Table 2.

Summary of processing protocols applied for encapsulating food materials with ultrasound.

Food Material Encapsulated	Wall Material	O:EM	F (kHz)	P (W)	St (min)	DS (µm)	Effect of Ultrasound	Reference
Encapsulation of Oils and Extracts
Anatto seed oil	Whey protein isolate Modified snowflake starch	1:4	19	480	5	0.7–1.5 µm	Formation of fine kinetically stable annatto seed oil emulsions. Intensification of the ultrasonication process had no positive effects in the reduction in the droplet size of the dispersed phase.	[177]
Bixin	Cassava starch Corn starch	-	50	150 W	20	-	Ultrasound successfully encapsulated bixin with good encapsulation efficiency. Sonication causes degradation and chemical modification of starch leading to the reducing of particle size, molar mass, and formation of shorter chain.	[178]
Tuna oil	Chitosin Maltodextrin Whey protein isolate	1:2	40	130 and 120	30	0.8–14.1 µm	Sonication improved the stability of tuna oil.	[161]
Soybean oil Mustard oil Pomegranate peel extract	Maltodextrin Whey protein isolate (1:1)	1:30	20	400	5	0–1 µm	Increased sonication time enhances the emulsion kinetic stability, decreasing the droplet size which then improves the emulsifier layering on smaller droplets of W/O emulsion.	[112]
Anthagonin rich extract/grape seed skin/oil	Alginate Pectin beads	20:80	40	200	7	15.3–17.1 µm	Significant decrease in droplet size of beads, alginate beads showed regular, round, and spherical shapes.	[179]
Ginger essential oil/powders	Gum Arabic (GA), Maltodextrin (MD), Inulin (IN)	1:4	20	160	2	GA:MD-6.3 µm GA:IN-5.42 µm GA-6.18 µm	More stable emulsion with smaller droplets. Higher shear stress during sonication leads to a higher level of particles disruption.	[180]
Annatto seed oil	Gum arabic	-	19	800	2	<1 µm	Ultrasonication power reduced the superficial mean diameter and polydispersity and creaming ability of freeze-dried annatto seed oil emulsions.	[65]
Pandan extract	Lysozyme chitosin	1:40 and 1:160	20	150	0.5	1.5 to 2.7 µm	Mean size of the microspheres was generally smallest when using 1 cm probe tip with lower core-to-shell volume ratio but largest when using the 3 mm tip with higher core-to-shell volume, pandan-encapsulated microspheres showed great stability.	[158]
Flaxseed oil	Whey protein concentrate Maltodextrin	1:10	24	150	15	464 nm	Flaxseed oil nanoemulsions helped to enrich muscles with ω-3 fatty acids in broilers by improving blood lipid profile and up-regulation of the hepatic expression of the desaturases and elongates genes. Improved the lipid oxidative stability.	[181]
Starch nano particle (SNP)+peppermint oil loaded SNP	Waxy maize starch	-	20–25	990	5–10	150–200 nm	SNPs showed good uniformity and an almost perfect spherical shape, with diameters of 150–200 nm. The PO-loaded SNPs also exhibited regular shapes.	[182]
Jack fruit extract	Maltodextrin Sucrose ester	-	47	-	5	0.07–7 µm	Submicronic emulsions loaded with jackfruit showed stability for 30 days at 25 °C. Maltodextrin emulsions processed by ultrasound presented a bimodal size distribution with a peak maximum at 138 nm.	[167]
Curcumin in olive oil	Whey protein isolate Primary emulsion Secondary emulsion	1:1	20	750	10	359 nm; 308–386 nm	An increase in the encapsulation efficiency due to enhanced stability of emulsion at higher sonication time. Uniform dispersion of the protein molecules to facilitate their adsorption at the oil-water interface which subsequently increases the retention period of curcumin present in the emulsified droplets.	[183]
Orange peel extract	Alginate chitosin	-	40	150	15	252 µm	Ultrasonication helped in improving the total antioxidant content of orange peel.	[118]
Orange peel using olive oil	Calcium alginate beads	-	40	150	15	0.78 nm	Reduced energy and solvent consumption and ensured high-quality oil. Alginate-oil emulsion was stable and resulted in an EE of 89.5% and oil-loaded beads were spherical with an average size of 0.78 mm. Olive oil successfully applied for ultrasonication of carotenoids from orange peel.	[184]
Butcher Broom Extract	Maltodextrin Gum Arabic	4:1	-	100	15	95.17 µm	Sonication of the extract showed higher DPPH, FRAP, phenolic, anthocyanin, and flavonoid activity.	[185]
