Place apples, golden raisins, currants, raisins, suet, allspice, cinnamon, brown sugar, citrus peel, almonds, lemon rind, lemon juice, brandy, ginger, and nutmeg in a large bowl and mix thoroughly. Cover and store in refrigerator for 2 days to allow flavor to mature.
Sterilize enough canning jars and lids to hold mincemeat.
Pack mincemeat into sterilized jars, making sure there are no spaces or air pockets. Fill jars all the way to top. Screw on lids.
Place a rack in the bottom of a large stock pot and fill halfway with boiling water. Carefully lower jars into pot using a holder. Leave a 2 inch space between jars. Add more boiling water if necessary, until tops of jars are covered by 2 inches of water. Bring water to a full boil, then cover and process for 30 minutes.
Remove jars from pot and place on cloth-covered or wood surface, several inches apart, until cool. Once cool, press top of each lid with finger, ensuring that seal is tight (lid doesn't move up or down at all). Mincemeat should be aged 2 or 3 months before using, but can be stored up to a year.