Table 2.

Advanced freezing techniques widely applied for different foods

Advanced freezing techniques	Technology involved	Application in foods		References
		Sample	Conclusions
High-pressure freezing	Involves freezing water at high pressure below 0 °C so that it forms small ice crystals instantly once the pressure is released Process takes place with the absence of heat Crystallization occurs instantly once high pressure is released Preservation of original properties and quality improvements noticed	Comparison of sugar-rich dairy-based food foams (ice creams) and a non-aerated liquid system Maximum pressure applied: 360 MPa at −25 °C	Volume fraction of the air after treatment—78% Crystal size reduction—40 μm to 34 μm Overall improvements in sensorial properties	Volkert et al. (2012); You et al. (2020)
		Kombu seaweed (Laminaria ochroleuca) Process conditions: 5 °C, 400–600 MPa, 5 min followed by refrigeration at 5 °C or freezing at -24 °C	Comparison of salted and unsalted seaweed Detection of 103 volatile compounds found. Major compounds detected were aldehydes, alcohols, ketones, alkanes, alkenes, and acids Freezing lowered levels of hydrocarbons, alkanes and thiazoles Salting increased levels of acids, alcohols, pyranones, lactones and thiazoles	López-Pérez et al. (2020)
Ultrasound-assisted freezing	Involves passing of sound waves in between the food. Can be of low frequency (< 100 kHz) or high frequency (20–100 kHz) No destruction of food Intensity, frequency of ultrasound, position of samples, cooling medium temperature key parameters for the process Can be used to treat both solid and liquid samples	Cantaloupe melon juice (Microcystis aeruginosa)	Testing for probiotic substrate Lactobacillus casei Study done for a period of 42 days at 4 °C Reduced caloric value observed	Zendeboodi et al. (2020)
		Grape juice Amplitude of 50% and 70% with treatment times of 0, 2.5 and 5 min Temperature maintenance: 50–80 °C	Comparison of ultrasound and pasteurization treatment was done Total phenolic content (TPC) was same for both the treatments at 10 min with amplitude of 70% pH decreased and total soluble solids increased with amplitude and treatment time Results indicated usefulness of juice sonication to enhance inactivation of pathogens	Margean et al. (2020)
		Pomegranate juice	Results showed ultraviolet 5.1 W/cm2 dosage, 3.5 L/min flow rate and 50 °C microbes were below the detection limits Lower temperatures could reduce the microbial activity preserving the bioactive compounds	Khan et al. (2020); Alabdali et al (2020)
Radioactive freezing	Not predominantly used in freezing Radio waves generate a turning force in the water molecule, and an ice cluster is created due to dielectric and dipolar properties of water	Onion, potato, ginger, carrot Dosage: 0.05–0.15 kGy	Inhibition of sprouting Shelf life enhancement	Prakash (2016)
		Cereals, fruits Dosage: 0.15–0.5 kGy	Phytosanitation Sterilization purposes Mycotoxin decontamination observed most effect with advantages in nutrient qualities	Ravindran and Jaiswal (2019); Mousavi Khaneghah et al. (2020)
Dehydration freezing or osmodehydrofreezing	Involves osmotic dehydration and freezing techniques Food is first dehydrated (water removal) and immediately frozen Shelf life extension observed due to accelerated freezing process Low energy consumption, low cost of packaging	Mango (Unripe vs Ripe “Kent” mangoes) Treatment: 50 °C in 60 brix sugar solution with 2 g calcium lactate/100 g with pectin methyl esterase	Unripe mangoes showed two- to fivefold soluble solid gain as compared to ripe Unripe samples had lowest water loss with reduction in lightness. Ripe samples were stable Pectin methyl esterase improved rigidity in mangoes	Sulistyawati et al. (2018)
		Pineapple with sucrose syrup Treatment: 2 h at 40 °C	Changes in pH, total acidity, soluble solids, and water observed Dry matter content increase during multiple stage osmodehydrofreezingStudy conducted showed multistage osmodehydrofreezing gave better performance than single stage osmodehydrofreezing	Fernández et al. (2020)