how the heck do I tell when the jam is ready to jar/can?

I am seriously confused.  I've read over a dozen books from the library, searched youtube and google... they just make me more confused.

The strawberry jam I made the other day passed the frozen plate test, but today I try it and it's more like a very thick compote, not jam texture.  

It's very good and a nice bread spread, but I'm expecting something that stays still when I tip the jar sideways.  

How do I get that?  

Please un-confuse me.

True "jam" uses the same number of pounds of sugar as fruit. When I was young, we used the "soft ball" stage which is like the frozen plate concept but you drop it into a clear glass cup of cold water and it should be round as it goes through the water. Maybe if you did it all the time, you'd get it right every time, but after several failures, my sister bought a candy thermometer. If the temp is correct on the thermometer, the jam should jell.

I've decided that I can accept inconsistencies, so long as it isn't so runny that it drips off the bread. The last time I tried a recipe that insisted it was easy and that the frozen plate method would work, it didn't. It's still waiting in its jars for me to be willing to pour them all out, heat them up, and use some Pomona's Pectin on them. It allows me to do low-sugar, but once the jam is open, it requires refrigeration and sometimes the liquid separates a little.

Wait!?!

I can just use a thermometer?  Why did no one tell me this before?!

Any idea what temperature I need?

When you're making jam with traditional amounts of sugar, you're aiming to cook it to 220°F. That's the temperature at which sugar forms a gel and can bond with the pectin (whether it naturally occurring in the fruit or you've added it).

from https://www.thekitchn.com/7-tips-to-make-sure-your-jam-sets-up-193268

I did specify a "candy thermometer" - not just any one will have the necessary accuracy. I tried faking it with my meat thermometer and it didn't jell. That said, they aren't hard to find - I suspect places like Canadian Tire or Home Hardware would have them.

R Ranson,
I think jam should have a soft gel consistency.  "Shop jams" add extra pectin to get more of a jelly consistency, but generally a home made jam will not be solid like that.  It obviously depends on how much pectin is in the fruit to start with.  If it annoys you to have a softer jam, you could either buy a pectin supplement to add to your jams or, as I do sometimes, add a third to one half cooking apples (like Bramley) to your fruit.  I usually cook them separately and then combine since many soft fruit don't need as much cooking as the apples.  I've never had much luck with the temperature method.....

You'll struggle to get a pure strawberry jam to set solid unless you add some pectin or an apple.

Jay Angler wrote:

When you're making jam with traditional amounts of sugar, you're aiming to cook it to 220°F. That's the temperature at which sugar forms a gel and can bond with the pectin (whether it naturally occurring in the fruit or you've added it).

from https://www.thekitchn.com/7-tips-to-make-sure-your-jam-sets-up-193268

I did specify a "candy thermometer" - not just any one will have the necessary accuracy. I tried faking it with my meat thermometer and it didn't jell. That said, they aren't hard to find - I suspect places like Canadian Tire or Home Hardware would have them.

How about a milk thermometer?   Like for making cheese?

The point of making jam at home is to make the jam I WANT to eat, the flavour I want it, the texture I want it, from the fruit I grow.  I'm fed up with buying jam that isn't to my liking.  The jam I got the other day is a lot like the almost-jam in the store - thick fruit, but still moves when the jar is tipped.  Only I got the flavour right, just not the amount of cooking.

My grandmother used to make jam from what they grew.  She was too frugal to buy ingredients in her older age and started making jam before things like pectin or foreign imported apples were available.  

I'm not going to be quite as strict as she was, as I can't seem to grow strawberries, but the rest of the fruit I want to make from the harvest.  It's the start of berry season here and apples won't be ready for months.  

How about you?  How do YOU tell when the jam is set?  

I'm not a jam person but my mum used to make it. She would use the greenest, sourest apples she could find. Ideally wild crab apples. I think quince work well too. Certainly don't need to buy or import fancy ones.

r ranson wrote:
How about you?  How do YOU tell when the jam is set?  

I use a plate. Not frozen, not even in the fridge just straight out of the cupboard. dribble a bit of jam onto it, wait 15 seconds or so and see if a skin forms when you poke it with a finger, if you need to tilt the plate up to the light and squint to see the skin it's not ready yet. Also be careful get some jam from the main body of the pot to check, the foamy bit on top normally sets harder than the rest and can throw off the test.

