Table 5.
Ultrasound combined hybrid and innovative techniques in Food Processing.
| Technique | Product | Condition | Salient findings | Reference |
|---|---|---|---|---|
| Frying | ||||
| US assisted osmotic dehydration (UAOD) as a pretreatment, followed by frying | Potatoes | Pretreatment conditions: 90 min Osmotic dehydration, 30 min UAOD, using 15% sodium chloride/50% sucrose solution prior to frying(170 °C) for 2–6 min | By 12.5% (db), UAOD reduced the oil content of fried potatoes, compared to untreated fried potatoes, at the end of frying. No significant difference between OD & UAOD in oil uptake reduction in fried potatoes. UAOD improved color of French fries and shortened the pretreatment duration of OD by about 67%. | [137] |
| ultrasonic-assisted frying | Meatballs | US power: 0, 200, 400, 600 and 800 WFrequency: 20 kHz applied during frying (12 min, 160 °C). | US-assisted frying was concluded as a potential approach in improving overall flavor of fried meatballs. US treatment significantly increased thiobarbituric acid reactive substances and decreased free fatty acids. US-fryingincreased the contents of 7 free amino acids including Lys, Glu, Gly, Ala, Tyr, Ser and Cys. Showed a positive impact on nucleotides formation and can enhance a more desirable flavor within 400 W. | [140] |
| US as a pretreatment before frying | Fried potatoes | Potato sticks in water treated with US. Frequency: 35 and 130 kHz) US power densities: 0, 9.5, 47.6 and 95.2 W/kg, Intensities: 10, 50 and 100% and water temperatures (30 and 42 °C). Followed by frying in refined sunflower oil (171 ± 1 °C) | At lower frequencies, US more effective in modification of weight gain, moisture and electrical conductivity during soaking, and on fried potatoes color. Soaking temperature had an impact on US effect. Treatment led to changes in total acrylamide content in fried potatoes. | [139] |
| Mushroom (Agaricus bisporus) chips | Vacuum frying (VF) Microwave vacuum frying (MVF) US assisted microwave vacuum frying (UMVF) | Microwave power: 800, 900 and 1000 WFrying temperature: 80, 85 and 90 ℃.US balancing sources: 120 W, 28 kHz. The frying temperature and vacuum pressure were set at 90 ℃ and 12 ± 1 kPa respectively | Optimum condition (1000 W, 90 ℃), gave higher moisture evaporation rate and low oil content. UMVF could reduce oil content (16–20%)compared to other treatments. UMVF chips: Better texture, most acceptable color, best matrices, accelerated frying, comparatively lower uptake of oil. | [141] |
| Fermentation | ||||
| US assisted fermentation | Lebanese apples | Microorganism: Hanseniaspora sp. yeast. US: 100 W, 40 kHz, power supply (220 V), Cyclic mode, variable periods of US pulses duration (0.5–2 s), followed by 6 s pauses. | Optimal US pulse duration on the yeast growth rate: 0.5 s followed by 6 s rest period, and during 6 h of both lag and log phases. Compared to untreated samples, US parameters resulted in faster glucose consumption in the medium during the fermentation. A significant enhancement in biomass growth and consumption of glucose, accompanied by significant decrease in the ethanol yield. | [142] |
| US assisted dough fermentation | Wheat dough | Bag with dough place in an US bath(40 kHz). Bath temperature maintained at 36–38 °C. Ultrasonic power density: from 15.38 W/L to 38.46 W/LTreatment time:20 min-50 min. Dough fermentation in tank: 40 min, 36 °C and 83% R.H. | US assisted dough fermentation improved the quality of the steamed bread. Fresh steamed bread hardness reduced by 22.4%.Specific volume enhancement: 6.7% at US power density; 23.08 W/L, 40 min. During storage, bread prepared by using US was softer compared to control. Springiness was lower when storage time under 48 h. | [144] |
| US assisted fermentation | Soyabean meal | US power density; 0.08 W/mL, Frequency:33 kHz Treatment time:1 hBacillus subtilis | Enhancement compared to control (peptide contents:31.27%; soluble protein :18.79%).Antioxidant activity and functional properties enhanced with US. | [145] |
