The Science of Jam Making

apricot jam

Yes, the last snows have just melted and any fresh fruit is still a while away, but being prepared never hurt nobody, right? Read on so you’ll be well-educated and ready when all those lovely local strawberries hit the stands of your farmers market!

Up until recently, I thought jam making was kind of an occult science. Weird, because I watched my grandmother and mother make batch after batch after batch as I was growing up, and it seemed to be the most straightforward thing in the world. Still, I was intimidated to try myself because I could only think of the ways it could go wrong – what if my jam spoils and I food-poison my family?

I don’t think either granny or my mom ever worried about their jar disinfecting practices or pectin percentages, but I am admittedly a bit of a nerd. So if you too are curious about how jam making works, geek out with me for a bit and learn the simple science behind this preserving method. It’s gonna be fun!

First of all, why bother with jam making at all? Two reasons. First, although the quality of commercial jams are improving, those are still just the shadows of a good homemade jam, often containing more coloring, preservatives and artificial flavors than actual fruit. And also because buying jam gives no way near the satisfaction of making it yourself!

Once I made my first batch, there was no stopping me. Pictured above is a vanilla-cardamom apricot preserve from last summer. I have dozens of flavor variations in a notebook that I want to try, and the list is growing.

So what is jam?

The wonderful jams of summers past are actually creative exercises in chemistry. Today, jam generally refers to a spreadable, chunky-textured mix made from the juice and flesh of fruit. A clever balance of pectins, sugar, and acid turns the cooked fruit into our favorite topping for toast.

The fruit

The choice of fruit for jam-making is simply endless. Always try to use seasonal fruit to get the best flavour. Remove leaves and twigs, wash if needed, remove cores and/or stones.

The equipment

You’ll need a wide-mouthed pan big enough that the fruit does not reach more than halfway up the side. Use one with a heavy bottom for even heat distribution – otherwise the jam will catch and burn. Also, a wooden preserving spoon (it has a flat head that helps keep the mixture moving and stops it sticking to the bottom of the pan), a ladle, a funnel, jars, and optionally a food thermometer.

The chemistry

To achieve a perfectly set jam, a number of factors need to be just right. The three key elements that go into jam making are sugar, pectin, and acids. Understanding the chemistry behind why jam sets can also help you identify and fix problems.

The sugar

Sugar imparts a preservative effect: binding water molecules to itself reduces the amount of water available in the jam, to the point at which it is too low for microbial growth. Binding the water molecules also frees up the pectin chains so they can form their network.

Finished jams have a sugar content of roughly 60%. To achieve this, recipes comprise mostly equal weights of fruit and sugar. While you can totally play with this 1:1 ratio, be aware that too much fruit and you may lose the preserving effect, while too much sugar and the jam will be the consistency of set honey, losing the color and aroma of the fruit.

The pectin

Pectins are long, chain-like sugar molecules found in the skins and cores of fruit. These compounds are the ones that turn the wet, sloppy fruit sauce into the semi-rigid, elastic substance of our dreams, a texture referred to as a gel.

Through boiling, pectin is released from the fruit and at one point forms a mesh structure that holds the liquid together. As the pectin content of different fruits varies, some may require an added dose in the form of commercially packed pectin or a pectin-rich other fruit. See this chart for specific pectin contents.

The acid

High acidity makes your jam an unpleasant place for micro organisms to breed, helping to extend the shelf life. Acids also help the pectin branches to bond. Fruits naturally contain acids (the most well-known is citric acid), but often this won’t be enough to reach the desired pH. For this reason, lemon juice or powdered forms of citric acid is added. As a rough guide, the juice of a whole lemon (30-40 ml) will be needed for low acid fruits, half a lemon will be enough for medium acid fruits, and you won’t need any for high acid fruits. In general, fruits with high pectin will also have high acidity.

The process

Heat the fruits slowly, without sugar, until a very gentle boil is reached, then cook until just tender. The heat will break down the structure of the fruit, release the moisture and cause the whole fruit to soften. Add the sugar (it may foam up, so be careful). Allow the sugar to dissolve over a low heat then bring to the boil. If you want larger fruit pieces, avoid stirring at this point. Not only does the texture change by boiling, the water content is also reduced, increasing the concentration of sugar and fruit components. Cook, stirring occasionally, until the setting point is reached.

How do I know it’s ready?

