There is a great overview here that has information about acid reflux diets, prevention and what to avoid. Jennifer Rackley is a resident expert who is also a nutritionist. You can read about Jennifer here and her share posts here.
Grapes are on the list of foods to watch because aparently the level of acidity is dependant on where the grapes are grown. For instance grapes grown in warmer climates tend to have lower acidity than grapes grown in cooler climates. Similarly the sugar content is the opposite. Warmer climates make for sweeter grapes. Now this information is only good if you are planning to make wine, but it is an interesting factoid. :)
Take care and stay in touch!
* Avoid: citrus fruits, cranberry juice, tomatoes and tomato-based foods, peppers, onions, spicy foods, most dairy products, caffeine, high-fat foods, deli meat, cheese, fatty cuts of meat, alcohol, and chocolate.
* Be Careful: berries, grapes, garlic, lean meats, yogurt, non-alcoholic beers and wines, sodas, reduced-fat cookies.
* Enjoy: apples, bananas, broccoli, carrots, peas, green beans, chicken breast, fish, fat-free or low-fat cheeses, whole-grain bread, brown rice.