Jams & Jellies

Causes and Possible Solutions for Problems with Jellied Fruit Products


Problem Cause Prevention
Formation of crystals 1. Excess sugar. 1. Use a tested recipe and measure ingredients precisely
  2. Undissolved sugar sticking to sides of saucepot. 2. Dissolve all sugar as jelly cooks. If necessary, wipe side of pan free of crystals with damp cloth before filling jars.
  3. Tartrate crystals in grape juice. 3. Extract grape juice and allow tartrate crystals to settle out by refrigerating the juice overnight. Strain juice before making jelly.
  4. Mixture cooked too slowly or too long. 4. Cook at a rapid boil. Remove from heat immediately when jellying point is reached. Make small batches at a time; do not double tested recipes.
Bubbles 1. Air became trapped in hot jelly. 1. Remove foam from jelly or jam before filling jars. Ladle or pour jelly quickly into jar. Do not allow jelly or jam to start gelling before jars are filled.
  2. May denote spoilage. If bubbles are moving, do not use. 2. Follow recommended methods for applying lids and processing. (See Mold or Fermentation, below.)
Problem Cause Prevention
Too soft 1. Overcooking fruit to extract juice. 1. Avoid overcooking as this lowers the jellying capacity of pectin.
  2. Using too much water to extract the juice. 2. Use only the amount of water suggested in the instructions.
  3. Incorrect proportions of sugar and juice. 3. Follow recommended proportions.
  4. Undercooking causing insufficient concentration of sugar. 4. Cook rapidly to jellying point.
  5. Insufficient acid. 5. Lemon juice is sometimes added if the fruit is acid deficient.
  6. Making too large a batch at one time. 6. Use only 4 to 6 cups of juice in each batch of jelly.
  7. Moving product too soon. 7. Do not move jellied products for at least 12 hours after they are made.
  8. Insufficient time before using. 8. Some fruits take up to 2 weeks to set up completely; plum jelly and jellies or jams made from bottled juices may take the longer time.
Syneresis or "weeping" 1. Excess acid in juice makes pectin unstable. 1. Maintain proper acidity of juice.
  2. Storage place too warm or storage temperature fluctuated. 2. Store processed jars in a cool, dark, and dry place. Refrigerate after opening.
Darker than normal color 1. Overcooking sugar and juice. 1. Avoid long boiling. Best to make small quantity of jelly and cook rapidly.
  2. Stored too long or at too high of temperature. 2. Store processed jars in a cool, dry, dark place and use within one year. Refrigerate after opening.
Cloudiness 1. Green fruit (starch). 1. Use firm, ripe fruit, or slightly underripe.
  2. Imperfect straining of homemade juice. 2. Do not squeeze juice but let it drip through jelly bag.
  3. Jelly or jam allowed to stand before it was poured into jars or poured too slowly. 3. Pour into jars immediately upon reaching gelling point. Work quickly.
Problem Cause Prevention
Mold or Fermentation (Denotes spoilage; do not use.) 1. Yeasts and mold grow on jelly. 1. Process in a boiling water canner. Test seal before storing. Pre-sterilize jars when processed less than 10 minutes in boiling water.
  2. Imperfect sealing. (Common also with paraffin-covered jellies.) 2. Use new flat lids for each jar and make sure there are no flaws. Pretreat the lids per manufacturer’s directions. Use ring bands in good condition – no rust, no dents, no bends. Wipe sealing surface of jar clean after filling, before applying lid.
  3. Improper storage. 3. Store processed jars in a dark, dry, cool place. Refrigerate after opening.
Too stiff or tough 1. Overcooking. 1. Cook jelly mixture to a temperature 8°F higher than the boiling point of water or until it "sheets" from a spoon.
  2. Too much pectin in fruit. 2. Use ripe fruit. Decrease amount if using commercial pectin.
  3. Too little sugar which requires excessive cooking. 3. When pectin is not added, try ¾ cup sugar to 1 cup juice for most fruits.


