engleski

Influence of temperature as a consequence of high intensity ultrasound treatment on physical properties of sheep milk

INTRODUCTION In this study, research was based on influence of high intensity ultrasound on inhomogeneous sheep milk Cavitation which mechanism is based on implosion bubbles produce powered shock waves in milk what is being reflected on changes of physical properties. METHODOLOGY Ultrasonic processor (maximal nominal power - 100W) with the constant frequency of 30 kHz was used. Changes on pH – value, density, viscosity and absorbance (500nm) are followed by given process parameters: amplitude (A = 20, 60 and 100 %) ; time of treatment (t = 2, 6, 10 and 15 minutes), full cycle (c = 1), probe diameters (d = 7, 10 and 14 mm). Statistical analysis was conducted and influence of process parameters and temperature was expressed over p – value (p<0.05 ; ANOVA ; ANCOVA). RESULTS AND DISCUSSION Applications of different probe diameter have significant influence on all observed physical properties. Longer time of treatment and amplitude showed significant influence on absorbance and changes on viscosity of sheep milk, while on pH – value and density has no influence. Analyses of covariance (ANCOVA) showed significant influence of the temperature on increasing of absorbance and viscosity, while temperature has no influence on pH – value and density of ultrasonically treated milk. CONCLUSIONS Influence of highest values of process parameters was expressed on increasing of absorbance and viscosity. Consequence of these significant changes is increasing of temperature during ultrasonic treatment.

ultrasound; sheep milk; temperature; physical properties

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