Mechanism of ultrasound assisted nucleation during freezing and its application in food freezing process

Figures & data

Figure 1. The frequency range of sound waves. ^[12^]

Figure 2. The schematic of cavitation induced by ultrasound: (a) Stable cavitation, (b) transient cavitation.^[32]

Figure 3. Photographs of ice crystals nucleated in a 15 w.t. % sucrose solution at −3.4oC by a commercial ultrasonic device (output 4, 10% duty cycle): (a) ice crystals following an ultrasonic pulse, (b) crystals 5 s later. ^[25^]

Figure 4. Ultrasonic secondary nucleation of ice crystals in pure water and the imagesare displayed at 1s intervals

Figure 5. The microscopic effect of ultrasound on the secondary nucleation of ice in a 15 wt. % sucrose solution. ^[44^]

Table 1. Comparison of ultrasound-assisted freezing devices

Type	Main components	Features	Frozen substrate	Freezing medium	Process parameters	References
Full-immersion type	Ultrasonic system, coolant-circulating system, refrigeration cycle system, and temperature-detecting system.	The propagation efficiency of ultrasound is high. However, the disadvantage is that the frozen product is completely immersed in the cooling liquid to freeze. Thus, the frozen products may be easily contaminated by the coolant.	Potato	Solution of glycerol and water (50/50, w/w)	35 kHz; Ultrasound processor: 300 W; Vibration amplitude: 0%-100%; Treatment time: 8 s; Pulses duration: 1 s; Immersion temperature: −6 °C	^[Citation59]
			Lotus root	Solution of calcium chloride and water (29/71, w/w)	30 kHz; UIF-1 (90 W, 30 s on/30 s off), UIF-2 (150 W, 30 s on/30 s off), UIF-3 (210 W, 30 s on/30 s off), UIF-4 (150 W, 15 s on/45 s off) and UIF-5 (150 W, 45 s on/15 s off); Immersion temperature: −25 ^oC.	^[Citation60]
			Common carp	95% ethanol	30 kHz; Ultrasonic power levels: 0, 125, 150, 175, 200, and 225 W; Duty cycle: 30 s on/30 s off.	^[Citation61]
			Strawberry	30% (w/v) CaCl2 solution	30 kHz; Ultrasound intensity: 0.09, 0.17, 0.28, 0.42, and 0.51 W/cm^2; Exposure time: 30 s;	^[Citation62]
			Red radish	30% (w/v) CaCl2 water solution	20 kHz; Power intensities: 0.09, 0.17, 0.26, or 0.37 W/cm^2; Duty cycle: 30 s on/30 s off.	^[Citation63]
			Agar gel samples	ethylene glycol-water mixture	Irradiation temperature: −2, −3, −4 and −5°C; Irradiation duration: 0, 1, 3 s, 5, 10 or 15 s; Ultrasound intensity: 0.07, 0.14, 0.25, 0.35 and 0.42 W/cm^2.	^[Citation49]
			Gelatin gel samples	30% (w/v) CaCl2 solution	20 kHz; Ultrasound intensities: 0.26, 0.38, 0.54 and 0.69 W/cm^2; Duty cycle: 10 s on/10 s off.	^[Citation64,Citation65]
			Water	A mixture of ethylene glycol and water (50%: 50% in volume)	25 kHz; Ultrasound intensity: 0.25 W/cm^2; Irradiation duration: 0, 1, 3, 5, 10 and 15 s; Immersion temperature: −20 ^oC;	^[Citation23]
			Chicken breast	Solution of 95% (v/v) ethanol and 5% fluoride	30 kHz; Ultrasonic power levels: 0, 125, 165, 205, and 245 W; Duty cycle: 30 s on/30 s off; Duration: 8 min.	^[Citation9]
Half-immersion type	Ultrasonic system, coolant-circulating system, refrigeration system, and temperature-controlling system.	The metal plate is tightly bound to ultrasonic transducers, while samples inside the container (basically liquid and semisolid samples) are placed on the plate with the medium to improve the propagation of ultrasound between the plate and the container. The nodal points exist on the plate surface caused by the resonance phenomenon of ultrasound. The finding of nodal points needs to be carried out in advance before starting the freezing process. These nodal points should be avoided for the location of vials during freezing.	Mannitol aqueous solution	Liquid nitrogen	35 kHz; Ultrasound intensity: 0.2 W/cm^2.	^[Citation27,Citation66]
Non-immersion type	Ultrasonic system, refrigeration system, and temperature-detecting system.	The samples are frozen directly without any coolant immersion. Thus, the frozen products are not contaminated by the coolant. However, the propagation efficiency of ultrasound in the air is relatively low, resulting in serious loss of ultrasonic energy during the freezing process.	Mushroom	– ^1	20 kHz; Ultrasound intensity: 0.11 W/cm^2; Duty cycle: 10 s on/20 s off.	^[Citation67]

¹None.

