After the milk has formed a firm coagulum, the next steps (cutting, stirring, and heating/ scalding) have the purpose of controlling the syneresis of the curd in order to achieve the appropriate level of moisture.
The coagulum is cut in grains by means of knives or fine steel wires. The size of the grains influence the syneresis—the finer the cut, the lower the moisture content in the cheese. For soft cheese, the grain size is 15 mm or larger; for semihard cheese, 5 to 10 mm; and for hard cheese, 2 to 5 mm.
After cutting, whey begins to be squeezed out of the grains and the syneresis begins. The mix of whey and grains is then stirred, at first gently, in order to enhance syneresis. The stirring is continued until the grains have reached the desired firmness. The stirring may take from one to two hours. The main factors for the syneresis are fat content of milk, size of the grains, pH, and temperature during stirring. Lower fat, smaller grains, lower pH, and higher temperature increase syneresis.
Heating during stirring is not usual for soft and semisoft cheeses; however, for semihard cheese, heating to 34-38C is typical, for hard/semihard cheeses 37-40C, and for hard cheeses
50-56C (scalding). The heating/scalding can be done by heating the mixture of whey and grains by steam in the jacket of the cheese vat or by the addition of hot water to the whey. Addition of water reduces the lactose content of the curd and, consequently, the amount of lactic acid produced in the pressed cheese. Another effect of heating/scalding is that the lactic acid bacteria, and their acid production under stirring, will be inhibited because the temperatures applied are above their optimum.
If a higher heating temperature for Gouda/Danbo cheese is used, the starter bacteria will grow slower in the cheese grains, and the pH at the end of stirring/molding will consequently be higher. Although higher pH during stirring will in itself reduce syneresis, the higher heating temperature will increase syneresis. Experience shows that the net result will be lower moisture content in the cheese. A higher heating temperature will also cause a higher pH minimum of the cheese because the cheese grains will have higher pH at the end of stirring/at molding and because the pressed cheese has a lower moisture content, and consequently, a lower content of lactose. In summary: Higher heating temperatures for a semihard cheese such as Gouda/Danbo type will result in a more firm and a less acid cheese.
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