There are simple ways of telling when the pectin network has formed and you are ready to pour the jam out. Get the thermometer: if the temperature is around 104-105°C, the sugar content is high enough to allow the pectin branches to join. A direct measurement can also tell the doneness: pour a small blob of jam on a saucer, let cool in the fridge and then push with your finger. If the surface wrinkles, it means the pectin network has solidified and setting point has been reached.

You can now take the jam off the heat. Note that if you don’t boil it long enough the pectin network will not form properly and you’ll end up with a sloppy liquid. Boil it too long though and you risk having a too thick preserve, losing the fresh flavour and color.

Time to can

Allow the jam to cool and thicken for about 10 minutes before pouring into prepared jars (read how to disinfect jars and lids here). Don’t leave it any longer, as lukewarm jam is a breeding ground for mildew spores present in the air. Each jar should be topped up to just less than a centimetre below the surface. Adjust lids, process, than cool jars.

Don’t forget to test your seals before labeling and putting jars away in your pantry! Gently press the middle of the lids with a finger – if the lid springs up when you release your finger, it’s not sealed properly. No need to throw these out, just keep refrigerated and consume shortly.

Store jars in a cool, dry, dark place away from direct sunlight and accidental freezing. Once a bottle of jam is opened, micro organisms have been reintroduced. The same applies as with unsealed jars: keep in the fridge and consume shortly.

Hope all this makes sense and you’ll try your hand at jam making too! Let me know!

Love,

Fruzsi

 

Illegally Delicious Plum Preserves Infused with Tonka Bean

plums in paper bag

I was raving about plums almost exactly a year ago and guess what, I’m still a huge fan of this slightly overlooked stone fruit. Since they are in season, you can get them on the cheap now and that’s exactly what I did.

The result: a new addition to my rapidly expanding jam collection. This time, it’s a thick plum preserve with no added sugar and an extra layer of flavor thanks to shavings of a firm, dark brown and somewhat wrinkly seed resembling a woody raisin: the tonka bean.

I haven’t even heard about this spice until my mother-in-law gave me a few pieces recently. Have you? This is what I’ve found out since:

This haute cuisine ingredient is actually the seed of the cumaru or kumaru tree, a plant native to Central America and Northern South America.

tonka beans

Tonka beans have been banned by the FDA for sale in the U.S. as a food item because they contain coumarin, a chemical that is believed to cause liver problems. In extreme concentrations, that is: at least 30 entire tonka beans would need to be eaten to approach levels reported as toxic, when a single bean is enough to flavor 50 servings of food.

Coumarin has since been found to occur naturally in cinnamon, lavender, licorice and other commonly eaten plants too by the way, which are, to my knowledge, still freely available. Seems to me as a rather overreaching ban, no?

“Dreaded” coumarin is responsible for the seed’s unique, complex and very pleasant odor coveted by the perfume industry for centuries: a rich, heady, fruity aroma somewhat similar to vanilla. Just the twist my humble plums needed! Lucky it’s legal here.

I wanted this jam to be not sweet. I’d like to try it with meat (duck and game come to mind instantly) and use it in desserts that call for some tartness. When you don’t add sugar, you need to increase the cooking time a great deal to ensure your jam won’t spoil. And that’s where a crock pot comes into play: the low and slow temps and the nonstick pan allows you not to stand next to the batch all day.

It’s hard to tell the exact time it takes for the plums to break down completely and thicken, but be advised it’s not a quick process. I turned the slow cooker on early on a Saturday morning, and it was already getting dark outside when I sealed the jars. It’s time intensive, but not labour intensive in return.

The washed, pitted and halved plums go in, the machine is set on low with the lid on. Every now and then you check on it to make sure it’s simmering slowly and not catching. As the preserve starts to thicken, you need to stir more frequently. Approaching the end of cooking time, grate a tonka bean with a microplane, as you would with nutmeg, to infuse the jam with the exotic notes. After preserves reach desired consistency, transfer to sterile jars and seal.

Love,

Fruzsi

Plums in paper bag hoto by Katrín Björk

Tonka beans photo by Rebecka G. Sendroiu

Making Jam Then and Now

flatlay jam

Strawberry season is at its peak, and all the other fruits will soon start arriving to your farmers market. Do you make jam?

By the way, what is jam? If you think this question is plain silly, you were not paying attention to the news. The heated debate over EU regulations concerning preserves, marmalade, fruit-spreads, jams and jellies is far from over, some describing those rules as an example of unnecessary red tape and “gold-plating” of European Union directives.

