Helpful Hints For Pressure Canning - Presto 01781 Instructions And Recipes Manual

HelPful HinTs foR
PRessuRe CanninG
 Bubbles often appear in the jar after it is removed from canner
because food is still boiling in jar. Ordinarily bubbles do not appear
once the product has been allowed to thoroughly cool.
 Jar breakage during processing is caused by: (1) Packing jar too
solidly or overfilling; (2) Weakened, cracked jars; (3) Jars touch-
ing bottom of canner; (4) Lids improperly tightened; (5) Use of
jars other than Mason jars.
 Liquid lost from jars during processing is caused by: (1) Packing
jar too solidly or overfilling; (2) Insufficient exhaust period;
(3) Variation or sudden lowering of temperature in the canner.
When processing food, pressure regulator should not be taken off
the vent pipe and cover should not be removed until air vent/cover
lock has dropped and pressure has been completely reduced;
(4) Failure to adjust jar lids according to manufacturer's
directions.
 The loss of liquid from jars during processing may be unattractive
but it will not affect the safety of the food as long as the jar was
processed correctly and is sealed.
 It is better to overprocess food than underprocess. Underprocess-
ing may result in spoilage and unsafe food.
 Food spoilage or jars not sealing is caused by: (1) Failure to fol-
low exact timetables and recipes; (2) Failure to wipe sealing edge
of jar clean before placing lid on jar; (3) Foods, seeds, or grease
lodged between lid and jar; (4) Jars which are nicked or cracked
or have sharp sealing edges; (5) Failure to adjust jar lids according
to manufacturer's directions; (6) Turning jars upside down while
jars are cooling and sealing.
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 Flat sour, a type of food spoilage, is caused by canning overripe
food or allowing precooked foods to stand in jar too long before
processing. It may be prevented by using fresh products and
properly processing, cooling, and storing. Flat sour shows no
indication of spoilage until jar is opened.
 Mold can form only in the presence of air. Therefore, jars are not
sealed if mold is present.
 The black deposit sometimes found on the underside of a lid is
caused by tannins in the food or hydrogen sulfide which is liberated
from the food by the heat of processing. This does not indicate
spoilage.
 If a jar does not seal, use the food at once, freeze or repack using
different lids. Reprocess for the full recommended processing
time.
 Two-piece vacuum caps seal by the cooling of the contents of the
jar, not through pressure of the screw band on the lid. Therefore,
although the screw band is firmly tight, the jar is not sealed until
cooled. During processing, the flexible metal lid permits air to be
exhausted from the jar.
 Adjust two-piece vacuum caps by screwing bands down evenly
and firmly until a point of resistance is met–fingertip tight. Do
not use undue exertion.
 It is not necessary for the liquid on canned meats to congeal. The
liquid will congeal only when there is a large amount of gelatin
from cartilage or connective tissue present.
 The loss of color from beets, during canning, is usually due to
the variety of beets used or beets that are too old. If possible, can
young, tender, very dark beets which are freshly gathered. Precook
beets with 2 inches of the stem and all of the root on, as this helps
to retain the juices.
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