Once you have
prepared your ingredients, filled the clean jars with your high acid preserve, and
then added the lids/seals, jars will require processing in a water bath canner
prior to pantry storage, as per the recipe. Processing refers to submerging
jars in water and boiling for a specific length of time. There are different
times for jar sizes, different times for types of preserves, and adjustments
for altitude if required.
Jar size options
for water bath canning recipes are:
o
Less than or equal to 500ml – i.e. pint/16oz jars
– these require shorter processing time than larger jars because they heat up quicker
(less volume of food in each jar);
o
500ml to 1 litre – i.e. quart/32oz jars – these
require a longer processing time than smaller jars because they need more time to heat up (they have a higher volume of food in each jar).
Note: some recipes list
just the maximum jar size i.e. up to 1 litre/quart (or less) for the processing
time in the recipe chart.
Water bath canning
recipes are either “cold packed” – which is also known as raw-packed (i.e. raw,
prepared fruit or vegetables) - or hot-packed (i.e. jam or chutney). How food
is prepared (and the density) determines the minimum processing time required.
o
Raw packed food requires longer processing time
than hot packed food as the food takes longer to come to the temperature
required to destroy microorganisms, and also requires cooking prior to pantry
storage;
o
Hot-packed food requires a shorter processing
time than raw packed food because the food has already been heated/cooked to a
high temperature and just requires the pasteurisation stage via a water bath
canner prior to pantry storage. Example of a processing chart below:
|
Processing Time
for BOTTLED PEACHES (HALVED
OR SLICED) in
a Boiling Water
Canner
|
|||||
|
|
Jar Size
|
Altitude
≤ 1,000 feet
|
Altitude 1,001
- 3,000 feet
|
Altitude 3,001
- 6,000
feet
|
Altitude
≥ 6,000 feet
|
|
Hot
Pack
|
≤ 500ml
(pints)
|
20 minutes
|
25 minutes
|
30 minutes
|
35 minutes
|
|
≤ 1 Litre (quarts)
|
25 minutes
|
30 minutes
|
35 minutes
|
40 minutes
|
|
|
Raw Pack
|
≤ 500ml
(pints)
|
25 minutes
|
30 minutes
|
35 minutes
|
40 minutes
|
|
≤ 1 Litre (quarts)
|
30 minutes
|
35 minutes
|
40 minutes
|
45 minutes
|
|
Water also boils at
different temperatures – the higher the altitude, the lower the temperature
required for water to boil. Therefore, a longer processing time is required
when altitude increases.
To ensure high acid food is
preserved in a water bath canner accurately, the processing time and cooling down
period (i.e. 12-24 hours at room temperature) must be followed, as per the recipe.
Choosing the correct processing time and allowing jars to naturally cool down
at room temperature is the best way to destroy microorganisms such as mould and
yeast that could otherwise spoil your preserves.
Author: Megan Radaich
Image Credit: Megan Radaich
Publication: www.foodpreserving.org