Figure 6. Schematic diagrams of ultrasound-assisted freezing devices. (A) Full-immersion type, (B) half-immersion type, and (C) non-immersion type.[80^]

Table 2. Applications of ultrasonic treatment in food freezing

Applications	Food substrate	Operating conditions	Significant results	References
Inducing ice nucleation	L-glutamic acid	20 kHz; Tip diameter: 6 mm; Continuous irradiation: 9.0–22.5 W, 100% duty cycle; Pulsed irradiation: 13.5 W, duty cycle of 16.7%, 50%, and 83.3%.	The induction time was shortened with application of ultrasound, and the induction time was further shortened with higher ultrasonic power.	^[Citation68]
	Agar gel sample	25 kHz; Irradiation duration: 0, 1, 3, 5, 10 and 15 s; Ultrasound intensity: 0.07, 0.14, 0.25, 0.35 and 0.42 W/cm^2; Irradiation temperature: −2, −3, −4 and −5oC	Ultrasonic irradiation can initiate nucleation in agar gel at different supercooling temperatures as long as the suitable ultrasonic intensity and time are selected.	^[Citation49]
	Radish cylinder	20 kHz; Duration: 0, 3, 7, 10 and 15 s; Ultrasound intensity: 0.09, 0.17, 0.26 and 0.37 W/cm^2; Onset temperature: −0.5, −1, −1.5 and −2 °C	Ultrasound irradiation temperature at −0.5°C for 7 s duration with intensity of 0.26 W/cm^2, was an optimal ultrasound application conditions for the nucleation inducement of radish cylinder samples.	^[Citation69]
	Supercooled water	28 kHz, 0–100 W	Ultrasound vibration forcefully facilitates the phase transition from supercooled water to ice.	^[Citation47]
	Supercooled water	39 kHz, 4.4 kW/m^2	The probability of phase transition was inseparable bound up with the number of nuclei induced by ultrasonic vibration.	^[Citation48]
Controlling ice crystals’ size and shape	Mannitol solution	35 kHz; Acoustic power: 0, 25, 70, 115, 140 a.u.; Supercooling degree: 2.9, 4, 6, 8, 9.1 K; Duration: 1 s	Increasing supercooling and acoustic power resulted in decreasing ice crystals’ mean size and increasing their mean circularity.	^[Citation70]
	Mannitol solution; BSA; Sucrose solution	35.89 kHz; Electric power: 40 W; Duration: 1 s	Higher nucleation temperatures caused by UAF contributed to initiation of comparatively larger and directional ice crystals.	^[Citation24]
	Agar gel sample	25 kHz; Irradiation duration: 90, 180 and 270 s; Ultrasound intensity: 0.07, 0.25 and 0.42 W/cm^2; Duty cycle: 30%, 50%, and 70%	The size distribution of ice crystals was affected by ultrasound induced nucleation temperature. However, no regular relationship between the evaluated parameters (intensity, duration and duty cycle) and the crystal sizes was detected.	^[Citation71]
Accelerating freezing rate	Frozen dough	5 kHz; Electric power levels: 0, 175, 224, 288, 360 and 418 W; Duty cycle: 30 s on/30 s off	At 288 or 360 W power levels, the total time for dough freezing shortened more than 11% significantly (P < .05), and the required time for each stage was reduced.	^[Citation72]
	Grass carp	40 kHz; Ultrasound intensity: 0, 0.30, 0.38, 0.48 and 0.60 W/cm^2; Duty cycle: 8 s on/2 s off	The application of power ultrasound at 0.38 W/cm^2 and above during immersion freezing can significantly shorten the length of precooling stage, phase transition and, total freezing time (P < .05), protect muscle fiber structure, resulting in decreased thawing loss.	^[Citation73]
	Broccoli	20 or 30 kHz; Ultrasound power: 0, 125, 150, 175 and 190 W; duty cycle: 60 s on/60 s off	The total freezing time and times required for pre-cooling, phase change and sub-cooling stages of broccoli were significantly reduced by the application of UAF (UAF) at 150 (30 kHz) or 175 W (20 kHz) power level.	^[Citation74]
	Potato	25 kHz; Actual ultrasound power: 0, 7.34, 15.85 and 28.89 W; Exposure time: 0, 1, 1.5, 2 and 2.5 min	The freezing rate was improved greatly when 15.85 W ultrasound power was applied for 2 min (P < .05).	^[Citation56]
Improving the Microstructure of frozen food	Porcine longissimus muscle	Ultrasound power: 180 W; the geometric center temperature: −18°C; storage time:0, 30, 60, 90, 120, 150, and 180 d	UIF at particular powers is an efficient method in reducing quality deterioration of muscles during long-term frozen storage.	^[Citation75]
	Potato	Ultrasound power: 270 W; Dual-frequency: 20 kHz, 28 kHz; Duty cycle: 50%; Total exposure time: 120 s	Orthogonal ultrasound-assisted freezing gives small ice crystals and effectively preserves tissue structure. Microstructure analysis proves effective upgrade in frozen product quality by orthogonal ultrasound-assisted freezing.	^[Citation26]
	Thunnustonggol	40 kHz; Ultrasound power: 0, 160, 280,400 W; Ultrasound intensity: 11.63 W/cm^2; Onset temperature: 15 ± 1°C	Tuna thawed at 280 W suffered fewer negative effects on its microstructure.	^[Citation76]
	Mushrooms	20 kHz; Acoustic intensity: 0, 0.13, 0.27 and 0.39 W/cm^2; Duty cycle: 10 s on/10 s off	Ultrasound at 0.39 W cm/^2 (20 kHz) resulted in the highest textural hardness values in all the three mushroom varieties.	^[Citation77]
	Potato	25 kHz; Actual ultrasound power: 0, 7.34, 15.85 and 28.89 W; Exposure time: 2 min	Under the ultrasonic power of 15.85 W, the tissue structure of potato was significantly improved.	^[Citation78]
	Broccoli	20 or 30 kHz; Ultrasound power: 0, 125, 150, 175 and 190 W; Duty cycle: 60 s on/60 s off	The application of UAF at selected acoustic intensity with a range of 0.250–0.412 W/cm^2 decreased the freezing time and the loss of cell-wall bound calcium content. Compared to normal freezing, the values of textural properties, color, l-ascorbic acid content were better preserved and the drip loss was significantly minimized by the application of UAF.	^[Citation79]

