Particles

Some sauces are thickened by containing a large number of tiny particles that keep the sauce from flowing as it would if it had no thickener. Typical of these thickeners are vegetable and fruit purées, ground nuts, spices, and other ingredients that break down into minute insoluble particles. These thickeners are especially useful when making vinaigrettes or other sauces in which the solid matter also functions as the emulsifier. A rotor stator homogenizer comes in very handy for this because you can purée on almost a molecular level; for home cooks, a powerful immersion blender is almost as good. Particle-based sauces should be stabilized with xanthan gum and other ingredients (see xanthan gum) to prevent syneresis, which is when sauces and purees separate.