If you are just getting started with jam, I think it is important to have a few food safety fundamentals under your belt. So I’m giving you a list of fundamentals and the resources you need before making your next batch.
The Principle: Use Fruit at the Peak Season
The USDA recommends using the freshest fruit possible for jam. I try to make jam about 1 day after I have procured the fruit. You should use tender berries, like raspberries, blackberries, and strawberries as soon as possible. Allow stone fruits like peaches, plums and nectarines to ripen for a day before preserving them. Use Local Harvest to search for farm stands, Upick farms and Farmer’s Markets near you. Got a friend with a peach tree? Ask if they will share their bounty. Not sure what is in season where you are? Check out the Epicurious Peak-Season Map.
The Principle: Start with a modern, reliable recipe
The Resource: Canning Books, Blogs
I know that heirloom recipes are en vogue. Over the years, our understanding of food safety and food preservation has evolved. Canning is science and science advances! Modern recipes are safer and more reliable than recipes even from the 1980s and 1990s. For example, in the 1980s it became popular to process jars in the dishwasher. We know now that this is unsafe and does not kill all Botulinum bacteria. And chances are, somebody learned that lesson the hard way. Avoid methods like open kettle canning, paraffin wax seals, and steam canners.
It is also not recommended to double jam recipes. This is because the cooking time needed is excessive. If you want to double a batch, simply make two batches. Believe me, it will take less time to make two smaller batches than one big one.
Books I like:
Put ‘Em Up by Sherri Brooks Vinton- Very clear How-Tos and Great Starter Recipes
Canning for a New Generation– For recipes that are a little different, but with clear instructions. This book will help build your jamming confidence!
You Can Can– Very basic. I like it a bit better than the standard Ball Book of Canning.
Jam It, Pickle It, Cure It: And Other Cooking Projects– This is the craftier, more creative side of jamming. If you want to use your jam as gifts or make edible gifts, this is the book for you.
Blogs I like:
Food in Jars– I think Marisa’s blog is fantastic and empowering. I have tried quite a few of her recipes and loved them. She also has an excellent list of resources, teaches jamming classes in Philadelphia and has a ‘Canning 101’ series on her blog.
Mrs. Wheelbarrow’s Kitchen– Mrs. Wheelbarrow has great recipes, helpful tips. She is also of Charcutepalooza fame. Mrs. Wheelbarrow teachings canning and preserving classes in the Washington D.C. area.
The Principle: Preventing Bacteria Growth
The Resource: USDA National Center for Home Food Preservation
Over at the USDA, they have a downloadable guide on the Principles of Canning. Amongst the most important information in this guide is why it is important to process jams, jellies, and pickles at the proper temperature. The main reason: to kill Botulinum Bacteria. For this you need two things (1) Acid or a Pressure Cooker and (2) A Vacuum Seal. This guide does a nice job of explaining the difference between a low-acid food (like preserved carrots, for example) and a high acid food (like raspberry jam). Most jams, jellies, marmalades, and fruit butters are considered high-acid. They should be processed in a water bath canner. Low-acid foods must be processed in a pressure cooker and often contain added acid, like vinegar. An example of this would be pickles. Processing time will vary depending on the fruit used, so follow the USDA guidelines.
The Principle: Pectin & the Proper Set
The Resource: Pomona, Certo, Ball
Pectin is a water-soluble fiber. When heated and combined with sugar, the pectin and sugar bond creating a tight set. Pectin naturally occurs in most fruit and it is what makes jams and jellies gel together. BUT you do not always need to use commercial pectin to get jam to set. In fact, I only use pectin for fruits that have very little. Apples and red currants contain the most pectin, while cherries contain very little.
Jam reaches a boiling point at 212, and typical setting or gelling point is 220 degrees Fahrenheit. I like to use a thermometer and the cold plate trick. Place a dollop of jam on a frozen plate. Allow to sit for a few seconds. Press on the jam. Does it wrinkle? Run down the plate? If it wrinkles or doesn’t budge, the jam is definitely done. If it running down the plate, cook for longer. Sometimes, inexplicably, jam does not set. This can be very frustrating. My advice is to jar it anyway. Chances are that it will set while in the jars or during the water bath. If it still doesn’t gel, don’t fret. Runny jam is still delicious.
The major producer of commercial pectin is Certo. Certo is made by food giant Kraft. It is generally a reliable product, but it is one of the only games in town, so I have found that Certo is a little different from year to year. The pros to Certo is that it comes in liquid form, is easy to use, and is readily available at all major grocery stores and super centers. Ball also has their own brand of pectin, but I have never tried it. Please let me know if you do.
I prefer to use either Pomona or homemade pectin, which is made from tart apples. Pomona is particularly useful in making low sugar jams and jellies, as the pectin is actually activated by calcium instead of sugar. So if you are diabetic and would like to eat some homemade jam, try the Pomona.
Have any questions? Leave me a comment and I’ll do my best to answer any questions about jamming and canning you might have.