ABSTRACT
One of the oldest methods to test stretchability is with the help of a fork. The “fork test,” as it is called, is performed by picking up a lump of melted cheese vertically with a fork until the bulk of the cheese strands break (Figure 9.2). The length of the strands at failure is taken to indicate stretchability. The test is usually performed on Mozzarella melted on a pizza crust containing pizza sauce. The type and size of crust, amount of sauce, oven used, and baking conditions are determined by the user. McMahon (1996) listed some additional details such as: crust size (8 to 14 in; 20 to 36 cm in diameter), amount of pizza sauce (2 to 5 oz; 60 to 150 g), amount of cheese (8 to 12 oz; 240 to 360 g), baking time (4 to 6 min), and oven temperature (400 to 550°F, 104 to 188°C or higher). He also stated that a typical test would be performed using a 12-in (30-cm) diameter crust, 4 oz (120 g) of sauce, and 10 oz (300 g) of shredded cheese. The pizza should be baked for 4 to 6 min at 500°F (160°C) and allowed to sit for 30 to 60 s before the fork is inserted to stretch the melted cheese. Despite these guidelines, the fork test is performed very differently in practice, especially in an industrial setting. The uncontrolled thermal (cheese temperature at time of stretching), rheological (direction and speed of stretching), and physical (sample size) variables make test results subjective even if some or all of the guidelines above are followed. Therefore, results of a fork test are only suitable for sample-to-sample comparison at the same location. When performed with care and replicated sufficiently, experienced operators can control some of the data variability and produce reasonably reliable results. This, and the fact that it is such an easy test to perform, contributes to its popularity and wide use by the industry.
