Ice recrystallization inhibition and acceleration by cellulose nanocrystals in the presence of anionic and neutral polymers

Abstract

Understanding mixed stabilizers' ice recrystallization inhibition (IRI) effect is important for ice cream formulation. The IRI effect of cellulose nanocrystals (CNCs) was investigated in the presence of sodium alginate (SA), carboxymethyl cellulose (CMC), polyethylene glycol (PEG), and inulin. Adding low concentrations of SA (≤0.13%) and CMC (≤0.05%) enhanced the IRI effect of CNCs. The enhancement became less at higher concentrations of SA and CMC. Recrystallization was even accelerated with a further increase in concentration of SA (≥0.5%) or CMC (≥0.2%). PEG and inulin had little influence on the IRI effect of CNCs. Rheological analysis of polymer overlap concentration, particle size analysis of CNCs dispersion, and microscopical observation of ice crystals accretion suggested that the dual effects of excluded volume might explain the IRI effect of CNCs in the presence of polymers: (1) adding polymers resulted in the macromolecular crowding, reducing the available volume for CNCs and increasing their effective concentration to interact with ice crystals, and led to an enhanced IRI effect; (2) depletion interaction promoted the aggregation of CNCs and merging of ice crystals, resulting in less enhancement and recrystallization acceleration. Our findings advance our understanding of the IRI effect for mixed stabilizers and are critical to ice cream formulation.