Learn how to create an interior fill to simulate liquid fills inside your models. Create an interior to your model, and apply a liquid fill.
Place your liquid at any angle to simulate pouring effects. Fill your models to accurate volumetric data. This will prepare your model for Ray Tracing. It is important when Ray Tracing, to achieve total photo realism to have an interior liquid fill inside your bottles and jars. This will allow you to get the right levels of refraction and reflections needed to create true photo realism.