Figure 7. Ice crystal size distribution in ultrasound-assisted freezing of agar gels nucleated at different temperatures (a) size distribution, −2 °C:■; −3 °C:▲; −4 °C:●; (b) corresponding microstructure images (b-d). ^[72]

Figure 8. Cavitation and acoustic streaming phenomena in the ultrasonic bath revolved at 25 kHz and 2800 W/m². ^[97^]

Figure 9. SEM images of potato microstructures under different freezing conditions. (a). IF: immersion freezing; (b). SUF: single-ultrasound assisted freezing; (c). DUF: dual-ultrasound assisted freezing; (d). TUF: triple-ultrasound assisted freezing. ^[102^]

Cheng, X.; Zhang, M.; Xu, B.; Adhikari, B.; Sun, J. The Principles of Ultrasound and Its Application in Freezing Related Processes of Food Materials: A Review. Ultrasonics Sonochemistry. 2015, 27, 576–585. DOI: https://doi.org/10.1016/j.ultsonch.2015.04.015.

 PubMed Web of Science ®Google Scholar

Zheng, L. ; Sun,D. 23-Ultrasonic Assistance of Food Freezing. Emerging Technologies for Food Processing, 2005: 603–626. DOI: https://doi.org/10.1016/B978-012676757-5/50025-6.

 Google Scholar

Chow, R.; Blindt, R.; Chivers, R.; Povey, M.A. AStudy on the Primary and Secondary Nucleation of Ice by Power Ultrasound. Ultrasonics. 2005, 43(4), 227–230. DOI: https://doi.org/10.1016/j.ultras.2004.06.006.

 PubMed Web of Science ®Google Scholar

Chow, R.; Blindt, R.; Chivers, R.; Povey, M. The Sonocrystallisation of Ice in Sucrose Solutions: Primary and Secondary Nucleation. Ultrasonics. 2003, 41(8), 595–604. DOI: https://doi.org/10.1016/j.ultras.2003.08.001.

