Applications of water blanching, surface contacting ultrasound-assisted air drying, and their combination for dehydration of white cabbage: Drying mechanism, bioactive profile, color and rehydration property.

This work studied the influences of water blanching pretreatment (30 s), surface contacting ultrasound (492.3 and 1131.1 W/m2) assisted air drying, and their combination on drying kinetics and quality of white cabbage. Contacting sonication was performed by placing samples on an ultrasonic vibration plate, and the drying temperature was 60 °C. Through drying kinetic analysis and numerical simulation considering internal and external resistances and shrinkage, it was found that both blanching pretreatment and contacting sonication during drying intensified internal water diffusion and external water exchange to shorten cabbage drying time. Meanwhile, blanching pretreatment was more effective to enhance the drying process. The largest reduction of drying time (from 145 min to 24 min) was obtained when sequential blanching and contacting sonication at 1131.1 W/m2 were conducted. Dehydrated cabbages with blanching pretreatment were characterized by green color and high retention of vitamin C, while a severe loss of vitamin C was found in dried cabbages without blanching pretreatment. Moreover, although both blanching and contacting sonication shortened the drying time, the losses of phenolics, glucosinolates and resulting breakdown products were not alleviated. Contents of total phenolics, one glucosinolates (sinigrin) and one glucobrassicin breakdown product (indole-3-acetoritrile) in only air dried cabbages were significantly (p < 0.05) higher than that in samples dried by sequential blanching and contacting ultrasound-assisted drying. The changes of glucosinolate profile and resulting degradation products under different treatments were irregular, due to complex bioconversion pathways included.

Parametric and phenomenological studies about ultrasound-enhanced biosorption of phenolics from fruit pomace extract by waste yeast.

In this work, sonication (20-kHz) was conducted to assist the biosorption of phenolics from blueberry pomace extracts by brewery waste yeast biomass. The adsorption capacity of yeast increased markedly under ultrasonic fields. After sonication at 394.2 W/L and 40 °C for 120 min, the adsorption capacity was increased by 62.7% compared with that under reciprocating shaking. An artificial neural network was used to model and visualize the effects of different parameters on yeast biosorption capacity. Both biosorption time and acoustic energy density had positive influences on yeast biosorption capacity, whereas no clear influence of temperature on biosorption process was observed. Regarding the mechanism of ultrasound-enhanced biosorption process, the amino and carboxyl groups in yeast were considered to be associated with the yeast biosorption property. Meanwhile, ultrasound promoted the decline of the structure order of yeast cells induced by phenolic uptake. The interactions between yeast cells and phenolics were also affected by the structures of phenolics. Moreover, the mass transfer process was simulated by a surface diffusional model considering the ultrasound-induced yeast cell disruption. The modeling results showed that the external mass transfer coefficient in liquid phase and the surface diffusion coefficient under sonication at 394.2 W/L and 40 °C were 128.5% and 74.3% higher than that under reciprocating shaking, respectively.

Ultrasound assisted adsorption and desorption of blueberry anthocyanins using macroporous resins.

In this study, the impact of ultrasound on the adsorption and desorption features of blueberry anthocyanins on macroporous resins were studied. Sonication was performed at 106-279 W/L and 20-30 °C in a pulsed mode, respectively. Generally, ultrasound treatments within the selected experimental range enhanced the adsorption/desorption process of anthocyanins on macroporous resins. The recovery of blueberry anthocyanins after ultrasound-assisted adsorption/desorption process at 279 W/L and 20 °C was 82.12%, which was 52.84% higher than that obtained after adsorption/desorption with shaking at 100 rpm. Meanwhile, higher acoustic energy density (AED) levels and lower temperatures benefited the adsorption process through enhancing the adsorption capacity and shortening the equilibrium time, whereas higher temperatures promoted the desorption process. Furthermore, malvidin-3-galactoside had the highest adsorption and desorption capacities among all the studied monomeric anthocyanins. No organic acids and sugars were detected after adsorption/desorption processes, indicating the successful improvement of anthocyanin purification. Sonication mainly enhanced the adsorption process by means of strengthening the formation of hydrogen bond on resins surface and increasing their surface roughness. Overall, ultrasound can be an effective tool to improve the purification of anthocyanins using macroporous resins.