Papain

Grades and forms of papain powder

Papain is a cysteine protease obtained from the dried latex of unripe papaya fruit (Carica papaya). Supplement manufacturers buy papain as a cream to light brown powder, and they buy it by enzyme activity rather than by mass. The declared activity, its unit and the assay method decide how much powder a formula needs.

Commercial papain ranges from crude dried latex to refined grades in which the enzyme is purified and standardised. Standardised grades are often blended with a food-grade carrier to reach a fixed activity per gram. Activity is quoted in several unit systems, and units from different assay methods are not interchangeable.

Three points decide the choice:

• Activity unit and method: match the unit used in your label or internal specification, not just the number.
• Carrier: identify the standardising carrier, because it may need to appear in your ingredient list.
• Degree of refinement: refined grades carry fewer latex impurities, which makes activity easier to control batch to batch.

The specification sheet and certificate of analysis state the declared activity, the assay method, the carrier and the microbiological limits. SoleChem sends both with its quote, so state the activity and unit you need in the quote form.

EU regulatory status

Papain is neither a vitamin nor a mineral, so Annexes I and II of Directive 2002/46/EC do not cover it. In food supplements it is used as an “other substance”, and national rules govern that use. These rules differ between member states: some keep lists of permitted substances, some require notification. Check each target market before launch.

Regulation (EC) No 1925/2006 sets an EU procedure to prohibit, restrict or place other substances under scrutiny through its Annex III. Confirm the current Annex III entries before publication of your label.

Novel-food status falls under Regulation (EU) 2015/2283. Confirm the status of the grade you buy against the Union list of novel foods; the guide to novel food status of supplement ingredients explains the check. When papain is added to another food for a technological purpose, such as protein hydrolysis during processing, separate EU food-enzyme rules apply.

On the label, papain appears in the ingredient list under Regulation (EU) No 1169/2011; a standardising carrier must also be listed unless it falls under the carrier exemption in Article 20(c). Any claim must comply with Regulation (EC) No 1924/2006. Check the EU Register of nutrition and health claims and the health-claims guide before writing label copy.

Formulation notes

Papain is a protein, and its activity is the quantity that must survive processing and shelf life. Heat, moisture and oxidising conditions reduce activity. As a thiol enzyme, it is also inhibited by heavy-metal ions. Process it dry, at controlled temperature, and away from oxidising ingredients.

• Capsules: the most common format for papain, see ingredients for capsules. Keep the fill dry. A protease in contact with moisture can act on a protein shell, so HPMC shells are worth testing against gelatin in stability trials.
• Tablets: compression generates heat and wet granulation adds water. Direct compression is usually the safer route, with activity measured after compression. See ingredients for tablets; a flow aid such as silicon dioxide helps fine enzyme powders.
• Powders and protein blends: papain hydrolyses proteins such as hydrolysed collagen or whey once water is present. Keep water activity low in dry blends. Hydrolysis can also release bitter peptides.
• Combinations: papain is often formulated with bromelain, another cysteine protease with the same handling needs. Other enzymes are listed under Enzymes.

For a label that declares activity per serving, powder per serving equals the declared activity divided by the activity per gram on the certificate of analysis. Add an overage set from your own stability data to cover activity loss over shelf life; the overage calculator does the arithmetic.

Enzyme dusts are handled as potential respiratory sensitisers. Use dust extraction and the protective equipment the safety data sheet specifies.