 PubMed Web of Science ®Google Scholar

Comandini, P.; Blanda, G.; Soto-Caballero, M.C.; Sala, V.; Tylewicz, U.; Mujica-Paz, H.; Fragoso, A.V.; Toschi, T.G. Effects of Power Ultrasound on Immersion Freezing Parameters of Potatoes. Innovative Food Sci. Emerging Technol. 2013, 18(18), 120–125. DOI: https://doi.org/10.1016/j.ifset.2013.01.009.

 Web of Science ®Google Scholar

Tu, J.; Zhang, M.; Xu, B.; Liu, H. Effects of Different Freezing Methods on the Quality and Microstructure of Lotus (Nelumbo Nucifera) Root. Int. J.Refrig. 2015, 52, 59–65. DOI: https://doi.org/10.1016/j.ijrefrig.2014.12.015.

 Web of Science ®Google Scholar

Sun, Q.; Zhao, X.; Zhang, C.; Xia, X.; Sun, F.; Kong, B. Ultrasound-assisted Immersion Freezing Accelerates the Freezing Process and Improves the Quality of Common Carp (Cyprinus Carpio) at Different Power Levels. LWT-Food Sci. Technol. 2019, 108, 106–112. DOI: https://doi.org/10.1016/j.lwt.2019.03.042.

 Web of Science ®Google Scholar

Cheng, X.; Zhang, M.; Adhikari, B.; Islam, M.N.; Xu, B. Effect of Ultrasound Irradiation on Some Freezing Parameters of Ultrasound-assisted Immersion Freezing of Strawberries. Int. J.Refrig. 2014, 44, 49–55. DOI: https://doi.org/10.1016/j.ijrefrig.2014.04.017.

 Web of Science ®Google Scholar

Xu, B.; Zhang, M.; Bhandari, B.; Cheng, X.; Islam, M.N. Effect of Ultrasound-assisted Freezing on the Physico-Chemical Properties and Volatile Compounds of Red Radish. Ultrason. Sonochem. 2015, 27(1), 316–324. DOI: https://doi.org/10.1016/j.ultsonch.2015.04.014.

 PubMed Web of Science ®Google Scholar

Kiani, H.; Sun, D.; Delgado, A.; Zhang, Z. Investigation of the Effect of Power Ultrasound on the Nucleation of Water during Freezing of Agar Gel Samples in Tubing Vials. Ultrason. Sonochem. 2012, 19(3), 576–581. DOI: https://doi.org/10.1016/j.ultsonch.2011.10.009.

 PubMed Web of Science ®Google Scholar

Xu, B.; Zhang, M.; Bhandari, B.; Sun, J.; Gao, Z. Infusion of CO2 in ASolid Food: ANovel Method to Enhance the Low-frequency Ultrasound Effect on Immersion Freezing Process. Innovative Food Sci. Emerging Technol. 2016, 35, 194–203. DOI: https://doi.org/10.1016/j.ifset.2016.04.011.

 Web of Science ®Google Scholar

Xu, B.; Azam, R.S.M.; Wang, B.; Zhang, M.; Bhandari, B. Effect of Infused CO2 in aModel Solid Food on the Ice Nucleation during Ultrasound-assisted Immersion Freezing. Int. J.Refrig. 2019, 108, 53–59. DOI: https://doi.org/10.1016/j.ijrefrig.2019.09.005.

 Web of Science ®Google Scholar

Kiani, H.; Zhang, Z.; Delgado, A.; Sun, D. Ultrasound Assisted Nucleation of Some Liquid and Solid Model Foods during Freezing. Food Research International. 2011, 44(9), 2915–2921. DOI: https://doi.org/10.1016/j.foodres.2011.06.051.

 Web of Science ®Google Scholar

Zhang, C.; Li, X.; Wang, H.; Xia, X.; Kong, B. Ultrasound-assisted Immersion Freezing Reduces the Structure and Gel Property Deterioration of Myofibrillar Protein from Chicken Breast. Ultrasonics Sonochemistry. 2020, 67, 105137. DOI: https://doi.org/10.1016/j.ultsonch.2020.105137.

