Flocc time and factor multiplier to clean break

[ialkohme]

Hi

My brain is twisted trying to think this through so I'm hoping someone can explain.

For context but I don't think its that important.  Yesterday I did a bloomy rind make (Caldwell) and went with the recipe but halved quantities (6 litres instead of 12L).  I was dubious of the rennet quantity for the target flocc time, but went with it for the first make.  From experience, when making milled curd (same milk quantity), the rennet dosage was twice as much to achieve a 18 min flocc.  Same milk with added calcium chloride in both recipes.

Anyway, the recipe:
 - 6l milk
 - 1ml single strength calf rennet + calcium chloride
 - Target flocc - 10 min
 - 5-6 x flocc factor - clean break +- 50 - 60 min

What occurred:
 - Actual flocc - 25 min
 - 60 min clean break (I was expecting 2.5 hours)
 - cut the curds and proceeded as per guiding recipe.

Is my understanding correct, that after flocc point, there was acceleration of the coagulation process, or is this normal?
Should I have waited the 2.5 hours regardless before cutting the curds?
What guestimate on outcome cutting at 60 min rather than 2.5 hours?
Or no difference as clean break was achieved after the recommended target time - i.e., when clean break is achieved is more important than the flocc factor multiplier target?

Hopefully that's somewhat clear. 

Thanks!

[Bantams]

"Clean break" is unfortunately a fairly useless term and I wish recipes did not use it.
Flocculation and an appropriate multiplier is the best method for determining when to cut curd. When the flocc time is roughly within the recipe's recommended time, the curd should be just right at the calculated time.
Flocc time also helps to highlight potential issues - as you experienced. When flocc time is abnormal - too long in this case -  you will want to troubleshoot so that the next batch will be within the proper time frame. 
Too long of flocc time can mean any number of things - milk too cool, too little rennet (or rennet is bad - too old, etc), milk from late lactation, needing more calcium chloride, milk is too old, cow has mastitis, etc.

So I think that you did fine with yesterday's batch given the flocc issue, but I would focus on troubleshooting your rennet or milk problem so next batch will be within normal range (8-13 minutes is pretty typical).

What type of rennet, how old is it?
Milk source?

[ialkohme]

"Clean break" is unfortunately a fairly useless term and I wish recipes did not use it.
Flocculation and an appropriate multiplier is the best method for determining when to cut curd. When the flocc time is roughly within the recipe's recommended time, the curd should be just right at the calculated time.
Flocc time also helps to highlight potential issues - as you experienced. When flocc time is abnormal - too long in this case -  you will want to troubleshoot so that the next batch will be within the proper time frame. 
Too long of flocc time can mean any number of things - milk too cool, too little rennet (or rennet is bad - too old, etc), milk from late lactation, needing more calcium chloride, milk is too old, cow has mastitis, etc.

So I think that you did fine with yesterday's batch given the flocc issue, but I would focus on troubleshooting your rennet or milk problem so next batch will be within normal range (8-13 minutes is pretty typical).

What type of rennet, how old is it?
Milk source?

Thanks Bantam for the clean break guidance.

I'm not too concerned about the flocc time as I had high confidence this would be the case, but went with it to have a baseline, learn and adjust from there.  The clean break at 60 min was a surprise though. 

When I make a milled curd (Caerphilly style); using the same milk and quantity (6 litres), 1.5ml veal rennet and 2.5ml calcium chloride, I get a reliable flocc around 18 min.   Sometimes there is bitterness, but I'm playing around with maturation duration for best time to eat.  It appears to be dependent on how long the maturation is rather than rennet quantity.

For the next bloomy rind I'll increase rennet to +-1.9 ml (1.0 ml gave me flocc 25 min) and see if that's closer to 10 min.  Hopefully it won't result in bitterness.  Would be handy to know a rennet/milk ratio bitterness boundary.

Veal rennet age - about 6 months stored in fridge in a blacked-out container
Milk source - Organic un-homogenised store bought
Milk temperature stayed around 34c for the required time

Cheers

[MacGruff]

Building on what Bantams was saying, check the strength of the rennet as well. I recently got a new bottle from a supplier new to me and my first two batches of cheese using this new rennet too forever to set up - flocculation times were much longer than normal!

I was wondering what was wrong and at one point picked up the bottle and was idly looking at it and noticed that it stated how much rennet to use per Gallon of milk. Aha moment occurred! it was diluted compared to my previous supply.

Once I adjusted for the strength of this supplier's rennet, my next make was right in line with what I was looking for.

