Rennet amount, follow recipe or bottle?

[Shalloy]

Last week I made a cam with 7.5 litres of milk and the recipe said to use 2mls rennet. My floc multiplier was 16 minutes using the bowl method.

Today I'm making a blue cheese  with 7.5 Litres of milk and the recipe (both recipes were from the country brewer website which sells the epicurean brand rennet) said to use 5mls of rennet. I did this and the floc multiplier was only 5 minutes. As soon as I put the bowl in it wouldn't spin. 
But the bottle says to use 2.5 mls per 10 litres of milk.  I wasn't sure if I should follow the recipe or the bottle but because the cam recipe said 2mls and the blue recipe said 5mls I followed the recipe thinking that perhaps blu cheese requires more rennet.

Another difference is with the cam I sprinkled the culture onto the milk.  With the blue I'm making today I made a starter Friday night and poured this into my milk then sprinkle the penicillium roqueforti on top.

Have I added too much rennet? Even the rennet set times in the recipes are different. The cam recipe says 60 minutes but the blue recipe says 45 minutes.  So because of that I'm hoping everything will be okay.

[Stinky]

Is it single or double-strength?

Different cheeses use different amounts. Adjust to hit your floc target.

[Shalloy]

Is what single or double strength?  The rennet? I have no idea. It just says 2.5 mls per 10 litres On the bottle. I used 5 mls for 7.5 litres as per the recipe.

I must admit the recipe said rest for 45 minutes which is what my floc multiplier time worked out to be.

[Stinky]

Is what single or double strength?  The rennet? I have no idea. It just says 2.5 mls per 10 litres in the recipe. I used 5 mls for 7.5 litres as per the recipe.

I must admit the recipe said rest for 45 minutes which is what my floc multiplier time worked out to be.

I usually use 1/2 teaspoon for 2 gallons milk. This gives me a set in 10 minutes.

[Andrew Marshallsay]

I use the same rennet as you and I usually use at the rate recommended on the bottle unless there is some reason to think that I should vary it for the cheese type.
The problem is that rennet strengths vary. The Epicurean brand animal rennet, which I gather you are using, is rated at 140 IMCU (International milk clotting units, I think). The whole "single", "double" strength question can get rather confusion and it appears that there are differences between the US and Europe. What that means here in Oz is anyone's guess.
You will find more discussion of this on this thread:
https://cheeseforum.org/forum/index.php?topic=13843.0

[Shalloy]

So what is the effect n the end result going to be because I used double the amount of rennet?

It's weird that the cam recipe was  2mls which is correct going if the rennet bottle but the blue recipe said 5mls.

[Andrew Marshallsay]

That does seem strange and the short floc time would indicate that you used too much rennet. It could be intended to give you a very firm curd or it could be a typo in the recipe (I suspect the latter).
A firmer curd could be beneficial because it will give you more mechanical openings for the blue mould to develop in. It will also retain fat better. I'm not sure what the downside of too firm a curd might be but it may be that the cheese will retain too much whey and not age well in the long term. Others may be able to give you more information on this.
If you have been using the flocculation method with an appropriate multiplier, it is likely that your coagulation time may be about right regardless of the amount of rennet used.
I have seen that Country Brewer advise starting cultures the day before. The reason seems to be simply to verify that the culture is still good. This does not appear to be general practice: I haven't seen reference to it anywhere else

[Shalloy]

Well after four hours in the hoops they have only dropped about an inch from the top of the moulds.  My last blues I made two years ago ended up drying out too much and were like hockey pucks so I'm hoping these ones will turn out.

I couldn't decide if I should use the amount on the bottle or the recipe. The wife said go with the bottle but silly me didn't listen and went with the recipe.

[H-K-J]

The wife said go with the bottle but silly me didn't listen

And that, I am thinking, is not the last mistake of the male home cheese maker
(Pssst, always listen to your BH)

[Shalloy]

This morning they still havent dropped more than about an inch from the top of the hoops and still look quite wet. I will let them drain until I get home from work tonight then take them out of the hoop's and salt them.

Here's an interesting article where an experiment was tried using different amounts of rennet. It seems the results showed that the cheese where he used more rennet tasted better. But...he still only used around 3 mls for my batch size compared to the 5 mls I used.

https://handyface.wordpress.com/2012/03/11/rennet-quantity-experiments-the-setup/

[awakephd]

I seem to recall reading somewhere that too much rennet can lead to bitterness in an aged cheese ... ?

[Stinky]

I seem to recall reading somewhere that too much rennet can lead to bitterness in an aged cheese ... ?

As I understand that takes quite a decent bit of rennet.

[awakephd]

Could be. That's the sort of thing that is learned from ...

... wait for it ...

... bitter experience.

Aren't you glad you waited for that?