 PubMed Web of Science ®Google Scholar

Fu, X.; Belwal, T.; Cravotto, G.; Luo, Z. Sono-physical and Sono-chemical Effects of Ultrasound: Primary Applications in Extraction and Freezing Operations and Influence on Food Components. Ultrasonics Sonochemistry. 2020, 60, 104726. DOI: https://doi.org/10.1016/j.ultsonch.2019.104726.

 PubMed Web of Science ®Google Scholar

Jabbari-Hichri, A.; Peczalski, R.; Laurent, P. Ultrasonically Triggered Freezing of Aqueous Solutions: Influence of Initial Oxygen Content on Ice Crystals׳ Size Distribution. J.Cryst. Growth. 2014, 402, 78–82. DOI: https://doi.org/10.1016/j.jcrysgro.2014.05.010.

 Web of Science ®Google Scholar

Islam, M.N.; Zhang, M.; Fang, Z.; Sun, J. Direct Contact Ultrasound Assisted Freezing of Mushroom (Agaricus Bisporus): Growth and Size Distribution of Ice Crystals. Int. J.Refrig. 2015, 57, 46–53. DOI: https://doi.org/10.1016/j.ijrefrig.2015.04.021.

 Web of Science ®Google Scholar

Islam, M.N.; Zhang, M.; Adhikari, B.; Xinfeng, C.; Xu, B. The Effect of Ultrasound-assisted Immersion Freezing on Selected Physicochemical Properties of Mushrooms. Int. J.Refrig. 2014, 42, 121–133. DOI: https://doi.org/10.1016/j.ijrefrig.2014.02.012.

 Web of Science ®Google Scholar

Zhu, Z.; Zhang, P.; Sun, D. Effects of Multi-frequency Ultrasound on Freezing Rates and Quality Attributes of Potatoes. Ultrason. Sonochem. 2020, 60, 104733. DOI: https://doi.org/10.1016/j.ultsonch.2019.104733.

 PubMed Web of Science ®Google Scholar

Kiani, H.; Sun, D.; Zhang, Z. The Effect of Ultrasound Irradiation on the Convective Heat Transfer Rate during Immersion Cooling of aStationary Sphere. Ultrason. Sonochem. 2012, 19(6), 1238–1245. DOI: https://doi.org/10.1016/j.ultsonch.2012.04.009.

 PubMed Web of Science ®Google Scholar

Inada, T.; Zhang, X.; Yabe, A.; Kozawa, Y. Active Control of Phase Change from Supercooled Water to Ice by Ultrasonic Vibration 1. Control of Freezing Temperature. International Journal of Heat and Mass Transfer. 2001, 44(23), 4523–4531. DOI: https://doi.org/10.1016/S0017-9310(01)00057-6.

 Web of Science ®Google Scholar

Zhang, X.; Inada, T.; Yabe, A.; Lu, S.; Kozawa, Y. Active Control of Phase Change from Supercooled Water to Ice by Ultrasonic Vibration 2. Generation of Ice Slurries and Effect of Bubble Nuclei. Int. J.Heat Mass Transfer. 2001, 44(23), 4533–4539. DOI: https://doi.org/10.1016/S0017-9310(01)00058-8.

 Web of Science ®Google Scholar

Kiani, H.; Zhang, Z.; Sun, D. Effect of Ultrasound Irradiation on Ice Crystal Size Distribution in Frozen Agar Gel Samples. Innovative Food Sci. Emerging Technol. 2013, 18, 126–131. DOI: https://doi.org/10.1016/j.ifset.2013.02.007.

 Web of Science ®Google Scholar

Nakagawa, K.; Hottot, A.; Vessot, S.; Andrieu, J. Influence of Controlled Nucleation by Ultrasounds on Ice Morphology of Frozen Formulations for Pharmaceutical Proteins Freeze-drying. Chemical Engineering and Processing: Process Intensification. 2006, 45(9), 783–791. DOI: https://doi.org/10.1016/j.cep.2006.03.007.

 Web of Science ®Google Scholar

Xu,B. ; Zhang,M. ; Ma,H. Food Freezing Assisted with Ultrasound. Ultrasound: Advances for Food Processing and Preservation, 2017, 293–321. DOI:https://doi.org/10.1016/B978-0-12-804581-7.00012-9.

 Google Scholar

Fang, C.; Tang, W.; Wu, S.; Wang, J.; Gao, Z.; Gong, J. Ultrasound-assisted Intensified Crystallization of L-glutamic Acid: Crystal Nucleation and Polymorph Transformation. Ultrason. Sonochem. 2020, 68, 105227. DOI: https://doi.org/10.1016/j.ultsonch.2020.105227.