[mikekchar]

1 ml of 200 IMCU/ml rennet in 6 liters of milk is 33.33 IMCU per liter, so yes that's a bit low for the style of bloomy right Caldwell is documenting.  Incidentally, that recipe is the only one in the book that I think is a bit wonky.  There are clearly some mistakes in it but I haven't quite figured out what she was *intending* to do...  Anyway 1.5 ml, I think will me just slightly more than you need, but not crazily so.  I usually go for 46 IMCU per liter and the standard is 40, but of course different recipes will be slightly more or less than that.

Keep in mind that flocculation time, assuming everything is working as intended, is a factor of rennet amount, pH and temperature.  So if you want to decrease the flocculation time a bit, you can increase the ripening time, or you can increase the temperature a bit.  Looking at my notes, it seems that I like 34 C, a ripening time of 1 hour (with mother cultures, so they bacteria are already going) and I still get a flocculation time of 15 minutes.

Which brings me to an interesting point.  What is the flocculation time?  Because generally you float and spin something until it doesn't spin any more.  But I've realised that the size of the thing you spin makes a rather large difference.  You get more torque with a larger object.  I was getting quite variable flocculation times -- out by as much as 10% or so.  So I now always use a soda cap (which is small) and I leave it until it leaves a mark in the curd.  I think this is a bit longer than most people use for flocculation time, but I've found that it is much more consistent.

Even with 33 IMCU per liter, 25 minutes is longer than I would expect for flocculation time.  I suspect it was actually a bit faster.  It doesn't have to be much faster to make quite a big difference.  Let's say it was actually 24 minutes (which makes math easy :-) ).  A 60 minute rest would be a factor of 2.5.  A factor of 2.5 will often give you a "clean break".  So it's actually completely reasonable to me that you got one at that point.

The idea of the multiplier is that for Caldwell's recipe, you are going well *beyond* a "clean break".  However, I think her multiplier is off here... Although I'm not 100% sure.  At least in my printing of the book, she actually says different multipliers in different places and neither of them make sense to me.  In fact, I've tried a factor of 4 and 5 and both were actually a bit too much IMHO.  But it makes a difference how you cut and how you stir and various things, so who knows...

Anyway, back to your bloomy rinds.  I'll say that your ~2.5x multiplier will be 100% fine as long as you treated the curds with kid gloves.  You may be missing some moisture at the end of the day and if so, your yield will be down and your cheese will be less runny, but it will be fine.  Bloomy rinds are actually incredibly forgiving, I've found.  Definitely don't go crazy jacking up the rennet.  Something like 1.4 ml is probably about right -- possibly a bit less, but I don't think I would go more.  If you were really getting a 25 minute flocculation time, I would keep my eye open on things like making sure to dilute with water that is *definitely* free of chlorine (this has caused problems for me!), etc.  But also pay attention to the rest of your make -- was your starter culture amount correct, was it in good shape, did you give it enough ripening time, etc, etc.

[ialkohme]

Building on what Bantams was saying, check the strength of the rennet as well. I recently got a new bottle from a supplier new to me and my first two batches of cheese using this new rennet too forever to set up - flocculation times were much longer than normal!

I was wondering what was wrong and at one point picked up the bottle and was idly looking at it and noticed that it stated how much rennet to use per Gallon of milk. Aha moment occurred! it was diluted compared to my previous supply.

Once I adjusted for the strength of this supplier's rennet, my next make was right in line with what I was looking for.

Thanks for the reminder.  I checked the use by date and it expired a couple of months back.  The bottle is wrapped up so it was out of mind.   

[ialkohme]

1 ml of 200 IMCU/ml rennet in 6 liters of milk is 33.33 IMCU per liter, so yes that's a bit low for the style of bloomy right Caldwell is documenting.  Incidentally, that recipe is the only one in the book that I think is a bit wonky.  There are clearly some mistakes in it but I haven't quite figured out what she was *intending* to do...  Anyway 1.5 ml, I think will me just slightly more than you need, but not crazily so.  I usually go for 46 IMCU per liter and the standard is 40, but of course different recipes will be slightly more or less than that.

Keep in mind that flocculation time, assuming everything is working as intended, is a factor of rennet amount, pH and temperature.  So if you want to decrease the flocculation time a bit, you can increase the ripening time, or you can increase the temperature a bit.  Looking at my notes, it seems that I like 34 C, a ripening time of 1 hour (with mother cultures, so they bacteria are already going) and I still get a flocculation time of 15 minutes.

Which brings me to an interesting point.  What is the flocculation time?  Because generally you float and spin something until it doesn't spin any more.  But I've realised that the size of the thing you spin makes a rather large difference.  You get more torque with a larger object.  I was getting quite variable flocculation times -- out by as much as 10% or so.  So I now always use a soda cap (which is small) and I leave it until it leaves a mark in the curd.  I think this is a bit longer than most people use for flocculation time, but I've found that it is much more consistent.

