This is less a recipe for plum jam, than it is a road map for how to make and bottle jam. The method described here is one of many ways to go about bottling jam, but there are some bottling universal truths that apply to all approaches and I hope to cover these. Although not beautifully illustrated, I hope you find this post enjoyable and useful. Please feel free to comment, I am always looking for ways to improve my technique and new ideas for things to put in bottles.
Universal truth # 1: choose quality, ripe fruit. Your final product is only ever as good as your raw material. You can save money by buying fruit direct from the grower that is wind-fallen, marked or too ripe to ship to markets further afield. You will find that you can even negotiate with the farmer to purchase top grade fruit in bulk for a good price (I negotiated to get 10 kg’s of plums for $3o, usually $4.99 /kg from the same grower). I prefer to buy fruit like this because it hasn’t been shipped long distance in cold storage through centralized transport networks run by the New Zealand supermarket duopoly. I think that you can taste the difference in the fruit and the final product. Some varieties will bottle better than others. In my experience to date, old fashioned varieties seem to make better jam because they were bred to be eaten as opposed to many modern varieties which often have been bred to ship well and look good on the supermarket shelf. For specifics in your region I suggest finding a local grandma and asking her. Finally, I would recommend scouting around your neighborhood. You may find back yard fruit laden trees with owners who would be happy to trade a box full for a couple of jars of jam. There are also some local food initiatives cropping up around the place that will help your foraging.
I used black doris plums, an old variety never seen in the supermarkets but a common sight in Kiwi back yards and farmers markets at this time of year. This fruit does not travel or keep very well so be prepared to make the jam soon after acquiring your black doris plums. I made plum sauce with these a couple of weekends ago and the recipe is posted here.
Universal truth # 2: bottling can be done on the cheep. There is no need to spend lots of money on jars and specialized equipment. My jam jars are mostly recycled jars that I have collected myself been gifted by friends and family. Recently a workmate gave me several boxes of large, mint condition bottling jars that his mother had stored unused in the shed on their farm. I am sure there are many such cashes of jars around, so scout on-line trading websites, ask your friends and colleges and find the hoarder out there who is ready to give up their stash. When recycling jars they must have perfect rims with no chips or cracks, otherwise the jars will not seal. If you must buy jars, look around for a jar and bottle wholesaling website. Most of these places will ship a single box of jars and they will be much cheeper than buying singly at a retail outlet. A large pot is a must, but you should be able to pick up a cheep stock pot. I would like a jar lifter for handling hot jars, but have yet to find a reasonably priced one, so I make do with barbeque tongues and thick hand towels to protect my hands. You can buy specialized bottling funnels or make your own by cutting the spout short on a cheep plastic funnel. The funnel will help you fill jars without splashing food on the rim (it’s really important to keep your rim clean). However, this is another specialized piece of equipment that I don’t have. I use a jug with a good spout that doesn’t drip, a steady hand and a clean tea towel to wipe away the occasional stray drop.
Universal truth # 3: clean equipment is the key to successful preserving. Although we live in an age where we are all barraged by advertisements about evil animated bacteria and all the products we can purchase to protect ourselves and our families from them, I feel like a lot of people don’t understand what it takes to make your preserving equipment clean. You can’t beat a good scrub in hot soapy water and a rinse in hot running water followed by drip drying. Do not use a tea towel to dry the inside of your jars as nine times out of ten they are just adding bacteria back into the mix.
Now your fruit and equipment are acquired and prepared you are ready to hit those long pored over recipe books for a recipe. Heres one…
Plum Jam Recipe
Quarter plums, remove stones, add to a large pot with 1/4 C water, stew fruit, measure fruit pulp, return to pot with about 1 C sugar for every cup of fruit pulp, boil sugar and fruit until the jam reaches setting point, pack into jars and seal.
