Preserves I make with frozen fruit don’t set well. Can you explain this? It seemed such a good idea to freeze fruit now and make jam when I am less busy.
Hilde, West Sussex
The summer months are made for jam sessions, Hilde. But, while freezing is a good way to preserve the season, it all depends on the type and condition of the fruit you’re using. “Jam is the hardest preserve to make, because it relies on a chemical reaction to get a set,” says Kylee Newton, owner of Newton & Pott and author of The Modern Preserver. “I would stick to freezing berries and rhubarb, and I wouldn’t freeze citrus fruit as it’s all just juice.” If you’re punting for apples, Newton blends the pulp before freezing.
Jam tastes best using freshly picked fruits that are not too ripe. “Frozen fruit can be used very successfully,” says Pam Corbin, author of Pam the Jam: The Book of Preserves, who recommends buying from britishfrozenfruits.co.uk. “However, if the fruit is wet, or over-ripe, and then frozen, this may result in runny jam.”
Fruit secured, do you defrost? This is where the camp splits: “Generally, you don’t, and certainly not for raspberries, strawberries or soft-skinned fruits,” Corbin says. “It’s best to get the sugar on to them quickly so they hold their shape and to draw out the juices.” Freezing, Corbin says, breaks down the skin tissue, so when it comes to gooseberries and plums, she heats them gently to soften the skins, while blackberries, raspberries, strawberries and apricots are left to macerate with sugar for half an hour. Newton does defrost, and advises against adding any extra water (frozen fruit retains enough), even if the recipe calls for it. If you’re mixing fresh and frozen fruit, the bulk of it should be frozen. “If I want whole bits of fruit in my jam, I cook down the frozen fruit first, bring it to a nice, bubbly heat – making sure it’s not sticking on the bottom – add the sugar, which should dissolve quickly, and then the unfrozen fruit.”
If you’re struggling to set your jam, it’s most likely down to the cooking: “If you’re getting a thick, syrupy mass, then you’re cooking it for too long and missing the setting point,” Corbin says. “I would much prefer undercooked jam, because you can always redeem it by boiling for a couple more minutes.” Besides opting for higher-pectin fruit, Corbin suggests (members of the WI, look away now) trying jam sugar, or a combination of jam and ordinary sugar. Her optimum temperature for setting is 104.5C. “Once you get there, the heat increases by the second, so err on the lower side: I always tell people that jam sets in the jar, not in the pan.” Corbin uses the gel (or wrinkle) test: “You’re looking for what I call a rhinoceros skin.” If it reaches setting point in 30 seconds on the plate, you’re there. The level of pectin in fruit becomes weaker over time, so Newton waits for the bubble change, from rolling boil to ploppy: “As the pectin reacts and wants to set, the bubbles find it harder to get through: At the beginning, you want to get that fast, rolling boil, then, as it gets heavier and ploppier, turn the heat off and do the wrinkle test.”
Keeping jam at a high temperature is key: “It gets spitty and nasty – it’s like beekeeping: you’re going to get stung.”
You want to get to setting point as quickly as possible – the longer you leave it, the more likely the fruits will turn to sugars and become super-sweet. “It is a fine line,” Newton warns. “You don’t want it to stick to the bottom and burn, but you also don’t want to stir it so much that a lot of air gets in and cools it down.”
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