Even with 33 IMCU per liter, 25 minutes is longer than I would expect for flocculation time.  I suspect it was actually a bit faster.  It doesn't have to be much faster to make quite a big difference.  Let's say it was actually 24 minutes (which makes math easy :-) ).  A 60 minute rest would be a factor of 2.5.  A factor of 2.5 will often give you a "clean break".  So it's actually completely reasonable to me that you got one at that point.

The idea of the multiplier is that for Caldwell's recipe, you are going well *beyond* a "clean break".  However, I think her multiplier is off here... Although I'm not 100% sure.  At least in my printing of the book, she actually says different multipliers in different places and neither of them make sense to me.  In fact, I've tried a factor of 4 and 5 and both were actually a bit too much IMHO.  But it makes a difference how you cut and how you stir and various things, so who knows...

Anyway, back to your bloomy rinds.  I'll say that your ~2.5x multiplier will be 100% fine as long as you treated the curds with kid gloves.  You may be missing some moisture at the end of the day and if so, your yield will be down and your cheese will be less runny, but it will be fine.  Bloomy rinds are actually incredibly forgiving, I've found.  Definitely don't go crazy jacking up the rennet.  Something like 1.4 ml is probably about right -- possibly a bit less, but I don't think I would go more.  If you were really getting a 25 minute flocculation time, I would keep my eye open on things like making sure to dilute with water that is *definitely* free of chlorine (this has caused problems for me!), etc.  But also pay attention to the rest of your make -- was your starter culture amount correct, was it in good shape, did you give it enough ripening time, etc, etc.

Thanks Mikechar for the detailed reply.  My calf rennet is 150 IMCU and have just ordered new as my current turned out to have expired.  I'll see how that goes this weekend and will look to increase the ripening time.

To determine the flocc point I spin a small glass rameken (bowl) as it sits deeper, so goes my thinking at the time, provide more grip for the milk.  Coincidentally and to your point, I had planned to switch to a plastic lid for the next make and see how that goes.

I'm familiar with the "1 IMCU sets 10ml of milk in 100 seconds", but you appear to have a different way of calculating and/or back testing if rennet is ok or degrading.  Would you mind elaborating on this as my trial and error approach (from make to make) could likely benefit from a bit more formality to it.

I think the curds turned out OK then.  I un-moulded yesterday and they were about 50 % reduced.  Their shape looks good with no bulging at the end of 24 hour drying period.

[mikekchar]

I'm familiar with the "1 IMCU sets 10ml of milk in 100 seconds"

I'm actually not familiar with that.  That would mean that 100 IMCU would set 1 liter of milk in 100 seconds.  I actually don't think that's correct at normal pH and temperatures.  I found a paper a while ago that discussed all of the methods for testing IMCU that were used commercially that that time.  My understanding is that the standard is 40 IMCU of rennet coagulates 1 liter of milk in 36 minutes at 36 C with a pH of 6.5 -- or something like that, where "coagulates" means a flocculation time of 12 minutes and a multiplier of 3.0.  As usual, I stupidly didn't record the reference or write down the details, so it's probably a bit different.  However, the standard is *definitely* 40 IMCU per liter.

As an aside, why these crazy values?  Again, based on my faulty memory: 12 minutes is 1/5 of an hour, 36 C is the temperature of a cow, pH 6.5 is the normal pH of milk after pre-acidifying it, 40 is 1/5 of 200, 200 is 1/5 of 1000 which means that if we set 200 IMCU per ml as the "normal" strength, then 1 tsp gives you 1000 IMCU which is enough for 5 liters.  5 liters is 1/5 of 25 liters which is the unit used for other dosing amounts (almost exactly 5.5 UK gallons).  Interestingly, this version of the standard is the UK version (named after somebody) and there are different standards which all largely agree but have slightly different processes to get there.  Somebody really likes the number 5, it seems.

As for adjusting my strength -- I literally just keep notes of the flocculation time for every batch.  If the flocculation time seems to be getting a bit higher, I dose with slightly more rennet next time.  So not really that exciting, but it is interesting that my liquid rennet is now 1 year out of date and I'm *still* using it with no problems (except using slightly more) :-)

[ialkohme]

I'm familiar with the "1 IMCU sets 10ml of milk in 100 seconds"

I'm actually not familiar with that.  That would mean that 100 IMCU would set 1 liter of milk in 100 seconds.  I actually don't think that's correct at normal pH and temperatures.  I found a paper a while ago that discussed all of the methods for testing IMCU that were used commercially that that time.  My understanding is that the standard is 40 IMCU of rennet coagulates 1 liter of milk in 36 minutes at 36 C with a pH of 6.5 -- or something like that, where "coagulates" means a flocculation time of 12 minutes and a multiplier of 3.0.  As usual, I stupidly didn't record the reference or write down the details, so it's probably a bit different.  However, the standard is *definitely* 40 IMCU per liter.