| Freezing/crystallization | ||||
| US during immersion freezing | Broccoli | 30 kHz, 150 W; 20 kHz, 175 W for 120–180 sec. | Microstructure and textural firmness were better than the normal immersion freezing. Drip loss was noticed to be minimised. US was found to be promising. | [170] |
| US assisted immersion freezing | Fish | Immersion freezing tank (−25 ± 0.5 °C), 30 kHz, 0–175 W. US (On and off 30 s) On: 30 sec on/30 s off) 9 min cycle | Samples had smaller ice crystals compared to air freezing and immersion freezing, resulting in less deterioration of tissues of muscle during storage. During storage, compared to the other methods, lower total volatile basic nitrogen values and thiobarbituric acid reactive substance were observed. | [171] |
| US assisted immersion freezing | Mushrooms | Frequency: 20 kHz; US intensity: 0.13 W cm−2, 0.27 W cm−2 and 0.39 W cm−2 | US (20 kHz, 0.39 W cm−2) reduced freezing time by 40%.Reduction in peroxidase enzyme activities and polyphenol oxidase and drip loss. Improved whiteness index, chroma and textural hardness value. | [173] |
| US assisted immersion freezing | Potatoes | 35 kHz0.32 W/g, 8 s,-0.5, −2.0 and −3.0 ℃ | Nucleation was anticipated and freezing time was reduced. At −2.0℃, the shortest time was observed. | [174] |
| Defrosting/ thawing | ||||
| Ultasound assisted thawing (UAT) | Bighead carp | 28 kHz, 0.135 W/mL, slow freezing(-18 °C) / fast freezing (-100 °C liquid nitrogen) frozen for 30 d at −18 °C, followed by water immersion thawing, air thawing and ultrasound assisted thawing. | Compared to water and air thawing, UAT drastically reduced thawing time. UAT was helpful in preserving the pH, color and lipid oxidation. Fast freezing UAT and Water immersion thawing, showed maximum muscle tissue destruction and water loss. UAT was found to be the best thawing method for big head carp which had undergone slow freezing. | [177] |
| UAT | Mango pulp | 28 kHz, UAT (intensities: 0.037, 0.074 and 0.123 W/mL in water bath at 4 ± 1 °C and 25 ± 1 °C, respectively | US was found to be a prospective alternative to conventional method of thawing. When compared with conventional method, a reduction in time by 16–64% was observed and more phenolic acids were obtained. US thawing (25 °C) reduced thawing time by 51–73% when compared with 4 °C. US intensities (0.074–0.123 W/mL) at 25 °C resulted in better thawing efficiency and nutritional quality. | [178] |
| Ultrasound assisted vacuum thawing (UVT) | Red seabream (Pagrus major) | UT; 200 W, 40 kHzUVT: 0.06 MPa, 0 °C, 200 W, 40 kHz | UVT samples showed poor viscoelasticity, the reason was considered to be the less denaturation of muscle proteins. Microwave assisted vacuum thawing (MVT) showed a viscoelasticity similar to fresh sample. UVT samples showed that the secondary structure was retained, while with MVT, non-uniform structure was observed. UVT and MVT were mentioned to have the potential to improve physicochemical properties of protein during thawing. | [177] |
| Low intensity ultrasound assisted thawing | Pork Longissimus dorsi muscle | 25 kHz. 0.2, 0.4, and 0.6 W/cm2 | US shortened thawing time by 87% through thawing from −5 to −1°C compared to air thawing. Ultrasound assisted thawing did not damage the textural and technological attributes. | [179] |
| Drying | ||||
| US pretreatment followed by hot air and freeze drying | Carrot discs | Probe system, 20 kHz, Amplitude: 24.4, 42.7 and 61.0 μm. Processing time: 3 and 10 min. Hot air drying (60 °C, 0.3 m/s). | Higher carotenoids and polyacetylenes retention in US pre-treated samples. US pre-treatment, a potential alternative to blanching, before drying carrots. | [180] |
| Hot air convective drying with contacting ultrasound system | Garlic slices | Sonication: 1513.5 W/m2Air velocity: 2.5 m/s Temperature: 50 °C, 60 °C and 70 °C. | Contacting US reduced drying time, enhanced water diffusion and reduced quality loss. Organosulfur compounds were better preserved, browning was minimized. | [181] |
