Proceedings of International Congress on Bioactive Compounds and International Workshop on Bioactive Compounds
Proceedings of 2nd International Congress on Bioactive Compounds

Dairy desserts have become increasingly popular with several variant types, which consumers appreciate. Although they usually are submitted to thermal processing, there is a need to evaluate non-conventional technologies, such as thermosonication (TS), which uses high-intensity ultrasound combined with heating. This study aimed to assess the effect of TS (90 °C, 200, 400, and 600 W) on rheological parameters (flow curves), fatty acid profile, and confocal laser scanning microscopy. In addition, engineering parameters related to TS were also determined. Products submitted to conventional pasteurization (HTST, 90 °C) or untreated (control, no HSTS or TS) were processed for comparisons. The engineering parameters of the TS treatments at 200, 400, and 600 W applied to the samples were acoustic power of 14.2, 39.4, and 64.76 W, acoustic intensity of 30.4, 84.7, and 139.4 W.cm-2; power density of 0.14, 0.39 and 0.64 W.ml-1; and specific energy of 102, 212.5 and 272 J.g-1, respectively. Rheological data presented a good fit using non-linear regression to the Herschel-Buckley model (0.96< R2 <0.99). TS increased the shear stress, with higher values observed when the system operated at 400 W (p < 0.05). This phenomenon can be related to the transient and steady cavitation mechanisms, which depend on sonication intensity. This way, TS at 200 W and 600 W kept the shear stress more similar to the values found in the control sample. All treatments (conventional heating and TS) resulted in increases in the consistency index compared to the control (p < 0.05). This behavior is more prominent for TS-treated samples at 200 W and 400 W, followed by HTST and 600 W (p < 0.05). In this sense, the increase in the TS power decreased the consistency index of the products (p < 0.05). The TS power significantly impacted the fatty acid profile, with TS600 resulting in minor changes compared to TS200 (p < 0.05). In the TS200 sample, it is noted that the concentration of fatty acids tends to increase, especially the concentration of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), compared to the control sample. This increase was associated with increases in the oleic and linoleic fatty acids (p < 0.05). In confocal laser scanning microscopy, it was possible to observe that the mean size of the fat droplets differed significantly (p < 0.05) between the TS samples (2.2 - 2.3 mm) and the control and HTST samples (3.2 - 3.3 mm). The TS samples did not differ from each other (p > 0.05). This indicates that the TS samples have better digestibility due to the smaller size of the observed fat droplets. Given the observed, TS proved to be an efficient emerging technology for processing dairy desserts regarding the adequacy of physical and processing parameters.