Plum jam with rosemary

This post is for my friend Annette Stenbäck in Sweden who has a bumper crop of plums and needs to come up with some yummy things to do with it. I wish she could send me some plums, but I suspect that customs might have a problem with that. 

This jam turned out beautifully: Deep rich color and tangy, sweet, and deep flavor.

I used a combination of prune plums and red plums (about half each), but you can probably use any combination of plums that you have available. The rosemary is entirely optional, but makes a nice flavor addition.

  
Now, making this jam takes two days. The work is minimal on the first day, but you should know and plan accordingly.

This is the base recipe. You can make up to three times as much (which I did by accident), but note that cooking time will be longer for bigger batches. Just multiply the following recipe by two or three, and you are good to go. Three kilos of cleaned plums yielded 11 eight-ounce jars of jam.

Here's what you will need:

• 1 kilo of quartered plums with the stones removed (in other words, you need a little more than a kilo of plums)
• 700 ml of white granulated sugar (I prefer to use organic, which has just the slightest scent of raw cane--mm, lovely)
• juice from one lemon, strained (if you don't have lemons, I suspect that about 100 ml of balsamic vinegar would yield an utterly amazing jam)
• 2-3 sprigs of fresh rosemary
• clean jars (sterilized if you are not planning to eat this right away, but more on that later)

Day 1

Prepare your plums. Cut them into quarters and remove the pits. You don't have to peel them; the peel is where the jam will get its pectin from. 

I love this color combination. 

When you have about 1 kilo of cut fruit, add the sugar in layers. Start and end with a layer of sugar so that the fruit is completely surrounded with the sugar. Also add the lemon juice. 

Then put your fruit-sugar-lemon juice combination into the refrigerator for one day. The reason for this is to draw the juice out of the plums and start to break down the cell walls. (You can let this sit for up to two days without any problems. Longer than that and your jam may start to get a little raisin-like.)  

Day 2

Today you will do most of the work. Start with washing your jars and lids and sterilizing them. You can do this in a water bath, but I like the oven technique that I learned from Rachel Saunders's book The Blue Chair Jam Cookbook, although I upped the heat a bit. 

To do this, place your washed jars and lids on a cookie sheet and place them in the oven. Turn on the oven (I prefer to place the jars into a cold oven so I don't risk cracking them with a big shock of heat) and let the temperature come up to 275 degrees Fahrenheit (that's 135 degrees Celsius for my international friends). When the oven is hot, the jars should remain in the oven for at least 30 minutes. Leave the jars in the oven until you need them. 

Next, put a plate with five metal spoons in the freezer. Now, pirouette and sing Oye Como Va. Ha ha! I just wanted to see if you were still paying attention. You don't have to sing and dance, but do put the spoons in the freezer, you will use them to test the doneness of your jam. 

When you made your preparations, you can start heating up your fruit mixture, which should be a lot more watery than it was when you first put it in the refrigerator. Start with medium-low heat and bring the temperature up slowly.

Once the mixture has started to simmer a bit, raise the heat to medium-high. Get a good boil going (the point is to let most of the water steam off and candy the sugar). Stir frequently (wear something to protect your hands; the jam will sputter a lot and it can burn you). When the mixture foams, skim off as much of the foam as possible. (Use a skimmer for this job; it really makes a difference. Also, keep your skimmer in a bowl of cold water, which will help the foam adhere to the skimmer.) You will skim very frequently for the first 5 to 10 minutes. 

Let it boil for about 20 minutes before you do your first doneness test (add about 10 minutes if you do a bigger batch). To do the test, remove a small representative sample from the pot (in other words, get both solids and liquid) and transfer it to one of the frozen spoons. Place the spoon back in the freezer for 3-4 minutes. Feel the bottom of the spoon, if it doesn't feel cold or hot, you can inspect the jam. The liquid part of the jam should move a little, but it should not run. If it runs, the jam is not ready yet. Keep cooking the jam for about 5-10 minutes and test again.

