Apple fruit pectin
To prepare liquid apple pectin use under-ripe sour apples. Quarter the apples, and place in pot with just enough water to cover. Place a lid on top & put it on low-heat for a long time until fully cooked with a runny sauce consistency (stir every 20 minutes). Strain liquid with a cheese cloth or material. The liquid that drips out (slowly over many, many hours) the bottom should be a clear, thick liquid that’s a little bit slimy to the touch. That’s your liquid apple pectin.
Modified from Source: http://www.wildflowers-and-weeds.com/The_Forager/pectin.htm