Why did my cheese fondue turn grainy?
Usually it is too much heat or adding the cheese too fast, but a few other things can tip it into grainy territory: low acidity (the wine and lemon juice help), using pre-shredded cheese (anti-caking agents can make melting weird), or letting it overheat after it is fully melted. Keep the heat gentle, add cheese in small handfuls, and stir constantly until smooth.
Do I have to use wine?
Wine helps with both flavor and texture, and the acidity matters for a smooth melt. If you want a non-alcohol option, try non-alcoholic dry white wine or apple cider for a similar vibe. You can also use low-sodium chicken broth plus 1 to 2 teaspoons lemon juice, then taste and add more if needed. Broth works, but it will shift the flavor more than wine.
Also, a quick reality check: at fondue temperatures, alcohol does not fully cook off. If you are avoiding alcohol entirely, choose a non-alcoholic swap.
Can I make it ahead?
You can grate the cheese and toss it with cornstarch up to 24 hours ahead. Keep it covered in the fridge. For the smoothest melt, let the cheese sit at room temperature for 15 to 20 minutes before you start. Fondue itself is best made right before serving so it stays silky.
What if my fondue is too thick?
Stir in warm wine (or milk) a tablespoon at a time over low heat until it loosens. Thick fondue is common as it sits, especially if the flame is too high.
What if my fondue separates or looks oily?
Take it off the heat and whisk gently. Adding 1 to 2 teaspoons lemon juice can often help it come back together. If it still looks broken, whisk in a small pinch more cornstarch mixed with a teaspoon of cold water, then return to very low heat and whisk until it smooths out. It is not a guaranteed rescue every time, but it is a solid save to try.