Boil together the sap, raisins and sugar for 5 minutes. Allow to cool, then add the orange juice, yeast nutrient, acid and tannin. When the temperature has fallen to 21°C add the active yeast and stir well. Cover the vessel and leave to ferment for four days.
Strain the must and fill the wine into a clean demijohn. Fill to approximately ½” below the cork, fit airlock and ferment until dry.
Rack and store in a cool place.
If the wine is too dry, sweeten with a heavy sugar syrup.