Many of the problems withapplesauce are caused by air. Although an apple is firm and solid, it actually contains air. In fact, twenty-five percent of an apple’s volume is air. Think of bobbing for apples at a Halloween party; it is the air that causes the apples to float. Unless the air is driven from the apple during the preparation of the sauce, there is oxygen present.

Enzymes in apples cause oxidation (browning) when cut surfaces are exposed to air. Many people report that the top of the jar ofapplesauce gradually turns brown. What is happening is that the sauce has not been heated enough to stop all enzymatic reactions and there is enough oxygen in the headspace to react with the enzymes. When air bubbles are not removed throughout the sauce after it is poured into the jar, the same problem will occur. A suggestion to reduce the enzymatic reaction is the addition of ascorbic acid. The applesauce recipe in the Ball Complete Book of Home Preserving® includes a tablespoon of lemon juice for each quart of sauce to preserve the apples’ color and to increase acidity. The addition of ground spices such as cinnamon or nutmeg adds natural color that may mask some of the oxidation.

Putting the cooked apples through a sieve, food processor, or blender incorporates additional air into the product. After making the apples into a puree, be sure to bring the mixture to a boil and maintain a gentle boil while filling the jars.

Cooking drives air out of the apple.  Air left in the apple will expand during processing causing the contents in the jar to overflow. This is called siphoning. When the sauce overflows, you not only lose good product, but you also increase the risk of a jar not sealing. You can reduce the chance of siphoning by using a plastic knife or bubble freer to remove air bubbles from the jar before applying the lid.  Leave adequate headspace (½ inch) to accommodate expansion during processing. It is common forapplesauce to siphon from the jars when they are removed from the canner. The thinner the applesauce, the less siphoning there seems to be. Try to maintain a constant rolling, but gentle, boil while processing; large fluctuations during processing forces product out of the jar. Another technique that helps to reduce siphoning is, after the processing time is complete, to set the canner off the heat and remove the canner lid. Wait 5 minutes before removing jars; this equalizes the temperature in the jar.

There are many potential sources of molds and spoilage organisms in applesauce.  The fresh apple likely contains some which is a reason for thoroughly washing the fruit and peeling it before cooking. It is also a reason for practicing good kitchen procedures (clean hands, clean utensils and counters). Molds are common in the air and can settle on the product after it is put into the jar and before the lid is applied.

Processing pints for 15 minutes and quarts for 20 minutes in a boiling water bath destroys microorganisms that may have gotten into the headspace during canning. Never open kettle canapplesauce—that means never just put the hot applesauce in the jar, apply the lid, and let it set until the lid goes down. Processing also gives a much stronger vacuum seal than open kettle canning. If there are signs of mold or other spoilage, discard the product.