Vim,

At higher pH (6.6 - 6.7) the main interactions between casein molecules involve calcium phosphate. As the pH decreases, the calcium phosphate dissolves from the casein

and is replaced by hydrogen, H+. There is an increase in melt and stretch as the pH decreases. However, if the pH falls too low, the stretch characteristic can be lost. At a low pH, the caseins aggregate into large masses but there are too few contacts or interactions between the

masses to allow stretch. The actual pH at which cheese will begin to melt or stretch, or lose stretch, depends on casein content and bound calcium phosphate.

Cheeses higher in fat content may require a higher bound calcium content (higher pH) to maintain stretch and desired melt and vice versa for lower fat cheeses. Bound calcium phosphate content of cheese is affected by many factors, including casein content of the milk and pH of the milk and cheese during cheese manufacture.

If you can share the following we can see if we can get you on the right track!!

Specifically the following:

•   How has the milk been processed prior to your cheese making excersize?(i.e. heat treatment, concentration etc).
• Can you share pH and temperature of milk prior to starter addition.
• Can you share pH and temperature of milk at coagulation and coagulant used.
• Can  you share Total time from coagulant addition to pH  5.2.
•         Curd Temperature at stretch

I use to calibrate  my pH meter daily using proper buffer.

Buffalo Milk is pasteurised for 63 min. for 30 min.

I used STM-5 at 37-38oC for 70 min. pH of milk at this time is around 6.7-6.8.

After 70 min. Rennet is added (Coagulant Stick 50 ltr. of milk by CHR Hansen). Temp remains stable as i keep my vessel in incubator. pH by this time doesnot drop significantly. HArdly 0.1-0.2.

It gets set in next 30-40 min.

Cutting into 1-1.5 cm cubes is made using kitchen knife

After cutting I wait for 5 min.

Then cooking is started. Its temperature is raised to 41-42oC in nearly 10 min.

As pH reaches around 5.8-5.9 half of the whey is removed.

As pH reaches around 5.3 curd is tranfered to perforated utensil to dry it up.

As pH reaches 5.2, I add hot water(80-85oC). It raises curd temperature around 58-60oC

Time to reach pH 5.2 from the time of addition of rennet is around 2 hr.

I don't know where is the issue which is causing to not melt the curd. As curd will not melt uniformly in hot water, how one can work it to induce stretch in it.

Hope you see major flaw in my process which is causing not to melt it in hot water.

Thx n rgds,

Vimlesh

I do not see any major flaw in your method.

At first glance I suggest lowering your pH at stretching.  Your times/temperatures listed do not indicate any concerns that should equate to poor stretching.  A quick review on the differences between Buffalo milk and Cow’s milk suggest significantly higher minerals(CA:P) in Buffalo’s milk.  Approximately 40% more Calcium is present in Buffalo’s milk compared to cow’s milk.

I suggest you lower you pH at stretching to further de-mineralize your curd.  Suggest dropping your pH to the 5.1 to 5.2 range to see if you see an improved stretch.

Keep us posted on your work and good luck.

One of my PhD students now Dr Alison Calvert developed a good procedure for making Mozzarella but using cows' milk.

The method used was somewhat different than yours and was based on a standard large scale commercial manufacturing process to produce blocks for Mozzarella for shredding.

Basically blocks of curd were produced. These were then milled when the pH reached 5.1-5.2 the curd was stretched using hot water to give a curd particle internal temperature of 53-57C.

We found that pH values b/w 5.1 and 5.2 gave good results.

Now to pH measurement. It was not clear that you were using 2 pH buffers say 4 and 6. If you are using only 1 buffer solution you will occasionally encounter problems!

Apart from these basic comments I can’t see a lot wrong in what you are doing.

humm.........