Factors affecting syneresis are associated with the milk or with the processing operations. Factors that affect syneresis associated with the milk include:
- % Fat. Increasing fat decreases syneresis as fat globules inhibit the movement of moisture to the surface of the curd piece. Increasing the fat content of milk increases cheese yield (Ya, actual yield) by 1.2 x mass of added fat due to increased retention of moisture.
- % Casein. Casein is the structural element in the reticulum of the curd and so increasing casein content of milk results in better syneresis.
- pH of milk. Reducing the pH of milk improves syneresis which is optimal at the isoelectric point of the caseins (pH 4.6). As pH moves towards 4.6 the net charge on the casein is reduced facilitating their interaction.
- Ca2+ generally improves syneresis.
- NaCl added to milk. At low levels, salt added to the milk improves syneresis but at higher levels it reduces syneresis. Addition of salt to milk is a practice used only in the manufacture of a very small number of varieties (e.g., Egyptian Domiati).
However, in general processing operations have a greater effect on syneresis than milk composition and will be discussed in future posts.