| Airborne ultrasound assisted convective drying | Potato | 25 kHz, 100 and 200 W, air velocity 4 m/s, 50 °C | US reduced processing time from 5 to 3 h. US lowered energy consumption and helped retain quality parameter. | [182] |
| Ultrasound combined vacuum pretreatment(UVP) and convective drying | Okra | 25 kHz, P = 80, 200 and 320 W, T = 25 °C, t = 5, 10 and15 min. Optimised (250 W, 0.5 cm thickness and ultrasonic treatment for 15 min) | UVP enhanced convective drying, maintained the physicochemical properties and also reduced the energy consumption. | [183] |
| Cooking | ||||
| US assisted cooking | Spiced beef | Power levels: 0, 400, 600, 800 and 1000 W. Frequency: 20 kHzCooking time 120 min. | Permeability of NaCl enhanced due to. High power US resulted in increase in the lipid oxidation, which helped in strengthening the volatile compounds. At 800 W, US improved chemical profiles of spiced beef flavour and taste | [185] |
| US assisted cooking | Spiced beef | Power level: 0, 400, 600, 800 and 1000, Frequency: 20 kHz, Cooking time (80, 100 and 120 min) | US improved salt penetration, affected tenderness and water holding capacity of spiced beef was improved. | [186] |
| US assisted cooking | Mortadella | US 25 kHz | US improved the cooking process,accelerated increase in internal temperature and more homogeneity were observed in the mortadellas. US did not accelerate protein and lipid oxidation and no color changes were observed and did not affect the microbiological quality. Positive effects of US on gel formation were found as an increase in hardness and chewiness was reported. | [187] |
| Combination of US and temperature hydration | White kidney beans | Hydration using US (28 W/L volumetric power), 45 kHz and temperatures (25, 35, 45 and 55C). | Both temperature and US enhanced the hydration process. When in combination, ultrasound effect decreased with increasing temperature of soaking. The cooking process was not affected by both the different temperatures and ultrasound. | [188] |
| US assisted cooking | Mortadella | US 25 kHz | US improved the cooking process, accelerated increase in internal temperature and more homogeneity were observed in the mortadellas. US did not accelerate protein and lipid oxidation and no color changes were observed and did not affect the microbiological quality. Positive effects of US on gel formation were found as an increase in hardness and chewiness was reported. | [187] |
| Filtration | ||||
| US assisted cross flow ultrafiltration | Skim milk | Small angle X ray scattering Cross-Flow US-coupled Filtration CellUS intensity: 0.6 to 2.9 W cm−2 . | Feed milk viscosity not affected at 20 kHz, 2 W cm−2. US improved filtration. Partial disruption of concentrated layer occurred by US, accelerating permeate flux. The effect of ultrasound was found to decrease when the feed concentration increased. US was found to be promising as the formation of reversible fouling layer was limited, therefore higher permeate flux was induced. | [193] |
| US assisted cross flow ultrafiltration | Skim milk | Small angle X ray scattering Cross-Flow US-coupled Filtration CellUS intensity: 0.6 to 2.9 W cm−2 . | Feed milk viscosity not affected at 20 kHz, 2 W cm−2. US improved filtration. Partial disruption of concentrated layer occurred by US, accelerating permeate flux. The effect of ultrasound was found to decrease when the feed concentration increased. US was found to be promising as the formation of reversible fouling layer was limited, therefore higher permeate flux was induced. | [194] |
| US assisted defouling | Whey solution | 50 kHz, 300 W, 55 kPa, 20–22°C. Membrane: Cross flow UF. | 112% flux recovery. Ultrasound led to physical cleaning. Surfactant along with ultrasound showed a synergistic effect. | [195] |
| US assisted defouling | Soyabean protein | 40 kHz, (0, 1.43, 2.13, 3.57 W.cm -2) Power, (20, 30, 40, 50, 60, 70 kPa) operating pressure, | Permeate flux: 86.3 kg.m-2h−1 Frequency: 23 kHz, 3.57 Wcm−2. US leads to formation of cracks on membrane surface. Polyvinylidenefluoride (PVDF) membrane more resistant compared to other membranes. | [196] |
