While it seems like everything can be canned and stored, there are some foods that are less safe to can. Food between 2.0 and 6.9 pH levels are usually ok to can at home. Anything over 6.9, like black olives, becomes difficult to can because they have to be specially cured before the storage process begins.

Food That Can’t

Besides the pH issues there are some other foods that make canning difficult. For instance, food consistency plays into the canning process. Foods such as pumpkin and squash purees are not the best things to can.  These thick liquids make it difficult to heat through, creating cold spots in the middle, which allow bacteria to grow and become prevalent in your canning process.

Other items, which shouldn’t be canned, for much the same reason, are refried beans, butter and leafy greens, like spinach and chard also make it difficult to can due to the cold spots in the middle of the food. Creams and soups also have a difficulty with canning because, you guessed it, and they become scorched and curdled on the outside while trying to raise the temperature in the middle.

Food That Can

On the flip side, if you have pumpkin and squash that you would like to can, putting them in a jar in raw chunk form will allow them the proper canning temperature in a pressure canner. It also begins to moisten them up for later use. Other than that, just about everything falls into the category of able to be canned. Foods such as lemons, plums, figs, apples and some tomatoes can be home canned with ease.

Here is a brief list of foods and their respective pH levels, which are good for canning:

• pH 2.0-3.0 – Lemons, limes, gooseberries and under-ripe plums
• pH 3.0-3.5 – Ripe plums, under-ripe apples, ripe oranges and
  grapefruit, strawberries, rhubarb, blackberries, cherries,
  raspberries, blueberries, very under-ripe peaches and apricots
• pH 3.5-4.0 – Ripe apples, oranges, grapefruit, overripe
  blackberries, cherries, raspberries, and peaches, ripe apricots,
  under-ripe pears, pineapple, sauerkraut and other pickled items
• pH 4.0-4.6 (BORDERLINE) –Tomatoes and figs Above 4.6 or so, must
  be pressure canned.
• 4.6-5.0 – Some tomatoes, depending on the variety (Green
  tomatoes are below 4.6). Pimentos, pumpkin. The USDA suggests that
  pumpkin butter cannot be canned safely.
• 5.0-6.0 – Carrots, beets, squash, beans, spinach, cabbage,
  turnips, peppers, sweet potatoes, asparagus, mushrooms, white potatoes
• 6.0-7.0 – Peas, tuna, lima beans, corn, meats, cow’s milk, salmon, oysters, shrimp

Please make note of the borderline items, which must be pressure canned. Remember the pumpkin butter, along with many other purees and thick substances, which the USDA does not consider safe for canning. The USDA site is always a fail-safe place to check when determining which foods can be properly canned and which ones are not recommended. Go gather up everything you can think of and start preserving for your own household stash.

Canning today, is easier than it’s ever been. In the old days it could take a whole week to can one section of vegetables from your garden. Today, a whole garden can be completed in a day or two. While industrial canning can take place in a matter of minutes now, there are still some standard precautionary measures to take while canning at home. Here are some things to remember when canning this year:

High Acid vs. Low Acid

It is important to know the acidity of the foods you are trying to can. Some foods have a high acidity, while others are extremely low. Knowing the acid level of your food gives you the knowledge of how to make sure they are safely canned. High acid foods can be safely canned in a boiling water canner, while the low acid foods can only be canned safely in a pressure cooker.

Low acid foods, strangely enough with a pH higher than 4.6, cannot stave off the harmful bacteria at low temperatures, like those found in a boiling water canner. These low acid foods are things like vegetables, proteins, sauces and soups. These must be canned in a pressure canner that reaches at least 240 degrees Fahrenheit.

High acid foods, with a pH lower than 4.6, can safely be canned in a boiling water bath because their natural acidity helps to kill and prevent the bacteria that can form. The lower temperature is enough, combined with the natural acidity of the food, to be safely preserved. These types of foods include fruit, jams, jellies, relishes and acidified tomatoes.

Follow Instructions

It is important to follow the instructions on the recipe exactly. Any deviation in technique could lead to spoiled foods or food that doesn’t taste right because too much salt or acid was used. Things to remember are times in the pressure canner or boiling water bath, how much acid to add to the can and the right amounts of spices to be added. You don’t want to to go the work of making all these jars of food, only to not be able to eat them because their flavor is gross.

Use Proper Materials

Make sure the jar is properly cleaned, the flat has not been used and the band is not rusted or warped in any way. It is important to use proper techniques when canning, otherwise the seal may not hold or certain bacteria may be incorporated into the food. Using the right types of canner for the job is also important. For example, having a pressure canner, which does not hold a proper seal, may make it difficult to get a proper seal on the can or can keep the food from reaching the proper temperature for it to preserve correctly.

Follow the rules in order to properly preserve your favorite foods. Know your food, follow the recipe and instructions and use the right materials to make sure your canning will work out for the best. Keeping it simple is the easiest way to make your canning go as quickly as possible because it helps reduce the amount of mistakes being made that can spoil your food.