Type of autoclave and its definition

 

Autoclave Definition

An autoclave is a machine that provides a physical method of sterilization by killing bacteria, viruses, and even spores present in the material put inside of the vessel using steam under pressure. Autoclave sterilizes the materials by heating them up to a particular temperature for a specific period of time. The autoclave is also called a steam sterilizer that is commonly used in healthcare facilities and industries for various purposes. The autoclave is considered a more effective method of sterilization as it is based on moist heat sterilization.
The autoclaving process takes advantage of the phenomenon that the boiling point of water (or steam) increases when it is under high pressure. It is performed in a machine known as the Autoclave where high pressure is applied with a recommended temperature of 250°F (121°C) for 15-20 minutes to sterilize the equipment.

Autoclave classes

1. Class N autoclave

Class N autoclave is the lowest class device. According to European standard EN 13060, since 2004 it can be used only as an auxiliary unit. Sterilizer of this class does not have a vacuum pump (which is present in higher class autoclaves), so only instruments with a solid structure can be sterilized within such device. It is also not possible to sterilize hollow or porous cartridges or sterilize items in packages. Class N sterilizers also do not have an effective drying option, unlike more advanced autoclaves.

2. Class S autoclave

Class S autoclave is an intermediate class between N and B. Within such device we can sterilize more complex instruments, B type batches, except for instruments of capillary construction (A type batches). Class S allows the sterilization of single-packed, multilayer packed and more massive instruments, which cannot be sterilized in class N autoclaves. Autoclaves of this class have a vacuum pump, which makes it possible to completely remove the air from the chamber before starting the sterilization process. However, only a single-stage pre-vacuum is used here; it is less effective than the vacuum used in class B autoclaves.

3. Class B autoclave

Class B autoclaves are the most advanced steam sterilizers. These are certified MEDICAL DEVICES USED IN BEAUTY PARLOURS, tattoo studios, private dental parlours, even in hospitals and large clinics. They also meet all the sanitary-epidemiological requirements. They can sterilize all types of batches, even the most complex ones. Class B autoclave, thanks to fractionated pre-vacuum, completely removes air from the chamber. It is the most effective modern technique of  sterilization of all types of tools.

Positive pressure displacement type (B-type)

• In this type of autoclave, the steam is generated in a separate steam generator which is then passed into the autoclave.
• 
  
• This autoclave is faster as the steam can be generated within seconds.

Negative pressure displacement type (S-type)

• This is another type of autoclave that contains both the steam generator as well as a vacuum generator.
• Here, the vacuum generator pulls out all the air from inside the autoclave while the steam generator creates steam.
• The steam is then passed into the autoclave.
• This is the most recommended type of autoclave as it is very accurate and achieves a high sterility assurance level.
• This is also the most expensive type of autoclave.

• Gravity displacement type autoclave

  • This is the common type of autoclave used in laboratories.
  • In this type of autoclave, the steam is created inside the chamber via the heating unit, which then moves around the chamber for sterilization.
  • This type of autoclave is comparatively cheaper than other types.

  Positive pressure displacement type (B-type)

  • In this type of autoclave, the steam is generated in a separate steam generator which is then passed into the autoclave.
  • This autoclave is faster as the steam can be generated within seconds.
  • This type of autoclave is an improvement over the gravity displacement type.

Fresh Meats and Poultry Microbiology

Fresh Meats and Poultry Microbiology

Fresh Meats and Poultry Microbiology

It is generally agreed that the internal tissues
of healthy slaughter animals are free of bacteria
at the time of slaughter, assuming that the animals are not in a state of exhaustion. When one
examines fresh meat and poultry at the retail
level, varying numbers and types of microorganisms are found. The following are the primary
sources and routes of microorganisms to fresh
meats with particular emphasis on red meats

• The stick knife. After being stunned and
hoisted up by the hind legs, animals such as
steers are exsanguinated by slitting the jugular vein with what is referred to as a "stick
knife." If the knife is not sterile, organisms
are swept into the bloodstream, where they
may be deposited throughout the carcass.
• Animal hide. Organisms from the hide are
among those that enter the carcass via the
stick knife. Others from the hide may be
deposited onto the dehaired carcass or onto
freshly cut surfaces

• Gastrointestinal tract. By way of punctures,
intestinal contents along with the usual
heavy load of microorganisms may be deposited onto the surface of freshly dressed
carcasses. Especially important in this regard is the paunch or rumen of ruminant

THE BIOTA OF MEATS AND
POULTRY
The major genera of bacteria, yeasts, and
molds that are found in these products before
spoilage are listed inTables 4-1 and 4-2. In general, the biota is reflective of the slaughtering
and processing environments as noted above,
with gram-negative bacteria being predominant.
Among gram positives, the enterococci are the
biota most often found along with lactobacilli.
Because of their ubiquity in meat-processing
environments, a rather large number of mold
genera may be expected, including Penicillium,
Mucor, and Cladosporium. The most ubiquitous
yeasts found in meats and poultry are members of the genera Candida and Rhodotorula

Genus	Gram Reaction	Fresh Meats	Fresh Livers
Acinetobacter	XX
Aeromonas	XX
Alcaligenes
Arcobacter
Bacillus

Genera of Fungi Most Often Found
on Meats and Poultry
Fresh and

Refrigerated

Genus	Meats	Poultry
Molds
Alternaria	X	X
Aspergillus	X	X
Aureobasidium	X
Cladosporium	XX	X
Eurotium	X
Fusarium	X
Geotrichum	XX	X
Monascus	X
Monilia	X
Mucor	XX	X
Neurospora	X
Penicillium	X	X
Rhizopus	XX	X
Sporotrichum	XX
Thamnidium

INCIDENCE/PREVALENCE OF
MICROORGANISMS IN FRESH
RED MEATS

The incidence and prevalence of microorganisms in some red meats are presented in
The aerobic plate counts (APCs) of
the fresh ground beef in this table are considerably

trending-down of bacteria in fresh ground beef
or of laboratory methodology is unclear. For
many decades, comminuted meats have been
shown to contain higher numbers of microorganisms than noncomminuted meats such as steaks,
and there are several reasons for this:

• Commercial ground meats consisting of
trimmings from various cuts that are handled
excessively generally contain high levels of
microbial contamination. Ground meats that
are produced from large cuts tend to have
lower microbial numbers.

• Ground meat provides a greater surface area,
which itself accounts in part for the increased flora. It should be recalled that as
particle size is reduced, the total surface area
increases with a consequent increase in surface energy.

• This greater surface area of ground meat
favors the growth of aerobic bacteria, the
usual low-temperature spoilage flora.

• In some commercial establishments, the
meat grinders, cutting knives, and storage
utensils are rarely cleaned as often and as
thoroughly as is necessary to prevent the
successive buildup of microbial numbers.
This may be illustrated by data obtained
from a study of the bacteriology of several
areas in the meat department of a large grocery store. The blade of the meat saw and
the cutting block were swabbed immediately
after they were cleaned on three different
occasions with the following mean results:
the saw blade had a total log10 per square
inch count of 5.28, with 2.3 coliforms, 3.64
enterococci, 1.60 staphylococci, and 3.69
micrococci; the cutting block had a mean
log per square inch count of 5.69, with 2.04
coliforms, 3.77 enterococci, <1.00 staphylococci, and 3.79 micrococci. These are
among the sources of the high total bacterial count to comminuted meats.

• One heavily contaminated piece of meat is
sufficient to contaminate others, as well as
the entire lot, as they pass through the
grinder. This heavily contaminated portion

 

Mechanically Deboned Meat, Poultry,
and Fish

When meat animals are slaughtered for human consumption, meat from the carcasses is
removed by meat cutters. However, the most economical way to salvage the small bits and pieces
of lean meat left on carcass bones is by mechanical means (mechanical deboning). Mechanically
deboned meat (MDM) is removed from bones
by machines. The production of MDM began in
the 1970s, preceded by chicken meat in the late
1950s and fish in the late 1940s.3336 During the
deboning process, small quantities of bone powder become part of the finished product, and the
1978 U.S. Department of Agriculture (USDA)
regulation limits the amount of bone (based on
calcium content) to no more than 0.75% (the
calcium content of meat is 0.01%). MDM must
contain a minimum of 14% protein and no more
than 30% fat. The most significant parametrical
difference between MDM and conventionally
processed meat relative to microbial growth is
the higher pH of the former, typically 6.0-7.0.3334
The increased pH is due to the incorporation of
marrow in MDM.
Although most studies on the microbiology
of MDM have shown these products to be not
unlike those produced by conventional methods,
some have found higher counts. The microbiological quality of deboned poultry was compared
to other raw poultry products, and although the
counts were comparable, MPN coliform counts
of the commercial MDM products ranged from
460 to >l,100/g. Six of 54 samples contained
salmonellae, four contained C. perfringens, but
none contained S. aureus.