Very Long Flocculation Time

[Raz21]

I am trying to make my first mozzarella. I have calf rennet with 150 IMCU/ml and it is written on the label to use 5-6 drops for 5 liters of milk. I used P&H cow whole milk. I was looking for a flocculation time of about 8-12 min and after more than one hour, instead of a set curd, I had a yogurt-like consistency in my milk. It was breaking into small particles when raised from the whey. This was not a curd. Why is this? I used this rennet a few days ago, with some raw cow milk and the floc time was about 35 min (4 liters to 4 rennet drops). This was also a long floc time, but at least I had a result.

The recipe which went wrong:

• 7 liters (1.5 gallons) of milk
  
• Warmed up the milk to 90 F
• Added 2 teaspoons of citric acid and stirred for 2 min
  
• Added 6 drops of rennet and stirred for 2 min
  
• Let it stand to reach the floc time (this never occurred) at 90 F
  
  

What went wrong?

Any advice would be highly appreciated. I am quite new to cheese making.

[RayJ]

Make sure the milk is not ultra pasturized (uht). If it was that would probably be your problem. Otherwise you will obviously need more rennet and probably some calcium chloride to get good coagulation. It might take some experimenting to get the amounts right.

[Sailor Con Queso]

In this case, the citric acid and NOT the rennet is the primary coagulating factor, so flocculation time is not really valid. You should get coagulation very quickly after adding the citric acid. If your set was the consistency of yogurt, then your milk is most likely the problem.

[RayJ]

My experience with quick mozzarella is that when you add the citric acid and stir it in it will start to curdle soon after and you will see strings start to form in the milk that stick  to the spoon. The actual setting of the curd is done by the rennet. The acid is what makes the cheese strech in the last stage of the make.

[Raz21]

Thanks for the reply RayJ and Sailor,

I have tried to follow the same recipe again today. I used the same P&H whole milk, added two tablespoons of citric acid and (1.66 ml) 33 drops of the same rennet.
Note: this is the right amount of rennet (with 150 IMCU) suggested for mozzarella recipes on the forum. Yesterday I had the wrong rennet quantity.
The result was the same. A yogurt like consistency which never coagulated completely.

A few questions:

• Am I doing the flocculation test wrong because of the citric acid?
  
• Should I add citric acid to mozzarella?
  
• What object to use for the flocculation test? If I use a small metal muffin cup, it seems too heavy. Should it be heavier? Should I use a lighter object?
  

One issue that I tend to have with the flocculation test is that a certain amount of whey gathers under my floc time tester (metal muffin cup) and it is always spinning, even though underneath, the milk is coagulated. Is it there a solution to this? How can I make a floc test that I can trust?

Looking forward to your answers.

[RayJ]

Either the milk is ultra high temp pasturized (which will never work for cheese making) or you need calcium chloride to make up for the calcium that is tied up during the pasturization process. The citric acid is needed in your quick mozza recepie or the cheese will not strech in the end. Traditional mozzarella uses a culture to acidify the cheese over time (about 2 to 3 hrs) while you monitor pH drop until it gets to around 5.3 before you strech it. As for the floc test I use a plastic bowl about 4 inches around and do not usually have problems determining floc time with it.

[Sailor Con Queso]

Flocculation is meaningless when using citric acid.

[RayJ]

Sailor why is floc meaningless when using citric? The coagulation is happening with the use of rennet the citric acid is added to get the pH down before hand to save the step of ripening unless I am way out to lunch?

[Sailor Con Queso]

The citric acid causes the milk to "curdle", which prevents the bowl from spinning properly. So how do you measure flocculation?

[stephmtl222]

Here's my two cents:
If the milk curdle substantially after the addition of citric acid, too much citric acid have been added for mozzarella. Some very limited curdling can occur when the citric is added but not enough to stop the bowl from spinning. The initial curdling can be limited by diluting the citric acid sufficiently to avoid too high local concentration when it's added and by adding when the milk is still relatively cold.

With this high acidity, the flocculation time should be very short if the standard amount of rennet is used. I usually use 30-40% of the regular amount of rennet to get a floculation time of 10-12min. If it doesn't happen, either the rennet or the milk is bad.

[scasnerkay]

I add the citric acid when the milk is very cold, stirring rapidly. Then heat to 90 degrees. I stir the rennet in for about 10 seconds only. I use 1/8 tsp double strength (veg) rennet for one gallon. Flocculation can be measured - usually within a minute or two after stirring in the rennet. Clean break is usually in 10 to 12 minutes.
I get much better results with with non-homogenized milk from the store.

[Raz21]

Thanks a lot for all the answers. It looks like it is not that easy to get the mozzarella right without a pH meter.

Does it have any impact on the cheese taste if you add too much rennet? What can happen if you add too much rennet?


I was thinking to try a different cheese now. I have a fridge set up with a thermostat which can be used for aging. Any recommendations for a cheese recipe that I can try? I was thinking about Edam or Gouda.
 

[GortKlaatu]

There is this widespread belief that Mozzarella is an easy, beginners cheese. ( I think this is due to the "30 minute mozzarella" recipes out there which insinuate that fast means easy.)
Actually, I think the idea of easy Mozzarella is a fallacy and should NOT be the first cheese that someone attempts.
My two cents.

[Stella]

Just want to chime in with the fact that mozzarella is not a beginner’s cheese!