Mixed Berry Jam

Add raspberries and blackberries to a bowl. Add Splenda and lemon juice. Mix and leave to macerate for 20 minutes. Heat mixture over medium heat in a small pot for 15-20 minutes until mixture reduces by about half and thickens. Mash berries with a potato masher to desired smoothness. Place into sterile mason jars and seal tightly. Leave to cool to room temperature and then store in the refrigerator. Jam will last about 3 weeks in the refrigerator, or store in the freezer.