Plum Jam

Ingredients

Equipment Needed

• •8-quart or larger wide stainless-steel preserving pan
• •Kitchen scale
• •Long flat wooden spoon
• •Two small freezer-safe saucers
• •Water-bath canner or deep stockpot with rack
• •Eight 250 ml preserving jars with new lids
• •Canning funnel, ladle, jar lifter, and narrow spatula
• •Sugar or preserving thermometer, optional

Instructions

1. 1

   Ready jars and tests

   Place two small saucers in the freezer for testing the set. Wash eight 250 ml preserving jars, prepare new lids according to their maker’s directions, and hold the jars hot in a water-bath canner fitted with a rack. Keep enough water in the canner to cover the filled jars by at least 1 inch (2.5 cm).

   Have the jars, funnel, ladle, and clean cloth waiting before the fruit cooks. Once the confiture reaches its set, it should move directly into hot jars.
2. 2

   Prepare the plums

   Stone the plums and weigh out 4 lb (1.81 kg) after the stones are removed. Halve small plums and quarter large ones so they cook at the same pace. Leave them unsugared beside the stove only while you make the syrup. Do not macerate them: the acid in the waiting fruit blackens its color.

3. 3

   Boil the sugar syrup

   Combine the sugar and 1½ cups (360 ml / 360 g) water in a wide, heavy, nonreactive preserving pan. Warm gently, stirring only until every grain dissolves and the syrup turns clear, then skim away any dull froth. Bring it to a full boil and boil uncovered for seven to eight minutes without stirring. This separate syrup is not brigade ceremony; it protects the fruit from a long wait under dry sugar. If crystals form around the sides, lower the heat and cover the pan for one minute so condensation washes them down, then continue. Ça se rattrape.

4. 4

   Cook the fruit quickly

   Slide the plums carefully into the boiling syrup. The syrup may stiffen briefly around the cooler fruit, which looks alarming but is exactly right; the plum juices will loosen it. Return the pan to a strong rolling boil and cook rapidly, stirring across the bottom with a flat wooden spoon so nothing catches. Begin checking after 12 minutes and expect 15 to 25 minutes altogether, depending on the variety and ripeness. Reine-claude needs this small batch, broad pan, and quick fire to keep its fine green color.

5. 5

   Judge the set

   Drop a teaspoon of confiture onto a frozen saucer, wait 30 seconds, then push it with one finger. It is ready when the surface wrinkles lightly and the path left by your finger does not immediately flood. The syrup should also fall from a cold spoon in a broad sheet rather than separate drops; at sea level, a thermometer usually reads 104 to 105°C (219 to 221°F), but the plate test governs. If it runs, boil for two more minutes and test again. If it turns stiff or ropey before filling, remove it from the heat and stir in boiling water 1 tablespoon (15 ml / 15 g) at a time until it relaxes. Skim the surface clean and stop cooking promptly, because the confiture firms further in the jar.

6. 6

   Fill and process jars

   Ladle the hot confiture into the hot jars, leaving ¼ inch (6 mm) headspace. Release trapped air with a clean narrow spatula, wipe the rims, fit the lids, and tighten the bands only to fingertip tightness. Lower the jars into the boiling-water bath, cover, and process for 10 minutes once the water returns to a full boil. Increase the processing time for altitude according to local preserving guidance.

7. 7

   Cool and store

   Lift the jars straight up and place them on a towel without tilting. Leave them untouched for 12 to 24 hours, then check that every lid is firmly sealed. The set may take a full day to settle, so do not condemn a soft-looking jar while it is warm. Remove the bands, label the jars, and store them in a cool, dark cupboard. Refrigerate any jar that fails to seal.

Chef Tips

• •Use the scale. The source proportion is exact: 12 oz sugar for every 1 lb stoned plums, which is 750 g sugar per 1 kg fruit. Measuring the fruit before removing the stones leaves the confiture short of sugar and weakens both its set and keeping quality.
• •Choose ripe, fragrant fruit that still holds its shape. Very soft plums collapse before the syrup reaches its set; damaged or fermented fruit belongs nowhere near a preserving jar.
• •For reine-claude, keep the batch small and the fire quick. This four-pound batch sits safely below the old kitchen’s six-to-eight-pound limit, allowing water to escape before the green fruit dulls.
• •Loaf sugar was highly refined white sugar sold in a solid form. Plain white granulated sugar is its honest home equivalent because it contributes the same clean sweetness and dissolves more evenly.
• •At elevations above 1,000 feet (305 m), extend the water-bath processing time according to tested local guidance. Canning safety follows altitude, not instinct.

Advance Preparation

• •Prepare the jars, canner, tools, and frozen testing saucers before stoning the plums. The fruit may be washed and dried earlier, but do not combine it with the sugar ahead of cooking.
• •Leave sealed jars undisturbed for 12 to 24 hours so the set can finish. Properly sealed jars keep their best color and flavor for about 12 months in a cool, dark cupboard.
• •After opening, refrigerate the confiture and use it within one month. Refrigerate an unsealed jar immediately and use it within three weeks.

Frequently Asked Questions

Nutrition Information

1 serving (about 310g)