The Dependence of Peleg's Coefficients on Selected Conditions of a Relaxation Test in Model Samples of Edam Cheese

The first aim of this work was to compare the influence of using two probes (a 100-mm plate and a 5-mm spherical probe) during a compression test on the trends of hardness changes during ripening of Edam cheese. Both of the above-mentioned probes were also applied in relaxation tests for a relaxation time of 30-300s (10 arbitrary times were used). By means of Peleg's model, the values of a parameter (the extent of material relaxation) and b parameter (the initial rate at which the stress relaxes) were calculated. Moreover, the values of a and b parameters, obtained during 10 different relaxation times of the probe after reaching the maximum deformation of the sample (30-300s), were compared (calculated on the basis of Peleg's model). Edam cheese during ripening (1-84 days) was used as a model product. The values of cheese hardness within the ripening period (determined by means of both of the above-mentioned probes) strongly correlated among themselves and also with the sensorially evaluated rigidity. Only a parameter was able to provide an adequate description of the actual changes in cheese within the ripening period but only at a relaxation time of 120s (after reaching the maximum deformation of the sample; valid for both probes tested). Longer relaxation times do not provide a relevant description of the changes in cheese texture during ripening. B parameter provided no relevant description of the changes in cheese during ripening in any of the relaxation times studied (concerning both probes). Practical Application The study compares the influence of the probes used (a 100-mm plate and a 5-mm spherical probe) on the ability to describe changes of selected texture parameters during the ripening period of Edam cheese by using simple compression and relaxation tests. Both types of probes proved to be successful in observing the actual changes in cheese texture during ripening by means of hardness parameter (determined by a simple compression test). Moreover, the information capability of both parameters of Peleg's model (a and b), applied to the data obtained from the relaxation tests with a relaxation time of 30-300s (after reaching the maximum deformation), was studied. It was observed that only a parameter is suitable for assessing the changes within the ripening period of cheese, which holds true only for a relaxation time of 120s (after reaching the maximum deformation; valid for both probes observed). Longer relaxation times do not provide a good correlation with sensorially evaluated changes in texture parameters. The users are given by instructions on how to perform relaxation tests and, above all, on how to choose the times after reaching the maximum deformation of a cheese sample.