Effect of Draw pH on the Development of Curd Structure During the Manufacture of Mozzarella Cheese

The impact of varying the pH of whey at whey drainage (5.9, 6.15 or 6.4) on the development of curd structure during the manufacture of Mozzarella cheese was investigated using scanning electron microscopy. Dramatic changes in curd structure were apparent with stage of manufacture , in particular the stretching step which aligned the protein fibers. Of additional interest is the effect of draw pH on the structure of curd at whey drainage. When whey was drained at pH 6.4, an open poorly fused network of paracasein particles was observed in the cheese curd. Jn contrast, lowering the draw pH (6.15 and 5.9) increased fusion of paracasein particles producing a more continuous three dimensional network. The degree of paracasein fusion in curd at whey drainage may be related to overall calcium levels and particularly to the calcium/ total protein ratio.