When the jam is done, take it off the heat and add your sprigs of rosemary (if you don't want to use rosemary, skip this step). Let them steep for about 5 minutes and then remove them. (You don't want slimy rosemary sprigs in your final product.)

Take your cookie sheet with jars out of the oven and fill the jars. Using a jam funnel is helpful for keeping things somewhat clean. Be very careful, the jam will be extremely hot.  

Don't completely fill the jars. Leave at least one quarter inch at the top. Clean the rims of the jars with a clean wet cloth (or paper towels, as long they aren't prone to tearing). Then place the lids on the jars and loosely screw on the rings. Put the jars back in the oven for 20 minutes. 

When you remove the jars from the oven, put them somewhere you will not disturb them for about a day. That will give the jam time to set and create the vacuum seal. Next day, check the seals. The bubble in the middle of the lid should be depressed. If it makes a popping sound when you press it with your finger, you didn't get a vacuum seal, which means you should use that jar right away. Just put it in the refrigerator and eat it within two weeks. The rest of the jars can go into a cool, dark place for enjoyment later in the winter. Yum!

If you want to learn more about jams and other preservation techniques, check out the National Center for Home Food Preservation.  

   

Jam update: How I went wrong and a recipe for peach-plum jam

A while back I wrote about making blueberry jam with maple syrup and lemon zest, but I have learned much about jam-making since then and I must confess that I was wrong. The basic recipe is just fine, but it turns out my technique could use a lot of improvement.

Now, you ask me, "Tora, how did you find out you were wrong? What should we be doing differently?"

Well, about two weeks ago (I think it was two weeks ago), Mike, Sebastian, and I decided we would go to Borders and see if we could find anything good at the going-out-of-business sale. We don't usually pick over scraps of dying stores like vultures, but it's a book store. If there was a 10-step program for book addiction, we might be candidates for it.

As we looked around, Mike found a book that he thought I might like: The Blue Chair Jam Cookbook by Rachel Saunders. This charming, lovely book is probably all you will ever need to become a master jam/jelly/marmalade maker. It has gorgeous photos, lots of great information about techniques, and recipes that range from the utterly simply and sublime to the complex and sophisticated. And within about 10 minutes of sitting down to read, I discovered that I have been doing it wrong. So, let me explain my mistakes and pass on some of my new-found knowledge to you.

1. I've been using the wrong kind of pot. Ideally, you should use a copper pan that's 11 inches at the base, 15 inches at the rim, and 5 inches high with a 11- to 12-quart capacity. Now, copper pans are not currently in my budget, as dearly as I would love to have one. What I gleaned from this information is that I need a lot more surface area. So I broke out my stock pot, which is definitely deep enough and has a 10-inch diameter. Not perfect, but I've already gotten better results. (If anyone feels especially generous, a copper pan would be a much appreciated Christmas gift.)
2. I've been using the wrong application of heat. Instead of low and slow, I should be cooking this stuff hot and fast to keep as much of the fruit's flavor and texture intact. The correct way to do it is to heat the mixture of fruit and sugar slowly at first, just until it starts to bubble and release a lot of juice, and then crank up the heat to get it up to a pretty fierce boil. What you are trying to accomplish is a lot of evaporation (which explains why you need a lot of surface area in your pan). While it cooks, you need to keep stirring frequently, both to aid evaporation and to ensure that the jam doesn't stick to the bottom and burn. Note that this will be extremely messy.
3. My testing for doneness has a lot to be desired. Rachel Saunders suggests doing this instead: Place a saucer with five metal spoons in the freezer. When you are ready to test your jam for doneness, take your pot off the heat, transfer a small amount of jam to one of the frozen spoons and return it to the freezer for a minute or two. When the bottom of the spoon feels neither hot nor cold, inspect the sample in the spoon. It shouldn't run but sort of clump up in a jelly-like blob on the spoon. If it doesn't, discard test spoon 1 and put the pot back on the heat for another five minutes or so and test again. The cooking process for jam (there are differences for jelly and marmalade, so be aware of that) will take about 15-30 minutes tops. 
4. I like her method of preparing the jars for preservation, but I am still not completely sold on it. Usually, I would transfer jam to hot sterilized jars that I have boiled, place the lids on them, and boil them for another 15 minutes. She recommends sterilizing the washed jars in a 250-degree oven for at least 30 minutes, adding the jam, closing the jars, and placing them back in the oven for another 15 minutes. It's a lot easier method than boiling the jars, but so far, every batch I have made this way has had at least one jar that didn't seal. Of course, that means I get to try the jam right away, which is great, but it rankles a little bit. 
5. The last clear technique difference is her method of flavoring the jam with herbs. I like to wrap up my herbs in a piece of cheesecloth and let it boil in the jam, whereas she prefers to add sprigs and let them steep in the hot jam for a few minutes after cooking and then fish them out. I haven't made up my mind on this one yet. I tried her method, adding some basil to a recent batch of plum-peach jam after it had cooked, but although the basil was extraordinarily fragrant (from my garden!), I can't taste it in the jam at all. So I will probably experiment a bit more before making my decision one way or another. 

