Author Topic: Does liquid animal rennet still work at 42C/108 Fahrenheit?  (Read 230 times)

Offline artmustel

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Does liquid animal rennet still work at 42C/108 Fahrenheit?
« on: August 10, 2017, 06:59:57 PM »
I had a cheese failure with a recipe that asks for heating milk@42c/108Fahrenheit,adding thermo, no ripening time and then adding CC and rennet. Time suggested for coagulation is 40 minutes, I waited for a whole hour then even more and nothing, milk coagulates very poorly, never got a clean break. I asked about this incident in other part of this forum but I never got a clear answer regarding maximum temperature for liquid animal rennet. Will it still work if added at 42c/108 fahrenheit?

Thanks!

Offline Gregore

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Re: Does liquid animal rennet still work at 42C/108 Fahrenheit?
« Reply #1 on: August 10, 2017, 10:52:37 PM »
http://www.cheesemaking.com/learn/faq/rennet.html

I think your issue is not the temp issue , 

could be the milk , could be a multitude of small things all adding up .  Milk, rennet strength , temps , ph , ??? 

I would hold the milk culprit first before all other things if it all worked normal last make .

Offline artmustel

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Re: Does liquid animal rennet still work at 42C/108 Fahrenheit?
« Reply #2 on: August 11, 2017, 12:05:21 PM »
I made 2 batches of cheese that very day, before this one I made a Queso Fresco (same milk and same rennet), only difference was it takes meso not termo, and milk is heated to only 30C, not 42C. I had no issues with that Queso Fresco. This makes me think my problem was a)too hot milk for rennet, and b) bad thermophillic (although I used it in previous cheeses which recipes ask for meso+thermo combined)

I love Bel Paese cheeses, want to try making them again but a cheese failure is too expensive for me.  BTW, this recipe of Bel paese doesn't ask for any ripening time for the thermo...is that normal?

Gregore, by your answer I understand that 42C/104 fahrenheit is not too hot for rennet to work. Is that correct? Thank you!

Offline awakephd

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Re: Does liquid animal rennet still work at 42C/108 Fahrenheit?
« Reply #3 on: August 11, 2017, 01:39:50 PM »
More than you ever wanted to know about coagulation:

https://www.cheesesociety.org/wp-content/uploads/2011/02/2011-Choice-of-Coagulant-Preparation-McCoy.pdf

http://www.umb.no/statisk/nordost/laht_renneting_jurmala.pdf

http://www.agriculturejournals.cz/publicFiles/50919.pdf

https://www.uoguelph.ca/foodscience/book-page/enzymic-coagulation-milk

The info in these various articles / presentations is a bit confusing - more than one of them says that the ideal coagulation temperature is 30-32°C, and yet they all suggest that the coagulation activity increases up to at least 40°C or higher. Note also that they do not make clear whether there is a difference between the temperature response of chymosin-only (e.g., GMO produced - which is what several of the above seem to assume as the primary variety) or animal (chymosin + peptide), and they don't really mention (or if they did, I missed it) vegetable rennet, e.g. made from thistle or such.

Some other possible variables - 1) When heating the milk to the higher temperature before adding the rennet, did you heat evenly / stir continually / prevent scorching? This could make a difference. 2) Assuming that you diluted the rennet in non-chlorinated water, was there any difference in how long it was between preparing (diluting) the rennet and adding the rennet? I have no first hand experience, but I have read that it deteriorates relatively rapidly once diluted. (Can anyone confirm this?) 3) Have you calibrated your thermometer? Easiest way to calibrate is to use two data points: first a pot of boiling water (full boil, and take altitude into consideration as necessary, and second a glass of ice water with lots of ice; you should get around 100°C and 0°, respectively. If not, calibrate your thermometer if possible, or calculate the error and adjust for it. As a final check, use the calibrated thermometer to prepare water at 37° (98.6°F, body temperature), and compare the reading against an oral thermometer. 4) Are you making sure to give your thermometer sufficient time to stabilize before taking a reading?

To answer one of your questions - yes, some recipes add the rennet with no ripening time. This will affect the coagulation, but it still should coagulate, as I understand it. Certainly I've made many cheeses with minimal (10 minutes) or no ripening time, and the results have been successful.

If it were me, I think I'd do some experimenting before committing to a full batch of cheese - using your calibrated thermometer, carefully warm one cup of milk to 30°C and one cup to 42°C, making sure to heat gently / not scorch. Prepare a dilution of rennet, put exactly the same amount (maybe 5 ml) in each cup, and float an upside-down bottle cap on the surface of each one. Check to see how it responds over the next 10-30 minutes by pushing the bottle cap around - as it begins to gel, the cap will stop moving easily. If you have used the same milk, same diluted rennet, same amounts of both, you should be able to get a sense of the effect of temperature apart from any other variable.
-- Andy

Offline artmustel

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Re: Does liquid animal rennet still work at 42C/108 Fahrenheit?
« Reply #4 on: August 11, 2017, 03:03:18 PM »
My thermometer is a digital one; I think I cannot calibrate it, however I could make adjustments.

The experiment with the 2 cups of milk sounds interesting, now I have a doubt here...will the rennet on this experiment still coagulate a milk with no added cultures to it?

And finally, thank you very much for all the advices and links, Andy! It is for sure a lot of valuable info.

Offline awakephd

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Re: Does liquid animal rennet still work at 42C/108 Fahrenheit?
« Reply #5 on: August 12, 2017, 12:42:40 PM »
Coagulation will be slower when it is not cultured, because the pH will be higher, but it will still coagulate - or t least that's my understanding. I have to confess I've not tried this experiment, since I've not had the problem / haven't tried to rennet at the higher temp.
-- Andy