Problem Cause Prevention
Not a characteristic fruit flavor 1. Overcooked or scorched. 1. Should be stirred frequently when mixture begins to thicken to prevent sticking. Cook only to jellying point.
  2. Poor quality fruit used. 2. Select only sound, good flavored fruit of optimum maturity.
Shriveled product 1. Syrup is too heavy. 1. Follow instructions for the type of fruit being preserved.
Tough product 1. Starting the cooking of fruit in syrup that is too heavy (too much sugar). 1. Cook each fruit according to directions; by evaporation the syrup concentration will gradually increase.
  2. Not plumping fruit properly. 2. Fruit should plump at least 24 hours covered in syrup before canned.
  3. Overcooking. 3. Cook according to directions.
Sticky, gummy product 1. Overcooking. 1. Follow recommended directions for each product. (Cook only until syrup is quite thick and fruit is fairly translucent.)
Darker than normal color 1. Cooking too large of quantities at one time. 1. It is usually best to cook not more than 2 to 4 pounds of prepared fruit at a time.
  2. Cooked too slowly. 2. A better color is usually produced if the product is cooked rapidly.
  3. Overcooked. 3. Cook only until syrup is quite thick and the fruit is fairly translucent.
Loss of color 1. Improper storage. 1. Store processed jars in a dark, dry, cool place.
Mold or Fermentation (Denotes spoilage; do not use.) 1. Imperfect sealing. 1. Use new flat lids for each jar and make sure there are no flaws. Pretreat the lids per manufacturer’s directions. Use ring bands in good condition – no rust, no dents, no bends. Wipe sealing surface of jar clean after filling, before applying lid.
  2. Yeast or mold growth. 2. Process in a boiling water canner. Test seal before storing. Pre-sterilize jars when processed less than 10 minutes in boiling water.
  3. Improper storage. 3. Store processed jars in a dark, dry, cool place. Refrigerate after opening.

For problems with jar seals, and other general canned food problems, see Causes and Possible Solutions for Problems with Canned Foods.


This document was adapted from "So Easy to Preserve", 6th ed. 2014. Bulletin 989, Cooperative Extension Service, The University of Georgia, Athens. Revised by Elizabeth L. Andress. Ph.D. and Judy A. Harrison, Ph.D., Extension Foods Specialists.

Recent Content

Can Splenda® (sucralose) be used in preserving food?

Granular Splenda® does not provide preservative properties like sugar. 

Canning Fruits:  Whereas we do not have published research work with using sucralose in the canning of fruits at home available to us, it is possible to use it for sweetening the water used to cover fruits when canning.  The texture and color preserving aspects of a sugar syrup will not be provided.  The result would be like canning in water except for the additional sweetness contributed by the Splenda®.  The USDA fruit canning directions do allow for canning in water (i.e., without a sugar syrup), as there is adequate preservation for safety from the heat of proper canning.  Some people do notice an aftertaste in other products and canned fruits, and it is possible some little changes in natural flavors may occur over storage time, since sugar can mask some of these.  For people used to sucralose sweetening and flavors, the aftertaste may not be an issue.  Based on some of our experiences in canning peaches and pickled foods, we suggest you start seeing what you like by trying less than a full substitution for the sugar in canning syrups.  For example, if you use a medium sugar syrup that is 5-/14 cups water to 2-1/4 cups sugar, try 1 to 1-1/4 cups Splenda® the first time.  You can always sweeten more when you serve the finished product if it is not quite sweet enough; then you can increase the canning liquid amount the next time you can.

Preserves and Pickled Fruits: In other cases, where sugar is important, like some preserves or pickled fruits, it is not recommended that substitution of Splenda® be used for sugar if the product is to be canned for shelf stability.  Splenda® cannot be used in several traditional Southern preserves we have on this website or in the University of Georgia Extension publications.  These are whole or uniform pieces of fruit in a very thick sugar syrup, usually made with figs, peaches or pears.  (These preserves are not jam or pectin gel products.)  Sugar is required for the preservation of these syrupy fruit preserves as published, with very short boiling water canner processes.  Without that heavy amount of sugar, these products become fruit pieces canned in water or lighter sugar syrups, and the usual (and longer) fruit canning process times and preparation directions would need to be used.

Jams and Jellies, or Fruit Spreads: You could use Splenda® as the optional sweetener in a jam or jelly made with a no-sugar needed pectin, such as Mrs. Wages™ Lite Home Jell® Fruit Pectin, Ball® No-Sugar Needed Pectin or Sure-Jell® for Less or No-Sugar-Needed Recipes.  With these low-methoxyl pectins, no sugar is required at all.  Sugar substitutes can be added as desired simply for flavor. The package inserts with these pectins give instructions on when to add the sugar substitutes (usually after all the cooking, right before filling the jars).  Do not try to substitute Splenda® for the required sugar in recipes calling for “regular” liquid and powdered pectins.  

