What is the Difference Between BHA and BHT

The key difference between BHA and BHT is that BHA is an oil-soluble waxy solid having the E number E320, whereas BHT is an oil-soluble white powder having the E number E321.

BHA and BHT are important antioxidants and food additives. These terms stand for butylated hydroxyanisole and butylated hydroxytoluene, respectively.

1. Overview and Key Difference
2. What is BHA
3. What is BHT
4. Similarities Between BHA and BHT
5. BHA vs BHT in Tabular Form
6. Summary – BHA vs BHT

What is BHA (Butylated Hydroxyanisole)?

BHA is butylated hydroxyanisole. It is an antioxidant composed of a mixture of two isomeric organic compounds known as 2-tert-butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole. We can prepare it from 4-methoxyphenol and isobutylene. This material appears as a waxy solid useful as a food additive. It has the E number E320. The primary uses of this compound include use as an antioxidant and preservative in food, food packaging, animal feed, cosmetics, rubber, and petroleum products. It is also commonly useful in medicine, such as cholecalciferol (vitamin D3), isotretinoin, iovastatin, and simvastatin.

The chemical formula of this compound is C₁₁H₁₆O₂. Its molar mass is 180.24 g/mol. It appears as a waxy solid with a density of 1.05 g/cm³. Its melting point is 48 – 55 degrees Celsius while the boiling point is 264 – 270 degrees Celsius. It is insoluble in water and freely soluble in ethanol, methanol, propylene glycol, fats, and oils.

When considering its antioxidant properties, it is added to edible fats and fat-containing food because of its antioxidant properties and because it can prevent the rancidification of food. Rancidification can cause objectionable odors. It can use its conjugated aromatic ring to stabilize free radicals, sequestering them. Therefore, they can act as free radical scavengers. This can prevent any further free radical reactions.

What is BHT (Butylated Hydroxytoluene)?

BHT is butylated hydroxytoluene. It is a lipophilic organic compound having the chemical formula C₁₅H₂₄O. The molar mass of this compound is 220.35 g/mol. It appears as a white to yellow powder and has a slight phenolic odor. The density of this compound is 1.048 g/cm³. Its melting point of BHT is 70 degrees Celsius, and its boiling point is 265 degrees Celsius. It has poor solubility in water and is flammable. It can be described as a derivative of phenol. It is useful due to its antioxidant properties. Therefore, this material is widely used to prevent free radical-mediated oxidation in fluids.

The chemical synthesis of BHT can be done using the reaction of p-cresol with isobutylene. The catalyst for this reaction is sulfuric acid. As an alternative method, BHT can be prepared from 2,6-di-tert-butylphenol via hydroxymethylation.

When considering the applications of BHT, it is mainly used as a food additive and as an antioxidant. The USA categorized it as a safe compound based on studies, and it is approved by the FD as well. As an antioxidant, it is used in metalworking fluids, cosmetics, pharmaceuticals, rubber, transformer oils, and embalming fluid. In the petroleum industry, this compound is considered as a fuel additive (AO-29) for gear oil, turbine oil, hydraulic fluids, and jet fuel.

What are the Similarities Between BHA and BHT?

BHA and BHT are used as food additives.
Both have antioxidant properties.
They have E numbers.
Both are butylated materials.
They can stabilize free radicals, sequestering them using the conjugated aromatic ring.