Rennet obtained from animal sources is used for curdling of milk in the cheese-making process. But vegetarians need not give up cheese, as a number of animal rennet substitutes are available in the market.
| Did You Know? The Fermentation-Produced Chymosin (FPC) was the first bioengineered product (enzyme) to be registered and allowed by the US Food and Drug Administration. FDA approved the use of FPC in food in 1990, and in 1999, about 60% of U.S. hard cheese was made with FPC. By 2008, approximately 80% to 90% of commercially made cheese in the U.S. and Britain were made using FPC. |
Most cheese makers use animal rennet to initiate the process of coagulation of milk. Rennet is an enzyme which is produced in the fourth stomach chamber (the abomasum) of ruminant mammals. Traditionally, the stomach of a slaughtered young ruminant was washed, salted, dried, and stored for use. The cooks used to snip off small pieces from the dried stomach, soak them in water, and use the extract for cheese making. These stomachs were obtained as a by-product of veal production. Some traditional cheese makers still use this method. Modern technology has made the process easier.
Cheese like Grana Padano and Gorgonzola are always made using animal rennet. Parmesan cheese is always made using calf rennet. As vegetarians avoid animal flesh and food made using animal flesh, they exclude this type of cheese from their diet. But there is no need to give up eating cheese.
Scarcity of mammalian stomachs (abomasum) has forced cheese producers to find out alternative sources of rennet. The enzyme rennet contains a unique compound called ‘chymosin’, that promotes curdling of the casein in milk. Researchers have found out many sources of rennet. It is now derived from certain plants, fungi, and microbes. Rennet obtained from these sources can easily substitute animal rennet.
These days, rennet is available in the form of liquid, powder, and tablets, which are quite easy to use. Some rennet alternatives are also certified for Kosher (under Jewish dietary laws, milk and meat cannot be mixed), and Halal use. You can choose from the vegetable rennet tablets, liquid vegetable (or liquid organic vegetable) rennet, etc.
| Vegetable Sources Vegetarians can consume cheese that is produced using rennet obtained from plant sources. In ancient times, the Greeks used to add fig juice to milk during the cheese making process. Certain enzymes from thistle or cynara, a genus of thistle-like perennial plants, are used in some traditional cheese making processes in the Mediterranean. Phytic acid, derived from unfermented soybeans, is also commonly used for the process. As you know, citric acid, or vinegar, or the lactic acid produced by soured milk, is widely used to coagulate milk. Bacterial fermentation such as in cultured milk promotes the acidification of milk. |
| Microbial Sources The enzyme chymosin is obtained by fermentation of the fungus Mucor miehe, Mucor Pusillus, and Endothia cryphonectria, or from bacteria like Bacillus subililis or Bacillus prodigiosum. Some molds like Rhizomucor miehei produce enzymes which are helpful in the process of cheese making. But cheese so produced is somewhat bitter. Although producers take care to avoid contamination with undesirable byproducts of the mold growth, governmental organizations like the European Food Safety Authority are not ready to offer QPS (Qualified Presumption of Safety) status to the enzymes produced by these molds. |
| Fermentation-Produced Chymosin (FPC) FPC is often referred to on labels as ‘microbial rennet’ or ‘vegetable rennet’. The product that contains FPC is described as ‘vegetarian’. Development of genetic engineering enabled researchers to extract rennet-producing genes from animal stomachs and insert them into certain bacteria, fungi, and yeasts. These genetically modified (GM) microorganisms produce chymosin during fermentation. After fermentation, these microorganisms are killed. Thus, chymosin obtained from the fermentation broth does not contain any GM component. This is an effective way of producing chymosin that has a high degree of purity as compared to animal rennet. The use of FPC is beneficial for cheese producers, as it results in higher production yield, better curd texture, and reduced bitterness. FDA has granted ‘Generally Regarded as Safe’ (GRAS) status to certain bioengineered chymosin products. According to FDA, it needs no special labeling, so the company need not declare its source or method of production. |
