Ice recrystallization is the change in size, number, and morphology of ice crystals during storage and thawing, which causes cell death in cryopreservation and quality deficiency of frozen foods. Recent studies link a facial amphiphilic structure to the IR inhibition (IRI) activity in antifreeze (glyco) proteins (AF(G)Ps) and mimics. It is well known that nanocelluloses are amphiphilic based on their emulsion stabilization ability. We hypothesized that nanocelluloses are IRI active and can be used to improve the cell viability in cryopreservation or quality of frozen foods.

The first part of this research explored the IRI activity in nanocelluloses. At mg/mL level, cellulose nanocrystals (CNCs) and 2, 2, 6, 6-tetramethylpiperidine-1oxyl oxidized cellulose nanofibrils (TEMPO-CNFs) inhibited ice recrystallization in 0.01 M NaCl without thermal hysteresis or dynamic ice shaping activity. The IRI activity of nanocelluloses was not affected by the quenching temperature but decreased with the increase of annealing temperature.

The second part investigated the relationship between surface charge density (SCD) and the IRI activity in nanocelluloses. Nanocelluloses with similar fibril lengths but varied SCDs were synthesized, characterized, and compared for IRI activity. Reducing SCD promotes the IRI activity until fibril aggregation occurred.

The third part studied the effect of fibril length on the IRI activity of nanocelluloses. TEMPO-CNFs with similar SCDs and fibril widths but with different fibril lengths were prepared, characterized, and compared for IRI activity. Longer nanocelluloses are more IRI active. The IRI activity was not correlated with the viscosity or gelling properties of nanocellulose dispersions.

Inhibiting Ice Recrystallization by Nanocelluloses

Dr. Tao Wu

Associate Professor, University of Tennessee Knoxville

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