Vegetable Glycerin

Biodiesel and soap makers turn plant oils into fuel or soap, leaving glycerin as a coproduct. Refiners remove water and processing residues before the thick liquid goes to food makers for its water-binding effect.^2,5,9

1. 01 // Source Plant oils Vegetable oils supply the fat molecules from which glycerin is separated.
2. 02 // Process Fats split Biodiesel or soap production separates glycerin from the oil's fatty acid portions.
3. 03 // Process Crude liquid collected The glycerin coproduct is drawn off separately from the fuel or soap.
4. 04 // Process Liquid refined Further processing removes water and residues that remain in crude glycerin.
5. 05 // Output Vegetable glycerin A thick liquid arrives at the food plant for blending into recipes.

1. 01

   Keeps a soft chew

   Glycerin binds water, making less of it available for microbial growth while the food stays pliable. Processing and packaging still matter to shelf life.^2,6,9

2. 02

   Adds usable energy

   Dogs absorb and use glycerin as fuel. Formulators can replace part of another energy ingredient with it while changing the food's texture.¹

3. 03

   Uses a bulk coproduct

   The Department of Energy describes about 10 pounds of glycerin produced alongside biodiesel from 100 pounds of oil or fat. That gives manufacturers supply at scale.⁵

4. 04

   Adds sweet taste

   An industry review reports that dogs favored a glycerin formula in a preference test, though the test formula also contained less corn.⁹

How much An 8-dog feeding study tested diets containing 3 to 9% glycerin; it did not measure a usual commercial recipe amount.¹

1. Brands say

   Glycerin gives dogs usable energy

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   An 8-dog crossover study estimated about 4,191 kcal/kg of metabolizable energy from its glycerin ingredient. The feeding periods were short. The result shows available calories, not a lasting health benefit.¹

2. Brands say

   Glycerin keeps soft treats chewy longer

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Glycerin binds water. In a pelleted feed storage experiment, a mold marker stayed lower in glycerol formulas under the tested conditions. That supports its texture and preservation job, but cannot predict a particular treat's shelf life.^2,6,9

3. Brands say

   Dogs prefer food sweetened with glycerin

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   An industry review reports a 2-bowl dog test with 84% of intake from the glycerin formula versus 16% from the control. The formula also replaced some corn, so glycerin alone cannot take the credit.⁹

4. Critics say

   Glycerin in jerky causes kidney disease

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   A treat brand raised the possibility. FDA found falsified glycerin paperwork at a jerky plant, but the supplier records it checked met glycerin standards. Its investigation did not identify glycerin as the cause of reported illnesses.^7,10