Structure and ice recrystallization in frozen stabilized ice cream model systems

Hydrocolloid stabilizers (carrageenan, carboxymethyl cellulose, xanthan gum, sodium alginate, locust bean gum (LBG) and gelatin) were labeled with rhodamine isothiocyanate and incorporated into solutions of sucrose with or without milk solids-not-fat (MSNF). Resultant solutions were quench frozen to - 50 degreesC and cycled between - 3.5 and - 6 degreesC, five times. The location of the stabilizer was observed using fluorescence microscopy. Significant retardation of recrystallization was observed in alginate and xanthan sucrose solutions without MSNF. In the presence of proteins, all stabilizers were effective retarding recrystallization except for gelatin. After cycling, a gel-like structure was observed in solutions containing LBG without MSNF, and in LBG, carrageenan and gelatin with MSNF. The fact that some non-gelling stabilizers (i.e. xanthan) were more effective retarding recrystallization than gelling stabilizers (i.e. gelatin) suggests that steric blocking of the interface or inhibition of solute transport to and from the ice interface caused by gelation of the polymer is not the only mechanism of stabilizer action. Molecular interactions between polysaccharides and proteins appear to be key factors in retarding ice recrystallization. (C) 2002 Elsevier Science Ltd. All rights reserved.