On rennet….

Flip a cheese over, read the label
Flip a cheese over, read the label

I’m sure a dairy diary should start with milk but I believe that will take a little longer to research. For now my focus is on rennet. I want to try and recreate some of the lost cheeses of Suffolk but also make them palatable for the 21st century. At various stages I will have to contend with modern tastes and ethics versus historical accuracy. Actually rennet makes a very good place to start.

Rennet is an enzyme (a complex mix of rennin and pepsin), traditionally from calves stomachs but also found in the stomachs of other young animals. For time immemorial rennet has also been extracted from plants from fig juice to lady’s bedstraw and nettles, many plants are known to coagulate milk.

Some of my first cheeses were made without rennet, fresh soft cheeses often need no more than a little vinegar or lemon juice to start the process. However for harder cheeses and some soft cheeses rennet in one form or another is essential. There are those that say that cheese was first formed when milk was carried in bags made from calves stomachs that still contained some natural rennet; also that cheeses that are matured for long periods require calves rennet or they become bitter. The rennet I have used more recently was liquid, vegetarian rennet from Lakeland, despite the comments from customers on their site I was quite successful with it. Since my class at High Weald Dairy I understand that liquid rennet can go off,  they recommend using the tablet version which you rehydrate just before use. Those readers who have followed my blog Grethic’s Grethica in the past will know my previous effort at ‘wild rennet’ failed miserably. I read a bad reference and tried using cleavers instead of bedstraw and failed to make milk go off at all! – I later discovered that cleavers are known as ‘milk sweet’.

For many European cheeses with PDO status there is an expectation as as to the type of rennet that is used and often this means calf rennet. As an exercise next time you are in the local supermarket (with apologies to my good friend J who had to listen to me spouting on for 20 minutes on the topic today), flip over the cheese and see if it tells you about the rennet. The @cooperatviefood are generally pretty good with their labelling, you may find ‘made using calf rennet’, ‘The rennet used in this Co-op cheese is NOT derived from genetically modified organism’, ‘made using a vegetarian rennet extracted from a genetically modified micro-organism’. The genetically modified organism is a bacteria, according to my Gourmet’s Guide Cheese the use of GM rennet is ‘a subject of dispute in Europe’, if it is it does’t seem to stop it hitting the supermarket shelves. Obviously with most artisan cheese you only discover the rennet type by discussion with your cheesemonger – ask them, test their knowledge, why not?

So, I have some thinking to do; go with a vegetarian rennet and risk bitter tastes in long storage or products that are not marketable to vegetarians or that cause concerns for those who resist GMOs……  I would welcome your thoughts and opinions, do you have strongly held beliefs, do you check your cheeses?


One thought on “On rennet….

  1. I have made cheese with microbial rennet, it also can leave a bitter flavour in cheese too, and calf rennet. I prefer calf rennet as I get a better curd set. I also help out at a local dairy and we use kid rennet with all our cheeses. The owners are very up front about it. There has not been any issues with customers.

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