What is Ascorbic Acid Powder Made of? The Production Process Explained

January 4, 2026 •

3 min read

Ascorbic acid, or Vitamin C, is one of the most widely produced vitamins globally, with annual production exceeding 100,000 tons. Despite its widespread availability, many are unaware of the industrial processes used to create pure ascorbic acid powder, which starts with a simple sugar and involves complex chemical and fermentation steps.

Quick Summary

Ascorbic acid powder is manufactured commercially from glucose, often derived from corn or wheat starch. The dominant method employs a two-step fermentation process to convert glucose into L-ascorbic acid, avoiding many of the toxic chemicals used in older synthesis routes.

Key Points

Source Material: Ascorbic acid powder is primarily made from glucose, which is typically derived from corn or wheat starch.
Industrial Process: Modern production uses a two-step fermentation method combined with chemical steps, offering a cleaner alternative to older processes.
Microbial Role: Specific microorganisms, like Acetobacter suboxydans and Ketogulonicigenium vulgare, play a crucial role in converting the glucose intermediate to a precursor of ascorbic acid.
Not Extracted from Fruits: Although also found in nature, commercial ascorbic acid powder is almost exclusively synthesized industrially, not extracted from fruits.
Pure Compound: The final product is a fine, crystalline powder consisting of pure ascorbic acid, with no other added ingredients in its raw form.

The Starting Material: Glucose from Starch

At its core, industrial ascorbic acid powder is made from glucose, a simple sugar. The glucose is typically sourced from starches, with corn and wheat being the most common origins. This means that a humble ear of corn can be the ultimate raw material for the vitamin C supplement found in stores. The process transforms this readily available natural product into a specific, high-purity chemical compound.

The Manufacturing Journey: From Sugar to Supplement

Modern ascorbic acid production is a sophisticated, multi-stage process that combines biological fermentation with chemical synthesis. The original method, known as the Reichstein process, has largely been replaced by more efficient and environmentally friendly alternatives.

The Modern Two-Step Fermentation Process

The most widely used modern method for manufacturing ascorbic acid involves two key fermentation steps, significantly reducing the reliance on harsh chemicals. The process follows this sequence:

Step 1: Glucose to Sorbitol. Glucose, derived from corn or wheat starch, is catalytically hydrogenated to produce D-sorbitol.
Step 2: Sorbitol to L-Sorbose. The D-sorbitol is then fermented using microorganisms, such as Acetobacter suboxydans, to oxidize it into L-sorbose.
Step 3: L-Sorbose to 2-Keto-L-gulonic Acid (2-KLG). A second fermentation step uses different, often genetically modified, microorganisms (e.g., Ketogulonicigenium vulgare) to convert the L-sorbose into 2-Keto-L-gulonic acid, or 2-KLG. This second fermentation is a key improvement over the older Reichstein process, which relied on chemical oxidation at this stage.
Step 4: 2-KLG to Ascorbic Acid. The final step is a chemical cyclization of the 2-KLG intermediate under acidic conditions to form L-ascorbic acid.
Step 5: Purification. The crude ascorbic acid is then purified, often through crystallization, to produce the fine, white crystalline powder sold commercially.

The Traditional Reichstein Process

Although mostly obsolete due to its reliance on toxic chemicals, understanding the Reichstein process provides historical context. It also begins with glucose and fermentation to produce L-sorbose. However, the subsequent conversion to 2-KLG and final cyclization involved multiple chemical steps using harsh reagents like potassium permanganate and strong acids. This method had a higher environmental impact and created more toxic byproducts.

Natural Extraction vs. Industrial Synthesis

While ascorbic acid naturally exists in high concentrations in many fruits and vegetables, almost all commercially available ascorbic acid powder is produced synthetically through the industrial fermentation methods described above. Natural extraction methods are available but are rarely used for large-scale production due to being less cost-effective and having lower yields. Examples of plants with high natural vitamin C include Kakadu plum, camu-camu, and acerola cherry, but extracting and stabilizing the vitamin on an industrial scale is complex and expensive.

Comparison of Ascorbic Acid Production Methods


Feature	Modern Two-Step Fermentation	Traditional Reichstein Process
Starting Material	Glucose (from corn/wheat)	Glucose (from corn/wheat)
Key Steps	2 fermentation steps, 1 chemical cyclization	1 fermentation step, multiple chemical steps
Environmental Impact	Lower; uses fewer toxic reagents	Higher; relied on toxic chemicals
Efficiency	Highly efficient and cost-effective	Efficient, but with high operational costs
Status	Predominant industrial method globally	Largely obsolete

The Final Product: A Pure Crystalline Compound

When you purchase pure ascorbic acid powder, you are buying a product that is, in essence, 100% ascorbic acid. It is a single, isolated chemical compound with the formula C₆H₈O₆. In its pure form, it is a white or slightly yellowish crystalline powder. Any additional ingredients, such as binders, fillers, or sweeteners, are added later if the ascorbic acid is used to make a tablet, capsule, or fortified beverage. The crystalline powder is stable when dry but can be destroyed by heat, light, and exposure to oxygen, which is a factor during manufacturing and storage. This is why industrial purification is often followed by a drying process to ensure product longevity.

Conclusion

What is ascorbic acid powder made of? The answer lies in a clever combination of biotechnology and chemistry. It is synthesized from glucose, commonly derived from corn or wheat, using a refined multi-step process that relies heavily on fermentation with specific microorganisms. This modern method is a significant improvement over older, more chemically intensive routes. The resulting product is a pure crystalline compound, chemically identical to the vitamin C found in fruits and vegetables, but produced on a massive, efficient industrial scale.

Frequently Asked Questions

The primary raw material for making ascorbic acid powder is glucose, which is typically extracted from corn or wheat starch.

Most commercial ascorbic acid powder is produced synthetically through an industrial fermentation process, though it is chemically identical to the vitamin C found in nature.

The modern method, called two-step fermentation, involves converting glucose to sorbitol, fermenting sorbitol to L-sorbose, further fermenting it to 2-Keto-L-gulonic acid, and finally, a chemical cyclization to produce ascorbic acid.

The source of the glucose (e.g., corn) does not impact the final ascorbic acid molecule, which is chemically pure. Concerns about potential GMO sources are separate from the chemical identity and efficacy of the final compound.

Industrial extraction from fruits is not cost-effective or high-yielding enough for large-scale commercial production, so fermentation-based synthesis is preferred.

The key difference is that the modern method replaces several of the chemical steps of the older Reichstein process with more environmentally friendly fermentation steps, particularly the oxidation of sorbose.

Pure ascorbic acid powder should be a fine, white or slightly off-white crystalline powder. Any additional ingredients would be listed separately on the product label if it's in a tablet or mixed formula.