Effects of Ultrasound and Change in Chemical Composition on the Rheological Properties of Processed Cheese Analogues

Abstract

The market of processed cheese analogues has expanded due to their simplicity in production and low cost in manufacturing. As an alternative to processed cheese, cheese analogues can fulfil specific requirement by easily modifying the texture of final analogues. The quality of cheese depends on the texture and meltability that can consequently affect the end-up applications and consumer acceptability of the final cheese products. In order to manipulate the texture and meltability of cheese analogues, different formulations and various treatments on the cheese emulsion are used to alter the rheological properties. The fat particle size was observed by the laser diffraction method. The dynamic moduli, complex modulus and loss tangent were determined in frequency sweep, strain sweep and temperature sweep tests. The main objective of this study was to study the effects of ultrasound and other treatments on the cheese emulsion with various formulations and the rheological properties of subsequent processed cheese analogues. The second objective was to find the relationship between the fat particle sizes of cheese emulsions and the viscoelastic properties of the final processed cheese analogues. High power ultrasound results in a remarkable size reduction of cheese emulsions prepare with sunflower oil, 1% calcium caseinate and water. The addition of sodium dodecyl sulfate (SDS) into the cheese emulsion induced further size reduction compared with the sunflower oil based emulsions without SDS. Increasing sonication time led to fluctuation of fat particle size of emulsions based on fresh cream with or without SDS. The higher the ultrasound power, the smaller the fat particle size in cheese emulsions. As frequency increased, the rheological behaviour of almost all the samples changed from liquid-like to solid-like. The frequency at which the dynamic moduli crossed over increased as the protein content was decreased and comparative moisture content was increased. The complex modulus, G*, increased as a function of protein content and decreasing comparative moisture content. Thus, higher protein content and lower moisture content can significantly increase the hardness of cheese analogues. Finally, the relationship between fat particle size and the viscoelastic properties have not been observed in this study.