With strawberry and other jams that do not want to set there's a few things you can do. you can add apple or any other pectin rich fruit like redcurrants. (freeze the strawberries until the other fruit is ready or make your own pectin the previous year and store it) If you really only want to use strawberries then to get them to set hard is possible, you will need to use a lot of sugar and boil it for a long time, to avoid turning the strawberries themselves to something approaching raisins sieve them out when they are how you want them and continue to boil the syrup/juice only until it will set, then put them back in and bring back to the boil before bottling. Stir often as it will want to catch on the bottom and burnt jam is not good.
This method will make it taste a bit more cooked.


My strawberry jam in general is a loose consistency, it won't fall of the bread but it's not slice-able, I have made it hard (following the method above) but I personally do not like the loss in fresh taste when you boil it long enough to set hard.

r ranson wrote;

How about a milk thermometer?   Like for making cheese?

So long as it goes up to 240F at least, it should work fine.

She was too frugal to buy ingredients in her older age and started making jam before things like pectin or foreign imported apples were available.

It doesn't just have to be apples - here's a link to a recipe from Leda Meredith for homemade fruit pectin from oranges - https://www.motherearthnews.com/real-food/canning/fruit-pectin-zerz1509zbay

I know others who say to pick Hawthorne berries for adding pectin, but they're still blooming in my area, so no fruit yet.

I've also read that adding some unripe fruit - ie some half green strawberries - will increase the pectin. That's one reason they tell you not to make jam from overripe fruit I think. A second reason is that you seem to need some sort of balance between the pectin content and the acid content. Modern fruit tends to be lower in acid (which is why a crab apple or Granny Smith would help your jam more than a modern eating apple.)

r ranson wrote:My grandmother used to make jam from what they grew.  She was too frugal to buy ingredients in her older age and started making jam before things like pectin or foreign imported apples were available.  

I'm not going to be quite as strict as she was, as I can't seem to grow strawberries, but the rest of the fruit I want to make from the harvest.  It's the start of berry season here and apples won't be ready for months.  

How about you?  How do YOU tell when the jam is set?  

If your grandmother made very thick strawberry jam with no pectin, the only thing she could have done that I know of is boil the hell out of it like Skandi described.

Good news is no foreign imported apples are needed to use the pectin in them. That withery granny smith you've got from last fall? It'll work. Any early season, totally not ripe apples growing now (okay maybe not right now, but soon)? Those work too. Doesn't matter what kind of apple it is, just use sweet ones before they're ripe. We used the local apples growing in abondoned orchards from the 1800s. Some are cooking apples, some are eating apples. We'd grate one up for a big pot of jam and that would be it. Our jam was always cooked less so it was a looser consistency than it sounds like you prefer. So maybe grate a second apple and cook longer. Actually, we also used less sugar than it sounds like you prefer, so even my vague ratios are probably of no help to you ;)

My point is, any old apple will work for pectin.

To tell when the jam is set, I did the plate thing. Room temp (or cold if I was uncharacteristically  organized) plate, spoonful of jam, put in fridge for a few minutes to hurry things along, look for skin.

Anything that really doesn't set can be used on top of pancakes, ice cream, granola, etc., or as an ingredient in baking.

Another idea with regards to both acid and pectin is to add a lemon.  I usually add quite a bit of lemon juice, because I find strawberry jam can end up a bit sweet, but if you add a chopped up lemon, pips and all in a net bag, that may add enough pectin to help the set as well.  Just a thought

We make jams to sell and have the odd failure - burns, does not set, to thick, stick jaw like.  You will never get it all right all the time so accept that you have done the best you can.  Jam needs two things: pectin so it will set and acid so it does not poison you.  We always harvest fruit that grows wild on the road side, use what we grow and what we are given.  Having used all the methods to see if the jam is set, we use the saucer method.  The trick with the saucer is that it has to be in the freezer and once the jam is on the saucer, you need to wait at least 20 seconds and roll it a around so you can see the jam surface.  If it puckers when being rolled, it is set or you can put your finger in it and if a strand lifts, it is also done.  https://www.youtube.com/watch?v=3tHesWunals  7 second video showing puckering of the skin.  Jam needs to come up to "Jam set" quickly or it will be like stick jaw.  If this happens, add 50 ml of water for each 250 ml cup and stir off the heat, return to the heat and boil rapidly for 5 minutes.  Any apple can be added to jam instead of buying pectin.  If you do not want to use the apple in the jam, put chopped apple in an old stocking (preferably rinsed beforehand) or muslin and pull it out when the jam is cooked.  Leave the skin on as that is where most of the pectin will be.  When bottling (canning) apples, we keep the skins for pectin by freezing them.
Our Strawberry recipe is:

1 Kg Fruit ( strawberries or 500g strawberries and 500g apples peeled)
1 Kg Sugar
100 ml water if strawberries are fresh, not frozen
100 ml Lemon Juice

Cook strawberries with 100 ml water until soft
Add Sugar and stir in over a low heat until dissolved
Bring up to a rapid boil until the bubble changes to more of a roll.
Add lemon juice and bring back to the boil.
After 5 minutes, check that the jam is set.  If not keep on a high heat until set.  Stir frequently so it does not stick or burn.
decant into sterile jars, cap and invert the jars to sterilise the lids for 1 minute than turn upright and put aside to cool.

