We get a lot of questions about the magical art of jam making and associated culinary chemistry. Here are the answers to some frequently asked questions. If you have a burning question that’s not here, please email the Jam Queens!
Q: What’s the difference between jam, jelly, preserves, marmalade and conserves?
A: Jelly is fruit juice and sugar (no chunks), jam is made from crushed or ground fruit pulp, preserves are made from whole or chunks of fruit, marmalade is a citrus based jelly with pieces of fruit suspended in it (usually citrus peel and juice, but other fruits can be added), and conserves are jams made with a mixture of fruit and nuts (often includes citrus, nuts, and dried fruit).
Q: What’s pectin?
A: Pectin is a naturally occurring substance (a polyscaccaride) found in berries, apples and other fruit. All fruit has some pectin, but the levels vary. When heated together with sugar, most commercial pectin cause a thickening that is characteristic of jams and jellies. Most commerical pectin is apple based and all natural, but requires large amounts of sugar in order to gel. This is why if we ever need to add pectin (very rarely), we use “Pomona’s Universal Pectin”, which is a sugar-free, low-methoxyl citrus pectin that is activated by calcium. Since it does not require sugar to jell, jams and jellies can be made with less, little, or no sugar.
Q: What’s an “heirloom”?
A: Uh-oh, long answer ahead (Laena’s a plant geek). An heirloom plant or heirloom variety is a cultivar that was commonly grown during earlier periods in human history, but which is not used in modern large-scale, industrial agriculture.
Before agriculture became industrialized, a much wider variety of plants were grown for human consumption. In modern agriculture in the industrialized world, most food crops are now grown in huge, monocultural plots. In order to maximize consistency, value and proprietary dominance by evil agribusiness warlords Cargill and Monsanto, only a few varieties of each type of crop are grown. These varieties are often selected for their productivity, ability to withstand mechanical picking and cross-country shipping, and tolerance to drought, frost, or pesticides (genetic engineering helps this and creates even less variety). Heirloom and organic farming is a reaction against this trend and a movement to bring back diversity, which many see as vital to ecological longevity. If you haven’t already, read Michael Pollan’s books or see Food, Inc for a good overview of the food business and it’s evil warlords.
Wait, what makes something heirloom? “Old” is a pretty vague term, but the exact date is debatable, of course. Some believe the cultivar must be over 100 years old, some say 50 years, and others prefer the date of 1945 which marks the end of World War II and the beginning of widespread hybrid use by growers, seed companies, and industrial agriculture. Often 1951 is the cut-off date, being the latest year a plant can have originated and still be called an heirloom, since that year marked the widespread introduction of the first hybrid varieties. Widespread adoption of hybrid seeds in the commercial seed trade took place in the 1970s. Of course, some heirloom plants are much older, a few varieties are even pre-historic in origin!
The trend of growing heirloom plants in farms and gardens has been growing in popularity in the United States and Europe over the last decade. We believe in freedom from food tyranny and are big fans–bring back those oldies but goodies!
Q: How long does a jar of jam last on the shelf?
A: Unopened, a jar will last one and a half years on the shelf, according to the FDA. Unofficially, they often last much longer. Store in a dark, cool place for maximum longevity. As long as the button on top of the lid is concave and not popped, you should be fine.
Once opened, refrigerate your jam. Because our products are made without preservatives, they’ll last in the fridge for a few months to a year — you’ll know they’re bad because they’ll start to mold just like fresh fruit does.
Moral of this story: eat your jam.
Q: Can jam kill you?
A: The short answer: probably not.
Here’s the long answer, for geeks like Laena who want to know why:
(Quoting the USDA) The high concentration of sugar (in fruit preserves) and the high concentration of sugar and salt (e.g. in pickles) serves as a dehydrating medium that makes it difficult for certain bacteria to survive. Canning preserves food by using heat to destroy the microorganisms that cause spoilage. Heat forces air out of the jar. As the jar cools, a seal (vacuum) forms.
If not canned properly, or once the jar is opened in the fridge, mold will form. This is gross, but it won’t kill you.
So, how do you prevent spoilage?
>Carefully select and wash fresh food.
>Worried? Nervous? Then prepare foods according to this official website. You may need to peel some foods, add acids (lemon juice, citric acid or vinegar) or use “hot packs”.
>Use glass jars and new lids with a rubber flange and pop-top seal (like Ball or Kerr).
>Process jars in a boiling-water bath or pressure canner according to instructions for the correct period of time.
Acidic foods, such as most fruit, contain enough acidity to either stop the growth of botulinum bacteria or destroy the bacteria more rapidly when heated.
Low-acid foods, such as green beans or carrots, are more tricky. If Clostridium botulinum bacteria survive and grow inside a sealed jar of food, they can produce a deadly toxin. Even a taste of food containing this toxin can be fatal. Boiling food for 10 to 15 minutes destroys this toxin. Low-acid foods don’t contain enough acid to prevent the growth of botulinum bacteria and you MUST use a pressure canner and proper techniques to prevent super bad bacteria (the kind that will kill you) from forming. Process these foods at temperatures of 240 to 2500F. These high temperatures are attainable only with pressure canners operated at 10 to 15 PSI. PSI means pounds per square inch of pressure. The exact time depends on the kind of food being canned, the way it is packed into jars and the size of jars.
Low-acid foods include red meats, seafood, poultry, milk, all fresh vegetables and some tomatoes. When you mix low-acid and acid foods, assume the mixture is low-acid.
Although tomatoes used to be considered an acid food, some have pH values slightly above 4.6, which means they are low-acid. To safely can them as acid foods in a boiling-water canner, you must add lemon juice or citric acid.
To summarize all the above: if you’re making jam follow the directions, dudes, and you’ll be fine. Although we’re jamarchists, we love jam and don’t like to kill or encourage deadly jam making.
Q: Can you make jam without sugar?
Yes. However, at Anarchy in a Jar, we use some sugar in all our jam. If you want sugar-free jam, we suggest you make it yourself!
Sugar is an essential aspect of preserving fruit. If you choose to go sugar-free, most likely you will be making what is called “freezer jam”.
Without the sugar, jam will quickly begin to mold on the shelf. It will keep in the fridge for a few weeks, but any jam you want to keep longer than that should be stored in the freezer.
The other issue with jam is that for most fruits, commercial pectin is added, which requires large amounts of sugar to gel. There is such a thing as commercial pectin without sugar (Pomona’s Pectin being our favorite), which is what we recommend people try when going sugar free.