There are different types of treacle, Black is only one, Golden Syrup is a lighter-coloured type of treacle and often substituted with corn syrup in recipes where black treacle is not available. In Britain, the main producer of black treacle (and Golden Syrup) is sugar refining company Tate and Lyle.
Roasted grapes are sophisticated. Toss grapes with olive oil, salt, and pepper, and roast them on a sheet pan for about 30 minutes at 425Â°F. The grapes will get blistered and caramelized on the outside, and extra juicy and practically jammy on the inside.
You will need somewhere between 50 and 60 pounds of grapes for each 5 gallons of wine that you wish to yield. (That's about 10 to 12 pounds per gallon.) Fifty pounds of freshly-picked grapes will fill about twelve gallons worth of volume (2 six-gallon buckets, etc.) There is a lot of debate about how many grapes to use. Some people use 100 pounds per five gallons, just as in a normal wine grape recipe.