Preheat the oven to 300 degrees.
In a large bowl, mix together the orange juice, oil, honey, sesame seeds, and poppy seeds.
Add the barley, rye, quinoa, oat bran, and rolled oats. Mix until all are well coated, using your hands if necessary.
Spread on two large, ungreased baking sheets and bake until lightly toasted, 45 minutes to 1 hour, stirring every 15 minutes or so. Stir in the walnuts after about 30 minutes.
Remove, let cool to room temperature, and stir in the raisins. (May be stored in airtight containers for up to three weeks.)