 PubMed Web of Science ®Google Scholar

Xu, B.; Zhang, M.; Bhandari, B.; Cheng, X. Influence of Power Ultrasound on Ice Nucleation of Radish Cylinders during Ultrasound-assisted Immersion Freezing. Int. J.Refrig. 2014, 46, 1–8. DOI: https://doi.org/10.1016/j.ijrefrig.2014.07.009.

 Web of Science ®Google Scholar

Saclier, M.; Peczalski, R.; Andrieu, J. Effect of Ultrasonically Induced Nucleation on Ice Crystals’ Size and Shape during Freezing in Vials. Chem. Eng. Sci. 2010, 65(10), 3064–3071. DOI: https://doi.org/10.1016/j.ces.2010.01.035.

 Web of Science ®Google Scholar

Li, B.; Sun, D. Effect of Power Ultrasound on Freezing Rate during Immersion Freezing of Potatoes. J.Food Eng. 2002, 55(3), 277–282. DOI: https://doi.org/10.1016/S0260-8774(02)00102-4.

 Web of Science ®Google Scholar

Hu, S.; Liu, G.; Li, L.; Li, Z.; Hou, Y. An Improvement in the Immersion Freezing Process for Frozen Dough via Ultrasound Irradiation. J.Food Eng. 2013, 114(1), 22–28. DOI: https://doi.org/10.1016/j.jfoodeng.2012.07.033.

 Web of Science ®Google Scholar

Tian, Y.; Zhang, P.; Zhu, Z.; Sun, D. Development of a Single/Dual-frequency Orthogonal Ultrasound-assisted Rapid Freezing Technique and Its Effects on Quality Attributes of Frozen Potatoes. Journal of Food Engineering. 2020, 286, 110112. DOI: https://doi.org/10.1016/j.jfoodeng.2020.110112.

 Web of Science ®Google Scholar

Shi, Z.; Zhong, S.; Yan, W.; Liu, M.; Yang, Z.; Qiao, X. The Effects of Ultrasonic Treatment on the Freezing Rate, Physicochemical Quality, and Microstructure of the Back Muscle of Grass Carp (Ctenopharyngodon Idella). LWT-Food Sci. Technol. 2019, 111, 301–308. DOI: https://doi.org/10.1016/j.lwt.2019.04.071.

 Web of Science ®Google Scholar

Xin, Y.; Zhang, M.; Adhikari, B. The Effects of Ultrasound-assisted Freezing on the Freezing Time and Quality of Broccoli (Brassica Oleracea L.Var. Botrytis L.) During Immersion Freezing. Int. J.Refrig. 2014, 41, 82–91.

 Web of Science ®Google Scholar

Zhang, M.; Xia, X.; Liu, Q.; Chen, Q.; Kong, B. Changes in Microstructure, Quality and Water Distribution of Porcine Longissimus Muscles Subjected to Ultrasound-assisted Immersion Freezing during Frozen Storage. Meat Science. 2019, 151, 24–32. DOI: https://doi.org/10.1016/j.meatsci.2019.01.002.

 PubMed Web of Science ®Google Scholar

Li, X.; Sun, P.; Ma, Y.; Cai, L.; Li, J. Effect Of Ultrasonic Thawing On The Water-holding Capacity, Physicochemical Properties And Structure Of Frozen Tuna (Thunnus tonggol) myofibrillar proteins. J.Sci. Food Agric. 2019, 99(11), 5083–5091. DOI: https://doi.org/10.1002/jsfa.9752.

 PubMed Web of Science ®Google Scholar

Rhim, J.; Koh, S.; Kim, J. Effect of Freezing Temperature on Rehydration and Water Vapor Adsorption Characteristics of Freeze-dried Rice Porridge. J.Food Eng. 2011, 104(4), 484–491. DOI: https://doi.org/10.1016/j.jfoodeng.2010.08.010.

 Web of Science ®Google Scholar

Xu, D.; Wang, H.; Wang, Y.; Zhang, Z. Ice Crystal Growth of Living Onion Epidermal Cells as Affected by Freezing Rates. Int. J.Food Prop. 2018, 21(1), 606–617. DOI: https://doi.org/10.1080/10942912.2018.1439506.

 Web of Science ®Google Scholar