After reading numerous articles and even a guideline leaflet on the subject, I still haven’t the faintest idea how my grandmother’s apricot jam would be correctly labeled under European law, were it ever to be sold commercially.

See, this is because our lekvár (pron. lehk-waar) is quite unique to this region. To try illustrate the difference: jams are gelled to a quite clear consistency, fruit pieces are still identifiable. Lekvár on the other hand takes longer to make, is homogenous and thick like a puree.

You must have noticed the worldwide revolution going on in the home canning and preserving front lately. I’m also trying my hands at making small batch jams, something I honestly never thought I’d do. But let’s take a short trip down memory lane to see how we got here.

What used to be necessary frugality for our grandparents in order to save as much food as possible has turned into a creative activity, yet not so long ago during the 90’s and early aughts, granny’s jams were far from trendy.

Post-soviet era Hungary, social gap growing swiftly. I was a kid then, and I used to look at those 25 oz. jars neatly labeled and lined up on the shelves of the village pantry – I know how bad this sounds – as a sign of not being well-off. My classmates ate jams bought from the store (which now also carried Kellog’s, I mean wow!) in pretty little hexagon bottles, their relatives not bothering with at-home preserving any more.

Little did I know (and care) at the time that most of those products have never seen actual fruit; all I remember is finding our homemade apricot and plum jams uncool. Well, times have definitely changed! I’ve tried many different flavors since, and as much I liked most of them, I’ve established that none are a match to the classics when it comes to crepes (What Nutella? Please…) or carnival donuts.

Anyway. The jam making frenzy of today is different from our ancestors’ ways in many aspects. First of all, fortunately it’s not about what we’re going to eat during a long winter any more. It’s rather a culinary hobby and the result of the demand to know what’s in our food.

I respect tradition, but I also like to create new and unique flavors in my kitchen through experimenting with fruit combinations and adding spices. Standing-next-to-the-stove-stirring-all-day jam making and 1:1 fruit to sugar ratios are a thing of the past. Modern jams are made quicker thanks to natural gelling agents with less sugar needed. Shorter cooking times also preserve more of the goodness of the fruit, result in better color and a more intense flavor.

So far I’ve cooked up a festive plum jam, a cardamom and vanilla flavored apricot jam, a strawberry and raspberry jam with ginger and a nicely tart vanilla-infused triple berry (raspberry, blueberry and blackcurrant) jam. Next up, strawberries with a hint of lavender. I’ll let you know how it turns out!

Last summer I did a blog series on the principles of home canning based on USDA’s Complete Guide to Home Canning. If you feel like jumping on the bandwagon, feel free to refer back to my posts on food safety, sterilizing jars, ensuring the quality of your canned goods, and the steps of filling the jar properly.

Love,

Fruzsi

‘Sweet jar raspberry jelly homemade’ image by mrsiraphol / Freepik

Festive Plum Preserves

festive plum preserves title

Plums are in season in the late summer and early autumn weeks. Right now that is, and I think they are unfairly underrated. This fruit is not getting the recognition it deserves, and that needs to change!

An incredibly nutritional powerhouse, plums are rich in fibers and antioxidants, high in potassium that helps control blood pressure, fortified with vitamins A, B and C, and have a low glycemic index to help control blood sugar.

Brought to Europe by Roman legions from Asia-Minor, this undemanding plant is grown throughout Hungary. And yet, all we seem to be making from it nowadays is szilvapálinka (seel-vah-pal-in-kah, a strong fruit spirit) whereas not so long ago, thousands of cauldrons were bubbling with another traditional plum product this time of the year.

The almost black, very thick plum jam distinct of this region was made with no added sugar on an open fire for 10-20 hours, requiring constant attention and quite the physique to stir. Of course, very few people want to make such labour-intensive things lately, but back in the day especially in poor rural territories you could not possibly let any food go to waste.

The original, hand-made variety is not easy to come by. However if you stumble across it – let it be a farmer’s market or a distant slightly masochist kinswoman – make sure to put your hands on a jar or two! It’s cooked for so long and to such a thick consistency that the jam keeps for years even without high vacuum (used to be stored in clay jugs simply covered with paper).

