# Current Applications of Ultrasound in Fruit and Vegetables Osmotic Dehydration Processes
## 5 Properties of the Product Treated with US before or during OD
### Functional Properties of the Product Treated with US before or during OD
[29] observed that the combination of blanching with US in the OD process caused a decrease in vitamin C content of semi-moist cranberries, while the same treatment with an addition of reduced pressure led to a similar retention of vitamin C as in the untreated dried cranberries [3]. Considering the phenolic compounds and antioxidant activity, [PERSON] et al. [120] observed that prolonged application of US (longer than 90 min) during OD process caused a loss of about 10% of TPC and anthocyanin in osmo-dried sour cherries. Similarly, UOD caused a decrease of TPC in semi-dried and dried apricot [90] and dried kiwifruit [109], while a higher retention of TPC and antioxidant activity was noticed in dried plum [110] and dried garlic [48]. Finally, no effect on the retention of TPC in dried strawberries was observed [114]. [PERSON] et al. [29; 30], studying the influence of different pretreatments on osmodehydrated cranberries, noticed that anthocyanins, TPC and antioxidant activity were strongly influenced by the applied treatment type and duration. The same research group observed a decrease of bioactive compound in BL + US + PEF treated osmodehydrated cranberries [16], while a better preservation of anthocyanins and similar retention of TPC and TF was achieved when the combination of BL + US + Vacuum was used as a pretreatment before drying of cranberries. Ultrasound-assisted OD caused a higher loss of carotenoids in sweet potato samples in comparison to the conventional OD [122], while no effect was observed in physalis [121]. However, for blueberries, the selection of appropriate conditions of UOD results in obtaining the highest antioxidant activity and total content of anthocyanins, flavonoids and polyphenols [106]. [PERSON] et al. [108] observed enhanced chlorophyll content in semi-dried kiwifruit subjected to the US pretreatment. When fruits and vegetables were subjected to the further drying, different behaviors in pigments were observed depending on both pretreatment and drying process parameters. For kiwifruits, [PERSON] et al. [109] observed a decrease of carotenoid as well as TPC in UOD samples compared to OD ones, while a better retention of these compounds was achieved when hybrid US-assisted conventional drying was applied. Better preservation of total carotenoids in UOD treated samples was observed in died at low temperature carrot samples [96] and in dried apricot subjected combined UOD and pectin + citric acid coating [119]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Product** & **Treatment Applied** & **Functional Properties after OD** & **Functional Properties after** \\
**[References]** & **Treatment Applied** & **Functional Properties after OD** & **Drying** \\ \hline Physalis & US (20 kHz, 30 min) + OD (55 \({}^{\circ}\)C, [121] & No influence on carotenoids content was reported. & - \\ \hline Plum & UOD (25 kHz, 30 and 60 min, [110] & - & Higher TPC and antioxidant activity when UOD was applied for 30 min in glucose solution. \\ \hline BL, blanching; US, ultrasound; OD, osmotic dehydration; V, vacuum; VOD, vacuum assisted osmotic dehydration; UOD, ultrasound assisted osmotic dehydration; P, pectin; CA, citric acid; AA, ascorbic acid. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._