Why is mozzarella not halal? Understanding rennet and Islamic dietary law

November 12, 2025 •

4 min read

While mozzarella is made primarily from milk, one key ingredient—rennet—can determine its halal status. Traditionally sourced from the stomachs of young animals, animal rennet can make mozzarella haram if the animal was not slaughtered according to Islamic law. This means not all mozzarella is automatically permissible for Muslim consumers, necessitating careful label reading and consideration of its production method.

Quick Summary

This article explores the primary reason why some mozzarella cheese is considered non-halal: the use of animal-derived rennet from non-slaughtered sources. It details the different types of rennet, explains how to determine a product's status, and offers guidance on finding certified halal options.

Key Points

Rennet is the key issue: Traditional mozzarella uses animal rennet, which is only halal if the source animal was slaughtered according to Islamic law.
Source transparency is a problem: Many manufacturers do not specify the source of the "enzymes" used, leaving the halal status of their product uncertain for consumers.
Pork rennet is explicitly haram: The use of rennet from a pig is absolutely forbidden in Islam, and some traditional cheeses may use it.
Halal alternatives exist: Mozzarella can be and is produced using vegetarian, microbial, or FPC (fermentation-produced chymosin) rennet, which are all halal.
Look for halal certification: The most reliable way to ensure mozzarella is halal is to find a product bearing a certification mark from a reputable organization.
Check for labels carefully: The FDA permits the generic term "enzymes," so look for explicit "vegetarian rennet" or a halal label, as ingredients can change.
Some scholars allow all cheese (Hanafi view): Based on historical precedents, some Islamic scholars in the Hanafi school consider rennet pure even from a non-halal source, but many recommend caution due to scholarly disagreement.

The Core Issue: Rennet in Cheesemaking

At the heart of the question, "Why is mozzarella not halal?" lies a specific enzyme used in cheese production: rennet. Rennet's function is to coagulate milk, separating it into solid curds and liquid whey. Without this agent, most hard and semi-hard cheeses, including traditional mozzarella, would not form properly. The issue arises from the origin of this crucial enzyme. Traditionally, rennet is extracted from the stomach linings of unweaned calves, lambs, or kids. For an animal product to be considered halal (permissible), the animal must be a lawful type and must be slaughtered in accordance with Islamic guidelines, known as dhabihah. If the animal was not slaughtered properly, the rennet is not halal, rendering the resulting cheese haram (forbidden).

The Challenge of Modern Food Production

In today's global food market, traceability and ingredient sourcing can be complex. Manufacturers often use generic terms like "enzymes" on ingredient lists, without specifying their source. This lack of transparency is a major reason why Muslim consumers cannot simply assume that non-certified mozzarella is halal. A cheese made with animal rennet from a non-halal source is considered impure by many Islamic scholars. Adding to the complexity, some traditional Italian cheeses may even use rennet from a forbidden animal, such as a pig, which is unequivocally haram. This variability makes due diligence necessary for observant Muslims.

Navigating the Rennet Landscape: A Consumer's Guide

Fortunately, modern food science and increased consumer demand have led to the development of several halal alternatives to traditional animal rennet. These alternatives mean that a wide range of mozzarella products are now available with a guaranteed halal status. Understanding the different types of rennet is the key to making an informed choice.

Types of Rennet and Their Halal Status

Animal Rennet: Sourced from the stomach of young mammals, typically calves. This is the most traditional type and its halal status depends entirely on the animal's slaughter method. It is considered haram if the animal was not properly slaughtered. Many traditional European cheeses, and some artisan mozzarellas, still use animal rennet.
Microbial Rennet: Derived from fungi or bacteria through fermentation. This type is universally accepted as halal, as it is not animal-based. Microbial rennet is widely used in commercial cheese production and is a common ingredient in vegetarian and halal-certified cheeses.
Vegetable Rennet: Extracted from specific plants like thistles, nettles, or figs. Historically used for centuries, it provides a plant-based alternative to animal rennet. While typically halal, consumers should verify that no alcohol is used during the extraction process.
Fermentation-Produced Chymosin (FPC): A genetically engineered enzyme that is molecularly identical to the chymosin found in animal rennet. This form is also considered halal by many scholars, as it is produced from microorganisms and not directly from an animal. However, some might avoid it due to its GMO origins.

Comparison of Rennet Types


Feature	Animal Rennet	Microbial Rennet	Fermentation-Produced Chymosin (FPC)
Source	Animal stomach lining (calf, lamb)	Fungi or bacteria	Genetically modified microbes
Halal Status	Doubtful unless certified halal. Haram if from non-halal source.	Accepted as halal due to non-animal source.	Accepted as halal, but some avoid due to GMO source.
Usage	Traditional, artisan cheeses.	Widely used in commercial production.	Very common in modern cheesemaking.
Flavor Impact	Clean, traditional flavor, especially for aged cheese.	Can be neutral but sometimes slightly bitter.	Identical to animal rennet's flavor properties.
Cost	Can be more expensive and limited.	Cost-effective and widely available.	Cost-effective and consistent.

A Path to Assurance: The Role of Halal Certification

With the complexities of modern food manufacturing, the most reliable way for a Muslim consumer to ensure their mozzarella is halal is to look for a certified halal product. Certification bodies, such as the Islamic Food and Nutrition Council of America (IFANCA), rigorously audit the entire production process, from sourcing ingredients to packaging. This ensures that any enzymes or other additives used are permissible according to Islamic guidelines. Many major food manufacturers now offer halal-certified versions of popular products to cater to the growing Muslim market. While not all mozzarella is halal, the availability of certified alternatives empowers consumers to make choices that align with their faith.

Conclusion: Navigating Choice with Information

The question, "Why is mozzarella not halal?", is nuanced. It is not inherently haram, as it is derived from milk. However, the use of animal rennet from a non-halal slaughtered animal makes it questionable for many Muslims. The emergence of microbial and vegetable rennet options, coupled with the increasing availability of halal-certified products, has made finding a permissible alternative much easier. By understanding the different types of rennet and prioritizing certified products, Muslim consumers can enjoy mozzarella and other cheeses with confidence. The power to make an informed choice lies in a close inspection of ingredient labels and the search for official halal certification marks. The Islamic Food and Nutrition Council of America (IFANCA) is one such organization that can provide helpful resources..

Frequently Asked Questions

Rennet is an enzyme used to curdle milk in cheesemaking. It is a concern for halal diets because if it comes from an animal that was not slaughtered according to Islamic law (dhabihah), the resulting cheese is not halal.

No, not all mozzarella is non-halal. While traditional and some artisan mozzarella may use non-halal animal rennet, many commercial brands use vegetarian or microbial rennet, making their product halal. Always check the label for certification.

Look for a halal certification mark on the packaging from a recognized organization. Alternatively, check the ingredient list for 'microbial rennet,' 'vegetarian rennet,' or specific 'enzymes' that come with a halal guarantee.

Alternatives include microbial rennet (from fungi/bacteria), vegetable rennet (from plants like thistle), and fermentation-produced chymosin (FPC), a genetically engineered enzyme.

Not necessarily, but it is a reason for caution. The term "enzymes" is generic and does not specify the source. Unless a product is certified halal, the source of the enzymes is unknown, making it mashbooh (doubtful).

Yes, it is possible. While mozzarella is typically made with rennet from calves or other ruminants, some traditional Italian cheeses and some manufacturing processes can use pork-derived rennet, which is strictly haram.

Yes, some scholars, particularly within the Hanafi school, hold a more lenient view, believing rennet is purified by the process. However, the majority and most cautious opinion considers such cheese impure if the animal was not properly slaughtered.