Hi! I know that itís been a long time, but I have some interesting
news about certain types of bacteria that you probably have encountered
on your farms. I would like to take this opportunity to pass some helpful
information to you. In this bulletin, I will be discissing thermoduric,
thermophilic, and psychotropic bacteria, the effects on your milk production,
and the treatment.
Thermoduric bacteria can survive exposure to temperatures considerably
above their maximal temperature for growth. In the dairy industry, the
term is applied to those organisms which survive, but do not grow, at
pasteurization temperature. They usually include species of Micrococcus,
Streptococcus, Lactobacillus, Bacillus, and occasionally gram-negative
rods. The sources of contamination are poorly cleaned and sanitized utensils
and equipment on farm and processing plants. These bacteria contribute
to significantly higher Standard Plate Count on pasteurized milk (LPC
counts). The thermoduric count has been used in the daity industry primarily
as a test of care employed in utensil sanitation and as a means of detecting
sources of organisms responsible for high counts in the final product.
In the dairy industry, the term thermophilic bacteria applies particularly
to bacteria which grow in milk held at elevated temperatures (55 C or
higher), including pasteurization, 62.8 C. The species that grow in higher
temperatures include Bacillus species which enter milk from various sources
in the farm, or from poorly cleaned equipment in the processing plant.
When the milk is held at high temperatures for long periods, these bacteria
rapidly increase in numbers and may cause flavors defects or problems
with respect to bacteria standards. Counts of thermophilic bacteria are
obtained by Standard Plate Count with plate incubation at 55 C. Numerous
large, rod-shaped bacteria stain strongly and are the thermophilic bacteria.
The microorganisms which play a significant role in biological processes
in low-temperature environments have usually been called psychrophilic,
meaning cold-loving. Psychotropic is used to refer to the bacteria that
are able to grow rapidly at 7 C and below. Species of Pseudomonas, Flavovacterium,
Alcaligenes, Acinetobacter, and Bacillus are often encountered among psychotropic
group. These group of are generally non-pathogens, but in dairy products
they can cause a variety of off-flavors, including fruity, stale, bitter,
putrid and rancid flavors. Psychotropic bacteria are rarely present in
the udder. The numbers of bacteria depend upon sanitary conditions prevailing
during production and upon time and temperature of milk storage before
processing. The influence of psychotropic bacteria in the shelf life of
pasteurized milk will depend mainly upon the number present after packaging,
the rate of growth, the storage period, and the biochemical activity of
The key concept for
avoiding these organisms is sanitation!!!!
By keeping the equipment
and processing plant properly sanitized, most of these organisms can be
avoided. If you have any questions regarding this newsletter or would
like more information on our tests for the thermoduric, thermophilic,
and psychotropic bacteria plese call us at (909)947-6065. Until next time.