Oil and water don’t mix — until an emulsifying agent is added.
Emulsifiers made from plant, animal and synthetic sources commonly are added to processed foods such as mayonnaise, ice cream and baked goods to create a smooth texture, prevent separation and extend shelf life. However, in this era of “clean labels,” consumers question the necessity of additives in food.
A food emulsifier, also called an emulgent, is a surface-active agent that acts as a border between two immiscible liquids such as oil and water, allowing them to be blended into stable emulsions. Emulsifiers also reduce stickiness, control crystallization and prevent separation.
Functions, Names and Labeling
Emulsifiers create two types of emulsions: either droplets of oil dispersed in water or droplets of water dispersed in oil. Within the emulsion, there is a continuous and dispersed phase. In an oil-in-water emulsion, the continuous phase is the water and the dispersed phase is the oil; conversely, in a water-in-oil emulsion, the oil is the continuous phase.
Emulsions also can be made by applying mechanical force from a blender or homogenizer, which breaks down the dispersed phase into tiny droplets that become suspended in the continuous phase.
Low-fat spreads, ice cream, margarine, salad dressings and many other creamy sauces are kept in stable emulsions with the addition of emulsifiers. These additives also are widely used in other foods such as peanut butter and chocolate.
“Emulsifiers enhance the structure of baked goods by increasing whip-ability of batters, conditioning of dough and helping foods like pasta be more resistant to overcooking,” says food scientist Kantha Shelke, PhD, CFS.
Commonly used emulsifiers in modern food production include mustard, soy and egg lecithin, mono- and diglycerides, polysorbates, carrageenan, guar gum and canola oil.
Lecithin in egg yolks is one of the most powerful and oldest forms of an animal-derived emulsifier used to stabilize oil in water emulsions, for example, in mayonnaise and hollandaise sauce.
Emulsifiers are required by law to be included on a food’s ingredient list.
Safety of emulsifiers is carefully regulated and tested by the U.S. Food and Drug Administration. Emulsifiers can be found on the Generally Recognized As Safe, or GRAS, list and are allowed in specific types of food and beverages at precise levels.
However, “FDA processes do not take into consideration individual diets of people who rely heavily on packaged foods,” Shelke says.
Although GRAS substances technically must meet the same safety standards as approved food additives, the GRAS process has evolved into a voluntary notification program and many GRAS additives have not been tested.
Congress defines safe as “reasonable certainty that no harm will result from use” of an additive. Additives are never given permanent approval. The FDA continually reviews the safety of approved additives, based on the best scientific knowledge, to determine if approvals should be modified or withdrawn.
Earlier in 2017, the FDA reviewed and confirmed the safety of carrageenan, an emulsifier whose safety has been questioned.
Most concerns about food additives target synthetic ingredients that are added to foods.
Published peer-reviewed intervention studies involving emulsifiers are limited to animals. A 2015 mouse study published in Nature found that two common synthetic emulsifiers, carboxymethylcellulose (CMC) or polysorbate 80 (P80), triggered weight gain and low-grade symptoms of inflammation and metabolic syndrome after 12 weeks.
“We suspect some emulsifiers act like detergents, upsetting the friendly bacteria in the microbiota, which triggers low-grade inflammation and causes excess eating,” says co-author Andrew Gewirtz, PhD.
A follow-up study by Gewirtz, a professor of biomedical sciences at Georgia State University, and his colleagues, published in Cancer Research, suggested the changes in gut bacteria from emulsifiers could trigger bowel cancer. A small clinical trial currently is underway to evaluate the role of CMC in humans.
In response to questions about the safety of some emulsifiers, a team of FDA scientists conducted a review of seven emulsifiers commonly used in food, including CMC and P80, to determine whether these ingredients pose any risk to human health. Their findings, published in 2017, confirmed that emulsifiers remained safe at the estimated exposure levels.
Food additives, including emulsifiers, play an important role in our food supply. Consumers who are concerned about these ingredients are encouraged to read labels and consume more minimally processed foods.