And do not try to substitute Splenda® in long-boil or no-pectin-added jams and jellies intended for room temperature storage as a canned product.  You might get some thickened fruit spreads with just fruit and Splenda®, but they may not have enough water control for processing like a gelled, high sugar-containing jam or jelly.  They might require longer processing to avoid spoilage at room temperature.  If you want to experiment with making these kind of fruit spreads we recommend freezing or refrigeration for storage. 

We have developed three recipes using Splenda® and they are on our website, www.homefoodpreservation.com. They are quick pickled sweet cucumber slices, pickled beets and pickled cantaloupe.  They are under the How do I....Pickle category, as well as National Center factsheets, http://www.uga.edu/nchfp/publications/nchfp/factsheets.html.

There is also a Peach-Pineapple Reduced Sugar Fruit Spread from the USDA Complete Guide to Home Canning that does not require added sugar.  Some other fruit substitutions are provided in the text.  The suggested sugar for sweetening can be left out, or you can add some Splenda® as desired for sweetness.  The process time is longer than regular jams and jellies, and is like that for a fruit puree. http://www.uga.edu/nchfp/how/can_07/peach_pineapple_spread.html

How can I become a Master Food Preserver?

“Master” volunteer programs that are connected to the Cooperative Extension System, such as Master Food Preservers and Master Gardeners, are currently state- or county-managed programs affiliated with the land grant universities and the Cooperative Extension Service in the state. In exchange for extensive education, the master volunteer returns contributions to the local Extension office, such as answering phone calls, developing and hosting exhibits, judging at competitions, etc. There are liabilities involved in someone conducting even volunteer work in the name of a state university; therefore, the guidelines and management procedures will vary among states. At this time, the National Center is not in a position to help individuals meet state guidelines for credentials and the title of Master Food Preserver.

If you would like to find out if your state offers this opportunity to become a Master Food Preserver, contact your local Extension Office (usually listed in local government pages of the phone book under Cooperative Extension Service, Ag Extension Office and/or 4-H Office). You could also contact someone at the state university to either ask your questions or let them know of your interest. These contacts can be found on a website managed by USDA:

Most states do not sell their Master Food Preserver curricula or notebooks to the general public. If someone wants information on preserving, they have other publications available with the actual recommendations and procedures. This website from the National Center is full of “How To” information for various types of food preservation. We will eventually have tutorials and a correspondence type course on line for self-study.

Is it necessary to thaw meat or fish before cooking?

No, meat and fish can be cooked from the frozen state if extra cooking time is allowed. The amount of time will depend on the size and shape of the cut. Large frozen roasts can take as much as 11/2 times as long to cook as unfrozen cuts of the same weight and shape. Small roasts and thin cuts such as steaks and chops require less time.

Can meat and poultry be thawed in the conventional oven?

No, meat and poultry should never be thawed in the conventional oven or at room temperature. There is greater danger of bacterial growth and food spoilage for food thawed at room temperature. Thaw meat and poultry in the refrigerator in the original wrappings. To speed thawing, loosen the wrapping. To keep other foods safe, put the thawing meat and poultry in a pan on the bottom shelf. For a quicker method, immerse meat or poultry in a watertight bag into cold water. Thaw until it is pliable. Meat and poultry can also be thawed quickly and safely in the microwave oven, followed by immediate cooking, either in the microwave oven or by some other method. Because microwave ovens vary, check your manufacturer's instructions for information on how to safely thaw in your microwave oven. Frozen meat and poultry can also be cooked without thawing.

What is blanching?

Heating or scalding the vegetables in boiling water or steam for a short period of time.

Is it recommended to blanch vegetables before freezing?

Yes. Blanching slows or stops the action of enzymes which cause loss of flavor, color and texture. Blanching cleanses the surface of dirt and organisms, brightens the color and helps retard loss of vitamins. Blanching also wilts or softens vegetables and makes them easier to pack.

Is it safe to freeze fruits without sugar?

Yes; sugar is not used as a preservative but only to maintain flavor, color and texture.

Can artificial sweeteners be used in place of sugar for freezing fruits?

Sugar substitutes can be used in place of sugar. Labels on the products give the equivalents to a standard amount of sugar. Follow the directions to determine the amount of sweetener needed. Artificial sweeteners give a sweet flavor but do not furnish beneficial effects of sugar, like thickness of syrup and color protection.


The University of Georgia Cooperative Extension has now published a 6th edition of its popular book, So Easy To Preserve. The book was reviewed and updated in 2020. Chapters in the 388-page book include Preserving Food, Canning, Pickled Products, Sweet Spreads and Syrups, Freezing and Drying.