Hints and tips:
Strawberry jam is known to foam up.  Add a cubic cm of butter or 1/2 teaspoon of olive oil into the pot.
Skim the scum off regularly to ensure the jam is not bitter.  Scum is pink and slimy looking.
Use a metal spoon to make jams as wood sometimes becomes excessively coated as it does not get as hot.
Use a saucepan with a very heavy base and tapered sides.  Our jam pots are stainless steel with copper bases and have a bucket handle as well as a tipping handle.
If you use strawberries that are frozen first, they require less cooking and have a more intense flavour.  No water is required and add sugar as strawberries are warming up.
If using raspberries, they are naturally high in pectin but still use lemon juice as an acidifier,
Do not wait for jam to cool before bottling as bacteria and mould can be introduced.

Depending on the type of fruit that you are using, some will set more easily than others due to the natural pectin content.

For me, dark plums will always set to the gel like consistency that you prefer. They are usually sharp when under ripe. I don't bother making jam with the sweeter yellow fleshed plums, they are too watery and don't set well, I just eat them or use for making chutneys.

Apricots and strawberries are on the low end of the pectin scale and added lemon juice helps them to set. As others have mentioned, adding pectin and using an equal weight of sugar to fruit guarantees a jam that will set.

To my mind, that defeats the purpose of making my own jam because I dislike the flavour of commercial jams due to them being far too sweet, not to mention the additives that are used.  

I have a notebook full of scribbles with the ratios of sugar and fruit and method used for jam making. When the fruit was picked also affects the pectin content - under ripe fruit sets more easily but it is normally the over ripe windfalls that get used in jam making.

Strawberry jam is the most challenging and I've settled onto the 4 day method which works equally well with fresh and frozen fruit.

Wash and weigh fruit, add 30% weight of sugar sprinkled evenly through whole strawberries (I like chunks of fruit in my jam, halve or quarter them if you prefer). Do not add any water.

Leave overnight, covered with a dishcloth. Next day, all the sugar will have liquified into a thick layer at the bottom of the pan.

Stir and bring to a boil for 15 minutes. Do not walk away and keep stirring.

Take off the heat and leave it another day.

Taste and add sugar if you wish. Repeat twice. If it foams, add a knob of butter as Paul suggests.

This is a soft set jam that retains its colour and flavour. Once opened, it does need to be refridgerated due to the low sugar content.

Always use a clean spoon to serve, the slightest speck of butter or crumb in the opened jar will go mouldy.

With apricots, I use the same ratio of sugar but don't add any water, wash an halve the fruit, add the juice of two lemons and gently soften the fruit over a low heat until it reaches the degree of chunkiness that i like. When the sugar is added, the jam will become runnier.

I read somewhere in Harold McGee's book that sugar stops the fruit breaking down further.

Pressure canning afterwards is not customary in NZ, some people will waterbath their jam afterwards but so long as the jars and lids are scrupulously clean, I have never had an issue and unopened jars have kept for two or three years.

The top of the jam may oxidise but that's the only thing I've noticed.

My husband is a marmalade man and only likes fine cut jelly marmalade. Even after 30 years of making it and purchasing  our Seville oranges from the same grower, I still manage to turn out dud batches.

Overcooked jams go rubbery before they caramelise and/or catch on the bottom of the pan and burn.

The jars that fail get set aside and mixed with another batch.

To test if a jam has set, I scoop a little jam into a wooden spoon, tilt to pour it out and if it hangs from the edge of the spoon without dripping, it's ready. It will hang in little scallops across the edge of of the spoon.  It is also known as the flake test.

Homemade jams taste the best and make great gifts!

Someone said to "boil the hell out of it" and that is what I do. Peaches, strawberries, grapes or what ever it is. I don't really care all that much about consistency or  appearance. What I'm after is that it is preserved and most importantly tastes good.

I got the idea when I got sick of everything tasting the same because everything was 1/2 sugar. Sure all that sugar and all the pectin and the rest makes a pretty jar but it tastes like crap. I researched how to make jam, preserves, jelly or what ever you want to call it without all that sugar and found a paper from back during WWII when things like sugar were had to come by.

