Lebar A., Blatnik O., Junkar M., Orbanić H. (2012): Vibration assisted cutting of Gouda cheese. Czech J. Food Sci., 30: 1-8.The influence of vibrations on the process of cheese cutting applied in order to reduce friction and the cutting force was studied. The forces needed to cut through the cheese samples were measured against the variations of the temperature, cutting speed, and vibration frequency. The hypothesis which induced the research work was that assisting vibrations reduce the cutting forces and make the cutting easier for the user. In the experiments, Gouda cheese was used at 10°C and 22°C. The further, a conventional kitchen knife was used with four different cutting speeds from 12.5 mm/s to 75 mm/s and six vibration frequencies from 0 Hz to 150 Hz. The results confirmed the hypothesis presuming that up to 3.4 times lower forces are needed to cut through a cheese sample at 22°C, and 1.55 times lower when cutting cheese samples at 10°C. The results also confirmed the already known facts that the cutting forces increase with increasing cutting velocity, 2-4 times on average with cutting at 75 mm/s instead of 12.5 mm/s. Also, 2.5, times lower cutting forces were measured in cutting the cheese sample at 22°C instead at 10°C.
Keywords: cutting forces; friction forces; knife bladeCutting the cheese with a steel blade knife is an arduous task. The main reason is the high friction in the interface between the cheese and steel. That is also why the cutting forces are higher than expected in spite of the cheese soft texture. With many cheese types also a lot of smearing occurs on the knife blade which additionally increases the friction force.Recently, our research group joined the efforts with a major producer of small home appliances. Based on decades of industrial experiences in the research into and development of kitchen food slicers our industrial partners clarified to us that cheese is one of the most difficult food types to cut, as we learned in a conversation with Pogacar (B/S/H Company, Director of Development. Factory Nazarje, Consumer Products) in 2009. After a few, more or less unsuccessful cut-and-try experiments done by Kozlovič (2008), a thorough study of cheese viscoelastic properties was started by Blatnik (2009) in order to understand better the underlying cheese cutting mechanisms and to optimise the cheese slicing system.In the mainframe of this study, the influence of electromechanically induced vibrations on the performance of cheese cutting was researched and is reported in this paper. Cheese is a member of a large group of materials with viscous and elastic properties exhibited at the same time, i.e. viscoelastic materials. As concerns the materials of viscoelastic type, it is known that if the material is stressed with a shear stress and then relaxed, Partially supported by Slovenian Research Agency in the frame of the P2-0248 (C) project.