Rennet Casein | whatsinit

About

What it is and where it shows up.

Rennet casein is the principal phosphoprotein of bovine milk, precipitated by the enzymatic action of rennet (chymosin/pepsin) on κ-casein, which destabilises casein micelles and causes milk to coagulate. It is used industrially as a high-protein ingredient in processed cheese, imitation cheese, sports nutrition, and food coatings owing to its excellent functional properties such as emulsification, water-binding, and film-forming.

Safety summary

The regulatory and scientific consensus.

Rennet casein is derived from a food (milk) with centuries of safe human consumption and is not assigned a specific ADI by JECFA, EFSA, or FDA, as it is considered inherently safe at normal dietary intakes. EFSA has concluded that toxicological data are unnecessary given the enzyme source and history of use; however, the risk of allergic reactions cannot be entirely excluded, particularly for individuals with documented milk protein (casein) allergy. No evidence of carcinogenicity, mutagenicity, or systemic toxicity has been reported in the peer-reviewed literature at typical food-use levels.

Regulatory landscape

What food-safety regulators have decided.

Jurisdiction	Status	Note
EFSA (European Food Safety Authority) (European Union)	Approved	Rennet (chymosin/pepsin from calf abomasum) evaluated under Regulation (EC) No 1332/2008 on food enzymes. EFSA CEP Panel concluded no toxicological data were required given centuries of safe use; risk of dietary allergic reaction considered low. Rennet casein as a resultant protein ingredient is permitted in processed and analogue cheese products across the EU. No specific E-number assigned to rennet casein itself; it is regulated as a food ingredient, not a food additive.source
FSSAI (Food Safety and Standards Authority of India) (India)	Approved	FSSAI FSS (Food Products Standards and Food Additives) Regulations 2011 permit casein (including milk protein of any type) as a thickener/stabilizer in dairy products up to 20.0 g/kg. Non-animal rennet and other safe coagulating enzymes are expressly permitted for use in fermented and acidified cream products.source
FDA (Food and Drug Administration) (United States)	Approved	Casein and casein salts (including rennet casein) are recognised under 21 CFR Part 184 as GRAS milk-derived proteins. Calcium caseinate is explicitly listed under Parts 133 and 135. Rennet casein is permitted as a food ingredient under GMP with no established upper intake limit.source

Who should approach with care

Whose guidance would steer them away.

Other — Individuals with a diagnosed cow's milk protein (casein) allergy must avoid rennet casein entirely, as it is a concentrated casein fraction and can trigger IgE-mediated allergic reactions; EFSA notes the risk of allergic reactions from dietary exposure cannot be excluded.

Lactose Intolerance — Although rennet casein is very low in lactose as a result of the coagulation and washing process, highly sensitive lactose-intolerant individuals should consult a doctor, particularly when casein is incorporated into processed foods that may contain residual lactose from other dairy ingredients.

Infants — Infant formula and early-life nutrition products are subject to specific compositional regulations; rennet casein should only be used in formulations explicitly authorised for infants, and parents should consult a paediatrician before introducing casein-containing products to infants with suspected milk protein intolerance.

Kidney Disease — Rennet casein is a high-protein ingredient; individuals with chronic kidney disease who are on protein-restricted diets should limit intake of casein-enriched products to avoid exceeding prescribed protein thresholds.

Research citations

The sources behind this verdict.

1FDA. Food Additive Status List — Casein and Casein Salts, 2026. fda.gov
2FSSAI. Food Safety and Standards (Food Products Standards and Food Additives) Regulations 2011 — Chapter 2.1: Dairy Products and Analogues (Version 3, May 2025), 2025. fssai.gov.in
3EFSA. Safety evaluation of the food enzyme rennet containing chymosin and pepsin A from the abomasum of suckling calves, goats and lambs, 2023. efsa.europa.eu
4EFSA. Scientific Opinion on the safety evaluation of the food enzyme rennet containing chymosin and pepsin A from the abomasum of calves and cows, 2023. efsa.europa.eu
5PubMed. Safety evaluation of the food enzyme rennet containing chymosin and pepsin A from calf abomasum (PMC full text), 2022. pmc.ncbi.nlm.nih.gov

Independently researched5 citations