| Making Cheese at Home The producers of FPC do not disclose the GMO (genetically modified organism) technique used. They are not compelled to declare it by law. They don’t even have to declare whether any allergens are used in the fermentation process. Although products made from FPC are labeled ‘vegetarian’, we know that the production of bioengineered chymosin begins with a natural (i.e., animal organ) source. In Pfizer’s patent application, it is mentioned that “Total RNA from animal pituitaries was obtained from a local slaughterhouse…”. The best way to have safe food is to prepare it at home. Examples of soft cheese which can be easily made at home are cream cheese, paneer, and rubing. They are traditionally made by curdling milk with natural foods like lemon juice, vinegar, and cultured or soured milk. Some other examples of acid-curd cheese are cottage cheese, pultost, chhena, raejuusto, queso blanco, tyrolean gray cheese, etc. Remember, soft cheese available in the market is as likely to be non-vegetarian as hard cheese. |
✦ The Danish company Chr. Hansen is the leading producer of FPC. It produces it from the fungus Aspergillus niger. It is marketed under the trademark CHY-MAX. A calf gene was initially used to produce this bioengineered FPC. There are different types of Chy-Max; for example, Chy-Max Plus, Extra, Ultra, and Special. The first three are 100% chymosin, while Chy-Max Special is 80% chymosin and 20% bovine pepsin (another type of enzyme). According to the product data sheet of Chy-Max Extra, it is ‘acceptable for the production of vegetarian cheese’. Chy-Max M, the latest variety, has been developed using a camel gene. This FPC is also described as ‘suitable for vegetarians’ by the company.
✦ The microbial rennet Hannilase by Chr. Hansen is not produced through recombinant animal gene technology. R. Miehei, which is listed both as non-GMO and vegetarian, is used to produce Hannilase.
✦ The Dutch company DSM produces FPC from Kluyveromyces lactis, and it is marketed under the trademark MAXIREN. It appears that, initially, they have used a calf gene to produce this FPC. It produces Fromase from R. Miehei.
✦ DSM also produces Suparen/Sure-curd from the fungus Cryphonectria parasitica. It is described as ‘vegetarian’ in product literature.
✦ Marzyme manufactured by Danisco-DuPont is a non-animal microbial rennet (produced through recombinant animal gene technology), and is less expensive than FPC.
✦ As mentioned above, lemon juice (citric acid), vinegar, soured or cultured milk (lactic acid), fig leaves, dried caper leaves, safflower, stinging nettle, lady’s bedstraw (Galium verum or curdwort), mallow, ground ivy, melon, wild thistle, cardoon thistle stamens, yarrow, etc., can be used for milk curdling.
According to Trader Joe’s list of cheese, Baby Swiss, Goat Gouda, Caprese Log Mozzarella, Mild Cheddar Cheese Sticks, Montery Jack Cheese Sticks, and Ovolini Mozzarella contain vegetable rennet, while Cream Cheese, Soy Cheese, and Whipped Cream Cheese do not contain rennet.
Most European cheese contain animal rennet. Still, it’s getting easier to find vegetarian, even vegan, alternatives to these types of cheese. A wide variety of cheese are now made with non-animal rennet. Even dairy-free cheese, suitable for a vegan diet, are available in supermarkets.
In spite of the availability of several high-quality alternatives for animal rennet, the rennet story does not end here. As the gene cloned in K. Lactis was isolated from calf gastric tissue, some vegetarians are not ready to consume cheese made from it. As the gene cloned in E. Coli was synthesized, vegetarians may accept the chymosin made from it. It should be noted that the cheese that has a non-GMO seal on it does not have bioengineered chymosin.
FDA’s guidelines for what is ‘GMO’ or ‘non-GMO’, and the rules for labeling products manufactured by genetic techniques or containing genetically modified organisms (GMOs) or their products are somewhat misleading. It seems that they support manufacturers rather than consumers. FDA has not made it mandatory for manufacturers to describe the type of rennet used in the list of ingredients printed on the label. Manufacturers can mix animal, plant, and microbial varieties, and just label them ‘enzymes’. Thus, the labels may not provide accurate information about the coagulant used. So, it is difficult for vegetarians to check whether a particular cheese contains animal ingredients or not.
It is equally true that the taste and texture of the cheese made from vegetable rennet can never be like that which is made from animal rennet or FPC. Even microbial rennet cannot be used for making cheddar or hard cheese.
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