Salad dressing is a sauce, which is used to make an entire salad tastier. A dressing is an oil-in-water emulsion and generally consists of a combination of oil, water, vinegar, citric acid, salt, spices and an emulsifier. A thickening agent, like xanthan gum or carrageenan, is often added to the low-fat salad dressings.
There are two main types of salad dressings:
The dressing with two layers must be shaken before use, to mix the two layers. In general, liquid salad dressings have a low pH between 3,5 and 3,9, which is the reason they keep fresh longer than spoonable salad dressings. A typical liquid salad dressing is vinaigrette.
These two types of salad dressings are produced in many different tastes and nowadays the low-fat varieties are produced more and more.
The production of the liquid salad dressing will be described below.
Production salad dressing
The basic ingredient in salad dressing is oil, like olive, soya or sunflower oil. To obtain the required viscosity and stabilise the emulsion, stabilizers or thickening agents are added, such as modified starch. Depending on the type of salad, also other ingredients can be added such as different spices, eggs, citric acid, vinegar, salt, sugar and for a homogeneous dressing, an emulsifier.
When vegetables and spices are in the salad dressing, generally blast-frozen vegetables and spices are used.
The mixing starts with water. To this water the ingredients salt, vinegar and modified starch are added. The whole is mixed and heated to approximately 90°C, in order for a starch paste to form. The whole is then cooled and the remaining ingredients are added, such as spices, eggs and sugar.
To get the desired emulsion, a continues mixing system is often used nowadays.
However, a colloidmill can also be used. The procedure is then as following: after the mixing, oil is slowly, while stirring, added to a part of the formed starch pasta. When approximately half of the oil is added, the remaining part of starch paste is also added, as slowly as the oil is being added. When the whole is mixed properly, it is lead through the colloidmill, to obtain an emulsion with a uniform consistency.
The emulsified salad dressing is pumped to the bottling station. Here, pre-measured amounts of salad dressing are dropped in pre-sterilized jars or bottles and these containers are immediately sealed with metal or plastic caps.
The containers are then labelled, packed in boxes and stacked on pallets.
Due to the low pH of the salad dressing, it will remain fresh for a long period of time. However, after opening, the salad dressing must be kept in the refrigerator.