Ellen and I had a great time yesterday making jam at the Ann Arbor Farmer's Market. We had a whole bunch of berries from Gibbs Berry Farm which I just discovered is in a town called Onondaga, Michigan, south of Lansing. This year, we had so much rain I guessed it would take a long time to get this strawberry jam to set up, and I was right. Normally, boiling the jam that I make with pectin rendered from apples and lemons takes about 20 minutes to get to the right jell temperature, but yesterday, it took much longer....at least 30 minutes. Looking at my jam today, it is still a little softer than what I would like - when I rotate the jars it comes away from the sides and has the viscosity of soft set jello. It can take a week to get to it's final jell state, so I am not concerned about it...it will be fine in a few days.
I wanted to answer some of the questions I have been getting about making jam this way:
How does the boiling point of water change with elevation?
The reason why the boiling point of water changes at elevation is because the atmospheric pressure decreases at higher altitude. When the pressure is lowever, water has an easier time changing to it's gaseous state (also known as steam). This is why baking and canning recipes always require modification due to your elevation. Roughly, the boiling point of water at sea level is 212 F, and so the jell temp is 8 F higher or 220 F. At 1000 ft elevation, it's 210 F so you'd shoot for 218 F, and at 2000 ft it's 208 F so your goal is 216 F. Here's a chart that shows how the boiling point of water changes with elevation. In the SE Michiga, our elevation is low and so we don't need to make any changes. The highest point in Michigan is Mt. Arvon, which is near L'anse, MI in the Upper Peninsula. It tops out at almost 2000 ft, but it's in the middle of a forest so I doubt anyone is making jam there. Check out this cool map that shows the topography of Michigan and other states.
Do different apple cultivars have different amounts of pectin?
Yes. I would love to have a chart that shows Michigan apples with their pectin content, but I can't find one on the internet. I will send an email to MSU to find out. I do know that sour apples and crab apples have more pectin than sweet ones. Also, unripe apples have more than ripe. In the famous French jam and jelly cookbook Mes Confitures, Christine Ferber makes apple jelly that she cans and uses the following year for pectin. Note - if you are a beginning jam and jelly maker, I caution you not to use this book to learn how to make jam or jelly. It is not a how-to book, rather I use it more as an inspiration. This is the book I refer to get ideas for some exotic flavor combinations, such as this Orange Pinot Noir Jelly.
What are some good books for jam and jelly making?
As always, I recommend the Ball Complete Book of Home Preserving. It's got some wonderful recipes for neophyte and experienced canners. Next, I'd give a shout out to my latest addition to my collection, Linda Ziedrich's The Joy of Jams, Jellies and Other Sweet Preserves. I love this book as much as I love Linda's Joy of Pickling. Check out my canning friend Tigress' interview of Linda Ziedrich for some great tips. I can still remember reading Linda's fact based "Nursing Mothers Guide to Weaning" back in my La Leche League days....I wonder if all La Leche League Leaders eventually take up canning and pickling and jamming?
Can I put up pectin when apples and lemons are in season?
Sure! Using the recipe I've been using, the ratio is 5:1 apples and lemons. You'd process it just like applesauce. I think that instead, this fall I will use crab apples from my neighbor's tree to make my own pectin There's a great method outlined for doing so in Linda Ziedrich's book. Come back this fall to my blog and I am sure I will post about it.