The salad dressing mixing process involves water base, oil base, and acidic ingredients, which means emulsification is required for this process. You first need to pre-mix the water, starch, vinegar, and salt at around 90°C in the pre-emulsifier. Then, as the second step, you need to add the oil to the colloid mill or emulsifier. Here, vacuum or pressure homogenizer is often employed as they can produce higher-quality dressing compared to conventional cooker or mixer.