• Wash the jars in hot soapy water and either put in a roasting tin and sterilise in the oven at 160°C/fan 140°C/gas 3 for 10 mins or put upside down in the top of the dishwasher and run a hot wash without detergent. The jars need to be warm when filled so time this carefully. Put two saucers in the freezer.
• Prepare your fruit by chopping into even sized pieces. Put in a large heavy-based pan with the lemon juice and sugar. Add flavourings of your choice, tied up in a muslin bag if necessary. If you are adding liqueur this is stirred in at the end.
• Heat the fruit and sugar gently, stirring until the sugar has dissolved, then increase the heat and bring to the boil. Keep the jam at a good boil, stirring, until the setting point of 105° C is reached on your Thermapen Mk 4. Or use the wrinkle test, see below.
• Skim off any excess scum from the surface of the jam using a slotted spoon, then stir in a knob of butter to remove any residue.  Cool the jam for 10-15 mins, then stir to distribute the fruit evenly and ladle into the warm jars, using a jam funnel if you have one. Add wax discs to the surface of the jam and screw on the lids. When cool add the label with the type of jam and date made.
• Store your jam in a cool dry place.

Testing your jam for set

• There are various ways of checking your jam is set. The most reliable is using a digital thermometer such as the Thermapen Mk 4 as it takes the guesswork out of the process and ensures you don't overcook the jam and preserve all the fruity flavours.
• Another test is to put a couple of saucers in the freezer when you start your jam making. When you think the jam has set, remove it from the heat and spoon a teaspoonful onto a chilled saucer. Leave a minute, then push the jam with your finger, if it wrinkled the jam is ready, if not return to the heat and boil for a further 5 mins before retesting.

Choice of sugar

PRESERVING SUGAR

• This is a large crystal sugar with no added pectin making it perfect for high- medium pectin fruits

JAM SUGAR

• This is large crystal sugar with added pectin for use with lower pectin fruits. Both these sugars produce clearer results with less scum than granulated sugar, though they are more expensive.

Choice of fruit

• Use fruit in season, preferably perfectly ripe or slightly underripe for the best results.Frozen fruit is also very good for making jam.

HIGH PECTIN FRUIT

• Plums
• damsons
• blackcurrants
• redcurrants
• white currants
• apples
• rosehips

MEDIUM PECTIN FRUIT (use either sugar)

• blackberries
• apricots
• blueberries
• loganberries

LOW PECTIN FRUIT

• peaches and nectarines
• strawberries
• rhubarb
• cherries
• passion fruit
• figs

Flavouring your jam

• Make the jam your own by experimenting with flavours. Here are a few suggestions to get you thinking. Whole spices and herbs need to be wrapped in muslin before adding to the fruit.
• Spices- cinnamon, star anise, ginger, fennel or mustard seeds, black pepper, cardamom, nutmeg
• herbs- bay, rosemary, basil, lemon verbena, mint, lavender
• Other flavourings-lime, orange, vanilla  pods, rosewater, orange flower water, liquorice, earl grey or lady grey tea
• Liqueurs
• Sweet wine such as moscatel, crème de cassis or sherry, or liqueurs such as  Cointreau or limoncello, or even a splash of gin, brandy or whiskey can be added after the jam has set, no more than 4 tbsp per batch.
• You can add half with the fruit and the rest after the jam has set to really cook in the flavour.