Cannot overcome Coagulation Problem -please HELP!!!

[nikro000]

Hello,
I have been making cheese for a year now, but in the last 6 months I encountered a problem that I cannot overcome.
I follow the recipe for cheddar or leicester. I add cultures, stir wait, add rennet, stir wait.
The top of the rennet gives a clean break. A few inches down however, the rennet becomes grainy mush.
The top curds, that were nice little squares begin to break apart soon, while stirring slowly and everything soon becomes grainy mush.
It started 6 months ago and has happened with every.single.batch.
This is what I tried to do so far:

1) Stir longer with up and down motions to distribute the rennet (up to 4 minutes on last batch)

2) Increase amount of rennet

3) Increase amount of calcium

4) Change milk 2 times ( all three types of milk have worked before - pasteurized and homogenized - one is cream top)

5) Change rennet twice

6) Use different cultures

7) Increase/decrease amount of culture

Increase/decrease temperature at which rennet sets

9) Increase amount of wait time after adding rennet (currently 90 min)

10) Use non-chlorinated water to dilute the rennet

I just don't understand, how the top can always be rock slid with a clean break and then turn to mush on the bottom.

Please help!
I don't know what to do anymore.

[steffb503]

While I would not consider myself an expert I will offer my thoughts.
4 mins is too long to stir.
How much and what type of rennet are you using?

I know if I stir too much the rennet does not work.
Have you tested your rennet?
This is how we test our rennet: Heat one cup (8 oz) of milk to 90F. (Do not add citric acid.) Dissolve 1/4 rennet tablet (or 1/4 tsp. liquid rennet) in 1/2cup of cool, non-chlorinated water and stir well. From this diluted rennet take 2 tablespoons and add it to the milk at 90F. Stir gently from the bottom to the top for 30 seconds.

If the rennet is working, the milk surface will begin to firm or form a slight film after two minutes. After six minutes, it will have formed a curd that will hold a knife cut.
http://www.cheesemaking.com/store/pg/244-FAQ-Cheesemaking-and-Rennet.html

[nikro000]

Steffb
Thank you for your reply.

1) 4 min stirring is an "up to" number ( I needed to clarify that). I started with 1 minute and went up and up with every batch when I thought I had not stirred the rennet to the bottom.

2) I use two liquid rennets (1 week and 3 months old) and 1 tablet rennet (5 months old).
I have not tested either of them, but get them same results with all of them: clean break on top, 2 inches towards the bottom, the curds shatter to mush.
However - without testing -  would not the solid top prove the viability of the rennet?

[Sailor Con Queso]

Curd shattering is usually a sign of over processed milk, however you have indicated that you had the same problem with creamline milk. I would increase the calcium, use the liquid rennet (toss the tablets), and stir for just 30 seconds. I would also test your flocculation time (search the Forum). This will tell you how the milk and rennet are working together.

[qdog1955]

Nikro---- have been having a similar problem----check this link http://cheeseforum.org/forum/index.php/topic,13858.msg105178.html#msg105178 ----read the whole thing----unfortunately there seems to be more questions then answers---all of the problems with coagulation have happened with the same milk that I have been using for months----except the raw milk, no problem there. I tried some of the same solutions you did, none helped. Someone did suggest that it could be caused by winter milk, as to the how and why that could be, I haven't a clue.
  I know this isn't much help----it is frustrating to have a certain amount of success, using methods that work and then something changes and you have no idea why and can't find answers. If I do come up with any solid info, I will let you know. Do the same for me, OK? Keep your chin up---there has to be an answer out there.
Qdog

[OzzieCheese]

Ok I'm going right out on a limb here - have you considered you might have Phage contamination problem ?  As it can lead to slow or even completely dead batches.

http://www.bacteriophagetherapy.info/ECF40946-8E2F-4890-9CA6-D390A26E39C1/What%20is%20it%20all%20about.html

Just a thought

-- Mal

[Kern]

Ok I'm going right out on a limb here - have you considered you might have Phage contamination problem ?  As it can lead to slow or even completely dead batches.

http://www.bacteriophagetherapy.info/ECF40946-8E2F-4890-9CA6-D390A26E39C1/What%20is%20it%20all%20about.html

Just a thought

-- Mal

Nikro made no mention of pH.  As I understand it phage kills the culture which largely prevents a pH drop.  Rennet works much better when the pH is lower than fresh milk (~6.5).  Not sure if phage works on rennet any other way than this.  Based on this theory I'd check the progress with a pH meter.  If the culture is not lowering the pH then get new culture.  Clean everything very well and then try the new culture and monitor the pH.  Use new rennet.  I'd think that this will solve the problem. 

One other thought:  Too much calcium can also "kill the curd" making it soft.   

[OzzieCheese]

Check this out:  Although they are talking E.coli the same thing happens to our Lactic Acid bacteria.  These little buggers actually stop Lactic Acid production, Hence no Acid - No coagulation.

http://www.hybridmedicalanimation.com/work/animation/t4-bacteriophage/

Jeez - horror stories are made from stuff like this

-- Mal

[OzzieCheese]

Just reading the description that it seems to occur at varing depths probably means there is a pH difference from top to bottom.  Phage are notoriously difficult to get rid of and they only target a specific bacterium, which is why Cheese factories rotate the cultures they use.  It's not so much as freshing your culture - it about actually changing the culture - for example the Ma 4000 range comes as MA 4001 and MA 4002 for this reason. 

Just a thought

I'd get out the Bleach and go to town in both the cooking environment and the the equipment used , Pots pans, spoons the lot.

Kill Phage

[qdog1955]

Ozzie----good stuff.
 Couple questions.
If there is a phage problem-----is it in the culture or the equipment, or both? The three makes I had this problem on, all used different cultures.
All my equipment is either boiled in water or Star San-ed. Is Star San not affective against these type viruses?
 
As for PH----two of the makes were spot on through the whole make.

Qdog

[Sailor Con Queso]

Not a phage problem. Not the right symptoms. Phage will inhibit coagulation entirely. Curd shatter is not the same. Phage problems generally occur only when you use the same bacteria very often and the bacteria have an opportunity to mutate. Very rare for hobbyists.

[OzzieCheese]

The varying Coagulation deeper in the pot is an interesting one - Temperature then - too hot on the bottom hence deactivated the rennet and get cooler towards the top ?

I'm out of ideas 

-- Mal

[awakephd]

Ah -- the possibility of a temperature gradient is interesting. To the OP, how are you heating the milk (direct heat, or water bath, or ?), and are you applying heat after adding rennet?

[qdog1955]

Nikro ----the guys might be on to something here. My problem may have started when I switched to an induction cooker and a larger heavier vat to heat my milk. I am still working on the best way to use these-----so how are you heating your milk? I know my milk was heating to fast at the bottom-----and now it's time for me to do a little experimenting------let you know the results.
  My apologies for hijacking your post----it wasn't my intention, just trying to help you get answers to a shared, frustrating problem.
Qdog

[tnbquilt]

I use an electronic roaster. They come in various sizes, I have some that hold 3 gallons and some that hold 4 gallons. The 3 gallons ones were $20 at Walmart after Christmas, the other ones were about $40 and have a removable liner for easy washing. Very easy temperature control.