Peel peaches, remove pits and purée flesh in a blender or food processor. Combine peach purée, sugar and corn syrup in a medium saucepan. If using, stir in a pinch of Aleppo chile flakes. Bring to a simmer, stirring constantly just until sugar is dissolved. Pour mixture into a metal pan or bowl and place in the refrigerator to cool for at least 2 hours or until well chilled. Combine cooled purée with beer. Freeze mixture in an ice cream freezer it is the consistency of soft whipped cream. Transfer to a storage container and press a piece of parchment onto the surface of sorbet. Freeze in the coldest part of the freezer for at least 4 hours or until firm.