I am lucky to have folks living in the countryside who provide us with such traditional goodies every now and then, so I get to be the modernist when it comes to preserves. I don’t think it’s cheating to use a slow cooker instead of wood and matches, and I’m not willing to process truckloads of produce either, but rather mix different fruits and play with spices. Although my jam making is still in its infancy, the latest batch I cooked up is something I need to tell you guys about.

festive plum preserves prepared fruit

Bought really beautiful plums for such a sweet price last week that I decided to try a knockoff version of the spicy plum jam that was given to us by my soon-to-be mother-in-law last year. Although I did not have the recipe, I’d say the concept is heavily borrowed from her (credit where credit is due). And.just.wow.

Everyone knows cinnamon and plums are BFFs, but this jam is in a whole different league. Ginger-effing-bread spice! That’s right. The house smelled like Christmas on an August afternoon while I was making it, hence the adverb festive. My long time fav is Kotányi’s spice mix – good news that they went international so you can probably buy it locally. Or you can always mix your own.

festive plum preserves seasoned

This preserve was ready in a fraction of the time required for the old-fashioned variety (sugar and some natural preservative needs to be added in return). I’d love to tell you an exact time, but it depends… so I just say this: look for the jellying point to determine when your preserves are done.

festive plum preserves cooking

You can use a food thermometer (105 °C or 220 °F is the number you’re looking for), or do this simple test: if syrup forms two drops that flow together and a sheet hangs off the edge of your spoon, it will set nicely.

festive plum preserves on bread

I’ll give you the recipe for 1 kg/2.2 lbs fruit (net weight), feel free to multiply.

Festive Plum Preserves

Ingredients

1 kg plums, washed, pitted, halved (or quartered if they are big)

30 dkg sugar

1 tbsp gingerbread spice

1 tbsp citric acid

Directions

  1. Put plums, sugar, citric acid and spice mix in slow cooker, set machine on medium. Fruit will start releasing juices.
  2. Bring to a boil, reduce to slow setting and simmer, scraping bottom occasionally to avoid sticking.
  3. When preserves reach jellying point, turn slow cooker off and transfer preserves to jars.
  4. Clean rims, adjust lids, and process in a water bath for 15 min.
  5. Let jars cool to room temperature, label and date.

Do you like plums? Is it a common fruit where you’re from? How do you eat them where you live?

Fruzsi

*Disclaimer: I like and use the products mentioned in posts on My Chest of Wonders. What I write about such items represent my genuine and unbiased opinion, I am not being compensated in any way through sponsorship or gifts.*

Preserving 101: Filling the Jar

preserving101-filling-the-jar-title

Ok, so we have safe, sterile jars and the fresh, beautiful produce to fill them with. No matter what recipe you decide on, there are a few principles that always apply when filling your jars. These include:

Controlling headspace. Headspace is the unfilled space above the food and below the lid. It is needed for the expansion of foods to be processed and for forming vacuums in cooled jars. Directions specify leaving 0,5 to 2,5 cm headspace. After wiping the jar rim clean, place the lid on and tighten.

Process times. To destroy microorganisms in your food, you must process jars for the correct number of minutes in boiling water or a pressure canner.  Take into consideration that if you live more than 300 m above sea level, you will have to adjust processing times due to water boiling at lower temperatures as altitude increases. For determining proper process times, consult the set of tables provided by USDA here.

Cooling jars. After removing hot jars from a canner (preferably with a jar lifter – safety first!), cool them at room temperature for 12 to 24 hours. Don’t try to rush the procedure by putting jars in cold water! My mother even puts jars under thick blankets to further slow the cooling process.

Testing jar seals. When jars have cooled, press the middle of the lids with a finger. If the lid springs up when you release your finger, the lid is unsealed. You can also check by holding the jar at eye level and looking across the lid, it should be curved down slightly in the centre as vacuum pulls it inward. If a lid fails to seal on a jar, change the lid and reprocess the jar, or store the food in the fridge and consume within a few days.

Storing canned foods. Clean completely cooled, tightly sealed jars if necessary. Label and date them, and store in a clean, cool, dark and dry place. Avoid direct sunlight, dampness (may corrode metal lids) and accidental freezing and thawing (may soften food).

Identifying spoilage. Very important: do not taste food from a jar with an unsealed lid or food that shows signs of spoilage! Swelled lids are a sign of gas produced be bacteria or yeasts. Also look for unnatural color or mold growth, smell for unnatural odors.

Hope you find this useful! Play by the simple rules I posted in this blog series and you can enjoy the fruit of your hard work, both literally and figuratively speaking. 🙂

Fruzsi

Preserving 101: Selecting, Preparing and Packing Foods

preserving101-selecting-preparing-packing-title

Welcome to the third part of the series! This time, it’s all about ensuring the high quality of canned foods. You’ll learn how to select and prepare products to best maintain color and flavor in canned goods, become acquainted with acidity levels and basic packing processes. Let’s get started!

