2. OBJECTIVES
Theory of canning
Factors to consider during canning
Equipment for canning
Effect of canning on the quality of food
3. THEORY OF CANNING
Canning is a food preservation method that involves
sealing of food in jars or cans and then heating them to
destroy microorganisms that cause spoilage.
This process helps to extend the shelf life of perishable
foods, making them safe for long term storage.
The theory behind canning is based on the theory of
principles of heat processing and creating a vacuum seal
to prevent the growth of bacteria, yeasts and molds
4. Process of canning
The first step of canning is preparing the food by
washing, peeling and cutting into appropriate
sizes.
The food is then placed in sterilized jars or cans
along with any necessary additives such as salt,
sugar or vinegar.
The jars are sealed with lids and then heated to a
specific temperature for a set amount of time
This heat treatment destroys harmful
microorganisms while also creating a vacuum seal
that prevents recontamination.
5. Methods of canning
There are two main methods of canning
i. Boiling water bath canning
ii. Pressure canning
6. Boiling water bath canning
Boiling water bath canning is suitable for high acid
foods like fruits, pickles and jams.
The process involves filling sterilized jars with
prepared food, sealing them with lids and rings and
then submerging the jars in a pot of boiling water (at
180°C)for about 10 minutes.
The heat from the boiling water kills any bacteria
present in the food and creates a vacuum seal as the
jars cools down.
7. Pressure canning
Pressure canning is necessary for low acid foods
such as vegetables, meats and poultry.
This involves placing prepared food into jars
sealing them with lids and bands, and then
processing them using a pressure canner at a
specific pressure level for about 20-100 minutes
depending on type of food and size of jars.
The high temperature achieved during pressure
canning kills bacteria such as Clostridium
botulinum, which can cause botulism if consumed.
8. Factors to consider during canning
PH
Food safety
Processing time and temperature
Altitude
Container/jar size
Quality of ingredients
Storage conditions
Equipment and maintenance
9. 1.PH
Low acid foods (pH > 4.6) such as vegetables,
meats require pressure canning to reach the high
temperatures necessary for sterilization.
high acid foods (pH < 4.6) like fruits can be safely
processed using water bath canner.
2.Food safety
Ensuring safety of canned foods is paramount.it is
essential to follow proper canning techniques,
including using clean equipment, fresh ingredients
and processing foods at the correct temperature
and pressure to prevent the growth of harmful
bacteria.
10. 3.ALTITUDE
Altitude can affect the boiling point of water, which in turn affect
processing time required for safe canning. Adjustments may be
needed to processing time when canning at high altitude to ensure
that foods are properly sterilized.
4.PROCESSING TIME AND TEMPERATURE
Different types of foods require specific times and temperature to
ensure proper preservation. It is important to follow tested recipe
and processing time to ensure that harmful bacterias are destroyed.
5.CONTAINER/JAR SIZE
Larger jars require more time to heat the entire contents to the
necessary temperature for safe preservation.
11. 6.QUALITY OF INGREDIENTS
Use fresh, high quality produce and follow proper
preparation techniques to maintain flavour and
texture of foods
7.STORAGE CONDITION
Once canned, it is important to store jars in a cool,
dark place with stable temperature to maintain the
quality and safety of the preserved food over time.
8.EQUIPMENT MAINTAINANCE
Regularly inspecting jars,lids,seals and canner for
damage and wear to ensure the function correctly
during canning process
12. Equipments for canning
Canning jars
Canning lids and bands
Canner
Canning rack
Jar lifter
Canning funnel
Jar wrench
Pressure canner or boiling water bath canner
13. Canning jars
Glass jars specifically designed for canning are
essential for storing preserved foods. Mason jars
are a popular choice due to their durability and
seal tight lids.
14. Canning lids and bands
Lids with sealing compounds and bands are used
to create and air tight seal on the jar during the
canning process.
It is important to use the new lids for each canning
session to ensure proper sealing.
15. canner
water bath canner are large pots with a rack to
hold jars and are used to hold high acidic foods.
Pressure canners are used for low acidic foods
and have a locking lid and pressure gauge for
precise control of pressure and temperature.
Canning Rack
It’s a rack rest inside the canner to keep jars off the
bottom during processing,ensuring even
distribution and preventing jars from cracking
16. Jar lifter and jar wrench
Canning funnel
Jar lifter is a tool with gripping tongs for lifting hot
jars in and out of the canner.
A jar wrench is a tool used for tightening bands
securely on jars before processing and for
removing them after cooling
A wide mouthed funnel designed to fit into canning
jars,making it easier to fill jars with hot liquids and
reduce spill.
18. Pressure canner or boiling water bath canner
A water bath canner is suitable for high acid foods
like fruits, pickles, and jams, while a pressure
canner is necessary for low acids foods like
vegetables, meats, and poultry.
These canner create necessary heat to kill bacteria
and create vacuum seal
19. Effects of canning on the quality of food
POSITIVE EFFECTS
Extended shelf life: canned food can be stored for long
periods without refrigeration, extending shelf life of
perishable foods.
Nutrient rentation: preserve nutrient content of foods by
minimizing exposure to air and light which can degrade
vitamins and minerals
Convenience: minimal preparation before comsuption
Food safety: canned foods are safe to consume as heat
processing kills harmful bacteria and microorganisms
that cause foodborne illness
20. Effects of canning on the quality of food
NEGATIVE EFFECTS
Loss of nutrients: the high heat used in the canning process
can lead to loss of water soluble vitamins such as vitamin C
and B
Formation of harmful compounds: the high temperatures
used during canning can lead to formation of compounds
such as acrylamide and heterocyclic amines which are
known carcinogens.
Loss of Texture and flavour:canning can cause softening of
texture especially in fruits and vegetables. Heat may change
flavor hence removing the freshness of the canned foods.
21. conclusion
Canning is a reliable method for preserving a variety of foods
ranging from fruits and vegetables to meats and soups
The process involves careful preparation, sealing, and cooling
to ensure safety, quality of foods using proper equipment's
methods.
Canning allows for enjoyment of seasonal produce, reduce
food waste, provide fresh foods and provide sense of
satisfaction in creating homemade preserve.
