Influence of high intensity ultrasound on temperature and stability of cow milk expressed by the emulsion stability index

Cilj ovog istraživanja bio je ispitati utjecaj ultrazvuka visokog intenziteta konstantne frekvencije od 24 kHz na temperaturu te stabilnost kravljeg mlijeka izraženog preko indeksa stabilnosti emulzije (ISE). Također smo željeli utvrditi utječe li porast temperature uslijed ultrazvučne obrade na ISE, apsorbanciju, gustoću i viskoznost kravljeg mlijeka. Praćen je utjecaj ultrazvuka visokog intenziteta snage 400 W na temperaturu, apsorbanciju, apsorbanciju nakon 24 sata, gustoću i viskoznost pri slijedećim procesnim parametrima ultrazvuka: amplituda (A = 37,5; 50; 62,5; 75; 87,5; 100 %); vrijeme obrade (t = 2, 6, 10, 15 minuta); primijenjeni ciklus (c = 0,6; 0,8; 1). Dobiveni rezultati statistički su obrađeni pomoću programskog paketa „Statistica 8“. Vrijednosti ISE izračunati su preko izmjerenih vrijednosti apsorbacije kravljeg mlijeka. Najveći utjecaj na porast ISE pokazao je primijenjeni ciklus, zatim vrijeme obrade ultrazvukom, te amplituda. Porast temperature utječe na povećanje vrijednosti prividne viskoznosti i smanjenje gustoće što indirektno djeluje na promjenu ISE.Main purpose of this research is to study the influence of high-intensity ultrasound with constant frequency of 24 kHz on temperature and stability of cow milk expressed by the emulsion stability index (ESI). Also, we wanted to determine whether the temperature increase, as the consequence of ultrasonic treatment effects the emulsion stability index, absorbance, density and viscosity of cow milk. The influence of high-intensity ultrasound (power 400 W) on temperature, absorbance, absorbance after 24 hours, density and viscosity was observed under following conditions: amplitude (A = 37,5; 50; 62,5; 75; 87,5; 100 %); processing time (t = 2, 6, 10, 15 minutes); applied cycle (c = 0,6; 0,8; 1). Obtained results are processed in the „Statistica 8“ software. Values of the ESI were calculated over measured values of absorbance of cow milk. Increase of the applied cycle showed significant influence on the increase of ESI, followed by the processing time and amplitude. Increase of temperature has influenced the increase of viscosity and decrease of density, which indirectly effects the change in ESI values