Salad dressing is a type of sauce used to bind and flavor greens and/or vegetables.
Using oil and vinegar to dress greens and vegetables dates to Babylonian times, some 2,000 years ago. The word salad can be traced to the ancient Romans who sprinkled salt on grasses and herbs, calling it herba salata. It was not long before Roman and Greek cooks experimented with combinations of olive oil, vinegar, and salt, then adding wine, honey, and a fermented fish sauce known as garum. The latter was made by soaking the intestines and other pieces of mackerel, salmon, sardines, and shad in brine and herbs.
The kings and queens of Europe were notably fond of salads with royal chefs tossing together as many as 35 ingredients. Henry IV of England was known to prefer a bowl of sliced new potatoes and sardines splashed with herb dressing. For Mary, Queen of Scots, it was lettuce, boiled celery root, truffles, chervil, and hard-cooked eggs in a mustard dressing.
Salad dressings were made from scratch in home kitchens until the turn of the nineteenth century when restaurant owners began packaging and selling their own dressings. One of the first was Joe Marzetti, proprietor of a Columbus, Ohio, restaurant. In 1919, Marzetti began to bottle a variety of dressings from old country recipes.
The Kraft Cheese Company entered the salad dressing industry in 1925; its first flavor was french, an oil and vinegar-based dressing flavored with tomato and paprika.
By the end of the twentieth century, over 60 million gal (227 million 1) of salad dressings were sold in the United States. The most popular flavor by far was ranch dressing. The original brand, Hidden Valley Ranch, was created by Steve Henson who devised the recipe as a dry mix to be blended with mayonnaise and buttermilk. Henson and his wife Gayle served it at their California dude ranch, called the Hidden Valley Guest Ranch, in the late 1950s and early 1960s. Guests reported that the dressing was so popular, they often poured it on steaks and ice cream as well as on salads.
Guests began to request jars of the dressing to take home with them. When one man wanted 300 jars to take back to Hawaii, Henson offered to provide him with enough packages of the dried mixture instead. This led to a very lucrative mail-order business. The family eventually sold the business, which is now owned by Clorex.
The primary ingredient in salad dressing is oil. In the United States, soybean oil is the most common type used in the production of salad dressings. Olive, peanut, and sunflower oils may also be used.
Stabilizers and thickeners, such as modified food starch, are mixed with the oil. The thickeners develop viscosity and protective colloid characteristics that help to prevent the breakdown of the blend during the various processing steps.
Other food ingredients are added depending on the type of dressing, including any or all of the following: eggs, vinegar, salt, honey, sugar, spices and herbs, tomato, vegetable bits, sherry, and lemon or lime juice. A large sub-industry is involved in the processing of these ingredients. Herbs and vegetables are usually blast-frozen and cut into pieces or reduced to flakes.
Monosodium glutamate (MSG) is a food additive developed in the early 1900s from seaweed. Today in the United States, MSG is extracted from the gluten of cereals. It is used in variety of foods, including salad dressings, to enhance flavor. However, the increase of allergic reactions experienced by consumers have caused some processors to cease using it.
The salad dressing industry is constantly creating new and so-called improved flavors. Low fat and non-fat varieties are of particular interest to the consumer. The larger companies have food laboratories on site. Smaller companies and start-up companies often rely on research conducted by university food science institutes.
The Manufacturing Process
Creating the emulsion
- 1 The commercial salad dressing industry uses a continuous blending system to attain the correct degree of emulsification so that the mixture does not break down. An emulsion, or colloid, forms when the blending of two liquids, such as oil and water, causes one of the liquids to form small droplets that are evenly dispersed throughout the other liquid. In the production of commercial dressings, this basic blend moves continuously through a series of pumps and heat exchangers as the other ingredients are added.
Positive replacement pumps feature a cavity or set of cavities fitted with rotary impellers. A regulated pumping action causes the cavities to fill and empty. The impellers move the blended fluid from one cavity to another.
- 2 Manufacturers may use a rotational viscometer to test the viscosity, or consistency, of the dressing. This machine consists of a solid cylinder fitted inside a hollow cylinder with a space of about (0.08 in) 2 mm in between. A sample of the dressing is poured into the space, the top is sealed and the cylinders are set spinning. As the dressing spins, it exerts torque on the center cylinder. A gauge then measures the consistency. Adjustments are made as necessary.
- 3 Pre-measured ingredients are piped through openings in the sides or from spigots up above.
Bottling the dressing
- 4 When the dressing is completely blended according to the recipe, it flows to the bottling station. Here, pre-sterizilized jars or bottles move along a conveyer belt as overhead spigots drop premeasured amounts of dressing into each container. The containers are immediately sealed with metal or plastic caps.
- 5 Labels are mechanically affixed to each container. All ingredients and nutritional information must be printed on each label.
In the United States, the Food and Drug Administration (FDA) sets Standards of Identity for french dressing, and the modified mayonnaise called salad dressing that is used as the basis for most creamy dressings. French dressing must contain at least 35% vegetable oil by weight, vinegar, and tomato and/or paprika products. Salad dressing must contain a minimum of 30% vegetable oil, 4% egg yolk ingredient, vinegar or lemon juice, and spices.
At the processing plant, each shipment of raw and processed ingredients are tested upon arrival. Daily samplings are taken of all stored materials to insure their freshness.
Where to Learn More
Coyle, L. Patrick, Jr. The World Encyclopedia of Food. New York: Facts on File, 1982.
Schlesinger, Chris, and John Willoughby. Lettuce in Your Kitchen. New York: William Morrow, 1996.
Trager, James. The Food Chronology. New York: Henry Holt, 1995.
Barr, Susan Leamer. "Well-dressed." Shape (August 1997).
Association for Dressings and Sauces. http://www.dressings-sauces.org (December 2000).
Kraft Unit Operations. http://www.kraftunitops.com (December 2000).
Hidden Valley Ranch. http://www.hiddenvalleyranch.com (December 2000).
Mayonnaise is a stable emulsion of vinegar in oil, made with egg. Salad cream was originally developed as a commercial substitute for mayonnaise (mid‐19th century); an emulsion made from vegetable oil, vinegar, salt, spices, emulsified with egg yolk and thickened. Legally, in the UK, it must contain not less than 25% by weight of vegetable oil and not less than 1.35% egg‐yolk solids. Mayonnaise usually contains more oil, less carbohydrate and water. By US regulations salad dressing contains 30% vegetable oil and 4% egg yolk; mayonnaise contains 65% oil plus egg yolk. Low fat mayonnaise and salad cream are widely available.
Red mayonnaise is prepared by adding beetroot juice and the coral (eggs) of lobster to mayonnaise; an accompaniment to seafood dishes.
Russian dressing is in fact American; made from mayonnaise with pimento, chilli sauce, green pepper, and celery, or sometimes by mixing mayonnaise with tomato ketchup. Thousand Island dressing is made from equal parts of mayonnaise and Russian dressing, with whipped cream.