Precautions When Canning Starchy Foods

Even people experienced with home canning sometimes steer clear of canning starchy vegetables because they can be more challenging and involve extra work in the canning process. But with a few precautions, many starchy foods can safely be canned, and the flavor of your home-canned summer corn will far surpass any store bought version!

With all canned vegetables, use ONLY the pressure canning method. Vegetables tend to be low in acidity, and need extra heat to prevent the growth of the botulism organism. Botulism is a serious food poisoning danger as it will make a person very sick, and can even be fatal on occasion!

The most commonly canned starchy vegetables are corn and varieties of beans such as lima beans. Find a recipe from a reputable source online (sites from universities and state extension services tend to be the most up to date and reliable) and prepare the foods according to directions. The foods can be raw packed (canned without cooking) or hot packed (boiled and canned while hot).

Here are some of the most common problems that can surface when canning starchy foods:

1. The food boils over during processing and prevents the jar from sealing properly–While many canned items require you to leave only 1/4” to 1/2” at the top of the jar, starchy foods tend to expand more. Most recipes recommend at least 1” of headspace in the jar.

2. When the canning process is completed, most or all of the liquid is gone from the jar–Starchy vegetables absorb more liquid than other vegetables do, and require more liquid in the jar to compensate for this. If the liquid level in the jar has lowered less than halfway, your items are still safe to store. However, the vegetables above the waterline may tend to darken over time. This is harmless but can affect the visual appeal and the taste of your vegetables. When labelling your jars from that batch, mark the labels on the lower liquid jars to remind yourself to use them first. If the liquid has been completely absorbed, store in the refrigerator and use within a few days for maximum safety.

3. The liquid in the jar has become cloudy over time — sediments can settle out of starchy foods over time, causing the liquid to become cloudy. This is harmless and the food can still be used. However, cloudy liquid can also signal spoilage. When using canned starchy vegetables that have become cloudy, carefully examine the jar contents when opened for visible signs of spoilage, or for any bad smells. If these are detected, discard the contents. If the food appears normal and smells okay, cook it for 10 minutes before tasting it. Again, if it tastes “off”, throw the contents away.

Many people believe that the ultimate starchy vegetable, potatoes, cannot be canned successfully. This is only partially true. If you choose the “waxier” potatoes such as fingerling or Yukon, you can have success in canning them. Avoid Russett and other “fluffy” potatoes as these will turn to mush when canned. Soups prepared with the waxy type of potatoes can therefore be canned safely. Barley in soups can also be canned successfully, however, avoid wheat or pasta for the same reasons as Russett potatoes–they tend to turn to unappetizing mush.

However, certain forms of starchy foods should never be canned. There are NO safe recipes for canning breads of any kind. Avoid making any “pie in a jar” recipe that calls for including the crust–this is only possible in commercially canned preparations.

Also avoid canning any pureed vegetables like corn, mashed potatoes, pumpkin or some squashes. The texture and thickness of the puree can prevent the contents from heating evenly during the canning process. Can only whole items (corn) or cut-up chunks (potatoes, pumpkins etc.)

So if you have had a bumper crop of lima beans this summer, or find a great deal on corn on the cob, take a deep breath, find a good recipe, and tackle canning those starchy vegetables!