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Freezing high-pressure-jet—treated ice cream mix: A study of the kinetics and microstructure.

G. L. Voronin




Freezing high-pressure-jet—treated ice cream mix: A study of the kinetics and microstructure.
G. L. Voronin*, G. Ning, J. N. Coupland, R. Roberts, F. M. Harte. The Pennsylvania State University University Park, PA.

High-pressure-jet (HPJ) processing, a recent development in high pressure technology, has been shown to enhance foaming, emulsifying, and rheological properties in a variety of dairy systems including skim and whole milk. Recently, we showed a 400 MPa HPJ treatment of low fat ice cream mix resulted in an ice cream mix with an increased consistency coefficient and reduced apparent ice crystal growth compared with a non-HPJ-treated control due to the formation of fat-protein complexes at 400 MPa, which were visualized using confocal scanning laser microscopy (CSLM). These results suggest potential for eliminating the need for hydrocolloids and emulsifiers in an ice cream formulation, however these benefits have not been demonstrated in a dynamically frozen ice cream. The objectives of the current work were to characterize the physical properties (overrun, apparent viscosity, particle size) of HPJ-treated (100—500 MPa) low fat ice cream (6% fat) throughout dynamic freezing and to determine the melting rate, hardness, and microstructure of the final ice cream after hardening. At each pressure, triplicate low-fat ice cream batches were produced. All results were analyzed using one-way ANOVA to identify significance at a 0.05 level (P < 0.05) with Tukey's test applied for mean comparisons. A combination of CSLM and transmission electron microscopy revealed unique microstructural components in ice creams treated at HPJ pressures ≥400 MPa including coalesced milkfat coated with disrupted casein micelles. The ice creams treated at these pressures (≥400 MPa) also had an increased apparent viscosity (when melted, 26.2 mPa.s at 500 MPa), hardness (3,824 g at 500 MPa), and melting rate (2.6 g.min−1at 500 MPa) compared with a non-HPJ-treated control (viscosity = 12.9 mPa.s, hardness = 2,506 g, and melting rate = 2.2 g.min−1). These differences were attributed to the unique microstructure developed during HPJ treatment. By altering the microstructure, apparent viscosity, and hardness of a low fat ice cream, HPJ technology shows some promise for alleviating some common ice cream defects including ice cream shrinkage and iciness.

Keywords: high-pressure jet, ice cream, transmission electron microscopy.

Biography: I am a second-year Ph.D. student in the department of Food Science at Penn State. I am working under Dr. Federico Harte and Dr. John Coupland with a focus in dairy chemistry and engineering. I earned my B.S. in Food Science from Penn State in 2018. My primary research involves characterizing the functional enhancements and microstructural changes caused by the high pressure jet treatment of various dairy products.