To better reveal the formation of thawing drip, this study investigated the ice crystallization and myowater dynamics changes in frozen bovine Longissimus dorsi muscle. In ultra-fast freezing a narrow distribution of ice crystals size was observed together with higher solubility, lower surface hydrophobicity and stable second structure of myofibrillar protein. Accordingly, ultra-fast freezing samples exhibited significantly lower thaw loss (4.35 %) than slow freezing (8.22 %) after 48 h of freezing. Upon thawing, 2D T1-T2 relaxation spectra indicated a myowater redistribution, in which slow freezing led to major migration of water from immobile water to free water. Besides, T1 and T2 relaxation times showed an increasing trend with freezing process. The proton density images displayed major free water seep from myofibrils to the surface of muscle. Consequently, the water from the "reservoir" (free water) flowed into the "channel" (the widened spaces between muscle fibres), and formed into the thawing drip.
Keywords: Freeze-thaw; Freezing rate; Ice crystallization; Myowater migration; Thaw loss.
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