| US assisted defouling | Carrot juice | 20 kHz, 400, 600, 800, 1000 W, 0.2, 0.5 bar. Microfiltration system with PVDF | US enhanced the flux. US reduced diphasic nature of juice, affected fouling. @ 1000 W, 100 ml solution, 30 min sonication | [191] |
| US-assisted emulsification | ||||
| US assisted emulsification | Mustard oil in water | Ultrasonic power amplitude of 40%, 30 min, Hydrophilic lipophilic balance value of 10, Ψs of 0.08 (8%, v/v), Ψo of 0.1 (10%, v/ v) | Good emulsion stability (up to 3 months). Only physical effects of US were observed and no changes in molecular structure of oil were seen. | [198] |
| High intensity US | Whipped cream | US 20 kHz (100 and 300 W) for 0, 5, 10 and 15 min (Pulse on-time: 2 s, off-time: 4 s). | US enhanced the quality and properties of whipped cream up to a particular US input energy. Protein chains underwent denaturation, and opened to cover fat cells, enhancing the properties. | [199] |
| Pickling/brining | ||||
| US assisted brining | Chinese cabbage | 35 kHz, NaCl (10, 15, and 20% w/w), 1:10 (sample: salt solution), 25 °C(room temperature). Samples removed at 0, 30, 60, 90, 120, 150, and 180 min and wrapped in absorbent paper for 2 min to remove excess solution | US enhanced the cabbage hardness and chewiness, improved brining process, gave a homogenous salt distribution and improved Kimchi quality. | [201] |
| High intensity US | Pork meat (Longissimus dorsi) | US: 40 kHz; 37.5 W/dm3NaCl concentration :50, 100, 150, 200, 240 and 280 kg NaCl/m3Brining:15, 30, 45, 60, 90 and 120 min. Water immersion: 20 s, blotting followed by wrapping in plastic waterproof film. Storage :18 ± 0.5 ⁰C. | US significantly influenced salt gain and enhanced brining. Reduced brining time. Gave uniform salt distribution. | [202] |
| US assisted diffusion | Pork | 70 W, 20 kHz, Ultrasonic power: 9.29 and 54.9 W cm−2. | ||
| 5% NaCl/ Salt replacer, brining time 120 min. | US enhanced the salt diffusion into the matrix, compared to static brining. US brined samples, improved the texture of brined samples both with NaCl and salt replacer. | [203] | ||
| Sterilization | ||||
| US assisted pasteurisation | Juices | Designing of batch ultrasonic reactor. | [205] | |
| Frequency: 20 kHzAmplitude: 45%E.coli and S.aureus. | E. coli inactivation: 60 °C, Staphylococcus aureus: 62 °C. 5-log microbial reduction achieved in 0.38 min and 0.55 min, respectively. US damaged cell structure leading to inactivation of microbes. Pasteurisation time reduced. No negative impacts on organoleptic characteristics and nutritional properties. | |||
| US assisted pasteurisation | Pear juice | US assisted pasteurisation was compared with conventional method. 25, 45 and 65 ⁰C for 10 min using a 750 W probe sonicator (frequency 20 kHz and amplitude 70%). Conventional: 65 ⁰C, 10 min; 95 ⁰C, 2 min. | Both US and conventional method were able to attain the complete inactivation of microbes and enzymes. US treated samples showed better ascorbic acid and other nutritive compounds retention. | [206] |
| US assisted pasteurisation | Chocolate milk beverage | US energy densities :0.3–3.0 kJ/cm3 | ||
| Conventional HTST pasteurization: 72 °C/15 s | High intensity US was more effective than conventional. | |||
| Energy density had a direct impact on mesophilic microorganisms, log reduction, fat globule distribution and rheological behaviour, antioxidant activity, Fatty acid profile and volatile compounds. | [207] | |||
| Depolymerization | ||||
| US assisted depolymerization | Guar gum | US (20 kHz frequency), 240 w with enzyme cellulase. | US and enzyme combination, better than stirring with enzyme alone. 98% extent of depolymerization was observed. | [210] |
| High power US depolymerization | Starch paste | Corn starch pastes, US: 20 kHzPower: 13.5/ 29.9 W) Time: 20 min | Viscosity & hydrodynamic radius reduced with increase in US treatment time. High amylose content pastes were resistant to US treatment. | [211] |