Riboflavin (Vitamin B2)

Grades and forms

Riboflavin is the parent form of vitamin B2 and counts as 100 % riboflavin, so label-claim arithmetic needs only the assay on the certificate of analysis. Riboflavin powder is one of two vitamin B2 forms listed for EU food supplements. It is also an authorised food colour, E101. Its sodium phosphate salt is the water-soluble alternative covered on the vitamin B2 guide.

Manufacturers buy riboflavin as a fine crystalline powder for premixes and direct blending. Some also use diluted or granulated preparations where flow and blend uniformity matter more than purity. The intended use decides the reference specification: food-additive specification, food-supplement specification or a pharmacopoeia monograph.

Particle size matters because vitamin B2 is usually a small fraction of the fill mass. SoleChem sends the specification sheet and certificate of analysis with its quote; they state assay, particle size and loss on drying. Ask for the grade you need in the quote form.

EU regulatory status

Annex I of Directive 2002/46/EC lists vitamin B2 as a vitamin that may be used in food supplements. Annex II lists riboflavin as a permitted form. Riboflavin is also listed for addition to other foods in Annex II of Regulation (EC) No 1925/2006. The full list of forms is on the permitted forms guide.

As a colour, riboflavin is authorised under Regulation (EC) No 1333/2008. Its purity criteria sit in Regulation (EU) No 231/2012. When it is added for colour, the conditions of use for food supplements in Annex II of Regulation 1333/2008 apply.

The EU has not harmonised maximum levels of vitamin B2 in food supplements. Member states set their own, as the maximum levels guide explains. The label declares vitamin B2 in milligrams, the unit set in Annex I of the Directive; see labelling a food supplement. For authorised claim wording, consult the EU Register of nutrition and health claims and the health-claims guide.

Formulation notes

Riboflavin is light-sensitive, most of all in solution. Limit light exposure during processing. Use opaque capsules or light-protective packaging. Plan shelf-life losses with the overage calculator.

It is more stable in acidic than in alkaline conditions. Avoid prolonged contact with alkaline excipients in wet processes.

Riboflavin is only very slightly soluble in water. It suits tablets, capsules and dry powders. For clear liquids and effervescent tablets, formulators usually choose the sodium phosphate salt.

The intense yellow colour tints white blends and can show as specks if dispersion is poor. Pre-blending on a carrier, or geometric dilution, improves uniformity. A flow aid such as silicon dioxide helps fine powders in capsule filling. The powder also stains equipment, so plan cleaning between batches.

Riboflavin has a slightly bitter taste. This is noticeable in chewables and unflavoured powders at higher inclusion. In B-complex blends it sits alongside thiamine hydrochloride and pyridoxine hydrochloride.

For the arithmetic, divide the label claim by the assay fraction on the certificate of analysis. Then add any overage you have set for losses during processing and storage.

How riboflavin compares to other forms

To declare 10 mg of vitamin B2 from the sodium phosphate salt, you need about 12.7 mg of anhydrous salt (10 / 0.787). Commercial material contains water and is hygroscopic. Correct for water content and assay using the certificate of analysis.