engleski

Physical Properties of Tribomechanical Micronized Whey Proteins

Whey proteins, because of their high biological value and specific functional properties, are today more and more used as an ingredient in various food products. The functional role of proteins depends on complex interactions of many factors such as heating or cooling rate, pH, ionic strength as well as by mechanical means like whipping, high pressures or ultrasonic vibrations. In this research the procedure of tribomechanical micronization and activation (TMA) was used with the aim to investigate its effect on the physical as well as functional properties of whey proteins. Namely the results obtained recently have shown that TMA process changes physico-chemical properties of some hard mineral substances (e.g. zeolite, calcite) improving their functional characteristics. In this investigation two samples of powdered whey protein concentrates containing 60 % (WPC-60) or 80 % (WPC-80) of proteins were tribomechanicaly treated at three differenc rotor's speed (16000, 20000, . 22000 rpm) using the laboratory equipment for TMA. The consequence was a significant decrease of particle size and an increase in specific area of materials. The pictures obtained using scanning microscopy have shown that also rupturing and splitting of protein globules has occurred. That was also confirmed by the results of electrophoresis. After tribomechanical treatment an increase of protein fractions and lowering of their molecular weight have occurred. Besides, the results of freezing temperature determination of 10 % whey protein suspensions have shown that after tribomechanical treatment a decrease of freezing point has occurred. At the same time the bulk density of powdered WPC increased and their solubility as well as dispersibility changed depending on the protein fraction and rotor's speed. The conductivity of 10 % tribomechanicaly treated whey protein suspensions was greater than those prepared with untreated proteins. All these results indicate that the procedure of tribomechanical micronization effects splitting of protein molecule what changes their physico-chemical and functional properties and the properties of the systems in that they are added.

whey proteins; tribomechanical treatment; functional properties; freezing temperature

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