Table 1.
Different systems of application of US by direct contact with food.
| Process | US system | Study | Results | References |
|---|---|---|---|---|
| Drying |
 Adapted from (45) |
Carrot slices US parameters: - Frequency: 20 kHz - Power: 100 W - Static pressure Conditions evaluated: - Airflow: 1 and 3 m/s - Air temperature: 22°C |
Improvement in the drying rate (70.0%) Lower final moisture |
(45) |
| Drying | The same as (45) Adapted from (46) |
Carrot, apple, and mushroom slices US parameters: - Frequency: 20 kHz - Power: 100 W - Pressure static (1): 0.05 kg/cm2 Conditions evaluated: - Airflow: 1.7–2 m/s - Air temperature: 20 and 55°C |
Reduction of drying time (carrots: up to three times, apples: 50.0–76.7% and mushrooms: 68.3–83.3%) Reduction of drying time (carrots: 50.0–58.3%, apples: 66.7–233.7% and mushrooms: 50.0–75.0%) |
(46) |
| Drying |
 Adapted from (47) |
Apples and potatoes slices US parameters: - Frequency: 20 kHz - Power: 25 and 50, W - Static pressure: 0.0155–0.050 kg/cm2 - Suction pressure: 10 and 20 mbar Conditions evaluated: - Airflow: 1 m/s - Air temperature: 31°C |
Increase in the effective diffusivity coefficient | (6, 37) |
| Drying |
 Adapted from (48) |
Apple slices US parameters: - Frequency: 20 kHz - Power: 75 and 90 W Conditions evaluated: - Air temperature: 40 and 60°C - RH% air: 25% - Airflow: 1 m |
Reduction of drying time (46.0–57.0 %) No differences in texture |
(48) |
| Drying |
 Adapted from (43) |
Red bell peppers and apples US parameters: - Frequency: 24 kHz - Power: 42 W - Effective amplitude: 6–13 μm Conditions evaluated: - Air temperature: 70°C - Continuous US treatment - Intermittent US treatment: • 50% net sonication time • 10% net sonication time |
No impact on final relative water content Intermittent US treatment at net sonication of 10 % did not improve the process, but at net sonication of 50% there was a reduction in drying time (18–20%) Continuous US treatment allowed to reduce drying time (18–27%) |
(43) |
| Drying | The same as (43) | Potato cylinders US parameters: - Frequency: 24 kHz Conditions evaluated: - Air temperature: 70°C |
US effect was strongest in the outermost layer (0.0–0.6 mm) and at the sonicated surface US treatment allowed to reduce drying time (by 10.3%) |
(49) |
| Drying |
 Adapted from (50) |
Purple-fleshed sweet potato slices US parameters: - Frequency: 28 kHz - Power: 30 and 60 W Conditions evaluated: - Air temperature: 40, 50, 60, and 70°C - Airflow: 1 m/s |
Drying time was reduced by increasing the US power (31.5–47.7 %) but the US effect was less pronounced at higher air temperature The drying rate was improved (50.8–100.0 %) at high US power and low temperature Increase in the effective moisture diffusivity (Deff) (17.6–48.1%) Distortions of the cellular tissue and the appearance of large cavities Improvement of the rehydration capacity |
(50) |
| Drying |
 Adapted from (51) |
Pear slices US parameters: - Frequency: 28 kHz - Power: 30 and 60 W Conditions evaluated: - FIR power: 100, 220, and 340 W - Air flow: 1.5 m/s |
Increase in the drying rate (at 45°C, the increase was 33.3% at 24 W and 140.1% at 48 W) Positive impact on total phenolic content, flavonoids, and ascorbic acid Appearance of more numerous and larger microchannels in the cell tissue |
(51) |
| Drying | The same as (51) | Kiwi slices US parameters: - Frequency: 28 kHz - Power: 18, 36, and 54 W Conditions evaluated: - FIR temperature: 120, 200, and 280°C - Airflow: 1.5 m/s |
Reduction of drying time (the increase at 120, 200, and 280°C was 32.2–48.4%, 22.2–38.9%, 14.3–33.3%, respectively) The drying rate was improved (66.7%) by increasing US power US decreased the resistance to internal diffusion, facilitated the migration and removal of the immobilized and bound water |
(52) |
| Drying | The same as (50) | Pear slices US parameters: - Frequency: 28 kHz - Power: 24 and 48 W Conditions evaluated: - Air temperature: 35, 45, and 55°C - Airflow: 1 m/s |
Best increase in drying rate (33.3–140.1 %) at low air temperature The microstructure of the pear samples showed more numerous and larger cavities Positive impact on total phenolic content, flavonoids, and vitamin C Improvement in rehydration capacity |
(53) |
| Drying |
 Adapted from (54) |
Garlic (Allium sativum L.) US parameters: - Frequency: 20 kHz - US treatment: 3 s on/ 1 s off Conditions evaluated: - Power: 216.8, 902.7, and 1513.5 W/m2. - Air temperatura 50, 60, and 70°C - Airflow: 2.5 m/s |
Reduction of drying time (the increase at 216.8, 902.7, and 1513.5 W/m2 was 5.0%, 12.5%, 35.0% respectively, at 50°C) The drying time was reduced by increasing air temperature Positive impact on thiosulfinate and TPC at 216.8 and 902.7 W/m2 Greater retention of organosulfur compounds Color improvement |
(54) |
| Drying | The same as (54) | White cabbage (Brassica oleracea L. variety Capitana L.) US parameters: - Frequency: 20 kHz - US treatment: 4 s on/2 s off Conditions evaluated: - Power: 492.3 and 1131.1 W/m2 - Air temperature: 60 °C - Airflow: 2.5 m/s - Pre-blanching treatment (100°C/30 s) |
Synergistic effect of blanching and subsequent US drying to intensify drying process No color differences Higher TPC (12.6 %) in un-blanched sonicated samples at 492.3 W/m2 No positive effect on Vitamin C content No clear effect on glucosinolate |
(55) |
| Freezing |
 Adapted from (56) |
Mushroom (Agaricus bisporus) US parameters: - Frequency: 20 kHz - Power: 300 W - 12 transducers Conditions evaluated: - US treatment: 10 s on/20 s off when the sample temperature reached −1°C - US treatment: 10 s on/ 10 min off during 3 weeks of frozen storage |
Earlier nucleation Smaller crystal size and more uniform shape The microstructure was more uniform, featuring more numerous and more dense pores |
(56) |
| Freezing |
 Adapted from (57) |
Chicken breasts US parameters: - Frequency: 40 kHz - Power: 50 W Conditions evaluated: - US treatment: 3s on/ 5s off throughout the entire freezing process - Air temperature −13 to −25° C - Air flow: <0.4 m/s |
Reduction of freezing time (19.9%) No difference in quality attributes such as WHC, CL and protein digestibility |
(57) |
| Freeze-drying |
 Adapted from (58) |
Red bell peppers Samples were frozen in a cooling chamber to reach a temperature of −20°C Then they were dried by applying US US parameters: - Frequency: 20 kHz Freeze-drying pressure was 46 Pa Conditions evaluated: - Power: 76, 90, and 110 W - Net sonicated time: continuo (100%), 25%, 14% and 10% |
Minimum US thermal effect at 76 W and net sonication time of 10 % Reduction of drying time No difference in quality attributes such as bulk density, color, ascorbic acid, and rehydration capacity |
(58) |