Impact of acoustic intensity on melting behavior of ice cream

Ice cream mixes (407 ± 12 total solids g/kg and 115 ± 14 fat g/kg) were subjected to different levels of acoustic intensity (11-18 W/cm2), and the resulting ice creams were evaluated for melting (oscillatory rheology from −20 to 10 °C) and meltdown (gravimetrical test) behavior. All samples showed a sigmoidal melting curve characterized by two plateaus and a linear segment between the plateaus. A dominant solid behavior (G′ >G″) was observed in ice creams made with sonicated mixes (11 and 18 W/cm2). Acoustic levels of 14.4 ± 0.5 and 18.4 ± 0.8 W/cm2 delayed the onset of meltdown by about 3.0-fold and increased the maximum meltdown compared with control ice cream. Sonicated samples resulted in approximately 2.0-fold viscosity increment within the high spectrum of shear rate compared with the control samples. Dynamic rheology showed a gel-like and strain-thinning behavior of sonicated mixes. The control ice cream displayed moderate hardness (91 ± 9 N) and an onset of meltdown of 642 ± 45 s, whereas the sonicated samples exhibited hardness of 156–218 N and onset of meltdown values of 1900–2200 s. The outcomes of this study demonstrate the ability of power ultrasound to delay the onset of meltdown, providing processing strategies for structuring frozen desserts with delayed meltdown.