Glass transition influence on ice recrystallization in Atlantic salmon (Salmo Salar) during frozen storage
Syamaladevi, Roopesh M.
Sablani, Shyam S.
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Low temperature transitions may occur in frozen foods due to the temperature fluctuations resulting in less viscous and partially melted food matrices; In the current study, the influence of glass transitions and temperature fluctuations on ice recrystallization during the frozen storage of salmon fillet was systematically investigated; The characteristic glass transition temperature (Tg') and onset temperature of ice crystal melting (Tm') in salmon determined using a modulated differential scanning calorimeter (MDSC) were -27 and -17oC, respectively; The temperature (T = -35oC) of frozen salmon fillets was modulated within glassy state (T<Tg') and to achieve a partial-freeze-concentrated state (Tg'<T<Tm') and a rubbery state (T>Tm'), by exposing the trays to room temperature (23oC) for predetermined periods (2 to 26 min) twice a day during the four weeks of storage; The characterization of ice crystals was conducted by observing the cavities formed after sublimation of ice crystals using (a) Environmental scanning electron microscopy (ESEM) (b). X-ray computed tomography (XCT); Ice crystal growth was observed in frozen salmon in the glassy state; however the ice crystal size was greatest in the rubbery state (when the temperature fluctuation resulted in temperature above Tm'); The findings of this study are important to the frozen food industries in optimizing the storage and distribution conditions to minimize textural quality loss due to recrystallization.