In its simplest form, a conserve is nothing more than a foodstuff that been processed with sugar. When I was a kid, our local brand, Mary Ellen Jams, had the slogan: ‘a cup to a cup’. They explained that the slogan meant that there was a cup of sugar for every cup of fruit. That has been my jam recipe ever since. As a means of preserving fruit, jams have been around for centuries. Two hundred years ago, most general cookbooks would have a whole section dedicated to preserving fruit in a myriad of methods, but it’s not until the last half of the nineteenth century that recipes for carrot jam become common.
The process of making carrot jam is not much different than that for using other ingredients. The pulp of the fruit or vegetable is cooked with sugar until it is hot enough to gel when cooled. By adding some lemon juice, the acidity is increased to help with preservation and to heighten the flavour. Classic recipes also add a bit of alcohol to help with the preservation. If you make the preserve with juice rather than pulp, you’ll have jelly. (This is not jelly in the sense of a gelatine dessert, but jelly like quince jelly or redcurrant jelly.)
Carrots are considered high in pectin, the polysaccharide that crosslinks to form the gel that differentiates jams from a simple purée and jelly from a glass of sweetened juice. Carrots also have a bit of calcium which induces the pectin to do its thing when conditions heat up.
The first thing to do when making the jam is to place half a dozen or so metal soupspoons in your refrigerator. I suppose my ancestors used silver spoons, but I settle for stainless steel.