It is hard to imagine a naturally-occurring nutrient that has been more maligned or more mischaracterized than potassium sorbate -- the potassium salt of sorbic acid (CH₃-CH=CH-CH=CH-COOH).
This is a big issue for us, because a number of health food stores, to this very day, exclude our product from their shelves because they claim that potassium sorbate is an unhealthful preservative -- this, despite the fact that they have no valid scientific basis for their claim. Truth is, the facts weigh heavily against their bias.
The issue is one of considerable hypocrisy because virtually all health food stores carry aloe vera juice and gels, along with other beverages which use sorbic acid and/or its salts (which includes potassium sorbate). I have never been to a store in my life, where it be health food store or supermarket, where there has not been a plentitude of products that contain potassium sorbate. I know of several which contain sorbic acid and do not list it on the label. You see this frequently in the health foods industry...
We are frequently asked why we add potassium sorbate to our products. We do so for two reasons: like many conscientious food producers in the natural foods market, we wish to use natural ingredients to not only provide the freshest, best-tasting, most convenient products in the market, but insure their safety. There is no greater threat to the modern system of food distribution than undesired, even pathogenic, micro-organisms. Many people falsely think that if a product is totally natural, or even organic, it doesn't need protection. This fantasyland thinking has no basis whatsoever in known food science, and, in fact, just the opposite is true. We add potassium sorbate for two reasons: (1) to natural inhibit microbes, particularly mold, and (2) increase the potassium level in our products. We could have used other known polyunsaturated fats that have this inhibiting quality, but we chose potassium sorbate for reasons we make clear in the following section.

Scientific Facts: What is Potassium Sorbate?

Potassium sorbate is a potassium salt version of sorbic acid, a polyunsaturated fat used to inhibit mold growth. Sorbic acid was first isolated from the oil of the unripened rowan berry (sorbapple or mountain ash berry) in 1959 by A.W. Hoffmann. Sorbic acid obtained its name from the scientific name for mountain ash (i.e. Sorbus aucuparia, Linne), the parent of the rowan berry. The chemical structure of sorbic acid was determined some time between 1870 and 1890 (see above), and then chemically synthesized by O. Doebner in 1900.
The value of sorbic acid, or its salts, was not immediately recognized. (It would only be much later that these compounds would be appreciated for their ability to interfere with ATP metabolism in microbes, while posing no health risk when consumed by mammals.) In 1939 and 1940, E. Mueller (Germany) and C.M. Gooding (U.S.) discovered sorbic acid's antimicrobial properties. Subsequently, in 1945, C.M. Gooding and Best Foods, Inc. were awarded the first patent for the use of sorbic acid as a fungistatic agent in foods.
Since the 1950's, sorbic acid has been repeatedly tested for safety and efficacy, and today stands as one of the most thoroughly tested food additives in history. In fact, few substances have had the kind of extensive, rigorous, long-term testing that sorbic acid and its salts have had. It has been found to be non-toxic even when taken in large quantities, and breaks down in the body into water and carbon dioxide in the Krebs Cycle.
The all-time critic of food additives, Dr. Michael Jacobsen (founder of Center For Science In The Public Interest in Washington, D.C.), has given sorbic acid and its salts his highest rating, SAFE. He has indicated that, "the body metabolizes s potassium sorbate like any other polyunsaturated fat." Many of the most common food additives which health-conscious Americans take for granted have not received this rating: hydrolyzed vegetable proteins, common food colorings (coal tar dyes), natural liquid smoke flavorings (distillates), BHA, BHT, TBHQ, nitrates, etc.
Lumen Foods chose to use this compound after thoroughly investigating the variety of naturally-occurring mold inhibits in the mid-80's. We use about 0.8% of this compound by weight. (Other natural preservatives, such as vinegar, salt, sugar, honey (yes, these are all preservatives), are inappropriate for this purpose when making Lumen products.) Our belief in the safety and effectiveness of potassium sorbate is reflected in the fact that Lumen Foods is today an importer of potassium sorbate, as well, in a joint project with foodchem.com.
We stand by the weight of scientific evidence on sorbic acid and its salts. It provides the very best method of inhibiting mold in intermediate moisture, soy protein products.

Additional Resources:
CSPI's Guide to Food Additives FDA's Food Additive Database
Other Natural Preservatives Sold by Lumen Foods Related Ingredient: Sodium Benzoate
Greg Caton, President
Lumen Foods