Rennet potency tests

[johnr]

Hi

Since we know that Rennet loses potency with time, how do you prepare to know what factor to multiply by before preparing to make cheese.  Or is the rule to use it for 3 months and then throw it out?. 

Is the pill form better?.  Would its qualities not remain more constant?

Thanks

[Stinky]

It loses potency, but slowly. If I notice that for the same amount of rennet coagulation takes longer, I can judge that it's losing its potency. The factor that it's multiplied by does not change, how long it takes for the initial floc can change. You're still going to want to multiply it by the factor to get a clean break.

[qdog1955]

johnr----you need to be careful that you don't fall into the trap of --exactitudal science  ---yes I made that up-----just follow the recipe as best you can-----if it says it will floc. in 12 to 15 min, and it took 16----your cheese should be fine---notice it already has a time that isn't exact----if it says to raise temp by ten degrees over 20 min. and it took 18 min. ---the cheese will survive----the point being ---don't assume the rennet is going bad----there are to many variables at work here. Keeping make notes is your key to success on future cheese makes, if something goes way off course-----then you might be able to pinpoint where the mistake may have happened---or if it really was a rennet problem.
  I have used liquid rennet up to 9 months with no visible change in the cheese and I believe it would have lasted longer, but I used it all.
  I prefer the liquid rennet, because I can get exact measurements in ml. using a syringe.
Qdog

[johnr]

Ok.  I really appreciate these responses.  I will take to heart and keep going

[JeffHamm]

Hi johnr,

Just so you know, I made a Lancashire yesterday using liquid rennet (750 ml strength) that had an expirey date sometime in 2009!  It's about 6 years past it (apparently).  The label says use 0.7 ml/10 Litres, which I found was too strong when  first started using it and backed down to 0.6 ml.  I used 0.6 ml yesterday, and it floc'd in about 20 minutes (11 litre make).  Bit slower than usual, but it was more the final firm setting that was slow as things were looking to be on time but the surface never quite gelled to leave a ring.  Cheese make went perfectly fine after that. 

In other words, don't worry about it.  Rennet may lose strength over time, but if it does, it's very slowly.

[Kern]

johnr,

Your concern is admirable and your questions reflect your desire to make a perfect cheese.  This alone is worth a cheese.  You are currently a virgin in this department so I'll simply say what you've undoubtedly seen many times:  AC4U.   

Kern

[Boofer]

Is the pill form better?.  Would its qualities not remain more constant?

I started out using mucor pills but moved away from them, because of bitterness worries, to dry calf rennet. I have used the same bag of dry calf rennet for the past six years. I keep it in the freezer under vacuum-seal.

-Boofer-