E300: L-Ascorbic Acid (Vitamin C Antioxidant & Flour Improver)
Food Additives & E-Numbers · 6 specs
Direct Answer
L-Ascorbic Acid (E300, C6H8O6) is a water-soluble antioxidant, dough conditioner, and vitamin fortifier that scavenges dissolved oxygen, prevents fruit enzymatic browning, and cross-links wheat gluten disulfide bridges in commercial baking.
Source: Codex Standard 192-1995 / EFSA FAF Panel / USP-FCC Monograph · Last reviewed Aug 28, 2026
Specs
| INS / E-Number | INS 300 / E300 |
| Chemical Formula | C₆H₈O₆ (Molecular Weight: 176.12 g/mol) |
| Functional Classes | Antioxidant / Flour Treatment Agent / Sequestrant / Nutrient Supplement |
| Acceptable Daily Intake (ADI) | Not Specified (Quantum Satis / GRAS under FDA 21 CFR 182.3013) |
| Solubility | 330 g/L in water at 20°C |
| Redox Potential | +0.06 V at pH 7.0 (readily donates two electrons to dehydroascorbic acid) |
Antioxidant Oxygen Scavenging in Beverages & Cut Fruit
E300 donates hydrogen atoms to oxygen radicals and polyphenol oxidase intermediates, preventing oxidation of fruit juices, purees, and beers. In cut apples and potatoes, it reduces brown quinones back to colorless diphenols, maintaining original market appearance without sulfur dioxide.
Dough Conditioning Mechanism in Bread Baking
In yeast dough, ascorbic acid undergoes enzymatic oxidation via endogenous flour ascorbic acid oxidase into dehydroascorbic acid (DHA). DHA oxidizes glutathione sulfhydryl (-SH) groups, preventing glutathione from cleaving wheat gluten proteins. This strengthens the 3D gluten macro-matrix, increasing loaf gas retention, oven spring, and bread crumb volume.