I've applied these modifications to three recent batches of jam—blackberry with lemon verbena, peach-plum with basil, and my blueberry with maple syrup and lemon—and I am definitely getting better results. The texture is better, the flavor is brighter, and the set is much better. I also love that I can get a jam in a lot less time. What's a bit of drag is that the yield seems to be a bit smaller, but I can live with that to get awesome jam. Here's a recipe for a jam experiment I tried with plums and peaches. The flavor is beautiful: bright, fruity, a little tangy, basically everything you get from a really good peach or plum eaten while dripping over a sink at the height of summer.  

Peach-plum jam with basil  

Yields about four eight-ounce jars 

• 500 grams peaches, peeled, cut into 1-inch pieces (discard the stones)
• 500 grams plums, cut into quarters (discard the stones) (any kind of plum will probably work for this, but I used red plums, which created a dark red jam; just be mindful that if you use, for example, greengages, the color may not be very pretty)
• 6 deciliters sugar
• juice from two lemons
• 4-5 basil stems (optional, but nice)

1. Background prep: Place a saucer with five metal spoons in the freezer, and sterilize your jars using whatever technique you prefer (keep them hot as you make the jam).
2. Layer the fruit and sugar in your jam pot (starting and ending with a layer of sugar).
3. Let the fruit-sugar mixture sit for at least an hour, up to overnight (refrigerate if you want to do this).
4. Add the lemon juice.
5. Heat the mixture slowly until the fruit produces a lot of juice, and it has started to bubble. 
6. Bring the heat up to high and stir continually to keep the jam from burning. Expect copious amounts of steam and a lot of spatter. If you have an apron, this would be a good time to wear it. (I really need to get one of those.)
7. Cook at high heat for about 15 minutes (skim off the foam).
8. Test for doneness: Take the pot off the heat, get a sample of jam from the pot and transfer it to a frozen spoon. Place the sample in the freezer for a minute or two. Touch the bottom of the spoon, if it's neither hot nor cold, it's time to inspect the doneness of the jam. It should not run, but be gelatinous. If it runs, put the jam back on the heat for another five minutes and test again. Keep testing until you reach doneness.
9. When the jam is done, take it off the heat and add your basil sprigs and let it sit for five to 10 minutes. Then remove the basil and pour the hot jam into your hot jars (be sure to leave at least an inch at the top) and sterilize them, using a hot water bath or oven as you prefer. 
10. When you let the jars cool, you will hear little popping noises as they create a vacuum seal. If one of the jars doesn't seal (you can tell if you can depress the lid with your finger and it pops up again), just let it cool and enjoy it right away. The rest will be good for several months. 

A note on cooling: Don't move jam around a lot while it cools. One of the things it does as it cools is creates a sort of lattice structure. If you disturb that structure while it's forming, the jam won't set very well (or possibly at all).

Update: Check out the National Center for Home Food Preservation for more information about keeping your jams and jellies safe.