Problems in Vegetable Canning

As the objective of canning to prevent the food from being spoiled before and during containment, as well  the canned product should in good quality distributed to the costumers. But there are sometimes found a litle products in the market not in good conditions and it usually caused by some problems when it was in the canning process. These very small amounts products generally produced and distributed by producers that not apply high standard in quality control.

There are quite a number of methods are used to prevent some problems when processing and preserving vegetables by canning.  And there are some recommendations you have read before in the previous article.  And the typical problems that could exist in vegetable canning are listed below.

Table 3. Problems in Vegetable Canning

Condition	Causes	Prevention
Food darkens in top of jar.	Liquid did not cover food. Food not processed long enough to destroy enzymes.  High vacuum not produced during processing.  Air was sealed in the jars either because headspace was too large or air bubbles were not removed	Cover food with liquid before capping Process each food by recommended method and for correct time. Pack and process as recommended. Use specified amount of headspace. Remove air bubbles with a non-metal spatula.
Black pots on underside of metal lid, may denote spoilage.	Natural compounds in some foods cause a black or brown deposit on the underside of the lid. This deposit does not mean the food is unsafe to eat. If jar has been sealed and then comes open, spoilage is evident. Do not use.	None. Use recommended processing methods and times; wipe jar rim before capping.
Cloudy liquid, may denote spoilage.	Spoilage (do not use). Minerals in hard water. Starch in vegetables. Fillers in table salt.	Process each food by recommended method and fo recommended time. Use soft water. None. Use a pure, refined canning salt.
Loss of liquid during processing. (Food may darken but will not spoil. Do not open jars to replace liquid.)	Food not heated before packing. Jars packed too tightly or too full. Air bubbles not removed before capping the jar Pressure canner not operating correctly. Pressure lowered suddenly. Starchy foods absorb liquid.	Heat food before packing Pack food more loosely. Leave recommended headspace. Remove air bubbles by running non-metal spatula between food and jar Pressure should not fluctuate during canning process. Keep heat constant during processing time Allow pressure to drop to zero naturally; wait 2 minutes before opening lid. None.
Jar seals, then comes open. Spoilage evident. (Do not use.)	Underprocessed. Particles of food left on the sealing surface. Hairline crack in jar.	Process each food by recommended method and for specified time. Wipe rim and threads of jar with clean, damp cloth before capping. Check jars prior to packing; discard ones unsuitable for canning.
Jars of food fail to seal.	Failure to follow instructions for using jar and lid. Food may have been forced up between the jar and lid during processing. Sealing compound defective. Edge of lid or rim of jar bent or chipped. Food particles on jar rim. Screw band tightened after jar removed from canner.	Carefully follow instructions. Use recommended headspace, do not let pressure fluctuate, allow pressure to drop to zero naturally. Use new lids. Check lids and jars prior to use. Wipe jar edge before putting on lid.  Allow jars to cool undisturbed.
Jars break.	Hairline crack in jar. Rack not used in bottom of canner. Screw bands applied too tightly so air could not escape during processing.	Check jars prior to processing. Be careful when packing and processing jars. Use rack and recommended amount of water. Apply screw bands more loosely.
Corn is brown.	Corn was too mature for canning. Liquid did not cover corn. Jars were processed at too high a temperature. Variety of corn used.	Use freshly picked corn. Cover corn with liquid before capping  jars. Keep pressure in canner at recommended pounds; gauge may be faulty and should be checked. Use different variety next year.
Green vegetables lose their bright color.	Heat breaks down chlorophyll, the green pigment in plants. Vegetables were too mature for canning.	None. Select young, tender vegetables.
Yellow crystals on canned green vegetables.	Glucoside, a harmless substance, naturally present in vegetables.	None.
White crystals in canned spinach.	Calcium and oxalic acid in spinach combine to form harmless calcium oxalate.	None.
White sediment in bottom of jars of vegetables. May denote spoilage.	Starch from the food. Minerals in hard water. Bacterial spoilage-liquid is usually murky, food soft. Do not use.	None. Use soft water. Process each food by recommended method and for specified time.