Rheology , texture and meltability of different types of cheese

A MCR301 rheometer from Anton Paar, fitted with a PP50 plate/plate system was used to investigate the rheological properties of some cheeses. The test conditions were relevant to cheese melting during preparing of typical food dishes. Both initial elastic modulus, stress and strain at the limit of the linear viscoelastic region, were measured before and after heat treatment of the cheeses. The cheeses were heated from 20 ○C to 90○C at a rate of 0.5 ○C/minute, and then cooled to 20○C at the same rate. The storage modulus, G', as a function of temperature, was measured to characterize changes in the stiffness of the cheese with temperature. Heat treatment caused large variations in the measured parameters. Low fat cheeses behaved very different from full fat cheeses. The results show significant differences between the chosen cheeses on all the measured parameters. INTRODUCTION Large amounts of cheese are used in food as an ingredient in various food retail applications. In these dishes, the cheese's melting properties are of crucial importance to sensory properties of the finished products1. Typical products where the melting behavior influence the final product's characteristics include pizza, lasagna, gratin, different sauces, toasts, sausages, cheeseburgers, cheese sticks, some baked foods and grilled products. In addition, some products such as frozenand grilled fishmeal’s can contain cheese as an ingredient. As an example, the amount of Jarlsberg cheese used for Grandiosa Pizza is very large in Norway. The cheese's melting properties are different for various types of cheese. The treatment of milk, cheese-making technique, salting method and maturation conditions are all factors affecting the melting properties of the cheese. The composition of the cheese, such as dry matter, fat-, proteinand calcium content, are also factors determining the melting abilities of cheeses. In addition, these conditions also influence on how thread-like the cheese will be in the melted state. The cheese structure determines, to a large extent, the mechanical and technological properties of cheese, as claimed in a recent comprehensive review of Lamichhane et al.2. According to these authors, the full extent of the relationships between cheese structure and the functionality of the cheese is not fully understood. Heating causes the cheese to melt and to release fat to a certain degree, whereby the original structure is altered by a complex melting process3. Melted fat may coalesce and result in the separation of fat from the protein matrix. This causes the undesirable effect of oiling off or fat leakage. The resolidification of fat during cooling may cause a less homogeneous distribution of fat, and a significant alteration of the cheese structure4. Above 40○C, milk fat is Rheology, texture and meltability of different types of cheese. Elling-Olav Rukke, Roger K. Abrahamsen, and Reidar Barfod Schüller Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O.Box 5003, N-1432 Aas, Norway ANNUAL TRANSACTIONS OF THE NORDIC RHEOLOGY SOCIETY, VOL. 26, 2018