As an aside, why these crazy values?  Again, based on my faulty memory: 12 minutes is 1/5 of an hour, 36 C is the temperature of a cow, pH 6.5 is the normal pH of milk after pre-acidifying it, 40 is 1/5 of 200, 200 is 1/5 of 1000 which means that if we set 200 IMCU per ml as the "normal" strength, then 1 tsp gives you 1000 IMCU which is enough for 5 liters.  5 liters is 1/5 of 25 liters which is the unit used for other dosing amounts (almost exactly 5.5 UK gallons).  Interestingly, this version of the standard is the UK version (named after somebody) and there are different standards which all largely agree but have slightly different processes to get there.  Somebody really likes the number 5, it seems.

As for adjusting my strength -- I literally just keep notes of the flocculation time for every batch.  If the flocculation time seems to be getting a bit higher, I dose with slightly more rennet next time.  So not really that exciting, but it is interesting that my liquid rennet is now 1 year out of date and I'm *still* using it with no problems (except using slightly more) :-)

Interesting.  I got it from here https://www.littlegreencheese.com/2019/07/rennet-strength-explained.html when I was researching flocculation tests.  I didn't find it useful and discarded trying to work with it when I saw that many people mentioned that recipes should be used as rough guidance and needed adjustment depending on your situation and observations during the make.

Anyway, I keep record of the times too but up until now have focused on a single cheese to learn the process; see if I can get consistency and make minor adjustments to see what the impact is on the end result.

 

[mikekchar]

I'd be interested to know if Gavin actually bought the ISO standard.  It's $78!  I must say that it's infuriating that things still work this way....  I'd love to take a peek, but not for that kind of money...  It would be pretty easy to test that claim, though.  I should give it a try one of these days.

But he also says, "200 ml is sufficient to set 1,000 kg of milk in 30 – 40 minutes at 30 – 32C."  This is definitely closer to what I remember.  That would be 1 ml per 5 liters with a flocculation time of 12 minutes and a multiplier of 3.0.  The only difference is the temperature and I could easily be wrong about that.  The abstract of the ISO standard confirms the 6.5 pH, though.

It may be that I'm sleepy (which I am), but the rest of his blog post seems to be complete nonsense: "If the IMCU of your rennet is 200IMCU/ml you multiply 200 x 0.01. This calculates the amount of milk in Litres that 1 millilitre of the 200IMCU rennet would set. So in this example, 1 ml would set 2 litres of milk."  One of us has got their maths screwed up and I don't *think* it's me (note the sleepiness, though... I'll review again in the morning ;-) ).

[ialkohme]

I'd be interested to know if Gavin actually bought the ISO standard.  It's $78!  I must say that it's infuriating that things still work this way....  I'd love to take a peek, but not for that kind of money...  It would be pretty easy to test that claim, though.  I should give it a try one of these days.

But he also says, "200 ml is sufficient to set 1,000 kg of milk in 30 – 40 minutes at 30 – 32C."  This is definitely closer to what I remember.  That would be 1 ml per 5 liters with a flocculation time of 12 minutes and a multiplier of 3.0.  The only difference is the temperature and I could easily be wrong about that.  The abstract of the ISO standard confirms the 6.5 pH, though.

It may be that I'm sleepy (which I am), but the rest of his blog post seems to be complete nonsense: "If the IMCU of your rennet is 200IMCU/ml you multiply 200 x 0.01. This calculates the amount of milk in Litres that 1 millilitre of the 200IMCU rennet would set. So in this example, 1 ml would set 2 litres of milk."  One of us has got their maths screwed up and I don't *think* it's me (note the sleepiness, though... I'll review again in the morning ;-) ).

Thanks.  I think when I worked it out for 6l using 150 IMCU I ended up with 4ml rennet.  That was rather bitter cheese and still had very long flocc time with raw milk!  As the timing and amount were so far off I looked at using calcium chloride in the next make.  Turns out my raw milk supply, as well as store bought, still needed calcium chloride help which brought the rennet quantity and timing into expected range.  In my inexperience I think I have overshot the flocc time too using a heavy spin object.

Anyway, another make this weekend with tweaked rennet and lighter lid for the flocc test.   

[ialkohme]

1 week in and the bloomy's are coming along nicely.  Made a second make on Saturday with better flocc time (12m) but curd looked really firm at 48 min so did a bit of a panic cut. 

When I did the first gentle stir I discovered the top was good but the bottom half of the curds looked like mush.  Let's see how these turn out.