Ingredients 
The answer is that you can always safely reduce the amount of sugar in a recipe, because sugar doesn't make things safe. The only thing that makes a jam, jelly or other sweet preserve safe for canning in a boiling water bath canner is the acid content, because that's what prevents any potential botulism growth.
As the jam reduces, it will thicken. You may need to reduce the heat to a slower boil as the jam thickens but keep stirring frequently. This stage should take about 30 minutes, but the deeper the pot, the longer it will take. It should take about 10 minutes if using a small 1 kg amount.
Standard recipes for canned jams and jellies rely on pectin to thicken the fruit and make it jell. Pectin, though, is very sour, so it must be offset with sugar?a good bit of it. The sugar also helps to preserve the quality of the fruit when canned. Read more: apricot jam no sugar.
Coarse-grain white granulated sugar is best for jam-making as it ensures a good clear jam, but fine caster sugar can also be used. The coarse grains dissolve more slowly and evenly, giving a better result. Granulated sugar with added pectin is also available, but it shouldn't be necessary to use this. Previously: confectioners sugar made of.
Further reading: raspberry jam no sugar.
Jams usually contain about 60% sugar, which is enough to stop most microorganisms growing.
It's too late to add more sugar if the jam has already set and cooled. In this case it can be thinned out by mixing in a little sugar syrup. If the jam is very firm and has a rubbery consistence, gently warm it while adding the syrup. But do not bring it to the boil again.
No Sugar Needed Pectin is a unique product that allows you to choose both the type and level of added sweetener. Unlike other pectins, fruit spreads made with this pectin do not require substantial quantities of sugar to gel. You can use no sugar at all, regular sugar, a sweetener or honey.
Do no stir jam once boiling, but use a wooden spoon to check it is not sticking on the base of the pan. Stirring lowers the temperature and delays setting point being reached. It is wasteful to remove scum too often. Do it at the beginning and at the end.
The lemon juice lowers the pH of the jam mixture, which also neutralizes those negative charges on the strands of pectin, so they can now assemble into a network that will “set” your jam.
Jams and jellies have a similar nutrient composition, and their pectin content may offer some health benefits. However, they're high in sugar and should be consumed in moderation. Also check: raspberry jam low sugar recipe.
Jams and Jellies with HoneyOntario honey may be substituted for sugar in most jam and jelly recipes. If a recipe calls for 4 cups sugar, use 2 cups honey. Cook the jam or jelly slightly longer than time stated in recipe using sugar. When substituting honey, use a commercial liquid or powdered pectin. Read about plum jam canning recipe.
Brown sugar can be used to make jam. You can use the same amount as if using granulated sugar. However, be prepared for some change in texture and flavor. In terms of flavor, you'll get an additional note since most commercial brown sugar is mixed with molasses. See also vanilla sugar definition.
jam sugar is sugar with added pectin. If you can't find preserving sugar then just use regular granulated sugar and skim any white froth off the surface of the marmalade once it has boiled and reached setting point and has been taken off the heat. Further reading: plum jam making.
Containing less sugar and more dietary fiber per serving, both apricot jam and jams in general are more healthful than marmalade. With much more vitamin C and iron, jam is both more beneficial and less detrimental to your diet than marmalade. See also: potato flakes woolworths.
While jelly has the smoothest texture of them all, jams are a bit thicker, and preserves boast the most body, thanks to their chunky fruit pieces. If you're more into a thick strawberry spread on your PB&J, buy a jam. And if you're looking for a more chunky mouthfeel, opt for preserves or an orange marmalade.
For our recipes, we're using anywhere from ¼ cup to ¾ cup sugar per pound of fruit. However, if you feel it needs a little more — if it's not sweet enough, or if it's too tart for your liking — you can add a bit of sugar to the recipe, to taste.
If your recipe called for lemon juice and you forgot to put it in, your mixture will not be acid enough for safe canning. You have to open the jars and put the mixture into a sauce pan. (If you made the jam or jelly recently and you carefully remove the lids without damaging them, you can re-use the same lids.)
Sugar: Sugar amount will vary depending on the sweetness of your fruit. Citrus: Orange or lemon work well and serve a few purposes. The juice of the citrus adds acidity, helping to bring out the fruity flavors. The zest adds natural pectin, helping to thicken the jam (while also bringing a lot of flavor!) Further reading: raspberry jam with jello recipe.
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