Butter is a dairy product. It is produced by whipping cream. The type of butter, its use and taste depend on the type of cream and production process. Determination of rheological properties of butter is a very important area for the dairy industry, as these properties have a strong influence on the taste of butter at the consumer. The two most measured sensory properties are butter hardness, which is important for butter used in the bakery industry, and butter spreadability, which is important for the average consumer.
The experimental part of the diploma thesis was carried out on four butter samples, which differed in the type of cream used and the addition of salt. Amplitude and frequency rheological tests were performed to determine the range of linear viscoelastic response and the behaviour of the samples at different oscillation frequencies. A temperature test was also conducted to obtain a better idea of the behaviour of the butter from the point at which it is taken out of the refrigerator to the point at which it is warmed up to room temperature. The results showed that the storage modulus dominated over the loss modulus for all samples and measurements in the temperature range examined, except at the amplitude tests where the sample at higher shear strains started to exhibit flow behaviour. The results showed that the butter samples are structured viscoelastic materials. From the results obtained, we can conclude that, although the samples differ from one another, they show similar rheological behaviour, which, given that all the samples are of industrial production, indicates a certain degree of quality.
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