To prepare rice, cook rice according to package directions, omitting salt and fat. Drain; place rice in a large bowl. Melt butter in a nonstick skillet over medium-high heat. Add pineapple; sauté 4 minutes or just until pineapple begins to brown. Add pineapple mixture, cilantro, and 1/4 teaspoon salt to rice in bowl; cover and keep warm. Wipe pan clean with paper towels.
To prepare patties, place 1 1/2 cups beans, garlic, cumin, and 1/8 teaspoon salt in a bowl; partially mash with a fork. Place 1/2 cup remaining beans and egg white in a food processor; process 30 seconds or until well combined. Add bean puree to mashed beans in bowl, and stir until combined. Add cheese and onion to bean mixture; stir until combined. Divide bean mixture into 4 equal portions, shaping each into a 1/2-inch-thick patty. Place cornmeal in a shallow dish. Dredge both sides of each patty in cornmeal.
Heat pan over medium-high heat. Coat pan with cooking spray. Add patties; cook 3 minutes on each side or until browned. Spoon about 1/2 cup rice onto each of 4 plates; top each serving with 1 patty and 1 tablespoon sour cream.