Vitamin D	Fish oil	-	20	400	10	300–450 nm	Vit D nanoemulsion stable for a longer period of time as no particle aggregation was observed in stable samples even when left undisturbed for more than 45 days. Improved the EE from 95.7 to 98.2%.	[186]
Essential oil (cumin, basil, clove, calmus, turbose) isoeugenol	Methyl β cyclodextrin	4:1	-	60	30	-	Extending the aqueous solubility and biological properties of the emulsion formed by various essential oils.	[187]
Soybean oil and vit D	Rabbit Bovine liver Oyster Sweet corn	-	20	160	0.75	0.3–8 µm	Sonication of native glycogens formed microcapsules with diameter between 0.3 µm and 8 µm. Sonication helped in improving the protein and glycogen content of soybean oil and vit D emulsion.	[175]
Sacha Inchi oil	Alginate chitosin	-	50	100	-	-	Sonication of Sacha inchi oil showed 30–40% more encapsulation with stable emulsion.	[168]
Encapsulation of flavor and pigments
Cinnamaldehyde and vegetable oil	Chitosin Pectin	7:3				-	Ultrasonicated chitosin and pectin microcapsules exhibited significantly higher cinnamaldehyde retention at high temperatures (>150 °C) and higher flavor retention. Ultrasonication induced amide cross-linking yields more stable polymer bonding.	[169]
Aspergillus oryzae	Polyamindo amine dendrine generation 0	-		1.5	1	4 µm	Sonication enhanced ACE inhibitor peptides.	[188]
Peppermint flavor	Gum arabic	-	22	200	-	45.2–255.7 nm	Fine emulsion which enhances the encapsulation and the efficiency of flavor. Ultrasound during encapsulation of peppermint in Gum Arabic, enhances the encapsulation efficiency to 87%.	[189]
Lycopene	Inulin maltodextrin	1:10	20	-	-	-	Sonication of emulsion of lycopene showed higer EE for maltodextrin (78.3%) than inulin. Maltodextrin has high content of encapsulating through lycopene microparticles.	[174]
Encapsulation of Nutrients
Astaxanthin	Alginate Chitosin beads	3:1	40	130 and 220	60 min	4.23 µm	Ultrasonication lead to the appearance of alginate beads with uniform rounded outer surface.	[170]
Oil soluble vitamin (A, D, E)	Raw egg white protein	4:1	20	400	1	5.2 µm	Sonication of egg white proteins stabilized the vitamin D droplets by adsorbing at the oil–water interface. Soluble proteins and small aggregates adsorbed at the oil (vitamin D droplets)-water interface and formed a composite shell likely stabilized by hydrophobic interactions and intermolecular disulphide linkages.	[172]
Vit A	Egg white protein Soy protein isolate CPI	19:1	20	160	1	10–50 µm	Smaller emulsion droplets, better emulsifying properties of proteins that stabilize the oil droplets. SDS-PAGE-sonicated EWP showed a much higher intense band, increase in particle size noted due to denaturation of protein by ultrasonication.	[172]
Soy protein hydrosylate	Nanoliposomes	-	20	100	0.33	193–286 nm	Small unilamellar vesicles by reducing the size of peptide-loaded liposomes 9.5 times in average and increased EE from 2 to 13% to 4–20%, improved the stability of nanoliposomes. Sonication showed a positive correlation with the EE of soy protein, indicating that no thermal degradation of phospholipids occurred.	[190]
Prebiotic Lactic acid bacteria, bioactive γ-aminobutyric acid	Dextran Whey protein	20:80	20	80	0.5–2.0	LAB-3 to 5 µm GABA-1.5 to 3 µm	Ultrasound parameters of LAB and GABA were refined to optimize the size of the W/O droplets and outer microcapsules (5–15 μm). Ultrasound treatment for up to 200 s had no significant effect on bacteria viability (>109 CFU/mL).	[171]
Lactiplantibacillus plantarum BCRC 10357	Calcium alginate	-	40	300	15	-	β-glucosidase activity of encapsulated L. plantarum was 11.47 U/mL at 12 h, then increased to 27.43 U/mL at 36 h and to 26.25 U/mL at 48 h in black soymilk at 37 °C, showing the high adaptation of encapsulated L. plantarum encountering ultrasonic stress to release high β -glucosidase.	[191]
Omega-3 fatty acid	DPA 10% EPA 42%	-	25	-	30–60	-	Ultrasound application helped in increasing the amount of healthy fatty acid in pork meat.	[192]

(F—frequency, P—power, EE—encapsulation efficiency, O:EM—oil: encapsulating material, DPPH—2,2-diphenyl-1-picryl-hydrazyl-hydrate, FRAP—ferric reducing antioxidant power, ACH inhibitors- acetylcholinesterase inhibitors, LAB-Lactic acid bacteria, GABA-γ-aminobutyric acid, LAB-Lactic acid bacteria, SDS PAGE—Sodium dodecyl-sulfate polyacrylamide gel electrophoresis, EWP—egg white proteins, DPA—Docosahexanoic acid, EPA—Eico sapentanoic acid).