All there is to it is to toss your fruit in a kettle with just small amount of sugar, no where 1/2 and 1/2, more like 85% fruit, 15% sugar.  Bring it to a hard boil, stirring constantly for ten minutes. Let it cool completely and do it again. Let it cool completely and do it again. The whole process can take place over a day or two.

I think what is really happening is it is being slowly dehydrated and around the 5th or 6th time of boiling it all of a sudden starts turning into a thick goo. When that happens plop it in the jars and hot bath it for another ten minutes.

Like I mentioned, I don't really know what to call it. It's got globs of fruit, its sticky and gooey. Compared to a lot of jams or jellies it looks awful but if it's made from peaches, it tastes like peaches, if it's made from grapes it tastes like grapes and so on. If it's made from wild black cherries it's incredible.

Jam: generally 1pt fruit to 1 or 1.5pts sugar. Sets semi-hard, will "move" when jar is tipped.

Jelly: generally 1pt fruit (juice) to 3/4pt sugar. Sets hard, like "jell-o", does not move when jar is tipped.

Spread: all fruit and little to no Sugar. Depending on how long it is cooked, and how much pectin (natural OR added) there is as to its final "firmness".

Strawberries along with peaches, apricots and blueberries are naturally SO low in acid and pectin, that one or both must be added for a firm texture.

RIPE apples, blackberries and or cherries are somewhat low in acid and pectin (naturally) so MAY need this added.

Sour apples, crab apples, currants and cranberries (IF NOT over ripe) have enough naturally occurring pectin and acid for gel formation with the addition of just sugar.

Perhaps you would be better off making a jelly and adding fruit back in at the end? Otherwise likely the boil, cool, boil, cool...method would be best.

Either a deep fryer or candy thermometer would work to accurately get a temp of 220F.

Mark Reed wrote:Someone said to "boil the hell out of it" and that is what I do. Peaches, strawberries, grapes or what ever it is. I don't really care all that much about consistency or  appearance. What I'm after is that it is preserved and most importantly tastes good.

Like I mentioned, I don't really know what to call it. It's got globs of fruit, its sticky and gooey. Compared to a lot of jams or jellies it looks awful but if it's made from peaches, it tastes like peaches, if it's made from grapes it tastes like grapes and so on. If it's made from wild black cherries it's incredible.

Hey Mark, when I was a kid we (kids) had to do all the picking of anything being canned. And I don't recall seeing any recipes lying around although I'm sure my mother had one as she also used a pressure cooker.

Thirty Five years plus - this old Dude moved back to Indiana from California to retirement. I got the house remodeled and things settled down somewhat so I decided to do some canning again. The first thing I had to do was buy the equipment and right beside that was the most recent version of the Ball Blue Book, now called something like Ball Preserving, and the best investment I made.

That book gives you a pretty good idea of what should be pressure cooked and what things you can just do water bath canning on. It is also loaded with recipes and I used those many, many times.

You get to a point of manipulating recipes. For instance when a kid my mother canned stewed tomatoes - and that was all that was in the jar, tomatoes. In MY recipe for Stewed Tomatoes I add about one cup each of cut up Celery, Onions, and Bell Peppers and that turns out fantastic. Another example is that I was shopping one day about 4 to 5 years ago and saw Peaches and Plums on an end cap at the market, and just went, "Hmmm, I wonder if that would make a good jam?". I picked up about 8 lbs of each and went home and searched for a recipe on the Internet and actually found one, tried it and you wouldn't believe how good that jam is.

I do like my jams "chunky" with enough evidence as to what the jams are made of, although I also use 2" X 4" labels printed on a laser printer to identify the jams, a short little synopsis of the recipe, and the date made.

As for WHEN jams are ready to funnel into jars, those recipes in the Ball Book usually give you details about how long to cook them, at what point to add the Pectin, whether you might want to add a bit of butter to hold the foam down, how long after adding the pectin to let the batch boil, and then the ladeling into jars and whether to water bath or pressure cook the batch.  CAUTHION: IF a Pressure Cooker is required - DO NOT, DO NOT use a low pressure Pressure Cooker for canning. Use a regular Pressure Cooker as this process requires some minimum lbs pressure.

The very best way to do canning is to invite a couple of female friends over to HELP!!  :-)

My Dear Wife makes low-sugar jams using the long-cook recipes from an old book. They are magnificent! Some set up more firmly, some like strawberry rhubarb are runny. Doesn't matter -- they are the quality standard IMO.

If you ask me the ridiculously sugar-stuffed commercial jams in the stores are overpriced rubbish. Shameless.

Jay Angler wrote:True ... and use some Pomona's Pectin on them.

I find myself collecting a lot of little nuggets from your posts.  Many thanks!