Much like gelatin and citric acid, pectin is one of those scientific-sounding ingredients that I misunderstood for years. I had some general awareness of its gelatinizing powers, but pegged it as another shelf-stable powder used almost exclusively in professional kitchens. Then I realized I had actually seen pectin in action many times before—and if you’ve ever made homemade jam, you probably have too.
Commercial pectin is available to buy at the grocery store, but it’s also found naturally in just about every fruit and vegetable. A long simmer on that stove will cause sugared fruit to soften, releasing juices and eventually thickening into glossy, spreadable jam. That’s pectin in action, baby! Pectin is the reason why jam gets so, well, jammy, and why certain fruits gel up faster than others.
Today, we’ll learn how to use pectin to perfect your homemade jams, jellies, and preserves.
What is pectin?
Pectin is a naturally occurring thickener and stabilizer, helping jams, jellies, and fruit preserves set. Scientifically speaking, it’s a soluble fiber (a.k.a. a type of polysaccharide) found in the cell walls of most fruits and vegetables. “When heated with sugar and acid, pectin forms a kind of mesh that traps liquid,” says Camilla Wynne, author of Jam Bake. “As it cools, it sets and suspends pieces of fruit.”
Certain fruits—like apples, quince, currants, cranberries, grapes, and citrus—naturally contain high levels of pectin. That’s why marmalade gets so glossy and cranberries transform into that wobbly Thanksgiving sauce. Other fruits—like strawberries, peaches, sour cherries, rhubarb, tomatoes, and pears—have much lower pectin levels. Instead of firming up when exposed to heat, these fruits are more likely to turn mushy. To make them into jam, you’ll typically need to add more sugar and/or an extra thickening agent, like commercial pectin. Then there’s the in-between: fruits that contain moderate pectin levels, but do not gel as quickly or easily as high-pectin fruits. This category includes apricots, raspberries, blackberries, mulberries, bananas, and plums.
The type of fruit isn’t the only consideration here. Generally speaking, the riper the fruit, the less pectin it contains. Lillie O’Brien, author of Five Seasons of Jam and chef behind the London Borough of Jam, recommends using fruit just as it begins to ripen—that’s when the pectin level is at its highest.
How does pectin work in jam?
Most jam recipes call for three core ingredients: fruit, sugar, and acid, like lemon juice (get our go-to jam formula here). As the mixture simmers, the sugar leaches water out of the fruit, allowing the pectin inside the fruit to react with the acid and bind into a powerful, liquid-trapping web. Like certain types of starch, pectin needs to heat to a certain temperature in order to activate. At 220°F (jam’s setting point), the pectin chains in the fruit naturally bind to each other to create that jelly feel. As soon as it hits that magic temperature, remove it from the heat: If pectin gets too hot, it loses its setting power.
If you’re working with a fruit with a moderate or high pectin level, you don’t need to do much to achieve a spreadable consistency. If you’re working with low-pectin or overripe fruit, adding flavorless commercial pectin is one way to achieve a thick, jammy texture. “There is absolutely nothing wrong with adding pectin to preserves, especially if you like a more consistent product,” says O’Brien.