RENNET: let’s find out together what it is.

The origins of animal rennet date back to about 7000 years ago.

Animal rennet was discovered by chance many years ago, thanks to the transport of milk in the skins obtained from the stomachs of ruminants, which with their natural content of enzymes gave life to the clot now defined as “cheese”.

This physicochemical process is based on the action of chymosins which, by removing the water-soluble parts of the caseins, break the equilibrium causing the collapse of the suspended mass which will then aggregate, forming a network of proteins commonly called “curd”.

This series of physicochemical reactions induced in milk by animal rennet is called “rennet coagulation”.

But what is animal rennet made from?

The rennet is obtained thanks to a process of extraction of the enzymatic complexes present in the fourth stomach of ruminants not yet weaned such as veal, lamb, kid and buffalo calf.

Within this group of enzymes, chymosin and pepsin are the ones that are of most interest from a dairy point of view.

AN IMPORTANT CLARIFICATION

The animals are slaughtered for their meat and not to make rennet and the stomachs are considered a ‘waste material’. So why not turn them into rennet?

With great attention to sustainability from a Circular Economy point of view, Caglificio Clerici recovers stomachs in selected and certified slaughterhouses, reducing pollution and food waste and creating a fundamental product for the dairy sector and for the production of cheese.

But what is rennet then?

Rennet is a natural ingredient of animal origin rich in enzymes such as chymosin and pepsin, essential for the production of cheeses.

As the scientists would say: it is a “natural enzyme compound that coagulates milk” whose main enzymes are chymosin (or rennin) and pepsin which vary in proportions according to the age of the animal and the type of diet. The younger the animal and the greater the role of milk in its diet, the higher the percentages of chymosin. Similarly, the fourth stomach – also called abomasum – of an adult bovine will almost exclusively contain pepsin.

The use of rennet as a coagulant in the dairy sector is very old, but perhaps not everyone is aware that there are different types of coagulants, which are distinguished by their origin and their fields of use.

On the market, we find different rennets of animal origin: bovine, goat, sheep and buffalo, some of which can be in powder, liquid or paste based on the use and type of cheese desired.

How is it used?

In the case of a Parmesan type cheese, the milk that arrives in the dairy is poured into special inverted bell boilers, the whey-graft (a natural population of lactic bacteria) obtained from the residual whey of the previous day’s processing is added and in the meantime, the milk is heated until it reaches the optimum temperature for adding rennet.

With varying times depending on the type and quantity of rennet used, the milk is expected to clot-forming a gel (curd), subsequently broken up to the size of a grain of rice and all cooked up to a temperature of 56 ° C. When the temperature is reached, the cooking phase is interrupted to move on to the extraction and putting into moulds, before moving on to the salting phase and then seasoned for a minimum of 9-11 months.

But which cheeses are made with rennet? Let’s learn to distinguish them…

Parmigiano Reggiano and Grana Padano, for example, are typically made with powdered rennet. For the production of the classic mozzarella as well as the delicious Mozzarella di Bufala DOP, classic liquid rennet and liquid buffalo rennet are used respectively.

For the fontina, we use the rennet powder in respect of tradition. For the provolone we use liquid rennet for the sweet version while for the spicy one we use rennet paste. In the case of Emmental, the rennet powder. In Gorgonzola, we use liquid rennet or rennet in veal paste for the traditional one according to the disciplinary and in the case of pecorino all three types of rennet can be used according to the type and respective disciplinary.

In short, for the production of cheese, rennet is as fundamental as milk and there are types for every need and for every dairy variety. 🧀