engleski

Viscosity measurements on confectionary fats

There was a study trip between mid of May and mid of June at J.J. Strossmayer University. The topic was the viscosity measurements on different type cocoa butter, cocoa butter alternative fats and fat-combinations. The base materials were offered by UHFI, Department of Phisycs and Control (the Department got these materials for other measurements) and the KANDIT chocolade factory in Osijek. The measurements were made in a laboratory of J.J. Strossmayer University, Faculty of Food Technology, in Osijek by a Rheomat 15 type instrument. During the tests we were aimed for keeping the specifications (specific temperatures, exact combination rate, international standards etc.). Based on specifications our measurements were made between 35-55 0C on cocoa butter and CBA fats. For the analysis of the results the Casson-way was used, available for the Bingham-type materials. The biggest difference of the viscosity on fats and fat-combinations was found in 35 0C. If the temperature is higher, the difference between the curves is smaller and the curves are converging or crossing. Based on rotational speed versus share-force on 35 0C, the difference is higher in most cases and these curves can show the diffference between storage ways. (There was Nobletan in cold storage and on room temperature for 1 year). The curves are approximating with straight line on bigger rotational speeds and this approach can give a good separation. The effect of temperature and rotational speed can be found in the crystallization properties of fats. The 35 0C is near the melting points of fats, and it is able to show also little differences. On smaller rotetional speed the drag of fats is too high and breaks off the differences. On the bases of the measurements the viscosity cannot be used to study the exact combination rate, because the difference are too small in viscosity of fats and fat-combinations but it can be used as an additional parameter in quality control.

viscosity measurements; conectionary fats; cocoa butter

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