agent or substance capable of destroying bacteria.
substance that prevents the growth of bacteria but does not kill them.
amount of oxygen required to maintain aerobic conditions during decomposition
of factory wastes such as whey. The effect of excessive waste in streams
is that it uses up dissolved oxygen, thereby creating objectionable
conditions and making it impossible for aquatic life to survive.
major protein of milk.
(cleaned in place)
stainless steel pipelines are cleaned by circulating washing solutions
coliform group of bacteria comprises all aerobic and facultatively
anaerobic, gram-negative nonspore forming rods capable of fermenting
lactose with the production of acid and gas at 90°F (32°C) within
48 hours. While the general source of these organisms is commonly
accepted to be the intestinal tract of warm-blooded animals, it is
emphasized that bacteria of both fecal and non-fecal origin are members
of this group. Typically, these organisms are classified in the genera
Escherichia and Enterobacter (formerly Aerobacter); but, in addition,
a few lactose-fermenting species of other genera are included in the
group. In proportion to the numbers present, the existence of any
of these types in dairy products is suggestive of unsanitary conditions
or practices during production, processing or storage.
coliform bacteria count is used as an index of the level if sanitation
and/or water quality employed in the handling and processing of milk
products. Coliforms have significance in milk and milk products because
(1) they are easily killed during pasteurization and because (2) they
are generally regarded to originate from the intestinal tract of warm-blooded
animals. Hence, the presence of coliform bacteria in pasteurized milk
products is suggestive of unsanitary conditions or practices during
processing, packaging; maximum standards for number of coliforms have
until now been set at a maximum of 10 per milliliter of gram in pasteurized
milk and milk products; however, numbers in pasteurized dairy products
should be less than 1 ml., as is the case with up to 90% of samples,
if packaging procedures are correct. California standard allows no
more than 750 coliforms per mL in raw milk. Less than 100 is considered
complex organic substance that will accelerate (catalyze) specific
chemical transformation. For example, lipase, fat splitting, and protease,
protein splitting enzymes are always found in milk, and are sometimes
involved in milk spoilage.
Coli (E. Coli)
serological groups of Escherichia coli are known to produce severe
diarrhea in infants and young children. Both animals and man are carriers
of Enteropathogenic E. coli, the organisms having been recovered from
the milk of healthy animals as well as those with mastitis.
that survive specific heat treatments (i.e., vat or high temperature
short time (HTST) pasteurization) are usually said to be thermoduric
(heat tolerant). A practical laboratory test involves heat treatment
of representative raw bulk milk samples at 145°F (63°) for 30 minutes
(equivalent of vat pasteurization minimum conditions). The Standard
Plate Count method is used to enumerate the surviving microorganisms.
In raw milk, less than 100/ml is desirable; more than 750/mL is illegal
under California regulations.
Temperature Time 145°F (63°C) (Batch) 30 minutes 161°F (72°C) (HTST)
15 minutes 191°F (89°C) (HHST) 1.0 second 194°F (90°C) (HHST) 0.5
second 201°F (94°C) (HHST) 0.1 second 204°F (96°C) (HHST) 0.05 second
212°F (100°C) (HHST) 0.01 second 280°F (138°C) (Ultra-pasteurized)
Incubation Count - this is a method of counting the bacteria in milk
that grow at low temperatures and are not usually counted by the Standard
Plate Count method. Incubation of the raw milk sample is at 55°F (13°C)
for 18 hours (or other time/temperature combination) prior to plating.
Good P.I. counts should be similar to raw milk SPS's, that is less
than 20,000/ml. Not all dairy researchers believe this count "adds"
to understanding troublesome counts in raw milk.
pre million. It equals milligrams per kilogram or microliter per liter.
tolerant. It refers to microorganisms that grow at low temperatures,
below 45°F (7°C), but have an optimum temperature of 59°F to 70°F
(15°C to 21°C). These organisms especially affect the shelf life of
refrigerated dairy products, such as cottage cheese.
term used to indicate the desirability and/or acceptability of an
animal or food product.
kill or remove injurious microorganisms but not necessarily to sterilize.
Dairy equipment is commonly sanitized with hot water or chemicals.
time after processing during which a product remains suitable for
human consumption, especially the time a food remains palatable and
acceptable to consumers.
Plate Count (SPC)
SPC has long been the primary test for determining the bacterial density
(quality) of fresh raw or pasteurized grade A milk. The SPC estimates
the total numbers of aerobic type microorganisms. In conducting this
procedure, careful consideration must be given to nutrients of plating
medium, the temperature and time of incubation, and proper dilution
of the sample to avoiding overcrowding of colonies on plates. Samples
must be representative, collected with contamination, and stored under
conditions that will not allow bacterial growth or destruction (below
40° but above 32°F) (below 4 °C above 0°C), and tested within 36 hours
remove or kill all living organisms.