When I first started making jam I was frustrated by the brevity of the recipes and the absence of definite quantities or times. After making a couple of batches I realized that once you know about how it’s meant to go, long complicated instructions aren’t required and definite quantities and times aren’t piratical because they vary depending on your raw material. I have found, however, that most recipes have more sugar than suits my taste. I would recommend tasting before adding all of the sugar and while bearing in mind the the basic flavors (salty, sweet, sour etc.) seem stronger when something is hot. When making this latest batch of jam I ended up adding 9 C sugar to 12 C fruit pulp (instead of the 1:1 most recipes recommend). Sugar is what preserves the jam and ensures the set, but I haven’t have any problems with my jam shelf life yet. The 1962 edition of the Good Housekeeping Cookery Book, from which I learnt much about jam making, says that you can make low sugar jam by reducing the recommended volume of sugar by 20%, but the jam will be runny and should be kept in the fridge and consumed within 6 weeks.
Before you add your sugar, however, you should consider weather your jam will set…
Universal truth # 4: you can boil jam until the cows come home, but it will never set if there is no pectin. Pectin is a natural protein and setting agent that is found in fruit, some more than others. Cooking apples, grapefruit, lemons, limes and quinces are relatively high in pectin. Apricots, blackberries, dessert apples, plums and rasberries have a medium amount of pectin. Soft fruits, such as strawberries and cherries, nectaries or pears, are low in pectin. Stems such as rhubarb (rhubarb and strawberry jam – nom nom) and vegetables are low in pectin. Acid assists in the extraction of pectin from fruit, so sometimes the addition of a tablespoon or two of lemon juice will help your set. If you are of the experimental ilk, you can test for pectin content just before adding the sugar to your jam. Take one teaspoon (5 ml) of fruit juice from your stewed fruit, cool and place in a jar with one tablespoon (15 ml) methylated spirit. Cap the jar, shake and rest for one minute. If the jam forms a jelly-like clot there is enough pectin to achieve a set. If the fruit juice remains distributed, your jam will not set without additional pectin. If you are making jams from low pectin fruits, you can add powdered pectin (available in the baking section of most markets – just follow the directions on the pack). Aulternativly, you can make your own pectin extract.
Homemade Pectin Extract
(Good Housekeeping Cookery Book, 1962)
Without peeling or coring, wash and chop 1 kg of sour cooking apples, crab apples, gooseberries or redcurrants. Cover with 600-900 ml of water and stew gently for 45 minutes, or until pulp. Strain through muslim cloth and test the pectin content using the method described above. Add 150-300 ml of homemade pectin extract for every 2 kg of low pectin fruit.
Setting point is the point at which you can be sure your jam will set. After you have added sugar and returned the jam to boiling point you can start testing for the setting point. Place a plate in the refrigerator and at five minute intervals place a spoonful of jam on the plate and return to the refrigerator. After five minutes test the last drop of jam by gently pushing it with your finger. When the setting point has been reached a skin forms. Pushing the drop of jam with your finger will rumple this skin and make it visible. You can also use a sugar thermometer to test this point; when the jam reaches 105 degrees Celsius it is ready. Taking a jam past its setting point will weaken its setting properties. The plum jam took nearly an hour to reach setting point. However, the marmalade I made earlier this summer only took 15 minutes to reach this this point.
Once your jam has reached setting point, rest it for 15 minutes. This will ensure that any whole fruit, like strawberries, or chunks of pulp do not sink to the bottom of the jar. In the mean time you can heat your clean jars to 100 degrees Celsius (I use the oven) and boil your clean lids for a least five minutes. Take care not to place your hot jars direct on the aluminum bench. The shock change in temperature will crack them. I place the oven tray of jars on a wooden chopping board to avoid this.
Fill your jars nearly all the way to the top, taking care not to spill jam on the lip of the hot jar. If you do drip a little, wipe away with a clean towel. Cap with one of the boiling hot lids. I use barbeque tongs to fish out the lids and thick hand towels to handle the jars and screw on the lids.
Set you jars of jam somewhere draft free to cool. Check the seal the following day. If your jam has not set to your liking, you can tip it back into the pot, bring back to the boil, add more pectin, test for setting point and re-bottle.
All this may seem a little complicated at first, but it soon becomes second nature. Making jam is an awesomely rewarding activity both in a culinary sense and a social sense. Commercial jams just don’t have the same depth of flavor as home made and jam makes a great gift. I love making personal labels for my jam and gifting it to friends and family. Let me know if you have any questions and I will do my best to answer them. Happy bottling.