Microstructure of fish ball without (a) and with the addition of S:S (b), trehalose (c) and inulin HD (surface) (d). Unfrozen fish ball (left image) and fish ball after 1 month frozen storage at −20 °C, subsequently thawed at room temperature before viewing at ×60 magnification (right image). Arrows refer to the cavity size on the surface of each unfrozen and frozen samples