Papain
A protein-digesting enzyme extracted from unripe papaya latex, used in meat tenderising, brewing, and some food processing.
Papain is structurally related to several known allergens, including those in kiwi, pineapple, soy, fig, and papaya. For people with latex-fruit syndrome, there is an additional cross-reactivity risk that cannot be excluded. Allergic reactions upon dietary exposure are possible for anyone with these fruit allergies.
What is it?
Papain is a cysteine protease enzyme extracted from the latex of unripe Carica papaya (papaya). It belongs to the same enzyme family as bromelain (from pineapple) and actinidin (from kiwi). It has been used in food processing for decades, traditionally in cultures where papaya leaves were used to wrap meat.
What does it do?
Papain breaks down protein chains by cleaving peptide bonds, a process called proteolysis. In meat, this loosens the fibrous structure, making it tender. In brewing, it digests proteins that would otherwise cause cloudiness in chilled beer. It works most effectively at body temperature and is largely inactivated by cooking at high heat.
Where you will see it
Most commonly used in meat tenderiser powders, marinades, and processed meat products. Also used in beer and ale brewing to improve chill stability, and in some dietary supplement products marketed for digestive support. May appear on labels as 'papain', 'papaya enzyme', or 'food enzyme (papain)'.
What the science says
Allergenicity: links to fruit and latex allergies
EFSA's 2026 safety evaluations found that papain's amino acid structure closely matches six food allergens and eight respiratory allergens. People allergic to papaya, kiwi, pineapple, soy, or fig may react to food-grade papain because the proteins are structurally similar. A risk of allergic reactions from dietary exposure cannot be excluded for these groups. For people with latex-fruit syndrome, the papaya latex source adds a further cross-reactivity pathway.
Homology searches identified matches between papain's amino acid sequences and allergens in papaya, kiwi (actinidins), pineapple (bromelain), soybean, and fig, as well as respiratory allergens including ragweed (Amb a 11) and house dust mite (Der p 1, Der f 1).
The EFSA panel concluded that a risk of allergic reactions upon dietary exposure to papain cannot be excluded for individuals with allergies to papaya, pineapple, kiwi, soy, or fig.
Papain originates from papaya latex, which contains additional proteins implicated in latex-fruit syndrome (including endo-polygalacturonase and endochitinase), which may be present as residuals in the final food enzyme preparation.
No numerical acceptable daily intake established
EFSA did not set a numerical acceptable daily intake for papain. Current food enzyme guidance does not require toxicological testing when the enzyme comes from an edible plant source and estimated dietary exposure is within the same order of magnitude as natural consumption of that plant. EFSA estimated maximum daily exposure in toddlers at around 0.409 mg total organic solids per kilogram of body weight, comparable to eating unripe papaya. Whether this comparison fully accounts for industrial concentrations in processed food remains an open question.
No numerical ADI was established for papain. Toxicological testing was not required because the source organism is edible and estimated dietary exposure through food use was considered comparable to natural papaya consumption.
Occupational and respiratory sensitisation
Papain is a well-documented occupational allergen. Workers in meat processing and brewing industries who are repeatedly exposed to papain dust or aerosols have developed asthma, rhinitis, and skin reactions. This body of evidence relates to inhalation exposure rather than eating papain in food, but the respiratory allergen matches identified in EFSA's homology search (including house dust mite proteins) suggest the underlying sensitisation mechanisms are relevant.
Papain is listed as a known occupational respiratory allergen causing occupational asthma in workers exposed to papain dust, with documented IgE-mediated sensitisation.
Homology with respiratory allergens including house dust mite allergens Der p 1 and Der f 1 was identified in sequence analysis of papain.
Where it stands with the regulators
Who should be careful
People with allergies to papaya, kiwi, pineapple, soy, or fig should be aware that papain shares allergenic proteins with these fruits and a reaction cannot be excluded. Those with latex-fruit syndrome face an additional risk because papain is extracted from papaya latex. Look for 'papain', 'papaya enzyme', or 'food enzyme (papain)' on the label. Workers in meat processing or brewing should note that inhaling papain dust is a documented cause of occupational asthma.
The honest read
Papain is an enzyme with a long history in cooking and food manufacturing. The main honest question at the moment is allergenicity, not toxicity: EFSA's 2026 evaluations confirmed it shares structural features with a range of fruit and respiratory allergens, and explicitly stated that allergic reactions in susceptible people cannot be ruled out. For the general population with no fruit allergies, EFSA found no toxicological concern at typical dietary exposures. The comparison to eating unripe papaya is reasonable but not perfectly analogous to industrially concentrated enzyme preparations in processed food. No numerical acceptable daily intake has been set, and the EU community list of approved food enzymes is still being finalised. In Great Britain, papain remains in use under a transitional assimilated framework while no domestic GB enzyme list yet exists.
Related additives
Common questions
Is E1111 banned in the UK?
Papain is not classified as a food additive under the UK approved additives list (Annex II of the assimilated EU Regulation 1333/2008), so the 'E1111' designation does not appear on that list. It is regulated separately as a food enzyme under assimilated Regulation 1332/2008. In Great Britain, no domestic food enzyme list has been established; until it is, enzymes in use continue to be permitted under the transitional assimilated framework. EFSA published safety evaluations in 2026 and found no basis for prohibition.
Can papain trigger an allergic reaction?
Yes, this is possible for certain groups. EFSA's 2026 safety review found that papain's protein structure closely resembles allergens found in kiwi, pineapple, soy, fig, and papaya itself, as well as some respiratory allergens. People with allergies to any of those foods should treat papain with the same caution they would the whole fruit. EFSA stated that a risk of allergic reaction cannot be excluded for these individuals.
What foods contain E1111?
Papain is most commonly found in meat tenderiser products, pre-marinated or processed meats, and certain ales and beers where it is used to prevent cloudiness. It also appears in some chewing gums, digestive supplement products, and bakery applications. On a label it may be listed as 'papain', 'papaya enzyme', or 'food enzyme (papain)'.
Is E1111 vegan?
Yes. Papain is derived from the latex of the papaya plant and contains no animal-derived ingredients.
Sources
- EFSA CEP Panel, Safety evaluation of the food enzyme papain, a cysteine endopeptidase complex from the latex of Carica papaya L. (EFSA Journal 2026)
- EFSA CEP Panel, Safety evaluation of the food enzyme papain from the latex of Carica papaya L. (EFSA Journal 2026)
- PMC full text: Safety evaluation of the food enzyme papain, a cysteine endopeptidase complex (PMC12797086)
- UK FSA Approved additives and E numbers
- EU Regulation (EC) No 1332/2008 on food enzymes
- HSE Occupational asthma agents: papain
- FSA Food enzymes authorisation guidance (Great Britain)
See this on every food you scan
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
Get NutraSafe on the App Store