Effect of ultrasonically induced nucleation on ice crystals’ size and shape during freezing in vials

Controlled nucleation in freeze‐drying: Effects on pore size in the dried product layer, mass transfer resistance, and primary drying rate

“…The effectiveness of ultrasound for inducing nucleation has been investigated on laboratory scales 9–11. Although ultrasound is an effective tool for studying the impact of nucleation on small numbers of freeze‐dried vials, it would be expected that uniform application of ultrasonic energy in a production‐scale freeze dryer would be a significant engineering challenge.…”

Ultrasound for Improved Crystallisation in Food Processing

“…The DNA is particularly useful to study the nucleation process as a stochastic model. Recently, Saclier et al [68] froze 10 % w/w mannitol aqueous solution samples to establish correlations between the final frozen product ice crystal characteristics and ultrasound-assisted freezing operating conditions. Their work revealed that an increase in supercooling and acoustic power resulted in decreased mean size and increased mean circularity of ice crystals as observed with optical microscopy.…”

Theoretical model of ice nucleation induced by inertial acoustic cavitation. Part 2: Number of ice nuclei generated by a single bubble

“…Moreover, if it is supposed that the greater the number of nuclei, the smaller the crystal size, then the trends predicted by the theoretical model described above corresponded quite well, qualitatively speaking, to those given by an empirical model based on an experimental design proposed previously by Saclier et al [12] (see preceding paragraph). A quantitative validation of the theoretical model was not possible, however, because the responses of the experimental design and of the simulations were not directly comparable.…”

“…It was shown that the nucleation could be readily triggered at selected sample temperature values below the equilibrium freezing temperature and that small and numerous ice crystals were obtained at lower nucleation temperature (higher undercooling level), while large and directional ice crystals (dendrite type) were obtained at a higher nucleation temperature (lower undercooling level). Saclier et al [12] continued the work on mannitol solution sono-freezing in vials. Using the same apparatus and methodology, they confirmed the above qualitative results but further adopted a second order experimental design and quantitatively assessed the effect of both the nucleation temperature and the acoustic power on the final crystal size and shape.…”