Pre-rigor salmon fillets were superchilled in an impingement freezer and stored at -1.7 +/- 0.3 degrees C for 29 days. The objective of this work was to study the ice crystal sizes in red muscle of pre-rigor salmon fillets that were partially frozen at fast (-30 degrees C, 227 W/m(2) K, 2.1 min) which is referred to as process F and slow (-20 degrees C, 153 W/m(2) K, 4.2 min) which is referred to as process S during superchilled storage. It was observed that the size of intracellular ice crystals in pre-rigor muscles at faster superchilling rate was significantly (p < 0.05) smaller than that at slower superchilling rate. The size of ice crystals formed in pre-rigor muscle was significant (p < 0.05) smaller than that formed in post-rigor muscle. It was also observed that the size of intracellular ice crystals formed in pre-rigor red muscles was significant smaller than that in white muscle. In addition, a large number of small ice crystals are formed within the muscle during partial freezing of pre-rigor muscle compared to post-rigor muscle. Future research should focus on tests of the quality parameters separately in red and white muscles (pre- and post-rigor) during superchilled storage of food products in order to understand more about their characteristics (quality and shelf life). (C) 2013 Elsevier Ltd. All rights reserved.