QUALITY
CONTROL OF PACKED FOOD AND CANNED FOOD
AIM: To
analyze the food as per the quality control procedure for detection of their
contamination level
INTRODUCTION:
Spoilage
of heat-processed, commercially canned foods is confined almost entirely to the
action of bacteria that produce heat-resistant endospores. Canning of foods
normally involves heat exposure for long periods of time at temperatures that
are adequate to kill spores of most bacteria. Particular concern is given to
the processing of low-acid foods in which Clostridium
botulinum can thrive to produce botulism food poisoning. Spoilage occurs
when the heat processing fails to meet accepted standards. This can occur for
several reasons: (1) lack of knowledge on the part of the processor (usually
the case in home canning); (2) carelessness in handling the raw materials
before canning, resulting in an unacceptably high level of contamination that
ordinary heat processing may be inadequate to control; (3) equipment
malfunction that results in undetected under processing; and (4) defective
containers that permit the entrance of organisms after the heat process.
In
this experiment you will have an opportunity to become familiar with some of
the morphological and physiological characteristics of organisms that cause
canned food spoilage, including both aerobic and anaerobic endospore formers of
Bacillus and Clostridium, as well as a non-spore-forming bacterium.
MATERIALS REQUIRED:
Samples
of canned food, hammer solder and soldering iron plastic bags gummed labels and
rubber bands, can opener, punch type, small plastic beakers, Parafilm,
gram-staining kit, spore-staining kit
PROCEDURES:
1.
Label the sample container and In addition, place a similar label on one of the
plastic bags to be used after sealing of the cans.
2.
With an ice pick or awl, punch a small hole through a flat area in the top of
each can. This can be done easily with the heel of your hand or a hammer, if
available.
3. Pour or take 1 ml or 1 g of a small amount
of the liquid or solid food sample from the can.
4. Use an inoculating needle to inoculate each
can sample in to the saline.
5.
Serial dilutes the sample from 10-3 up to 10-8 and transfer
the diluted sample in the appropriate nutrient agar plate.
6.
Tranfer 1 ml of serially diluted sample in to the nutrient agar plate which
should be labeled their corresponding dilution.
7.
Incubate the inoculated nutrient agar plates in the room temperature such as 37o
C for 24 hrs.
8.
The same procedure can be repeated for detection of fungal load in the canned
food. SDA Media can be used instead of nutrient agar and incubation can be
extended up to 3 – 5 days to get fungal mycelia.
9.
Record your observations on the report sheet on the demonstration table.
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