Place the plums, pineapple, apple juice, orange juice concentrate and lemon juice into a large pot over medium-low heat, cover, and cook until the plums are soft, 15 to 20 minutes. Mash the plums and pineapple with a potato masher until thoroughly broken up, but leave small chunks of fruit in the mixture. With the fruit mixture at a slow simmer, stir in the cloves, allspice, pectin and butter (to reduce foaming). Raise heat to high and bring the mixture to a full, rolling boil for 1 minute, stirring constantly. Mix in the sugar, stirring constantly, and cook for 1 more minute at a full, rolling boil. Remove from heat, stir in red food colouring until even in colour, and skim off any foam.
Sterilise 350ml canning jars and lids in boiling water for at least 5 minutes. Pack the plum jam into the hot, sterilised jars, filling the jars to within 5mm of the top. Run a knife or a thin spatula around the insides of the jars after they have been filled to remove any air bubbles. Wipe the rims of the jars with a moist paper towel to remove any food residue. Top with lids and screw on rings.
Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil over high heat, then carefully lower the jars into the pot using a holder. Leave a 5 cm space between the jars. Pour in more boiling water if necessary until the water level is at least 3 cm above the tops of the jars. Bring the water to a full boil, cover the pot, and process for 10 minutes.
Remove the jars from the stockpot and place onto a cloth-covered or wood surface, several centimetres apart, until cool. Once cool, press the top of each lid with a finger, ensuring that the seal is tight (lid does not move up or down at all). Store in a cool, dark area.