Abstract:
As Mozzarella cheese is usually consumed as a pizza topping, its melted properties are more important than its unmelted properties. Because of the sensory requirements of consumers, the functional properties of Mozzarella, including meltability, free oil, viscoelasticity and stretchability when melted, are of great importance. Changing the production process (processing conditions etc.) during Mozzarella manufacture usually produces cheese with different functional properties, because production processes influence both the composition and the microstructure of cheese. This relationship between cheese properties, processing and structure has frequently been studied empirically, often because of the limited number of production processes that are used to produce samples, which potentially produces biased results. Therefore, we aimed to objectively investigate the complex correlations between the production processes, composition, microstructure and functional properties of Mozzarella cheese. Objective methods for evaluating the functional properties of Mozzarella cheese are essential initially before further investigation. Stretchability is one of the most important functional properties of Mozzarella cheese, but there is no objective and widely accepted evaluation technique. Therefore, a novel and relatively simple technique for evaluating stretchability was developed and tested for repeatability. Mozzarella cheese has a specific stretching process during manufacture, which contributes to its great stretchability; most other cheeses have poor stretchability. The pizza baking performances (especially blistering and browning) of cheeses are different, which may be related to their different functional properties. To investigate how cheeses act when baked on pizzas, methods for evaluating the pizza baking performances of cheeses (mainly image acquisition and analysis) were developed. To further investigate how the functional properties of Mozzarella cheese influence the formation of blisters during baking on pizzas, we investigated Mozzarella cheeses made with different starter cultures. We found that different amounts of free oil were released from the cheeses, which affected the number of blisters. Mozzarella cheeses with different salt and moisture contents were also investigated; the results indicate that the elastic and the stretching parameters of the melted cheese determined the size of the blisters, whereas free oil had no obvious effect on their blistering behaviour. However, free oil was still the determining attribute, if all these two groups of samples were counted. The investigations confirmed the complex correlations between the production processes, functional properties and pizza baking performances of Mozzarella cheese. Finally, to investigate these complex correlations, Mozzarella cheeses were manufactured using a range of production processes to produce three groups of cheeses, with different fat contents, draining pH or calcium contents and stretching conditions. Principal Component Analysis was used to analyse the correlations within each group, to find correlations that were common to the three groups, which showed that stretchability, meltability and free oil were correlated with the protein content and the size of the fat globules.