89A-9

A. M. LICEAGA GESUALDO¹, A. L. Creagh², and E. C. Y. Li-Chan¹. (1) Food, Nutrition and Health Program, The Univ. of British Columbia, 6650 NW Marine Drive, Vancouver, BC V6T 1Z4, Canada, (2) Michael Smith Laboratories, The Univ. of British Columbia, 237-6174 University Blvd, Vancouver, BC V6T 1Z3, Canada

Changes in texture and protein functional properties occur during freezing and frozen storage of fish, shortening its shelf-life. While a commercial blend of 4% sucrose with 4% sorbitol is widely used as a cryoprotectant, it can impart an undesirable sweet taste. Fish antifreeze proteins (AFPs) are known to modify and suppress ice crystal growth, making them potential alternatives to sucrose-sorbitol. However, AFPs have also been shown to induce intracellular ice formation causing cell damage. Our objective was to study the possible application of AFPs (antifreeze glycoprotein and type I AFP) as cryoprotectants for frozen fish mince. Mince from ling cod was subjected to freeze-thaw abuse in the absence (control) or presence of AFPs (5, 10, 50, or 500 ppm), AFPs (50 ppm) with 0.3% phosphates (PO), polyols (4% sucrose + 4% sorbitol or 8% trehalose), or AFPs (50 ppm) with polyols (2% sucrose + 2% sorbitol). Physicochemical properties were analyzed before and after freeze-thawing. Results showed that commercial blend was effective in retaining salt extractable proteins (%SEP) and expressible moisture (%EM) in fish mince after freeze-thawing. AFPs showed higher textural hardness, lower %SEP, and %EM compared to commercial blend, while blends of AFPs with polyols yielded intermediate results. Freeze-thawed fish mince containing AFPs formed a layer of ice crystals on the surface, which was not observed in commercial blend, trehalose or control mince. Differential scanning calorimetry showed more unbound water in mince with AFPs than in control or polyol treatments. In conclusion, AFPs did not prevent recrystallization or protein denaturation in fish mince during freeze-thawing. Compared to commercial blend and trehalose, AFPs did not impart a cryoprotective effect; and instead, allowed for more water within the mince to become frozen (unbound). This information could be useful for applications of AFPs in situations where intense ice crystallization formation is desired.

Session 89A, Aquatic Food Products: General
2:00 PM - 5:30 PM, Tuesday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana