As the dressing industry has grown into a billion-dollar business, dressings have evolved into a category of products from which consumers demand excellence in flavor and texture. “It’s all in the presentation and expectations from consumers,” says Michelle Ludtke, senior food technologist, Grande Custom Ingredients Group, Lomira, WI. “Texturizing, thickening, suspending and emulsifying effects are important to manufacturers of dressings because they rely on the presentation to the consumer.”
Despite the innumerable styles and types of dressings, texturally speaking, dressings are separated into two groups: pourable and spoonable. The former, as the name would imply, is thinner, characterized by varying degrees of flowability, generally applied directly from a bottle or other container. The latter is thicker, typically applied as a dollop or by spreading.
Salad dressings are emulsions—colloidal structures formed by combining two immiscible liquids. In this case, oil (discontinuous phase) dispersed and stabilized in water (continuous phase). Generally speaking, smaller oil droplets are more stable, i.e., less likely to coalesce and separate. In addition to maintaining homogeneity, stable emulsions also provide a major portion of the dressing’s body.
“The order the ingredients are added and the mixing conditions are critical to build a proper emulsion,” says Karen Carlson, director of research and development—dressings, sauces, and dips, Ventura Foods, Brea, CA. “A few extra seconds of shear during processing of an emulsified vinaigrette will make it too light in color. Not enough shear, and the product will separate during processing and fill unevenly. Over-processing a spoonable dressing can cause the emulsion to break and, ultimately, separate on the store shelf.”
In many cases, formulations include emulsifying agents to assist in maintaining emulsion stability. Emulsifiers are polar on one end, and nonpolar on the other. By aligning the polar (hydrophilic) end with the water, and the non-polar (hydrophobic) end with the oil, emulsifiers surround the oil droplets, hindering their ability to come together.
Monoglycerides are made by breaking the glycerin backbone of a fat triglyceride, leaving a single fatty acid with a lipophilic end and a hydrophilic end. Another common emulsifier, lecithin, is a combination of phospholipids obtained from soybean oil. Other ingredients can exhibit emulsification properties by virtue of their structure. Some proteins can “isolate” oil droplets by forming a film around them. Molecules of gum arabic have hydrophilic and hydrophobic areas that can provide some emulsifying, as well.
More than a feeling
A dressing’s character has many facets, each of which affects the way that product behaves, feels and tastes.