What is DL-Malic Acid?
DL-malic acid presents as a white crystalline powder, typically odorless or with a faint characteristic smell. It can be used as an acidifier, color retainer, preservative, etc. in the food industry, and can also be used in pharmaceuticals; it can be used as a descaling agent, fluorescent whitening agent, etc. in the industry.
When producing DL-malic acid, benzene undergoes catalytic oxidation to yield maleic acid and fumaric acid, which are subsequently hydrated under high temperature and pressure. The main reaction products are malic acid along with a minor quantity of fumaric acid. The fumaric acid crystals are isolated via filtration, while the remaining solution is concentrated and solids are separated through centrifugation to obtain crude malic acid. This crude product is further purified and crystallized to obtain the final product.
It is also possible to catalyze fumaric acid or maleic acid with water under high temperatures and high pressure to obtain DL-malic acid or to use fermentation to produce L-malic acid by fermenting fumaric acid with biological enzymes.
Related parameters:
| Testing Item | Standard | |
| Sensory Requirement | Colour and Lustre | White or Almost White |
| Smell | Special Sour Taste | |
| Appearance | Crystalline Powder or Crystalline Granules | |
| Physical and chemical index | DL-Malic Acid w/% | 99.0~100.5 |
| Specific Rotation am(25℃，D)/[(°)·dm2 ·Kg-1] | -0.10~+0.10 | |
| Fumaric Acid w/% | ≤1.0 | |
| Maleic Acid w/% | ≤0.05 | |
| Burning Residue w/% | ≤0.1 | |
| (As)/(mg/kg) | ≤2 | |
| (Pb)/(mg/kg) | ≤2 | |
| Water Insoluble Matter w/% | ≤0.1 | |
