REGULATING CHEESE ACIDITY AND MOISTURE CONTENT:
(Moisture in Fat Free Cheese)
The methods available can be summarized for practical purposes into three groups:
a) Factors which affect fermentation speed of milk sugar.
b) Factors which increase whey drainage and thereby departure of
c) Other factors (change of rennet amount, salt addition to the whey
and change in final stirring time).
Cheese minimum pH and moisture % in fat free cheese controls the cheese quality.
1 FACTORS WHICH INFLUENCE THE FERMENTATION OF MILK SUGAR:
1.1 Cheese Milk Pre-Ripening:
In cheese milk's pre-ripening, we have one of the most important and most effective methods for regulating fermentation speed of the milk sugar. It is not clear which method is the most suitable. Some claim that the reduction time is useful because it gives an indication of bacterial activity. Others have claimed that actual change of reduction time during ripening period gives a better indication. In addition, one can determine the total number of bacteria, the actual increase of the number and finally the increase in acidity (the titrated acidity). The simplest method is without doubt the latter (change of the titrated acidity). This method is simple and quick to do.
Investigation has shown that this change corresponds quite well to the change in bacteria numbers. The weakness is that this method requires great measuring accuracy.
Others have suggested a coagulation test (Marshall's Rennet Test) at certain intervals, as it is believed that it gives a more accurate account of the change which takes place with the acidity. Coagulation time is reversed with the hydrogen concentration. Even a very small change is possible to detect. One must not apply this method to milk which has been cooled for a longer period. Right after heating the results will be doubtful, but after approximately 1 hour the condition will have been stabilized.
Which pre-ripening method is used differs first with the cheese type, length of pre-cheesemaking, cooking temperature, etc.....
A prolonged pre-ripening causes pH-decrease to occur earlier in the cheese making process. A 10 minute pre-ripening is relatively insignificant, whereas a 45 minute pre-ripening will be more effective on the bacteria. The result is a lowering of pH after 14 hours in the cheese and a larger amount of calcium to be dissolved. A pre-ripening will, therefore, always cause increased acid development and demineralizing than when cheese is not pre-ripened. An exaggerated pre-ripening can also cause the cheese to become split and acidic after storage.
A prolonged of pre-ripening causes the milk at the beginning of cheese making to become more acidic and the bacteria to surpass the lag phase so that right from the start more acid is developed. This stronger acid development in the cheese curds causes more of the calcium, which is bound to the casein, to dissolve and go into the whey as it drains from the cheese.
Cheese acid development can be enhanced considerably by pre-ripening of cheese milk and the pre-ripening should normally be altered by only 10-15 minutes at a time.
A "too strong" pre-ripening can easily cause the cheese to split, sour and brittle; while on the other hand, a too weak acid can give a tough consistency and unclean taste.
At the same time, strong acid development will result in less moisture content in the cheese and vice a versa.
Finally, it is important to use a stable culture. Normally one uses an inoculation rate of 0.5-1.0 %, a pre-ripening of 20-40 minutes and a temperature of 28-32 C.(approx. 82 - 90 F.)
Determination of pre-ripening by titration usually indicates a titration of 0.75-1.25.
Use manufacturer?s recommendations for direct set (e.g. Visbyvac DIP). Danlac has cheese recipes using direct set (Visbyvac DIP) and bulk starters (Visbyvac B).
Pre-stirring refers to all operations in the cheese vat from cutting to start of cooking.
The temperature is similar to that of pre-ripening and coagulation. The length of pre-stirring can also influence speed of acid development. A too weak pre-ripening (poor bacteria activity) can, therefore, to some degree be offset by a longer pre-stirring; and conversely, a too strong pre-ripening offset with a shorter pre-stirring.
Pre-ripening of cheese milk must therefore be considered in conjunction with pre-stirring.
The setting temperatures are closer to lactic acid bacteria's optimal temperature than the cooking temperature. A prolonged intermediate stirring will give lactic acid bacteria better development conditions. Large amounts of acid production will result. At the same time, the delayed cooking will cause the whey to stay inside the single cheese curds a little longer, and the acid curds will therefore dissolve a greater part of the calcium in the cheese curds. The resulting whey drainage which takes place under cooking will result in large amounts of calcium filtering out in the whey so that the finished cheese ends up with lesser amounts of calcium phosphate. As phosphate usually buffers the cheese, with fewer amounts, the cheese will become sourer. When the calcium is removed, the cheese becomes less elastic.