Food Sources of Phenylalanine. Protein rich foods like beef, poultry, pork, fish, milk, yogurt, eggs, cheese, soy products, and certain nuts and seeds contain appreciable amounts of phenylalanine.Artificial sweetener aspartame also contains high amount of the amino acid.Top 10 Food Containing Phenylalanine. Cottage Cheese: Dry cottage cheese contains 2300 mg of phenylalanine per cup, and the creamed product contains 1647mg/cup. 2  Roasted Peanuts: Roasted peanuts without skin contain 3500 mg of phenylalanine per cup. 3  Sesame Seeds: Sesame is a phenylalanine rich food (3000 mg/cup), and can be incorporated in many recipes.