Food acidity. To decide on the suitable preserving process for your goods, you have to get familiar with the acidity of foods. Low-acid canned foods are not acidic enough to prevent the growth of bacteria, while acid foods contain enough acid to block their growth or destroy them when heated. Acidity may be natural, as in most fruits, or added, as in pickled food. Acidity levels can be increased by adding lemon juice, citric acid, or vinegar. The measure of acidity is pH; the lower its value, the more acidic the food. Foods that have a pH level of 4,6 or higher are considered low-acid. I find this chart useful:

food-acidity-chart
Acidity of Foods Chart found on fix.com

Selecting products for canning. Either you buy from a grocery store, at the farmer’s market, or pick from your own garden, always examine food carefully for freshness and wholesomeness. Food products are mostly at their peak of quality within 6 to 12 hours after harvest, but apricots, nectarines, peaches, pears and plums can be ripened 1 or more days before canning. Keep fresh produce in a cool place, not exposed to direct sunlight. When preparing, discard moldy food, trim small diseased or bruised spots.

Retaining optimum color and flavor. Oxygen and enzymes are the enemy when it comes to looking good. Most fresh foods contain 10 to more than 30% air, and high quality depends on how much of that air is removed before the jar is sealed. Don’t expose prepared foods to air unnecessarily: while preparing a batch, keep peeled, halved, sliced or diced produce in a solution of 3 grams (1 tsp) ascorbic acid to 4 litres of cold water to prevent discoloration.

And now packing processes, or in other words, the methods used for preparing and placing food in a jar prior to sealing.

Raw-packing is the practice of filling jars tightly with freshly prepared, but unheated food. Such produce, especially fruit, will float in the jars, and the entrapped air may cause discoloration. The juice, syrup, or water to be added to the foods should be heated to boiling before adding it to the jars.

Hot-packing is the practice of heating freshly prepared food to boiling, simmering 2 to 5 minutes, and promptly filling jars. This method helps to remove air from food tissues, shrinks food, helps keep the food from floating, increases vacuum in sealed jars, thus improving shelf life. Use this process whenever possible! Within the storage period, both color and flavor of hot-packed foods will be superior to that of raw-packed.

That’s that for the day. In the next part of the series we are filling the jar!

Fruzsi

Preserving 101: How to Sterilize Jars

preserving101-how-to-sterilize-jars-title

Welcome back! In the second part of the blog series, we are going to discuss jars, lids and the sterilization process.

According to USDA, glass jars are the best choice for home canning because with careful handling, they may be reused many times. When canning properly, you can achieve an excellent vacuum and glass breakage is very rare. Tempered, Mason-type jars dedicated to home canning are sold widely, but most commercial jars may just as well be used. Every glass jar could be weakened by repeated use however. Seemingly insignificant scratches can cause cracking, and lids get tired after a while too. Make sure your glassware is free of nicks, check the condition of rubber seals on the lids.

how-to-sterilize-jars

Before every use, wash jars in hot water with detergent and rinse well (or wash in a dishwasher), let dry upside down on a clean teatowel. After this your jars are not ready to be filled yet! Choose from the 3 methods below to sterilize them. Be extra careful not to burn yourself. Jars and lids will be very hot, wear kitchen gloves to protect your hands.

Oven dry heat sterilization. Put pre-washed jars upright on a metal tray not touching each other, transfer to preheated oven for 45 min. on 160°C, 25 min. on 180°C, or 10 min. on 200°C.

how-to-sterilize-jars-in-oven

Boiling-water sterilization. Put jars right side up in a large pot with a rack at the bottom, fill with enough water to cover them completely. Bring water to a boil and simmer for 10 min. Remove and drain hot sterilized jars.

Steam sterilization. Some modern, top-of-the-line dishwashers have steam cycles (look for `Sanitize´ option) capable of reaching and maintaining 70°C or above. If yours is like that, simply fill it up with jars and let it do the rest for you.

Sterilizing lids. Use the boiling-water method. Dry heat can damage the rubber gaskets and thin out plastic parts, resulting in bad seal.

how-to-sterilize-jars-lids

There! You did everything to make sure your containers are safe to fill with all the deliciousness, and it wasn’t even complicated. And now, onto packing processes in the next part of the series. Stay tuned!

Fruzsi