The fossilized remains of single-celled algae called diatoms are largely what make up the powdery substance known as diatomaceous earth. Food-grade diatomaceous earth consists of about 80-90 percent silica with trace amounts of other materials like aluminum, clays, iron, limestone, phosphorus, salt, sulfur, volcanic ash, and water. Silica particles of diatomaceous earth for food-grade applications are largely classified as amorphous, meaning they have no particular shape.

In contrast, crystalline-structured silica particles make up between 20 and 50 percent of non-food-grade diatomaceous earth. Food-grade diatomaceous earth, however, consists of no more than 2 percent crystalline silica. The differences between diatomaceous earth for food-grade applications and non-food-grade applications are largely due to processing, as non-food-grade applications use heat and chemicals to increase the amount of crystalline silica.

Diatomaceous Earth: Food Grade Applications 

When it comes to diatomaceous earth, the “food grade” label doesn’t necessarily refer to its edibility, but rather to the fact that no demonstrable harm comes from humans ingesting it. Ironically, pest control is one of the prime uses for diatomaceous earth. Food-grade applications also include its use in the food industry, medicines, and cosmetics.

Pest & Parasite Control

Food-grade applications for diatomaceous earth include controlling insects and arachnids with hard exoskeletons, such as ants, bedbugs, beetles, cockroaches, crickets, fleas, spiders, and ticks. It’s also used to control caterpillars, maggots and other insect larvae as well as land-based mollusks like slugs and snails. As a pesticide, diatomaceous earth causes dehydration and death in these creatures while not harming humans, livestock or pets.

For this reason, diatomaceous earth for food-grade applications is used to control fleas or lice in pets or livestock, along with food storage areas to protect against these pests. However, its use as a pesticide relies on dry conditions, as once wet diatomaceous earth loses this dehydrating effect. Additionally, there is evidence that diatomaceous earth may control internal parasites like hookworms, pinworms, roundworms and tapeworms.

Food Processing & Animal Feed Industries

Due to its chemical inertness and nontoxicity, small quantities of diatomaceous earth can be safely ingested by humans and other vertebrates. However, this depends on the purity and proportion of crystalline silica in the diatomaceous earth, with food-grade applications benefiting from diatomaceous earth’s high absorbency, low density, and porousness.

The food industry uses food-grade diatomaceous earth as a:  

  • Anti-caking agent: To improve flow during packaging and storage as well as to prevent clumping, it’s used with flour, powdered milk, spices, sugar and other food powders to ensure consistency and quality.
  • Filtration aid: For beer, cooking oils, fruit juices, syrups, wine and other potable liquids, diatomaceous earth helps clarify and filter out fine particles without changing composition or taste.
  • Preservative: Used to preserve stored foods like bread, fish and meat, diatomaceous earth due to its ability to absorb moisture.
  • Thickener: Diatomaceous earth helps thicken beverages, candies, dairy products, seasonings and other foods to improve consistency and texture.

Grain silos and other food storage facilities protect against pests like beetles, certain types of moths, and weevils with food-grade diatomaceous earth. Food-grade applications for diatomaceous earth also extend to its use as an anti-caking agent in animal feed, with anecdotal evidence that it supports digestive health.

Medicine

The chemical stability and large surface area of particles make it useful for medicines. Powdered medications normally use diatomaceous earth as an anti-caking agent or filler. While it plays a vital role in supporting fluidity and stability in certain medicinal emulsions, diatomaceous earth is also helps ensure a medicine’s efficacy. For oral care, diatomaceous earth’s abrasiveness makes it useful for toothpaste, as it promotes plaque removal without destroying tooth enamel. Food-grade diatomaceous earth is also touted for treating constipation and high cholesterol, as well as improving bone, hair, nail, skin, and teeth health, though these claims are not yet scientifically proven.

Cosmetics

Personal care products sometimes include diatomaceous earth. Food-grade diatomaceous earth’s abrasive qualities make it useful for skin scrubs and exfoliating cleansers, removing dead skin to promote smoother complexions. Its chalklike texture helps control oily skin while it also acts like a thickener to provide better coverage for cosmetics used on an everyday basis. Additionally, food-grade diatomaceous earth in toothpastes helps whiten teeth.  

Processing Diatomaceous Earth for Food-Grade Applications

When processing for food-grade applications, manufacturers need to ensure that it’s safe for people and animals. Additionally, equipment must be able to handle abrasive powders like diatomaceous earth. Food-grade applications also require proper processing. Prater Industries understands the challenges in processing diatomaceous earth for food-grade applications and builds equipment that can handle it.

Prater equipment can deal with: 

  • Calcination: For diatomaceous earth, food grades must avoid calcination, so equipment should limit heat during processing, while ideally utilizing air-drying methods to ensure silica structure remains amorphous; Prater’s Rotormill utilizes airflow to minimize internal heat, while our Mega Mill Hammer Mill grinds uniformly with minimal heat buildup.
  • Cross-contamination: For processing diatomaceous earth for food-grade applications, Prater makes its equipment with construction materials like stainless steel to support hygienic design.
  • Dust: Diatomaceous earth requires equipment that can handle powders, such as Prater’s Dust Collector Series of rotary airlock valves.
  • Moisture: Due to diatomaceous earth’s porous structure, it absorbs moisture; the Rotormill’s continuous airflow during processing helps control humidity.
  • Wear: Because of diatomaceous earth’s abrasiveness, equipment must be robust; Prater equipment is made from durable materials, with optional anti-abrasive coatings.

To learn more about how our equipment can assist with processing diatomaceous earth, contact the material handling experts at Prater today.