and Kramer
and Gilbert (1989) have cited outbreaks of
Bacillus - related foodborne illness associ-
ated with milk powder and infant formula.
Furthermore, toxin - producing B. subtilis and
B. lichenformis strains caused an outbreak of
foodborne intoxication in a school nursery in
Croatia in 2000 (Pavic et al., 2005 ).
A public health concern has arisen because
pasteurization and spray drying can induce