Cryostabilization Mechanism of Fish Muscle Proteins by Maltodextrins

Maltodextrins of varying mean molecular weights (MW) were evaluated for cryoprotective ability in Alaska pollock surimi (leached mince) versus sucrose or a sucrose–sorbitol mixture. Treatments were stored either isothermally at −8, −14, or −20°C for 3 months or freeze–thaw (F/T) cycled six times to induce freeze-related protein denaturation, measured as a decrease in myosin Ca+2ATPase activity and change in heat-induced gel-forming ability. Results indicated good cryoprotection by all maltodextrins at −20°C isothermal storage irrespective of MW, but poor cryoprotection by higher MW maltodextrins at higher isothermal storage temperatures or after F/T cycling. These observations, and surface tension measurements of maltodextrin solutions, indicated that lower MW maltodextrins likely cryoprotect by a preferential solute exclusion mechanism, similar to sucrose and sorbitol. Higher MW maltodextrins presumably cryoprotect at lower storage temperatures via a reduced water mobility mechanism. As the MW of maltodextrins increased the gelling ability of the surimi was increasingly impaired, such that evidence of cryoprotection from gelation data was obscured.